Reduction of NOX and n2o in the exhaust gas of ship motors operated using nh3

Abstract

The invention relates to the reduction of the content of NOX and N2O in the exhaust gas of an internal combustion engine operated using NH3. The internal combustion engine is installed in a ship and is used to move the ship.

Description

__________________________________________________________________________________ Reduction of NO X and N2O in the exhaust gas of NH3-powered ship engines __________________________________________________________________________________

[0001] Priorities are claimed from European patent application No. 22216421.2, filed on December 23, 2022, and from European patent application No. 23165192.8, filed on March 29, 2023.

[0002] The invention relates to the reduction of the NO content X and N2O in the exhaust of an NH3-powered internal combustion engine. The internal combustion engine is mounted on a ship and serves to propel the ship.

[0003] Ammonia is one of the most widely produced and distributed chemicals in the world and is best known for its use as a fertilizer in agriculture. In recent years, it has sparked interest in its potential use as a high-quality energy carrier and as a carbon-free fuel in internal combustion engines (H. Kobayashi et al., Proceedings of the Combustion Institute 37 (2019) 109-133; D. Erdemir et al., Int J. Energy Res. 2021, 45, 4827-4834; C. Tornatore et al., Frontiers in Mechanical Engineering, 2022, 8, Article 944291). Its use in aircraft is also being discussed (A. Boretti et al., ACS Energy Lett. 2022, 7, 2557-2564).

[0004] Ammonia contains no carbon and has a globally available transport and storage infrastructure. It can be produced directly from renewable electricity, water, and air and is therefore currently considered a smart energy carrier and combustion fuel.

[0005] Ammonia has a comparatively low calorific value and a low flame propagation rate, and carries the risk of flame loss resulting in incomplete combustion. Furthermore, the combustion of NH3 carries the risk of increased emissions of nitrogen oxides (especially NO, NO2, N2O), which impacts its suitability as a combustion gas. Gaseous ammonia / hydrogen / air mixtures have been proposed, in which a certain proportion of hydrogen is used as a combustion accelerator, which could be generated, for example, by catalytic or heat-assisted NH3 dissociation (Ch. Lhuillier et al., 14th International Conference on Engines & Vehicles, 2019, Capri; S. Mashruk et al., Chemical Engineering Transactions, 89, 2021; S. Mashruk et al., Combustion and Flame 244 (2022) 112299).

[0006] Operating limits for ammonia-fueled spark-ignition engines were investigated. It was found that NH3 emissions in the exhaust gas decrease with increasing engine speed, with the highest values ​​being reached with a rich mixture. NH3 emissions can reach up to 1 vol.%. The NO X Emissions consist mainly of NO, and the effect of engine speed appears to depend on the equivalence ratio. Although NH3 does not produce carbon content in the exhaust, it can emit N2O, one of the most potent greenhouse gases. For both NO X as For N2O, the highest emission values ​​are also observed on the lean side, decreasing with increasing equivalence ratio. Finally, even during the combustion of pure ammonia under rich conditions, H2 is produced in the exhaust gas, indicating local decomposition of the ammonia. Exhaust temperatures were also monitored and appear to be sufficiently high for the use of NOX selective catalytic reduction (SCR) catalysts to reduce both NH3 and NOX emissions, at least below 2000 rpm (Ch. Mounaim-Rousselle et al., Energies 2021, 14, 4141).

[0007] YK Park, Chemical Engineering Journal, Volume 461, 141958, published on April 1, 2023 is a review on the catalytic removal of nitrogen oxides (NO, NO2, N2O) from exhaust gas generated when ammonia is used as a fuel.

[0008] JP 2023026798A, published on March 1, 2023, relates to an exhaust gas processing system of an ammonia engine, comprising as a first catalyst an oxidation catalyst comprising a catalyst layer containing Pt and zeolite, and as a second catalyst a denitration catalyst comprising a catalyst layer containing zeolite ion-exchanged with Cu, Co or Fe ions.

[0009] WO 2011 / 136034 relates to an NH3-burning internal combustion engine having an exhaust gas purification catalyst capable of purifying NH3 and NOX in the exhaust gas, and a flow gas control unit capable of controlling the ratio of NH3 to NOX in the exhaust gas flowing into the exhaust gas purification catalyst.

[0010] US 2003 / 0143142 A1 and US 2017 / 0334722 A1 describe processes for reducing the NOX concentration and the N2O concentration of the residual gas from nitric acid production.

[0011] US 2022 / 0323905 A1 relates to an emissions treatment system for NOX reduction in an exhaust stream of an ammonia-fueled engine, wherein the emissions treatment system comprises a selective catalytic reduction catalyst (SCR catalyst) arranged on a substrate in fluid communication with the exhaust stream, a noble metal-containing oxidation catalyst arranged on a substrate arranged either upstream or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst, and optionally one or more adsorption components arranged on a substrate arranged upstream and / or downstream of the SCR catalyst and in fluid communication with the exhaust stream and the SCR catalyst, wherein the adsorption component is selected from low-temperature NOX adsorbers (LT-NA), low-temperature ammonia adsorbers (LT-AA),Low-temperature water vapor adsorbers (LT-WA) and combinations thereof.

[0012] CN 114412668 A relates to ammonia fuel engines, in particular to an ammonia-hydrogen fusion type hybrid energy system and engine.

[0013] CN 115773169 A relates to an ammonia-fueled marine engine system and an exhaust aftertreatment system therefor. The device comprises a nitrous oxide reactor, a denitrification oxide reactor, an ammonia oxidation catalyst reactor, and a discharge system arranged sequentially.

[0014] CN 116877253 A relates to a device for purifying the exhaust gas of a marine engine with a high ammonia-diesel ratio and a method for purifying the exhaust gas of a marine engine with a high ammonia-diesel ratio.

[0015] Current research focuses on optimizing ammonia combustion itself, particularly with regard to energy yield and economic efficiency, but also with regard to the formation of undesirable nitrogen oxides. However, it is assumed that the formation of NOx (i.e., NO and NO2) and N2O during the combustion process cannot be completely suppressed.

[0016] However, emissions of NOX, N2O, and possibly other components that may be present in combustion gases (e.g., CO, HCN) must be avoided or at least reduced as much as possible to protect the environment and the climate. Many industrialized countries have therefore issued corresponding regulations.

[0017] In addition, the combustion of hydrocarbons (CH4, natural gas, etc.) in the presence of NH3 produces exhaust gases that may contain hydrogen cyanide (HCN, hydrogen cyanide). Even small amounts of HCN are problematic because it is classified as highly toxic, and correspondingly low limits for HCN emissions into the environment must be observed. Exhaust gases contaminated with HCN can, in principle, be purified using various measures. Cyanides can be formed and separated through alkaline scrubbing, but these, in turn, must then be disposed of as highly toxic compounds. Using special oxidation catalysts based on precious metals, HCN can be converted to CO2, H2O, N2, and various nitrogen oxides. However, this entails considerable processing and cost expenditure. The resulting nitrogen oxides must be broken down in a further process step, e.g., using SCR. Passing the cyanide through special catalysts, e.g.,based on TiO2, for the hydrolysis of HCN according to HCN + H2O. CO + NH3 is described. In this case, further oxidation using appropriate separate oxidation catalysts is also necessary. Therefore, there is a need for purification processes for HCN-contaminated exhaust gases that are characterized by simple and cost-effective operation and low equipment (cost). Furthermore, these processes should convert HCN into non-toxic substances that do not require further treatment.

[0018] Another problem is the incomplete combustion of ammonia, which means that the exhaust gases of internal combustion engines powered by ammonia as fuel can contain significant amounts of unburned ammonia (so-called NH3 slip, NH3 breakthrough). Acceptable limits for ammonia release into the atmosphere are comparatively strict. Therefore, in such cases, it must be ensured that ammonia is oxidized to nitrogen before the exhaust gas is released into the atmosphere. So-called ammonia slip catalysts (ASCs) have been developed for this purpose. These are usually based on precious metals from the platinum group (i.e., Ru, Rh, Pd, Os, Ir, Pt). Such catalysts are not only cost-intensive, but also not very selective (i.e., they may convert NH3 into NOX or N2O) and are susceptible to chlorine and chlorine compounds, which are particularly unavoidable in shipping. For example, the air taken in for combustion always contains a certain amount of sea salt, which is present in the atmosphere as an aerosol.

[0019] There is a need for measures which are suitable for - at least partially removing nitrogen oxides (in particular N2O and NOX (i.e. NO and NO2)), - any excess NH3 which may be present, and - any other environmentally harmful components of the exhaust gases (such as CO or HCN) which are or may be contained in the exhaust gases of internal combustion engines powered by NH3 as a result of combustion, so that the exhaust gases can then be released into the ambient air in compliance with all environmental regulations.

[0020] The internal combustion engines, preferably reciprocating piston engines, should be able to be used as marine engines and therefore be compatible with the special conditions of shipping.

[0021] In this context, the special circumstances resulting from the most efficient combustion of NH3 for powering internal combustion engines must be taken into account. In addition to the varying composition of the exhaust gas, key parameters include, in particular, the pressure and temperature of the exhaust gas. These parameters can differ significantly from those of other exhaust gases for which measures to eliminate NOX and N2O have been developed to date.

[0022] For example, in the industrial production of nitric acid, NH3 is deliberately oxidized to NOx, which is then converted into nitric acid by reaction with water in an absorption tower. Special catalysts made of precious metals are used for the oxidation, and the reaction often takes place at elevated pressure. The goal of NH3 combustion is to achieve the highest possible NOx yield, and typical water contents in the exhaust gas range from approximately 1 to 3 vol%.

[0023] In contrast, during combustion to drive internal combustion engines, NH3 is preferably only oxidized to the stage of N2, for which no catalysts are usually necessary, and where, for example, if the internal combustion engine is a reciprocating piston engine, this conversion usually takes place at comparatively high pressure, whereby in the case of a reciprocating piston engine according to the compression ignition principle, maximum cylinder internal pressures in the range of 20 to 100 bar are typically reached before or during the combustion process. The aim of the combustion is to lowest possible yield of NO Xand N2O. Typical water contents in exhaust gases are well above 3 vol.%. For example, the combustion of pure NH3 in air with a residual oxygen content of 3 mol% produces more than 28 mol% water. The primary goal of NH3 combustion is to generate energy. Low nitrogen oxide levels in the exhaust gases formed during combustion are advantageous because only a comparatively small exhaust gas treatment system is required to reduce the nitrogen oxide content in the flue gas and thus meet official regulations regarding permissible emissions, and because only then can sufficiently low residual concentrations be achieved using known nitrogen oxide reduction processes.

[0024] In contrast to conventional exhaust gas treatment systems, such as those used for exhaust gases from plants for the production of HNO3, the combustion of NH3 according to the invention, preferably in a mixture with H2, entails special features that require special measures.

[0025] On the one hand, the comparatively low pressure of the exhaust gas stream, typically no more than 5 bar, and on the other hand, the very high water content are crucial. Low pressure means that when using conventional catalyst beds based on beds of particulate shaped bodies, etc., the pressure losses could potentially be too great. The high water content, due to the hydrothermal stress on the catalysts in the exhaust gas treatment system, particularly in the case of zeolite material, combined with a simultaneous high temperature, may lead to progressive deactivation of the catalysts. The maximum temperature should therefore be limited. Apart from aging, the chemical reduction of NOX is hardly affected by the high water content, while the removal of N2O by decomposition and / or chemical reduction is significantly impaired by the high water content.

[0026] A further difference between the exhaust gases to be treated according to the invention compared to the production of HNO3 is the relatively high NOX content, which can amount to several thousand ppmv. The NOX content depends on the conditions of the combustion of NH3, in particular on the NH3 content, any other combustible gases present (H2 and / or CH4 (natural gas)) and the air ratio λ. Due to the high temperatures during combustion of up to 1000°C and more, the NOX is initially present almost exclusively as NO, i.e. with a very high proportion of NO and a very low proportion of NO2. Even with preferential cooling, only a small proportion of the NO is converted into NO2 due to the slow formation kinetics of NO2 at high temperatures. This means that the oxidation degree (β) of the NO X , ie the molar fraction of NO2 in the total NO X(β = n (NO2) / (n (NO) + n (NO2)), is small when the exhaust gas enters the exhaust gas treatment system, typically <5 vol.%. This in turn means that the desired selective catalytic NO X -reduction can actually only take place very poorly or slowly, corresponding to the slow so-called normal SCR.

[0027] These are fundamental differences to the established exhaust gas purification in HNO3 plants, in which the N2O and NO X containing residual gas under an overpressure of mostly 4-10 bar after leaving the absorption tower from a “cold” state (the thermodynamic NO X -equilibrium lies almost entirely on the side of NO2) is gradually heated. Thus, the NO X -Oxidation degree of residual gases in HNO3 production before entering the corresponding exhaust gas treatment plant is typically between 30 and 70 vol.%, ie close to the ideal stoichiometric ratio for NO X-Reduction according to the very fast SCR.

[0028] The high NO X content, combined with a very low NO X The high degree of oxidation and high water content combined with a low operating pressure (near atmospheric pressure) pose particular challenges to the effectiveness of the exhaust gas treatment system according to the invention. Added to this is the challenge and necessity of removing the N2O also present in the exhaust gas, which cannot be reduced using conventional SCR processes based on V2O5 / TiO2 catalysts.

[0029] The objectives and the reaction products obtained during the combustion of NH3 therefore sometimes differ considerably.

[0030] In conventional plants for the production of nitric acid, the exhaust gas often has, at comparatively high pressure, - a comparatively low NOX content; - a comparatively high NO2 content; - a comparatively high N2O content; - a comparatively low water content; and - possibly no unburned NH3 content (NH3 slip).

[0031] In contrast, in internal combustion engines the exhaust gas often has, at comparatively low pressure, - a comparatively high NOX content; - a comparatively low NO2 content; - a comparatively low N2O content; - a significantly higher water content; - possibly a not insignificant proportion of unburned NH3 (NH3 slip); and - possibly a not negligible proportion of HCN, if NH3 is burned together with CH4 (natural gas).

[0032] These special circumstances must be taken into account when removing NO Xand N2O from the exhaust gases, which represents a particular challenge.

[0033] Further challenges in the removal of NO X and N2O from exhaust gases, compared to existing industrial plants, so-called stationary plants, arise from the use of NH3-powered internal combustion engines in ships. These systems are therefore not permanently installed and operated at one location, but rather are mobile. However, mobile systems have special requirements, for example, with regard to weight, size, safety, resistance to vibrations, etc. In addition, the operating mode of internal combustion engines can sometimes change spontaneously, for example, when switching from partial load to full load, such as during brief acceleration or deceleration. This also presents a particular challenge for the removal of NO X and N2O from the exhaust gases.

[0034] It is an object of the invention to reduce the content of NOX (i.e. NO and NO2), N2O and optionally NH3, CO and / or HCN in exhaust gases which arise from internal combustion engines powered by NH3. This should be possible in an economical manner and enable optimal utilization of NH3. Catalysts based on platinum group metals should be avoided if possible. Furthermore, the exhaust gas treatment according to the invention should be suitable for a wide range of combustion fuel-air ratios, i.e. from very lean (relatively high content of N2O, comparatively low content of NOX, comparatively low NH3 slip) to close to stoichiometric (relatively low content of N2O, comparatively high content of NOX, comparatively pronounced NH3 slip).This is intended to achieve the best possible fuel utilization under a wide range of conditions, including the advantageous use of broken-through fuel.

[0035] This problem is solved by the subject matter of the patent claims.

[0036] The invention relates to a device comprising (i) an internal combustion engine which is configured to be driven by the combustion of NH3 and which is mounted in a ship and configured to move the ship; and (ii) an exhaust gas treatment system which is configured to reduce the content of NOX and N2O in an exhaust gas which is generated by the combustion of the NH3 in the internal combustion engine and which comprises N2, H2O, NOX and N2O; wherein the exhaust gas treatment system comprises - an N2O decomposition catalyst which is configured to decompose N2O; and / or an N2O reduction catalyst which is configured to chemically reduce N2O with a reducing agent; and - a NO X -Reduction catalyst, which is used for the chemical reduction of NO X configured with reducing agent includes.

[0037] The invention also relates to a method for reducing the NO content Xand N2O in the exhaust gas of an NH3-powered internal combustion engine which is mounted in a ship and serves to move the ship, the method comprising the following steps: (a) burning NH3 (optionally in a mixture with one or more other combustible gases, such as H2, CH4, etc.) to drive the internal combustion engine to produce an exhaust gas which comprises N2, H2O, NOX and N2O and optionally HCN and which leaves the internal combustion engine; (b) transferring the exhaust gas from the internal combustion engine to an exhaust gas treatment system; (c) reducing the N2O content in the exhaust gas by (c1) decomposition of N2O on an N2O decomposition catalyst and / or (c2) chemical reduction of N2O with reducing agent on an N2O reduction catalyst; and (d) reducing the NOX content in the exhaust gas by chemically reducing NOX with a reducing agent on a NOX reduction catalyst.

[0038] The order of steps (c) and (d) is arbitrary; according to the invention, all possibilities are encompassed, from sequentially in any order to simultaneous or mixed forms thereof.

[0039] It was surprisingly discovered that broken-through fuel (NH3 slip) can be advantageously utilized in the exhaust gas treatment system as a reducing agent for the chemical reduction of NOX and, if necessary, also of N2O. This advantageously reduces the amount of NH3 that may need to be oxidized to keep its emissions low, thus increasing fuel utilization.

[0040] The exhaust gas treatment system according to the invention comprises at least - an N2O reduction catalyst and / or an N2O decomposition catalyst; and - a NOX reduction catalyst; which may be identical or different depending on the given functionality or multiple functionality and may be present in common or separate reaction zones (catalyst beds).

[0041] In preferred embodiments, the exhaust gas treatment system according to the invention comprises - a N2O reduction catalyst; - a N2O decomposition catalyst; and - a NO X -reduction catalyst; which may be the same or different depending on the given functionality or multiple functionality and may be present in common or separate reaction zones (catalyst beds).

[0042] In preferred embodiments, the exhaust gas treatment system according to the invention additionally comprises at least one further catalyst or fulfills one of the above-mentioned N2O reduction, N2O decomposition or NO X -reduction catalyst at least one further functionality selected from - NH3 oxidation catalyst; - HCN degradation catalyst; and - CO oxidation catalyst.

[0043] The NH3 oxidation catalyst is preferably used when the proportion of unburned NH3 in the exhaust gas (NH3 slip) is greater than the demand for NH3 as a reducing agent for NO X and / or the N2O in the exhaust gas treatment system, so that after passing through steps (c1) and / or (c2) and (d), the exhaust gas still contains residual amounts of NH3, which should not or must not be released into the environment. These residual amounts of NH3 can then be broken down by oxidation of NH3 with the help of the downstream NH3 oxidation catalyst.

[0044] The HCN degradation catalyst is preferably used when the fuel contains hydrocarbons (CH4, natural gas, etc.) in addition to NH3, and the exhaust gas formed during combustion contains certain amounts of HCN. The resulting HCN can then be degraded (removed) with the help of the HCN degradation catalyst by hydrolysis of the HCN and oxidation of the resulting hydrolysis products (hydrolysates), i.e., NH3 and CO, with NOX and N2O, preferably contained in the exhaust gas.

[0045] It was surprisingly found that HCN in water-containing exhaust gases, which simultaneously contain NOX and N2O in a molar amount that is greater than or equal to the molar amount of HCN, can be degraded to N2, H2O and CO2 by passing the exhaust gas over a zeolitic catalyst loaded with transition metals, e.g. a pack of catalyst pellets containing an iron-loaded zeolitic material of the structure type BEA, at temperatures of 300 to 600°C (preferably 350 to 550°C).

[0046] In contrast to known processes, this method allows complete removal of HCN, i.e. conversion into non-toxic substances, in a single step without the need for expensive precious metal catalysts. To remove excess NOX and N2O levels, NH3 can be added to the exhaust gas containing HCN, NOX and N2O to reduce the NOX and N2O, and if necessary CO or hydrocarbons such as CH4 or propane can be added to reduce the N2O. In this case, the amount of reducing agent is to be calculated according to the molar input amounts of N2O and NOX, each reduced by the molar amount of HCN contained in the exhaust gas. If the exhaust gas contains excess N2O, which is to be reduced with NH3 or CO or hydrocarbon, the NOX content must in any case be reduced to zero (or close to zero) using NH3.If CO or hydrocarbons are used as additional reducing agents, an additional CO oxidation catalyst may be used downstream of the zeolite catalyst to eliminate any CO emissions.

[0047] The CO oxidation catalyst is preferably used when (i) hydrocarbons (CH4, natural gas, etc.) are used as reducing agents for N2O; and / or (ii) an HCN degradation catalyst is used to degrade HCN, the degradation products of which contain CO. The Any CO that may be produced can then be broken down into CO2 by oxidation using the downstream CO oxidation catalyst.

[0048] If the exhaust gas treatment system according to the invention comprises an NH3 oxidation catalyst, it may be preferable according to the invention to initially adjust the exhaust gas within the exhaust gas treatment system using a temperature control device to a different temperature than at the inlet to the exhaust gas treatment system, so that the NH3 oxidation catalyst can optimally develop its effect. In preferred embodiments, the exhaust gas treatment system according to the invention therefore additionally comprises one or more temperature control devices.

[0049] For the purpose of description, "and / or" means either "or" or "and", so that, for example, "A and / or B" has the following three meanings: (i) only A but not B, (ii) only B but not A, and (iii) both A and B.

[0050] For the purpose of description, "NOX" includes nitric oxide (NO) and nitrogen dioxide (NO2), but not nitrous oxide (N2O).

[0051] Catalysts accelerate certain chemical reactions by lowering their activation energies.

[0052] The device according to the invention is configured to carry out the method according to the invention. All preferred embodiments of the method according to the invention, which are described with reference to steps (a), (b), (c1), (c2), and (d), also apply analogously to the device configured according to the invention or to its parts that are configured to carry out these steps. Thus, the internal combustion engine according to the invention is configured to carry out step (a), and the exhaust gas treatment system according to the invention is configured to carry out steps (c1) and / or (c2) and (d).The exhaust gas treatment system is also configured to treat the exhaust gas generated in the internal combustion engine, in particular to reduce the N2O content in the exhaust gas and the NOX content in the exhaust gas, so that the device according to the invention is also configured to carry out step (b); the internal combustion engine and the exhaust gas treatment system are configured, in particular connected to one another in such a way that the exhaust gas generated in the internal combustion engine is transferred to the exhaust gas treatment system.

[0053] Unless expressly stated otherwise, all data in ppm are by volume, i.e., ppmv. Unless expressly stated otherwise, all percentages with respect to the gas composition are by volume, i.e., vol%. Unless expressly stated otherwise, all other percentages are by weight, i.e., wt%.

[0054] Steps (a) and (b) of the method according to the invention are carried out successively in alphabetical order, followed by steps (c) and (d) in basically any order, or the device according to the invention is configured accordingly. Step (c) can therefore be carried out before step (d). or after step (d) or simultaneously with step (d). Mixed forms of partial simultaneity are also possible. This can be particularly relevant when one and the same catalyst material is capable of catalyzing several reactions. Such embodiments are particularly preferred according to the invention. These reactions then optionally take place simultaneously according to the invention, although the kinetics of the respective reactions can vary, so that a first reaction can be completed earlier or have achieved a higher conversion than a second reaction running in parallel. Consequently, the N2O decomposition catalyst and / or the N2O reduction catalyst can be arranged upstream or downstream of the NO X-reduction catalyst, whereby mixed forms can be realized by one and the same catalytically active material catalyzing several of these reactions simultaneously.

[0055] Step (c1) or the decomposition of N2O on an N2O decomposition catalyst and step (c2) or the chemical reduction of N2O with reducing agent on an N2O reduction catalyst are considered separately for the purpose of description, but both serve the common purpose of reducing the N2O content in the exhaust gas.

[0056] Steps (c1), (c2) and (d) can also be carried out in any order, whereby mixed forms of partial simultaneity are also possible in this regard.

[0057] In preferred embodiments, the method according to the invention comprises steps (a), (b), (c1) and (d); steps (a), (b), (c2) and (d); or steps (a), (b), (c1), (c2) and (d), or the device according to the invention is configured accordingly.

[0058] In preferred embodiments, the exhaust gas passes through the steps of the method according to the invention or the correspondingly configured parts of the device configured according to the invention in one of the following sequences: (i) (a) → (b) → (c1) → (d); (ii) (a) → (b) → (d) → (c2); (iii) (a) → (b) → (d) → (c2) → (c1); (iv) (a) → (b) → (d) → (c1+c2); or (v) (a) → (b) → (d) → (c1).

[0059] In this case, (c1+c2) means that both step (c1) and step (c2) are carried out, wherein the execution of these two steps (c1) and (c2) takes place at least partly simultaneously, ie both steps run in parallel, or the device according to the invention is configured accordingly.

[0060] Between these steps, further steps not explicitly mentioned may occur.

[0061] It has surprisingly been found that NH3-fuelled internal combustion engines can be advantageously operated in a state which results in a comparatively low degree of NH3 slip (NH3 breakthrough) from the internal combustion engine into the exhaust gas. This can be achieved by increasing the air ratio λ can be achieved, which is then typically accompanied by an increase in the concentration of NO X and / or N2O in the exhaust gas. When using pure ammonia as fuel, it is expected that the NO X-formation, depending on the air ratio λ, has a maximum in the lean range (at approximately an equivalence ratio = 1 / l=0.8). If λ is lower, the oxygen supply limits the formation of NOX. If λ is higher, the combustion temperature limits the formation of NOX and instead the N2O content can increase. If the air ratio is increased, NH3 slip still occurs, but not to such a great extent. With this type of operation of the internal combustion engines, excess NH3 can be effectively oxidized by using NH3 oxidation catalysts, preferably oxidation-active zeolite catalysts. NH3 oxidation catalysts containing precious metals, in particular NH3 oxidation catalysts containing platinum group metals (i.e. Ru, Rh, Pd, Os, Ir, Pt), can thus be dispensed with, which is particularly advantageous on ships.Such NH3 oxidation catalysts are cost-intensive, show low selectivity at high NH3 concentrations (i.e., they form secondary NOX and N2O in addition to N2 during the oxidation of NH3), and are susceptible to poisoning with chlorine from sea air.

[0062] For the purposes of this description, "platinum group metal-free" means that it contains essentially no platinum group metals (i.e., Ru, Rh, Pd, Os, Ir, Pt). However, analytically detectable traces of platinum group metals are possible.

[0063] For the purposes of this description, "precious metal-free" means that it contains essentially no precious metal. However, analytically detectable traces of precious metal are possible.

[0064] The inventive utilization of NH3 as a fuel for internal combustion engines is better and the NH3 slip is lower if the mixture of air and fuel burns significantly leaner (or secondary air is fed in), which is accompanied by a higher formation of N2O and NOX.

[0065] The solution according to the invention makes it possible to operate an internal combustion engine (dual fuel) on a ship in a manner in which NH3 slip (in the quasi-stationary operating mode of the ship) can be minimized by using a lean combustion characteristic or secondary air.

[0066] If oxidation of excess NH3 is required, zeolite catalysts loaded with iron or copper and with sufficiently high NH3 oxidation activity can preferably be used according to the invention. Thus, the use of noble metal-containing NH3 oxidation catalysts, especially NH3 oxidation catalysts containing platinum group metals, is not necessary and can be excluded.

[0067] Furthermore, it was surprisingly found that the catalytic decomposition of N2O in the exhaust gas of an NH3-powered internal combustion engine can be used advantageously, in particular if the exhaust gas treatment system has two reaction zones arranged one behind the other, which each independently contain zeolite catalysts loaded with iron or copper, wherein the two reaction zones are preferably separated from each other by at least one metering / injection system for at least one reducing agent. It has been found that the first reaction zone in a NO X -rich environment, when the NH3 slip of the internal combustion engine is low, it performs a significant function as a N2O decomposition catalyst. However, when the NH3 slip is high, the first reaction zone provides additional catalyst volume for the chemical reduction of N2O and NO X and the oxidation of NH3.

[0068] In step (a) of the method according to the invention, NH3 is burned to drive an internal combustion engine, which generates heat through combustion processes, or the device according to the invention is configured accordingly. Heat is generated by burning fuels, which also drives a machine. The term includes engines for propelling ships. In the internal combustion engines, NH3 is oxidized with O2 (preferably from the air) with the aim of producing N2 and H2O as the main products.

[0069] Plants in which NH3 is oxidized with O2 with the aim of producing nitrogen compounds with higher oxidation numbers (e.g. NOX) as the main products, as is the case in the production of nitric acid, for example, are not internal combustion engines within the meaning of the invention.

[0070] The combustion of NH3 means the oxidation of NH3 with O2. According to the invention, this conversion does not have to be complete, so that the exhaust gas may contain residual, unburned (unoxidized, unconverted) NH3 (NH3 slip, NH3 breakthrough), or the device according to the invention is configured accordingly. The same applies if NH3 is not burned in its pure form, but together with other combustible gases, in particular H2 and / or CH4 (natural gas). The O2 used for combustion can be used in the form of combustion air, which may optionally be enriched with O2.

[0071] Larger amounts of NH3 slip are not preferred according to the invention because they require special measures to prevent the escape of NH3 above permissible maximum values, in particular the use of NH3 oxidation catalysts (ammonia slip catalysts, ASC), which are intended to oxidize broken-through NH3 with O2 to H2O and N2.

[0072] According to the invention, the combustion of NH3 in step (a) preferably takes place or the internal combustion engine is configured such that the exhaust gas has an NH3 content of at most 35,000 ppmv; preferably at most 30,000 ppmv, more preferably at most 25,000 ppmv, even more preferably at most 20,000 ppmv, most preferably at most 15,000 ppmv, and in particular at most 10,000 ppmv.

[0073] According to the invention, the combustion of NH3 preferably takes place in step (a) or the internal combustion engine is configured such that the exhaust gas has an NH3 content of at most 9000 ppmv; preferably at most 8000 ppmv, more preferably at most 7000 ppmv, even more preferably at most 6000 ppmv, most preferably at most 5000 ppmv, and in particular at most 4000 ppmv.

[0074] According to the invention, the combustion of NH3 in step (a) preferably takes place or the internal combustion engine is configured such that the exhaust gas has an NH3 content of at most 3500 ppmv; preferably at most 3000 ppmv, more preferably at most 2500 ppmv, even more preferably at most 2000 ppmv, most preferably at most 1500 ppmv, and in particular at most 1000 ppmv.

[0075] Suitable methods for reducing NH3 slip in internal combustion engines are known to experts. In particular, NH3 slip can be achieved by increasing the air ratio λ. Such an increase in the air ratio λ may, if necessary, be accompanied by an increase in the NOX and / or N2O content in the exhaust gas of the internal combustion engine. However, this can be accepted according to the invention because, with a favorable ratio of NH3 to NOX and possibly also to N2O, broken-through NH3 serves as a reducing agent for the chemical reduction of NOX and possibly also N2O, so that all of these gases can be broken down simultaneously in the exhaust gas treatment system and the gas leaving the exhaust gas treatment system contains only very small and harmless amounts of NH3, NOX and N2O.

[0076] Preferably, the internal combustion engine is configured such that the exhaust gas has a molar ratio of NH3:NOX of at most 5.0; preferably at most 4.5, more preferably at most 4.0, even more preferably at most 3.5, most preferably at most 3.0, and in particular at most 2.5.

[0077] Preferably, the internal combustion engine is configured such that the exhaust gas has a molar ratio of NH3:NOX of at most 2.3; preferably at most 2.1, more preferably at most 1.9, even more preferably at most 1.7, most preferably at most 1.5, and in particular at most 1.3.

[0078] According to the invention, the combustion of NH3 preferably takes place in a mixture with H2 or fossil fuels, e.g. CH4, or the device according to the invention is configured accordingly.

[0079] In step (a) of the method according to the invention, NH3 is burned to drive an internal combustion engine, or the device according to the invention is configured accordingly.

[0080] "Internal combustion engines" (heat engines) within the meaning of the invention are in particular combustion engines, preferably piston heat engines with internal combustion, such as reciprocating piston engines or rotary piston engines.

[0081] Preferably, the internal combustion engine comprises a reciprocating piston engine or is a reciprocating piston engine, each preferably with compression ignition. Step (b)

[0082] In step (b) of the method according to the invention, the exhaust gas is transferred to an exhaust gas treatment system, ie from the internal combustion engine to an exhaust gas treatment system, or the The device according to the invention is configured accordingly. Steps (c) and (d) of the method according to the invention take place in the exhaust gas treatment system according to the invention, or the device according to the invention is configured accordingly. For this purpose, the exhaust gas treatment system is equipped with the N2O decomposition catalyst for the decomposition of N2O according to step (c1) and / or with the N2O reduction catalyst for the chemical reduction of N2O with a reducing agent according to step (c2), as well as with the NOX reduction catalyst for the chemical reduction of NOX with a reducing agent according to step (d).

[0083] If the exhaust gas treatment system according to the invention additionally comprises at least one further catalyst or one of the aforementioned N2O reduction, N2O decomposition or NOX reduction catalysts fulfills at least one further functionality, at least one of the following steps (e1) to (e4 is preferably additionally carried out in the exhaust gas treatment system according to the invention: (e1) tempering the exhaust gas in at least one tempering device, which is preferably arranged within the exhaust gas treatment system; preferably upstream of the NH3 oxidation catalyst in the flow direction of the exhaust gas; (e2) reducing the NH3 content in the exhaust gas by oxidation with an oxidizing agent on an NH3 oxidation catalyst; wherein the oxidizing agent preferably comprises O2; (e3) reducing the HCN content in the exhaust gas by hydrolysis and oxidation of the hydrolysates with an oxidizing agent on an HCN degradation catalyst;wherein the oxidizing agent preferably comprises NOX and / or N2O; and (e4) reducing the CO content in the exhaust gas by chemical oxidation with an oxidizing agent on a CO oxidation catalyst; wherein the oxidizing agent preferably comprises O2. Step (c);

[0084] In step (c) of the process according to the invention, the N2O content in the exhaust gas is reduced, or the device according to the invention is configured accordingly. This can be achieved by decomposing N2O on an N2O decomposition catalyst according to step (c1) and / or chemically reducing N2O with a reducing agent on an N2O reduction catalyst according to step (c2).

[0085] During the decomposition of N2O, N2 and O2 are formed according to the following overall reaction: 2 N2O → 2 N2 + 1 O2.

[0086] Decomposition of N2O therefore means decomposition into N2 and O2. A "N2O decomposition catalyst" within the meaning of the invention catalyzes the decomposition of N2O. The achievable reduction of N2O by catalytic decomposition depends not only on the type, ie the chemical nature and physical design of the N2O decomposition catalyst and the prevailing pressure and temperature conditions, but also, above all, on the selected space velocity, ie the ratio of exhaust gas volume flow to the catalyst volume. However, the catalytic activity of an N2O decomposition catalyst does not have to be limited exclusively to this reaction. It is therefore entirely possible and, according to the invention, also preferred for the N2O decomposition catalyst to also catalyze other reactions, for example, the chemical reduction of N2O and / or the chemical reduction of NOX. Whether such further reactions actually take place depends on the conditions of the individual case, in particular the type of catalyst, and the kinetics of any parallel processes, for example, the presence or amount of the reducing agent and the presence or amount of other reactants.

[0087] During the chemical reduction of N2O with a reducing agent, different reaction products are formed depending on the reducing agent.

[0088] In the case of the reducing agent NH3 which is preferred according to the invention, N2 and H2O in particular are formed during the chemical reduction of N2O, e.g. according to: 3 N2O + 2 NH3 → 4 N2 + 3 H2O or 4 N2O + 4 NH3 + O2 → 6 N2 + 6 H2O or also in the joint reduction with NO according to 2 NO + N2O + 2 NH3 → 3 N2 + 3 H2O.

[0089] In the case of hydrocarbons, which are also preferred as reducing agents according to the invention, in particular CO and H2O are formed during the chemical reduction of N2O, e.g. according to (2n+1) N2O + CnH2n+2 → (2n+1) N2 + n CO + (n+1) H2O or also CO2 and H2O according to 4n N2O + CnH2n+2 → 4n N2 + n CO2 + 2n H2O.

[0090] According to the invention, CO is also preferred as a reducing agent. It can react further with N2O to form CO2, e.g., according to: N2O + CO → N2 + CO2.

[0091] An "N2O reduction catalyst" within the meaning of the invention catalyzes the chemical reduction of N2O with a reducing agent. However, the catalytic activity of an N2O reduction catalyst does not have to be limited exclusively to this reaction. Thus, it is entirely possible and, according to the invention, also preferred for the N2O reduction catalyst to also catalyze other reactions, for example, the decomposition of N2O and / or the chemical reduction of NOx. Whether such further reactions actually occur depends on the conditions of the individual case, in particular the type of catalyst, and the kinetics of any parallel processes, for example, the presence or amount of the reducing agent and the presence or amount of other reactants. Step (d)

[0092] In step (d) of the process according to the invention, the NO content is reduced Xin the exhaust gas by chemical reduction of NO X with reducing agent on a NO X -reduction catalyst, or the device according to the invention is configured accordingly.

[0093] Preference is given to such NO X -Reduction catalysts, which, if possible, enable the selective catalytic reduction (SCR) of the nitrogen oxides contained in the exhaust gas, in particular NO X enable, ie the NOX reduction catalysts primarily catalyze the oxidation of NH3 with NOX and not or secondarily the oxidation of NH3 with free oxygen (O2) possibly present in the exhaust gas.

[0094] In the chemical reduction of NO XWith reducing agents, different reaction products are formed depending on the reducing agent. In the case of the reducing agent NH3, which is preferred according to the invention, N2 and H2O in particular are formed during the chemical reduction of NOX, depending on the type of NOX reduction catalyst and the ratio of NO to NO2, e.g., according to: 4 NH3 + 2 NO + 2 NO2 → 4 N2 + 6 H2O (so-called fast SCR) 4 NH3 + 4 NO + O2 → 4 N2 + 6 H2O (so-called normal SCR) 8 NH3 + 6 NO2 → 7 N2 + 12 H2O (so-called NO2 SCR).

[0095] The joint selective catalytic reduction is called so-called fast SCR and is generally much faster than the so-called normal SCR or NO2 SCR.

[0096] A "NOX reduction catalyst" within the meaning of the invention catalyzes the chemical reduction of NOX with a reducing agent. However, the catalytic activity of a NOX reduction catalyst does not have to be limited exclusively to this reaction. Thus, it is entirely possible and, according to the invention, also preferred for the NOX reduction catalyst to also catalyze other reactions, for example, the decomposition of N2O, the chemical reduction of N2O and / or the establishment of the NOX equilibrium, or even the selective oxidation of excess NH3 with free O2. Whether such further reactions actually occur depends on the conditions of the individual case and the kinetics of any parallel processes, for example, the presence or amount of the reducing agent and the presence or amount of other reactants. Catalysts

[0097] N2O decomposition catalysts are known per se, and a wide variety of substance classes can be used. Preferred N2O decomposition catalysts are those that exhibit high catalytic activity for the decomposition of N2O into N2 and O2, for example, in the temperature range of 350 to 600°C.

[0098] Preferred examples of N2O decomposition catalysts according to the invention are metal-loaded zeolite catalysts, for example zeolite catalysts loaded with copper or cobalt or, in particular, with iron, noble metal catalysts, or transition metal oxide catalysts, such as catalysts containing cobalt oxide. Examples of suitable catalysts are described, inter alia, by Kapteijn et al. in Appl. Cat. B: Environmental 9 (1996), 25-64, in US-A-5,171,553, in Actes du 2ieme Congres International sur la Catalyse, Technip, Paris 1961, 1937-1953, and in WO-A-01 / 58,570. When iron-loaded zeolite catalysts are used in the first catalyst bed, the NO still present in the gas accelerates. X As expected, the desired N2O decomposition is achieved by an activating effect (co-catalytic effect), as is the case for different N2O / NO X -relations were described by Kögel et al. in Catal. Comm.2 (2001) 273-276.

[0099] Further preferred examples of N2O decomposition catalysts according to the invention are catalysts whose N2O decomposition activity is significantly limited by the presence of NOX. Such N2O decomposition catalysts are also referred to as "NOX-sensitive N2O decomposition catalysts" for the purposes of this description. These catalysts contain one or more catalytically active compounds of elements selected from groups 5 to 11 of the Periodic Table of Elements (PSE). Particular preference is given to compounds of the elements from groups 9 to 11 of the PSE. Of these, compounds of the elements Co, Pt, Pd, Ir, Rh, Ni and / or Cu are in turn preferred, preferably Co, Rh, Ni and / or Cu, and in particular Co or Rh.Preferably, the N2O decomposition catalyst is based on noble metals, which are preferably supported on refractory oxides, or on mixtures of transition metal oxides, in particular mixed oxides or simple transition metal oxides, in each case either supported or preferably as unsupported catalysts.

[0100] The catalytically active compounds themselves can be metallic and / or oxide compounds, the latter being present either as singular oxides or as binary, ternary, or polynary mixed oxides of various structural types, such as perovskites or spinels. Such compounds are described, for example, in Catalysis Letters 35 (1995) 372-382, Applied Catalysis 73 (1991) 165-171, Catal. Rev.-Sci. Eng.; 34(4), 409-425 (1992), or Actes du 2ieme Congres International sur la Catalyse 97 (1961) 1937-1953. Mixtures of various catalytically active compounds can also be used. Examples of particularly preferred catalytically active compounds are metallic rhodium, rhodium oxides such as RhO2 or Rh2O3, CoO, Co2O3, Co-containing spinels such as Co3O4, CuxCo3-xO4 or Co-containing perovskites such as LaCoO3 or Co-containing perovskites substituted on A and B sites.

[0101] The catalytically active compounds can be contained in the catalysts in pure form or applied to or mixed with suitable support materials. In the first case These are so-called full catalysts, which, in addition to active compounds, may also contain additives known to experts such as binders or other manufacturing-related additives such as plasticizers, pore formers, fiber reinforcements or pressing aids.

[0102] The methods for producing such catalysts are known to those skilled in the art. In the case of "supported catalysts," the catalytically active compounds are applied to the support material. This disperses and stabilizes the catalytically active compound against both mechanical and thermal stress. The methods for producing such catalysts are also known to those skilled in the art. The support materials are preferably refractory oxides, such as SiO2, TiO2, ZrO2, or Al2O3, or mixtures of two or more thereof, or materials that themselves exhibit a certain catalytic activity for N2O decomposition, such as MgO, zeolites, hydrotalcites, or mixtures of two or more thereof. Preference is given to using catalysts that contain no or essentially no zeolites, preferably less than 15 wt.% zeolites, in particular less than 5 wt.% zeolites.

[0103] Preferred support materials for Rh-containing compounds are ZrO2, TiO2, Al2O3, hydrotalcites, or zeolites, e.g., of the MFI structure type. These are described, for example, in Chemical Engineering and Technology 24 (2001) 281-285 or in Catalysis Today 35 (1997) 113-120. Particularly preferred supports for Rh-containing compounds are ZrO2, TiO2, and hydrotalcites. The Rh content of these catalysts is preferably 0.1 to 10 wt.%, more preferably 0.5 to 5 wt.%. Particularly preferably, Rh-containing catalysts contain CeO2 in addition to Rh. The proportion of CeO2 is preferably 5 to 50 wt.%, in particular 10 to 30 wt.%.

[0104] Preferred supports for Co-containing compounds are zeolites, or the preferred supports contain magnesium oxide. In the case of zeolites, Si-rich structural types such as MFI, BEA, FER, MEL, or MOR are particularly preferred. The preparation of such Co-doped zeolites is known to those skilled in the art. In the case of magnesium oxide supports, these can be pure MgO or MgO-containing compounds such as hydrotalcites. Such catalysts are described, for example, in Appl. Catal. B: Environmental 7 (1996) 397-406 or Appl. Catal. B: Environmental 13 (1997) 69-79.

[0105] Particularly preferred catalysts are those which essentially consist of at least one oxidic magnesium compound and at least one oxidic cobalt compound, wherein the content of oxidic cobalt compounds is in the range from 0.1 to 50 wt.% and the content of oxidic magnesium compounds is in the range from 50 to 99.9 wt.%, in each case based on the total mass of the catalyst, and at least 30 wt.% of the Co atoms present in the catalyst are in the chemically trivalent state. Such catalysts and their preparation are described in EP 1257 347 B1. Also particularly preferred when using oxidic Co compounds as the active component are catalysts with a support which consists of at least 50 wt.% MgO or of a mixed oxide which consists of at least 50 wt.% MgO, and wherein A cerium oxide functional layer is applied to the support. Such catalysts and their preparation are described in DE 102007038711 A1.

[0106] The N2O decomposition catalyst can be in the form of a shaped body of any size and geometry, preferably in geometries with a high surface-to-volume ratio and with the lowest possible pressure drop during flow. Typical geometries are all known in catalysis, such as cylinders, hollow cylinders, multi-hole cylinders, rings, granular fragments, trilobes, or honeycomb structures.

[0107] N2O reduction catalysts and NOx reduction catalysts are also known per se, and a wide variety of material classes can be used. Examples include metal-loaded zeolite catalysts, such as copper- or cobalt-loaded zeolite catalysts, or, in particular, iron-loaded zeolite catalysts, or precious metal catalysts or catalysts used in the well-known SCR (Selective Catalytic Reduction) processes.

[0108] In particularly preferred embodiments according to the invention, the exhaust gas comprises NH3, and the exhaust gas treatment system is configured to reduce the NH3 content in the exhaust gas. For this purpose, the exhaust gas treatment system preferably comprises an NH3 oxidation catalyst configured for the chemical oxidation of NH3 with O2; preferably for the chemical oxidation of NH3 with O2 to N2 and H2O.

[0109] Preferably, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOX reduction catalyst and / or the NH3 oxidation catalyst independently of one another contain a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably an iron- or copper-loaded zeolite; even more preferably, independently of one another, an iron- or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL.

[0110] Preferably, each of the N2O decomposition catalyst and / or the N2O reduction catalyst and the NOX reduction catalyst independently comprise a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably, independently of one another, an iron- or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI, and / or MEL.

[0111] These can be different catalysts or the same catalysts. Iron-loaded zeolite catalysts used particularly preferably according to the invention contain essentially, preferably > 50 wt.%, in particular > 70 wt.%, of one or more iron-loaded zeolites. For example, in addition to an Fe-ZSM-5 zeolite, another iron-containing zeolite, such as an iron-containing ferrous zeolite, can be present in the catalyst used according to the invention.

[0112] In addition, the catalyst used according to the invention may contain further additives known to those skilled in the art, such as binders.

[0113] The iron content of the preferred zeolites can be up to 25% based on the mass of zeolite, but preferably 0.1 to 10%.

[0114] The process according to the invention also includes the use of zeolites in which the lattice aluminum is partially isomorphously substituted by one or more elements, for example, by one or more elements selected from B, Be, Ga, Fe, Cu, Cr, V, As, Sb, and Bi. Likewise included is the use of zeolites in which the lattice silicon is isomorphously substituted by one or more elements, for example, by one or more elements selected from Ge, Ti, Zr, and Hf. Precise details on the composition or structure of the zeolites preferably used according to the invention are given in the Atlas of Zeolite Structure Types, Elsevier, 4th revised Edition 1996, which is hereby expressly incorporated by reference.

[0115] Zeolite catalysts that have been treated with steam ("steamed" catalysts) are very particularly preferably used in the process according to the invention. Such a treatment dealuminated the lattice of the zeolite; this treatment is known per se to those skilled in the art. These hydrothermally treated zeolite catalysts are characterized by particularly high activity in the process according to the invention. Preference is given to using hydrothermally treated zeolite catalysts that have been loaded with iron and in which the ratio of extra-lattice aluminum to lattice aluminum is at least 1:2, preferably 1:2 to 20:1. Preferred catalysts for the degradation of N2O and NOX

[0116] The N2O decomposition catalysts, N2O reduction catalysts, and NOx reduction catalysts according to the invention preferably contain, independently of one another, zeolitic materials (also referred to as "zeolites" for the purposes of the description) loaded with at least one transition metal (atomic numbers 21-30, 39-48, 57-80, 89-112) and / or with at least one lanthanide (also called "lanthanide"; atomic numbers 57-71). For the purposes of the description, transition metals and lanthanides are referred to collectively as "transition metals" for the sake of simplicity. The transition metals iron ("Fe zeolites"), copper ("Cu zeolites"), and cobalt ("Co zeolites") are preferred. Iron-loaded zeolitic materials (ie Fe-zeolites) are particularly preferred and may be loaded with or contain other transition metals in addition to iron, for example manganese, vanadium, chromium, nickel or mixtures thereof.

[0117] The zeolitic materials according to the invention preferably exhibit high hydrothermal resistance. Particular preference is given to SiO2-rich zeolites, so-called "high-silica zeolites," which have a molar ratio of [SiO2] to [AlO2] units, and thus a molar Si / Al ratio, of at least 8, preferably at least 9, more preferably at least 10, even more preferably at least 11, most preferably at least 12, and especially at least 13.

[0118] Zeolitic materials preferred according to the invention essentially have a zeolite structure of the BEA, MFI, MOR, MEL, or FER structure type, more preferably of the MFI and BEA structure type, and even more preferably of the BEA structure type. For the MFI structure type, the ZSM-5 type is particularly preferred. Further information on the designation of the structure types of zeolitic materials and their composition can be found in the Atlas of Zeolite Structure Types, Elsevier, 4th revised edition 1996.

[0119] Particularly preferred N2O decomposition, N2O reduction or NO X Reduction catalysts independently contain at least 50 wt.% Fe zeolite based on the total weight of the zeolitic material, more preferably at least 70 wt.% Fe zeolite, wherein a single structural type or multiple structural types may be present. In preferred embodiments, in addition to Fe-BEA zeolite, another Fe zeolite of a different structural type is present, preferably Fe-MOR zeolite.

[0120] The loading (doping) of the zeolitic materials with the transition metals / lanthanides can be carried out using relevant methods for loading or doping zeolites with transition metals / lanthanides, which are known to those skilled in the art. Loading is preferably carried out starting from the commercially available H form or, preferably, NH4 form of the zeolitic materials by ion exchange with corresponding salts of the transition metals, either in the aqueous phase or by solid-state reaction. The loaded zeolitic materials thus obtained are subsequently calcined, preferably in air in an oven at temperatures in the range of 400 to 650°C. After calcination, the loaded zeolitic materials are thoroughly washed in distilled water, and the filtered-off loaded zeolitic materials are then dried.The loaded zeolitic materials thus obtained are preferably admixed with suitable binders, such as aluminosilicates, boehmite, or silica sol, and optionally with auxiliaries for plasticizing or for producing slurries, and mixed. In preferred embodiments, the resulting mixtures are extruded into catalyst bodies (full catalysts) and subsequently calcined. In other preferred embodiments, the resulting mixtures are applied to catalyst supports (supported catalysts) and subsequently calcined. These methods are also known to those skilled in the art and established in many technical applications.

[0121] The N2O decomposition, N2O reduction, NOX reduction, NH3 oxidation, HCN degradation, and CO oxidation catalysts according to the invention can be present independently of one another as shaped bodies of any size and geometry, preferably in geometries that have a high surface-to-volume ratio and through which the lowest possible pressure drop is generated. Typical geometries are all geometries known in catalysis, such as cylinders, hollow cylinders, multi-hole cylinders, rings, trilobes, or star-shaped extrudates. Monolithic catalyst elements with parallel channels, e.g., monolithic honeycomb bodies, so-called "Catalytic converter honeycombs," as known, for example, from the purification or denitrification of power plant or automotive exhaust gases. Catalytic converter honeycombs, honeycomb bodies, and honeycomb modules

[0122] The exhaust gas treatment system according to the invention or the catalyst beds comprised therein preferably comprises catalyst honeycombs, preferably a plurality of catalyst honeycombs, which are arranged parallel to one another in the exhaust duct [SMD1], each with honeycomb channels aligned longitudinally to the flow direction of the exhaust gas. The geometry of the cross-sectional area of ​​the catalyst honeycombs (perpendicular to the flow direction of the exhaust gas) is, in principle, freely selectable. The catalyst honeycombs preferably have a rectangular or, in particular, square cross-sectional area, but other cross-sectional areas are also possible, in particular hexagonal, triangular, trapezoidal, etc. Suitable geometries are known to those skilled in the art. Accordingly, the term "honeycomb" is not limited to a rectangular or square cross-sectional area according to the invention.

[0123] If the exhaust gas treatment system according to the invention comprises a first reaction zone (first catalyst bed) and a second reaction zone (second catalyst bed) downstream in the flow direction of the exhaust gas, which is preferred according to the invention, the first and second reaction zones (the first and second catalyst beds) preferably have a plurality of catalyst honeycombs which are arranged parallel to one another with honeycomb channels each aligned longitudinally to the flow direction of the exhaust gas in the exhaust gas channel.

[0124] In preferred embodiments, several catalyst honeycombs, i.e., several monolithic honeycomb bodies, are combined to form a honeycomb module, preferably by a metal frame that is open in the direction of exhaust gas flow. Preferably, two, four, or six honeycomb bodies, preferably monolithic honeycomb bodies, are combined to form a honeycomb module. This modular design allows for effective utilization of the available cross-sectional area of ​​the exhaust duct and easy replacement of defective or deactivated honeycomb bodies.

[0125] The honeycomb bodies preferably have a rectangular cross-section. The rectangular cross-section preferably has a first edge length (perpendicular to the flow direction of the exhaust gas) in the range of 5 to 20 cm, more preferably 10 to 15 cm, and a second edge length (also perpendicular to the flow direction of the exhaust gas) in the range of 5 to 20 cm, preferably 10 to 15 cm. The height of a honeycomb body (flow direction of the exhaust gas) is preferably in the range of 5 to 25 cm, preferably in the range of 7.5 to 15 cm.

[0126] The so-called cell density, ie density of the channels of the catalyst honeycomb, is preferably 150 to 500 cpsi, more preferably 180 to 450 cpsi (cell per square inch).100 cpsi, ie 100 cells or honeycomb channels per square inch.

[0127] Preferably, the individual honeycomb modules are arranged one above the other in the direction of flow and stacked next to each other and fixed by appropriate holders so that the best possible use of the inflow area, i.e. cross-sectional area of ​​the exhaust duct, is achieved. Bypass flows between the individual honeycomb modules or in the outer edge region between the outer edge of the honeycomb modules and the inner wall of the exhaust duct should be avoided. For this purpose, suitable sealing materials are preferably applied between the individual honeycomb modules and between the outer honeycomb modules and the inner wall. In the case of larger wall distances, cover plates are used which are attached to the inner wall of the exhaust duct in the direction of flow in front of and / or behind the packing of the honeycomb modules. The cover plates are preferably covered with seals at the contact points with the honeycomb modules.Preferably, the honeycomb modules are arranged and sized so that the usable inflow area of ​​the catalyst is preferably at least 60% of the inner cross-sectional area of ​​the exhaust duct, more preferably at least 70%, even more preferably at least 80%.

[0128] In circular exhaust ducts or exhaust pipes, the gaps created in the edge area of ​​the honeycomb module packing, unless they can easily be filled with rectangular honeycomb modules, are preferably not filled with specially cut honeycomb modules, but rather closed with blanking plates. This has the advantage that when replacing used honeycomb modules, only standardized honeycomb modules need to be replaced, and no special adaptations are required.

[0129] When using exhaust pipes, individual, larger honeycomb bodies with a circular inflow cross-section adapted to the pipe cross-section can also be used. In a preferred embodiment, several of these bodies can also be arranged one behind the other in the flow direction. In this case, it is not necessary to arrange several honeycomb bodies parallel to one another.

[0130] In preferred embodiments, the honeycomb bodies or honeycomb modules are arranged in the flow direction of the exhaust gas in a plurality of layers offset along the longitudinal axis. The honeycomb bodies or honeycomb modules are preferably arranged in 2 to 5 layers, particularly preferably in 2 to 3 layers. A distance is preferably provided between the layers, i.e. between the end faces of the honeycomb bodies or honeycomb modules, preferably in the range of 3 to 30 mm, more preferably 4 to 20 mm. The distance can enable intermediate, in particular radial, mixing of the gas stream emerging from a first layer of the honeycomb bodies or honeycomb modules. Furthermore, it can be prevented that a possible slippage of unreacted reducing agent and / or of its not yet fully oxidized reaction products from the first layer of the honeycomb bodies propagates into a subsequent, second layer of the honeycomb bodies.

[0131] The supply and distribution of reducing agents for NO X and if necessary N2O is preferred via a multiply branched piping system provided with a plurality of openings or nozzles, which is arranged in the exhaust duct or in the exhaust line in the flow direction upstream of the respective catalyst bed, preferably the packing of the catalyst honeycombs as honeycomb bodies or honeycomb body modules.

[0132] The distribution pipes are preferably designed in the form of grids or in the form of concentrically connected circles, which extend as far as possible over the cross-sectional area of ​​the exhaust gas duct or the inflow area of ​​the catalyst bed.

[0133] The specific design and dimensioning of these distributors, including suitable outlet nozzles, is part of the expertise in catalytic exhaust gas purification technology and is widely used, for example, in the exhaust gas purification of coal-fired power plants. NH3 oxidation catalyst

[0134] NH3 oxidation catalysts are known to experts.

[0135] The NH3 oxidation catalyst is preferably platinum group metal-free, more preferably noble metal-free.

[0136] For the purposes of this description, "platinum group metal-free" means that it contains essentially no platinum group metals (i.e., Ru, Rh, Pd, Os, Ir, Pt). However, analytically detectable traces of platinum group metals may be present. For the purposes of this description, "precious metal-free" means that it contains essentially no precious metals. However, analytically detectable traces of precious metals may be present.

[0137] The NH3 oxidation catalyst is preferably an iron- or copper-loaded zeolite; preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structural type (hereinafter referred to as "NH3 oxidation-active, iron- or copper-loaded zeolite catalyst").

[0138] Preferred platinum group metal-free NH3 oxidation catalysts are selected from transition metal oxides (e.g. of Fe, Mn, Cu, Cr, Co, Ni ...), metal-loaded zeolites, e.g. described in Handbook of Heterogeneous Catalysis, Wiley-VCH, Edited by Ertl, Knötzinger, Schüth, Weitkamp, ​​2nd Ed. 2008, Volume 5, Chapter 11.5 "Solid Catalysts for the Oxidation of Volatile Organic Compounds".

[0139] Preferred NH3 oxidation catalysts include - cobalt-containing catalysts; in particular Co3O4; mixed oxides derived from Co3O4 (Co 3-y M yO4), which preferably crystallize like Co3O4 in the spinel structure, where M is preferably selected from Zn, Cu, Fe, Mn and V; cobalt-loaded zeolites, preferably of the structure type MFI, BEA, FER, Mor, FAU, CHA, or AFI; - manganese-containing catalysts, especially MnO X with x = 1-2; of MnO X derived mixed oxides (Mn x-y M y O x ), where M is preferably selected from Zn, Cu, Fe and Mn; manganese-loaded zeolites, preferably of the structural type MFI, BEA, FER, Mor, FAU, CHA or AFI; - copper-containing catalysts; in particular CuO X with x = 0.5-1; of CuO Xderived mixed oxides (Cux-yMyOx), where M is preferably selected from Zn, Co, Fe and Mn; copper-loaded zeolites, preferably of the structure type MFI, BEA, FER, Mor, FAU, CHA, AFI; - silver-containing catalysts; in particular supported, preferably supported on Al2O3, TiO2, or SiO2, more preferably e.g. X% Ag / TiO2, X% Ag / Al2O3, or X% Ag / SiO2, each with X=1-10.

[0140] In preferred embodiments, the device according to the invention contains no further NH3 oxidation catalyst besides the iron or copper loaded zeolite.

[0141] In preferred embodiments, the NH3 oxidation catalyst, preferably the NH3 oxidation-active, iron-loaded zeolite catalyst, has a molar ratio of iron to zeolitic aluminum n(Fe) / n(Al) of less than 0.50 to greater than 0.05; preferably less than 0.40 to greater than 0.05, more preferably less than 0.25 to greater than 0.05, even more preferably less than 0.15 to greater than 0.05.

[0142] In preferred embodiments, the NH3 oxidation catalyst, preferably the NH3 oxidation-active, copper-loaded zeolite catalyst, has a molar ratio of copper to zeolitic aluminum n(Cu) / n(Al) of less than 1.00 to greater than 0.10; preferably less than 0.80 to greater than 0.10, more preferably less than 0.50 to greater than 0.10, even more preferably less than 0.30 to greater than 0.10.

[0143] Surprisingly, it was found that iron- or copper-loaded zeolites, in which only a part of the potentially available cation sites are occupied by Fe or Cu ions, so that the remaining cation sites are essentially saturated by protons, exhibit a significantly increased activity for the oxidation of NH3 with free oxygen.

[0144] The ratio of iron or copper to zeolitic aluminum can be adjusted by selecting the Al content during the synthesis of the zeolitic material, in particular by the proportions of the selected Si and Al starting materials, as well as by the subsequent loading with iron or copper ions.

[0145] In the synthesis of zeolites, the selected Si and Al starting materials are usually heated in alkaline solution, often under elevated pressure, which causes crystallization to form the microporous aluminosilicates, the zeolites, composed of three-dimensionally linked AlO2 and SiO2 units. By carefully selecting the synthesis conditions, for example, by adding structure-directing reagents such as organic cations, not only the Si / Al ratio and thus the Al content, but also the structural type of the zeolite can be specifically adjusted or controlled. The synthesis methods are industrially established. Zeolites of various structural types with different Si / Al ratios and loaded with different cations, e.g., in Na or NH4 form, are commercially available.

[0146] Using suitable methods known to those skilled in the art, such as liquid-phase or solid-state ion exchange, the cations contained in the zeolite, such as NH4+, can be specifically exchanged for other cations, such as iron or copper ions (J. Weitkamp, ​​L. Puppe, Catalysis and Zeolites – Fundamental and Applications, Springer-Verlag Berlin Heidelberg New York, 1999 or Kucherov, AV Slinkin, A. a.: Solid state reactions as a method of introducing transition metals cations into high-silica zeolites, Russ. Chem. Rev. 1992, Vol. 61, No. 9, pp. 925-943). If all of the negative charges generated by the AlO2 units are compensated by cations, the so-called degree of exchange is 100%.

[0147] The exact Al content of the zeolitic material or the catalyst moldings produced from it, as well as the Fe content, can be determined by X-ray fluorescence analysis (XRF). This is conveniently performed according to DIN EN 169-2 (Section 5) after determining the loss on ignition and after lithium tetraborate digestion.

[0148] If the Al content of the underlying zeolitic material is to be subsequently determined on the finished molded body, it must be noted that the molded body may also contain Al-based binder components that cannot be distinguished from zeolitic Al by XRF. In this case, an additional investigation of the molded body is required, e.g., using 27Al solid-state NMR, which allows differentiation between the Al bound in the zeolite structure and the extra-lattice Al. Details on the principles, implementation, and evaluation of such investigations are known to experts (J. Weitkamp, ​​L. Puppe, Catalysis and Zeolites – Fundamental and Applications, Springer-Verlag Berlin Heidelberg New York, 1999, Chapter 4.2 (NMR Spectroscopy; especially sections 4.2.4.1( 29 Si MAS NMR Spectroscopy of SiO4 Tetrahedra in the Zeolite Framework) and 4.3.4.2 ( 27 Al NMR Spectroscopy of Framework and Non-Framework Aluminum in Zeolites)).

[0149] Preferably, the NH3 oxidation catalyst, preferably the NH3 oxidation-active, iron-loaded zeolite catalyst, has a total iron content (expressed as the mass content of Fe2O3) of less than 10.0 wt.% to greater than 2.0 wt.%, preferably of less than 7.0 wt.% to greater than 2.0 wt.%, more preferably of less than 5.0 wt.% to greater than 2.0 wt.% and even more preferably of less than 4.0 wt.% to greater than 2.0 wt.%.

[0150] The NH3 oxidation catalyst, preferably the NH3 oxidation-active, copper-loaded zeolite catalyst, preferably has a total copper content (expressed as mass content of Cu2O) of less than 9.0 wt.% to greater than 1.5 wt.%; preferably of less than 6.5 wt.% to greater than 1.5 wt.%, more preferably of less than 4.5 wt.% to greater than 1.5 wt.%, and even more preferably of less than 3.5 wt.% to greater than 1.5 wt.%.

[0151] In preferred embodiments, the NH3 oxidation catalyst, preferably the NH3 oxidation-active zeolite catalyst loaded with iron or copper, is configured for the selective oxidation of NH3 with O2 to N2 and H2O, and when filled as a particulate bed, the particles of which have a Equivalent diameter of 3.5 to 5.5 mm, which is defined as the diameter of a spherical particle of the same volume, and wherein the ratio of the outer, geometrically detectable surface of the particles to the volume of the particulate bed is 1000 m2 / m3 to 1500 m2 / m3, in an amount of 8.0±0.5 mL in an isothermally operated, axially flowing tubular reactor with an inner diameter of 20±3 mm, subjected to a volume flow of a gas mixture consisting of 500±50 ppmv NH3, 2.5±0.1 vol% O2 and 0.30±0.05 vol% H2O in N2 at a space velocity of 10,000±500 h-1 based on standard conditions (0°C; 1.01325 bara), a total pressure of 6±0.5 bara and a temperature of 380°C±5 K an NH3 conversion of at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80%, in particular at least 90%.

[0152] In preferred embodiments, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOX reduction catalyst and / or the NH3 oxidation catalyst independently of one another have a honeycomb-shaped monolithic structure.

[0153] In preferred embodiments, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOX reduction catalyst and / or the NH3 oxidation catalyst independently of one another have a honeycomb-shaped monolithic structure.

[0154] The N2O decomposition catalyst and / or the N2O reduction catalyst as well as the NOX reduction catalyst preferably each independently comprise transition metal-loaded zeolites, more preferably each iron-loaded zeolites (Fe zeolites), even more preferably each iron-loaded zeolites of the same structural type, most preferably with the same external shape (e.g. honeycomb or pellet).

[0155] In preferred embodiments, the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material.

[0156] In preferred embodiments, the N2O decomposition catalyst and the NOX reduction catalyst are made of the same material.

[0157] In preferred embodiments, the N2O reduction catalyst and the NOX reduction catalyst are made of the same material.

[0158] In preferred embodiments, the N2O decomposition catalyst, the N2O reduction catalyst and the NO X -Reduction catalyst made of the same material.

[0159] In preferred embodiments, the NH3 oxidation catalyst and the N2O decomposition catalyst are made of the same material.

[0160] In preferred embodiments, the NH3 oxidation catalyst and the N2O reduction catalyst are made of the same material.

[0161] In preferred embodiments, the NH3 oxidation catalyst and the NO X -Reduction catalyst made of the same material.

[0162] In preferred embodiments, the NH3 oxidation catalyst, the NO X -reduction catalyst and the N2O decomposition catalyst made of the same material.

[0163] In step (a) of the method according to the invention, NH3 is combusted to drive an internal combustion engine, or the device according to the invention is configured accordingly. During combustion, an exhaust gas is generated which comprises N2, H2O, NOX, and N2O, preferably also NH3. The exhaust gas leaves the internal combustion engine and is subsequently fed to step (b) of the method according to the invention, or the device according to the invention is configured accordingly.

[0164] Preferably, the internal combustion engine, which is preferably a reciprocating piston engine, comprises a compression ignition.

[0165] The internal combustion engine preferably comprises a turbocharger comprising a turbocompressor and an exhaust gas turbine. Preferably, all components of the exhaust gas treatment system are arranged upstream of the exhaust gas turbine in the direction of exhaust gas flow.

[0166] Preferably, the internal combustion engine comprises an exhaust gas recirculation (EGR) system.

[0167] Preferably, in step (a) or in the internal combustion engine configured according to the invention, the combustion of NH3, ie the oxidation of NH3 with O2 (or the mixture of NH3 with another combustible gas, such as H2, CH4, etc.), does not take place on a catalyst, ie the combustion is not carried out in the presence of a heterogeneous catalyst.

[0168] In preferred embodiments, the internal combustion engine is an ammonia dual-fuel engine.

[0169] In preferred embodiments, in step (a) or in the internal combustion engine configured according to the invention, the combustion of NH3 takes place in a mixture with one or more other combustible gases, ie both NH3 and at least one other combustible gas are oxidized with O2.

[0170] In preferred embodiments, the additional combustible gas is a fossil fuel.

[0171] In preferred embodiments, the further combustible gas is selected from hydrocarbons and hydrocarbon mixtures, preferably methane, ethane, propane, butane, natural gas, gasoline and / or diesel.

[0172] In preferred embodiments, the further combustible gas is selected from alcohols, preferably methanol and / or ethanol.

[0173] In other preferred embodiments, the further combustible gas is H2.

[0174] Particularly preferred is the additional combustible gas H2, which is formed by thermal and / or catalytic cracking of NH3. The integrated combustion of NH3 with O2 preferably provides the energy for cracking. Therefore, in step (a) or in the internal combustion engine configured according to the invention, the combustion of NH3 is preferably integrated into a process for thermal and / or catalytic cracking of NH3 into N2 and H2.

[0175] The device according to the invention preferably comprises a cracking device for the thermal and / or catalytic cracking of NH3. The cracking device and the internal combustion engine are preferably configured such that the combustion of NH3 in the internal combustion engine provides the energy for the cracking of NH3 in the cracking device. The cracking device and the internal combustion engine are preferably configured such that the cracking of NH3 in the cracking device provides the additional combustible gas for combustion in a mixture with NH3 in the internal combustion engine.

[0176] Preferably, the splitting device is arranged in the flow direction of NH3 downstream of an NH3 reservoir and upstream of an NH3 injection of the internal combustion engine.

[0177] In particularly preferred embodiments, step (a) of the process according to the invention comprises the substeps, or the internal combustion engine according to the invention is configured for this: (a1) thermal and / or catalytic cracking of NH3 to produce a cracked gas comprising N2, H2, and optionally residual NH3; (a2) optionally, mixing the cracked gas with further NH3 to produce a mixture comprising H2 and NH3; (a3) ​​combustion of the cracked gas or the mixture.

[0178] Suitable processes for the thermal and / or catalytic decomposition of NH3 into N2 and H2 are known to those skilled in the art. Suitable catalysts for the decomposition of NH3 into N2 and H2 include, for example, Ru supported on Al2O3 or SiO2, Fe, Co, Ni, Cu, or Ru supported on MgAl2O4, or Co3Mo3N (A. Boisen et al., Journal of Catalysis 230 (2005) 309-312; I. Lucentini et al., Ind. Eng. Chem. Res. 2021, 60, 18560-18611; HJ Lee et al., Catalysts 2022, 12, 1203).

[0179] If the fission in sub-step (a1) is incomplete, the fission gas (i.e., the fission product) contains, in addition to N2 and H2, residual, unreacted NH3. This results in a mixture of NH3 and H2, which can either be burned directly as such or first enriched with additional NH3 in the optional sub-step (a2).

[0180] When the fission in sub-step (a1) is complete, the required amount of NH3 must be added to the fission gas in step (a2).

[0181] Preferably, by sub-step (a1) and optional sub-step (a2) a mixing ratio of NH3 and H2 is set, which is optimized with regard to the subsequent combustion The proportion of H2 is preferably at most 80 mol%, more preferably at most 70 mol%, even more preferably at most 60 mol%, most preferably at most 50 mol%, and in particular at most 40 mol%. The proportion of H2 is preferably at least 10 mol%, more preferably at least 20 mol%, even more preferably at least 30 mol%, most preferably at least 40 mol%, and in particular at least 50 mol%, or the device according to the invention is configured accordingly.

[0182] In particularly preferred embodiments, the molar ratio of H2:NH3 in the mixture is in the range from 45:55 to 90:10, preferably 50:50 to 85:15, more preferably 55:45 to 80:20, even more preferably 60:40 to 75:25, most preferably 65:35 to 70:30, or the device according to the invention is configured accordingly.

[0183] In sub-step (a3), the mixture is burned, typically with air. In preferred embodiments, the air ratio λ for the combustion in sub-step (a3) ​​is in the range from 0.9 to 1.7, preferably 1.05 to 1.7, more preferably 1.0 to 1.6, even more preferably 1.1 to 1.5, most preferably 1.2 to 1.4, or the device according to the invention is configured accordingly.

[0184] Preferably, the internal combustion engine is configured such that the air ratio λ during combustion is at least 1.05; preferably at least 1.10, more preferably at least 1.15, even more preferably at least 1.20, most preferably at least 1.25, and in particular at least 1.20.

[0185] Preferably, the internal combustion engine is configured such that the air ratio λ during combustion is at least 1.25; preferably at least 1.30, more preferably at least 1.35, even more preferably at least 1.40, most preferably at least 1.45, and in particular at least 1.50.

[0186] The air / fuel ratio λ (i.e., the combustion air ratio) indicates the mass ratio of air to fuel relative to the stoichiometrically ideal ratio for a theoretically complete combustion process. It is defined as the ratio of air to fuel that contains a sufficient mass of oxygen to achieve complete combustion of a given mass of fuel (see, for example, K. Soman, Thermal Engineering, PHI, 2011, page 224, no. 5.4.2). In principle, the ratio can be expressed in terms of mass or quantity of substance (see, for example, P. Majumdar, Design of Thermal Energy Systems, Wiley 2021, page 66, no. 2.13.5.2). For descriptive purposes, the ratio is mass. If a combustion process uses another oxygen-containing gas instead of air, "air" should strictly be replaced by "oxygen carrier." However, the parameter λ is still used in the above definition.

[0187] In preferred embodiments, the equivalence ratio NH3 / H2(Φ) (not to be confused with the inverse of the air ratio 1 / λ) is in the range from 0.55 to 1.40, more preferably 1.05 to 1.20, or the device according to the invention is configured accordingly.

[0188] In other preferred embodiments, in step (a) or in the internal combustion engine configured according to the invention, the combustion of NH3 alone takes place, ie NH3 is the only combustible gas that is burned.

[0189] Preferably, the internal combustion engine is configured such that the combustion of NH3 accounts for at least 90% of the total energy obtained; preferably at least 95%, more preferably at least 96%, even more preferably at least 97%, most preferably at least 98%, and in particular at least 99%.

[0190] The internal combustion engine is mounted in a ship and is used to move the ship.

[0191] In preferred embodiments, the exhaust gas has a content of NO X which is greater than the N2O content, or the device according to the invention is configured accordingly. Preferably, the NOX content is at least twice as high, more preferably at least three times as high, even more preferably at least four times as high, most preferably at least seven times as high, and in particular at least ten times as high as the N2O content, or the device according to the invention is configured accordingly. Preferably, the molar ratio of NOX:N2O is more than 10:1, more preferably at least 20:1, even more preferably at least 30:1, most preferably at least 40:1, and in particular at least 50:1.

[0192] In preferred embodiments, the exhaust gas has a NO content that is greater than the N2O content, or the device according to the invention is configured accordingly. Preferably, the NO content is at least twice as high, more preferably at least three times as high, even more preferably at least four times as high, most preferably at least seven times as high, and in particular at least ten times as high as the N2O content, or the device according to the invention is configured accordingly.

[0193] In preferred embodiments, the exhaust gas has a NO2 content that is greater than the N2O content, or the device according to the invention is configured accordingly. Preferably, the NO2 content is at least twice as high, more preferably at least three times as high, even more preferably at least four times as high, most preferably at least seven times as high, and in particular at least ten times as high as the N2O content, or the device according to the invention is configured accordingly.

[0194] The exhaust gas preferably has a NOX content of at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 30 ppmv, even more preferably at least 40 ppmv, and in particular at least 50 ppmv, or the device according to the invention is configured accordingly.

[0195] Preferably, the exhaust gas has a content of NO Xof at least 75 ppmv, preferably at least 100 ppmv, more preferably at least 150 ppmv, even more preferably at least 200 ppmv, and in particular at least 250 ppmv, or the device according to the invention is configured accordingly.

[0196] Preferably, exhaust gas contains NO X of at least 500 ppmv, preferably at least 1000 ppmv, more preferably at least 2000 ppmv, even more preferably at least 3000 ppmv, and in particular at least 3500 ppmv, or the device according to the invention is configured accordingly.

[0197] The exhaust gas preferably has an N2O content of at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 30 ppmv, even more preferably at least 40 ppmv, and in particular at least 50 ppmv, or the device according to the invention is configured accordingly.

[0198] The exhaust gas preferably has an N2O content of at least 75 ppmv, preferably at least 100 ppmv, more preferably at least 150 ppmv, even more preferably at least 200 ppmv, and in particular at least 250 ppmv, or the device according to the invention is configured accordingly.

[0199] Preferred exhaust gases have a NOX content in the range of 1500 to 3000 ppmv, preferably 2000 to 3000 ppmv, and a N2O content in the range of 20 to 100 ppmv, or the device according to the invention is configured accordingly.

[0200] In preferred embodiments, the exhaust gas has an H2O content of more than 4.0 vol.%; preferably at least 5.0 vol.%, more preferably at least 6.0 vol.%, even more preferably at least 7.0 vol.%, most preferably at least 8.0 vol.%, and in particular at least 9.0 vol.%, or the device according to the invention is configured accordingly.

[0201] In further preferred embodiments, the exhaust gas has an H2O content of at least 10 vol.%; preferably at least 12 vol.%, more preferably at least 14 vol.%, even more preferably at least 16 vol.%, most preferably at least 18 vol.%, and in particular at least 20 vol.%, or the device according to the invention is configured accordingly.

[0202] In preferred embodiments, the exhaust gas has an H2O content in the range of 10±8 vol.%; preferably in the range of 10±7 vol.%, more preferably in the range of 10±6 vol.%, even more preferably in the range of 10±5 vol.%, most preferably in the range of 10±4 vol.%, and in particular in the range of 10±3 vol.%, or the device according to the invention is configured accordingly.

[0203] In preferred embodiments, the exhaust gas has an H2O content in the range of 15±8 vol.%; preferably in the range of 15±7 vol.%, more preferably in the range of 15±6 vol.%, even more preferably in the range of 15±5 vol.%, most preferably in the range of 15±4 vol.%, and in particular in the range of 15±3 vol.%, or the device according to the invention is configured accordingly.

[0204] In preferred embodiments, the exhaust gas has a H2O content in the range of 20±8 vol.%; preferably in the range of 20±7 vol.%, more preferably in the range of 20±6 vol.%, still more preferably in the range of 20±5 vol.%, most preferably in the range of 20±4 vol.%, and in particular in the range of 20±3 vol.%, or the device according to the invention is configured accordingly.

[0205] In preferred embodiments, the exhaust gas has an H2O content in the range of 25±8 vol.%; preferably in the range of 25±7 vol.%, more preferably in the range of 25±6 vol.%, even more preferably in the range of 25±5 vol.%, most preferably in the range of 25±4 vol.%, and in particular in the range of 25±3 vol.%, or the device according to the invention is configured accordingly.

[0206] In preferred embodiments, the exhaust gas has an H2O content in the range of 30±8 vol.%; preferably in the range of 30±7 vol.%, more preferably in the range of 30±6 vol.%, even more preferably in the range of 30±5 vol.%, most preferably in the range of 30±4 vol.%, and in particular in the range of 30±3 vol.%, or the device according to the invention is configured accordingly.

[0207] Preferably, the exhaust gas has an N2 content of at most 95 vol.%, preferably at most 90 vol.%, more preferably at most 85 vol.%, even more preferably at most 80 vol.%, most preferably at most 75 vol.%, and in particular at most 70 vol.%, or the device according to the invention is configured accordingly.

[0208] The exhaust gas preferably has an N2 content of at least 40 vol.%, preferably at least 50 vol.%, more preferably at least 60 vol.%, even more preferably at least 70 vol.%, most preferably at least 80 vol.%, and in particular at least 90 vol.%, or the device according to the invention is configured accordingly.

[0209] The exhaust gas preferably comprises further gaseous components; preferably selected from the group consisting of O2, CO, CO2, NH3, CH4 and mixtures thereof, or the device according to the invention is configured accordingly.

[0210] Preferably, the exhaust gas comprises NH3, or the device according to the invention is configured accordingly

[0211] Preferably, the exhaust gas has a temperature in the range of 250 to 450°C when leaving the internal combustion engine, or the device according to the invention is configured accordingly.

[0212] Preferably, the exhaust gas is cooled after leaving the internal combustion engine during the process according to the invention, whereby steps (c1) and / or (c2) and / or (d) can introduce new heat, or the device according to the invention is configured accordingly. Preferred variants of combinations of steps (c) and (d):

[0213] In preferred embodiments, steps (c1) and / or (c2) and / or (d) of the process according to the invention are carried out at different temperatures, ie at different temperature levels, wherein a step carried out earlier in time or upstream in the flow direction of the exhaust gas preferably takes place at a higher temperature than a step carried out later in time or downstream in the flow direction of the exhaust gas, or the device according to the invention is configured accordingly.

[0214] Preferably, the exhaust gas has a pressure of at most 5.0 bar upon leaving the internal combustion engine; preferably 2.5 to 4.0 bar, or the device according to the invention is configured accordingly.

[0215] Preferably, the exhaust gas upon leaving the internal combustion engine has an oxidation level of NOX of at least 10%, more preferably at least 20%, even more preferably at least 30%, most preferably at least 40%, and in particular at least 50%, or the device according to the invention is configured accordingly.

[0216] Preferably, the exhaust gas upon leaving the internal combustion engine has an oxidation level of NOX of at most 90%, more preferably at most 80%, even more preferably at most 70%, most preferably at most 60%, and in particular at most 50%, or the device according to the invention is configured accordingly.

[0217] Preferably, the exhaust gas leaving the internal combustion engine has an O2 content of less than 2.0 vol.%, or the device according to the invention is configured accordingly.

[0218] Preferably, the exhaust gas leaving the internal combustion engine has an O2 content of more than 4.0 vol.%, or the device according to the invention is configured accordingly.

[0219] In step (b) of the method according to the invention, the exhaust gas which has left the internal combustion engine is transferred to an exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0220] This can be achieved, for example, through pipelines connecting the exhaust gas treatment system's outlet to the exhaust gas treatment system's inlet. Since the method according to the invention is preferably carried out at atmospheric pressure, or the device according to the invention is configured accordingly, such pipelines typically do not have to meet any special requirements with regard to possible pressure stress.

[0221] However, the pipes should be able to withstand the temperatures that the exhaust gas reaches when leaving the internal combustion engine or when entering the exhaust gas treatment system.

[0222] In preferred embodiments, the temperature of the exhaust gas is measured at the outlet of the internal combustion engine and, if necessary, changed using suitable devices so that the exhaust gas has a temperature upon entering the exhaust gas treatment system which, under the given conditions, for carrying out steps (c) and (d) of the method according to the invention within the exhaust gas treatment system is optimized, or the device according to the invention is configured accordingly. The optimized temperature depends in particular on the type of catalyst materials used for the N2O decomposition catalyst and / or N2O reduction catalyst as well as the NO X-reduction catalyst. The optimized temperature depends on the selected design of steps (c) and (d), ie on the type and sequence of the individual process steps for N2O reduction and NO X -reduction and in particular according to the type of catalyst materials used for the N2O decomposition catalyst and / or N2O reduction catalyst as well as the NO X -reduction catalyst.

[0223] Suitable devices for changing the temperature of the exhaust gas are known to those skilled in the art and include, in particular, heat exchangers, which can be designed, for example, as plate heat exchangers or tube heat exchangers.

[0224] In order to avoid heat losses, it may be preferable according to the invention to choose the distance from the outlet of the internal combustion engine to the inlet into the exhaust gas treatment system as short as possible and in this way to achieve a compact design.

[0225] Depending on the type of catalyst used, however, the steps may not be completely separable from one another, neither spatially nor temporally. If a catalyst used is suitable for catalyzing several of steps (c1), (c2) and (d) at the same time, these steps may occur simultaneously and / or sequentially. In the flow direction of the exhaust gas, individual segments of one and the same catalyst can be considered, through which the exhaust gas flows one after the other and on which different reactions may dominate. Which reaction dominates in which segment depends in particular on the respective reaction kinetics, the local temperature and the local concentrations of the reactants, possibly including the concentration of reducing agent and possibly including the concentration of co-catalytically active species.

[0226] The exhaust gas treatment system according to the invention serves in particular to carry out steps (c) and (d) of the method according to the invention, or the device according to the invention is configured accordingly. However, it is also possible for further steps to be carried out within the exhaust gas treatment system in addition to steps (c) and (d), and for chemical reactions to take place, or for the device according to the invention to be configured accordingly.

[0227] This preferably relates to the installation of a catalyst bed arranged downstream in the flow direction of the exhaust gas for the oxidation of incompletely converted reducing agents or their incompletely oxidized reaction products, e.g. for the oxidation of NH3 (NH3 oxidation catalyst) or CO (CO oxidation catalyst; when using hydrocarbons as reducing agents). In such embodiments, the exhaust gas is preferably cooled before it is the downstream catalyst bed is introduced, ie the oxidation of NH3 and / or CO preferably takes place at a lower temperature than steps (c) and (d).

[0228] When carrying out steps (c) and (d) of the process according to the invention, there are various preferred variants of the process according to the invention, which may differ from one another with regard to the sequence of the reactions taking place, the catalysts used, the reducing agents used, the space velocities and other reaction conditions.

[0229] In preferred embodiments, these reactions are carried out in a common reaction zone (catalyst bed) which is equipped upstream with a device for metering reducing agent into the exhaust gas.

[0230] In other preferred embodiments, these reactions are carried out in two successively arranged, separate reaction zones (catalyst beds), of which preferably at least one reaction zone, and preferably both reaction zones, are equipped independently of one another upstream with a device for metering reducing agent into the exhaust gas. The exhaust gas then flows first through the first reaction zone and subsequently through the second reaction zone.

[0231] Particularly preferred variants / embodiments comprise [a] (c2) the chemical reduction of N2O with NH3 and (d) the chemical reduction of NOX with NH3, preferably together in one reaction zone; [b] (c2) the chemical reduction of N2O with hydrocarbon (CH4, natural gas, etc.) and (d) the chemical reduction of NOX with NH3, preferably together in one reaction zone; [c] (c1) the decomposition of N2O and (d) the chemical reduction of NOX with NH3, preferably together in one reaction zone; [d] (c1) the decomposition of N2O and (c2) the chemical reduction of N2O with NH3 and (d) the chemical reduction of NOX with NH3, preferably together in one reaction zone; [e] (c1) the decomposition of N2O and (c2) the chemical reduction of N2O with hydrocarbon (CH4, natural gas, etc.) and (d) the chemical reduction of NOX with NH3, preferably together in one reaction zone; [f] (c1) the decomposition of N2O, preferably in a first reaction zone; and subsequently (d) the chemical reduction of NO. X with NH3, preferably in a second reaction zone; [g] (c1) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (c2) the chemical reduction of residual N2O with NH3 and (d) the chemical reduction of NO X with NH3, preferably in a second reaction zone; [h] (c1) the incomplete decomposition of N2O, preferably in a first reaction zone; followed by (c2) the chemical reduction of residual N2O with hydrocarbon (CH4, natural gas, etc.) and (d) the chemical reduction of NO Xwith NH3, preferably in a second reaction zone; [i] (c1) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (c1*) the decomposition of residual N2O and (d) the chemical reduction of NOX with NH3, preferably in a second reaction zone; [j] (c1) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (c1*) the decomposition of residual N2O and (c2) the chemical reduction of residual N2O with NH3(d) and the chemical reduction of NO Xwith NH3, preferably in a second reaction zone; [k] (c1) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (c1*) the decomposition of residual N2O and (c2) the chemical reduction of residual N2O with hydrocarbon (CH4, natural gas, etc.).) and (d) the chemical reduction of NOX with NH3, preferably in a second reaction zone; [l] (d) the incomplete chemical reduction of NOX, preferably in a first reaction zone; and subsequently (c1) the decomposition of N2O and (d*) the chemical reduction of residual NOX with NH3, preferably in a second reaction zone; [m] (d) the incomplete chemical reduction of NOX, preferably in a first reaction zone; and subsequently (c1) the decomposition of N2O and (c2) the chemical reduction of N2O with NH3 and (d*) the chemical reduction of residual NOX with NH3, preferably in a second reaction zone; or [n] (d) the incomplete chemical reduction of NOX, preferably in a first reaction zone; and subsequently (c1) the decomposition of N2O and (c2) the chemical reduction of N2O with hydrocarbon (CH4, natural gas, etc.) and (d*) the chemical reduction of residual NOX with NH3, preferably in a second reaction zone.

[0232] However, this does not mean that the explicitly mentioned reactions must be the only reactions that take place in the respective reaction zone. Depending on the catalyst used, it is rather preferred according to the invention that additional reactions also take place simultaneously, which are not explicitly mentioned but can proceed in parallel. The explicitly mentioned reactions are therefore only those reactions that at least take place in the respective variant / embodiment.

[0233] If NO X , N2O and NH3 are present in the mixture and the catalyst used enables both the chemical reduction of NO X with NH3 as well as the chemical reduction of N2O with NH3, is the chemical reduction of NO Xwith NH3 is typically significantly faster than the chemical reduction of N2O with NH3. If the catalyst used also catalyzes the decomposition of N2O, the decomposition of N2O is typically superimposed on the chemical reduction of N2O with NH3, whereby the extent of the chemical reduction of N2O can be increased by increasing the amount of NH3 added.

[0234] For the purpose of description, "*" indicates a process sub-step which was previously only incompletely carried out in a similar process sub-step, whereby the process sub-step marked with "*" subsequently continues the previously only incompletely carried out process sub-step, possibly however in a different reaction zone or a different catalyst bed. As with all other process steps, unless expressly stated otherwise, the result achieved at the end of all process sub-steps is not quantitatively determined. Thus, if, for example, NOX is incompletely chemically reduced in a first process sub-step (d), the fact that process sub-step (d*) is subsequently carried out does not necessarily require that the total amount of NOX must have been completely chemically reduced at the end of process sub-step (d*), i.e., down to 0.0 ppmv.Rather, it is quite possible that a residual amount of NOX is still present at the end of process step (d*).

[0235] The exhaust gas treatment system includes at least one injection point for reducing agents. The exhaust gas treatment system may include multiple injection points for reducing agents.

[0236] The method of introducing the reducing agent into the exhaust gas stream to be treated is freely configurable according to the invention, as long as this occurs upstream of the N2O reduction catalyst or NOX reduction catalyst. The reducing agent can be introduced in the form of a gas or a liquid or aqueous solution that evaporates in the exhaust gas stream to be treated. The feed occurs through a suitable device, such as a corresponding pressure valve or appropriately designed nozzles, which opens into a mixer for the exhaust gas stream to be treated and the supplied reducing agent. When using different reducing agents for NOX and N2O, the feed and introduction into the exhaust gas can occur separately or together.

[0237] When the catalyst beds are designed as a packing of catalyst honeycombs or honeycomb modules, the supply and distribution of the reducing agents for NO Xand optionally N2O to the one or more reaction zones (catalyst beds), preferably via a multiply branched pipeline system provided with a plurality of openings or nozzles, which is arranged in the flow direction of the exhaust gas upstream of the respective reaction zone (catalyst bed), ie the packing of the catalyst honeycombs or honeycomb modules.

[0238] The distributors are preferably designed in the form of grids or concentrically connected circles, which extend as far as possible over the cross-sectional area of ​​the exhaust gas duct or the inflow area of ​​the reaction zone (catalyst bed).

[0239] The specific design and dimensioning of these distributors, including suitable outlet nozzles, is part of the specialist knowledge in catalytic exhaust gas purification technology and is widely used, for example, in the exhaust gas purification of coal-fired power plants.

[0240] The exhaust gas treatment system according to the invention can comprise a single reaction zone. In this case, the catalyst used in this single reaction zone serves as an N2O decomposition catalyst and / or N2O reduction catalyst as well as a NOX reduction catalyst. In this case, steps (c) and (d) of the process according to the invention take place essentially simultaneously within this reaction zone, or the device according to the invention is configured accordingly. However, it should be noted that the kinetics of the individual reactions can vary considerably. For example, depending on the catalyst material used, the chemical reduction of NOX with NH3 as the reducing agent can occur significantly faster than the chemical reduction of N2O with NH3.If NOX and N2O are present in the mixture and NH3 is fed in as a reducing agent, different reactions take place in the front section of the single reaction zone than in the rear section of the single reaction zone. Due to the faster kinetics, the chemical reduction of NOX predominantly occurs in the front section, and the chemical reduction of N2O only occurs in the rear section, once the majority of the NOX has been removed.

[0241] Alternatively, the exhaust gas treatment system can comprise multiple reaction zones, which is preferred according to the invention. If multiple reaction zones are included, they are preferably arranged one behind the other, i.e., the exhaust gas flows through them successively, first through the first reaction zone, then through the second reaction zone, and optionally subsequently through the third reaction zone, or the device according to the invention is configured accordingly.

[0242] In preferred embodiments, the reaction zones are each spatially separated catalyst beds.

[0243] In preferred embodiments, the exhaust gas passes through the steps of the process according to the invention in one of the following sequences or the device according to the invention is configured accordingly: (i) (a) → (b) → (c1) → (d); wherein step (c1) preferably takes place in a first reaction zone; and step (d) takes place in a second reaction zone; (ii) (a) → (b) → (d) → (c2); wherein step (d) preferably takes place in a first reaction zone; and step (c2) takes place in a second reaction zone; (iii) (a) → (b) → (d) → (c2) → (c1); wherein preferably step (d) takes place in a first reaction zone; step (c2) takes place in a second reaction zone; and step (c1) takes place in a third reaction zone; (iv) (a) → (b) → (d) → (c1)+(c2); wherein preferably step (d) takes place in a first reaction zone; and steps (c1) and step (c2) take place in a second reaction zone; (v) (a) → (b) → (d) → (c1); wherein preferably step (d) takes place in a first reaction zone; and step (c1) takes place in a second reaction zone; (vi) (a) → (b) → (c1)+(d) → (d*); wherein preferably step (c1) and, incompletely, step (d) take place in a first reaction zone; and the remaining step (d*) takes place in a second reaction zone; (vii) (a) → (b) → (c1)+(d) → (d*)+(c2); wherein preferably step (c1) and incomplete step (d) take place in a first reaction zone; and step (c2) and the remaining step (d*) take place in a second reaction zone;(viii) (a) → (b) → (c1)+(c2)+(d) → (c1*)+(c2*)+(d*); wherein preferably incomplete step (c1) and incomplete step (c2) and incomplete step (d) take place in a first reaction zone which preferably does not contain any zeolitic material as catalyst; and the remaining step (c1*) and the remaining step (c2*) and the remaining step (d*) take place in a second reaction zone which preferably contains zeolitic material as catalyst; (ix) (a) → (b)→ (c1)+(c2)+(d) → (c1*)+(c2*)+(d*); wherein preferably incomplete step (c1) and incomplete step (c2) and incomplete step (d) take place in a first reaction zone which preferably contains zeolitic material as catalyst; and the remaining step (c1*) and the remaining step (c2*) and the remaining step (d*) take place in a second reaction zone which preferably contains a NOX-sensitive N2O decomposition catalyst as catalyst; (x) (a) → (b) → (c1) → (c1*) + (c2) + (d);wherein step (c1) preferably takes place incompletely in a first reaction zone which preferably contains zeolitic material as catalyst; and the remaining step (c1*) as well as step (c2) and step (d) take place in a second reaction zone which preferably contains zeolitic material as catalyst; (xi) (a) → (b) → (c1) → (c1*) + (c2) + (d); wherein step (c1) preferably takes place incompletely in a first reaction zone which preferably contains a NOX-sensitive N2O decomposition catalyst as catalyst; and the remaining step (c1*) as well as step (c2) and step (d) take place in a second reaction zone which preferably contains zeolitic material as catalyst. ;

[0244] If, for engine-related reasons, the use of an NH3 oxidation catalyst is necessary, which cannot be made of the same material as the catalyst for step (c) and / or (d), this can be arranged in a separate, additional reaction zone, in which the oxidation of NH3 with O2 can take place.

[0245] In preferred embodiments, this takes place in the flow direction of the exhaust gas upstream of the respective reaction zones for steps (d) and (c).

[0246] In preferred embodiments, this takes place in the flow direction of the exhaust gas downstream of the reaction zones for steps (d) and (c).

[0247] According to the invention, it is also possible to implement such a dissimilar NH3 oxidation catalyst within one or more of the reaction zones for step (c) and / or step (d), particularly if the reaction zones are configured as honeycomb bodies. The NH3 oxidation catalyst is then preferably present in a layered configuration, with the layer of catalyst for step (c) and / or step (d) preferably covering the layer of the NH3 oxidation catalyst.

[0248] However, it is also possible for multiple reaction zones to be realized by a single catalyst bed. Two reaction zones on a common catalyst bed can be formed, in particular, by feeding reducing agent into the center (or another position along the longitudinal extent) of the catalyst bed, or the device according to the invention is configured accordingly. Upstream of the feed point, no reducing agent is then present, so that steps (c2) and (d) of the process according to the invention cannot take place due to the lack of reducing agent, or the device according to the invention is configured accordingly. The decomposition of N2O according to step (c1) (first reaction zone) then essentially takes place upstream, or the device according to the invention is configured accordingly.Reducing agent is present downstream of the feed point, so that steps (c2) and (d) of the process according to the invention can take place, optionally superimposed on step (c1) of the process according to the invention (second reaction zone), or the device according to the invention is configured accordingly. In this case too, due to the different reaction kinetics, different reactions can take place in the front section of each reaction zone than in the rear section of each reaction zone; however, the first reaction zone and the second reaction zone differ from one another in that, in the absence of reducing agent, no chemical reduction of N2O and also no chemical reduction of NOX takes place in the first reaction zone, or the device according to the invention is configured accordingly.

[0249] In particularly preferred embodiments, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone. Additional reaction zones may be present.

[0250] In preferred embodiments, the first reaction zone and the second reaction zone are spatially separated from one another. In this case, they are preferably separate catalyst beds. With spatial separation of the catalyst beds, it is possible to adjust the temperature of the second catalyst bed or of the gas stream entering it by removing or adding heat so that it is lower or higher than that of the first catalyst bed. The temperature of an individual catalyst bed can conveniently be determined as the arithmetic mean of the temperature of the gas stream at the inlet and outlet of the catalyst bed.

[0251] In preferred embodiments, the temperature in the first reaction zone (in the first catalyst bed) is higher than the temperature in the second reaction zone (in the second catalyst bed), or the device according to the invention is configured accordingly.

[0252] Preferably, the temperature of the exhaust gas upon entry into the first reaction zone is in the range of 280 to 400°C, depending on the load and the properties of the internal combustion engine.

[0253] The temperature in the first reaction zone (in the first catalyst bed) is preferably at least 450°C, more preferably at least 500°C, even more preferably at least 550°C, most preferably at least 600°C and in particular at least 650°C, or the device according to the invention is configured accordingly.

[0254] Preferably, the temperature of the exhaust gas upon entry into the second reaction zone is in the range of 280 to 400°C, depending on the load and the properties of the internal combustion engine.

[0255] Preferably, the temperature in the second reaction zone (in the second catalyst bed) is at most 600°C, more preferably at most 550°C, even more preferably at most 500°C, most preferably at most 450°C and in particular at most 400°C, or the device according to the invention is configured accordingly.

[0256] Preferably, the temperature in the first reaction zone (in the first catalyst bed) is relatively higher by at least 20°C, more preferably by at least 40°C, even more preferably by at least 60°C, most preferably by at least 80°C and in particular by at least 100°C than the temperature in the second reaction zone (in the second catalyst bed), or the device according to the invention is configured accordingly.

[0257] Preferably, the temperature in the first reaction zone (in the first catalyst bed) is relatively higher by at least 120°C, more preferably by at least 140°C, even more preferably by at least 160°C, most preferably by at least 180°C and in particular by at least 200°C than the temperature in the second reaction zone (in the second catalyst bed), or the device according to the invention is configured accordingly.

[0258] Preferably, the temperature of the exhaust gas at the inlet into the first reaction zone (into the first catalyst bed) is at least 400°C, more preferably at least 425°C, even more preferably at least 450°C, most preferably at least 500°C, or the device according to the invention is configured accordingly.

[0259] Preferably, the temperature of the exhaust gas at the outlet from the second reaction zone (from the second catalyst bed) is at most 600°C, more preferably at most 550°C, even more preferably at most 500°C, or the device according to the invention is configured accordingly.

[0260] In preferred embodiments, the temperature of the exhaust gas at the inlet to the first reaction zone (into the first catalyst bed) is relatively higher by at least 20K, more preferably by at least 40K, more preferably by at least 60K, most preferably by at least 80K and in particular by at least 100K higher than the temperature of the exhaust gas at the inlet into the second reaction zone (into the second catalyst bed, or the device according to the invention is configured accordingly.

[0261] In preferred embodiments, the temperature of the exhaust gas at the inlet into the second reaction zone (into the second catalyst bed) is relatively higher by at least 10K, more preferably by at least 20K, even more preferably by at least 30K, most preferably by at least 40K and in particular by at least 50K than the temperature of the exhaust gas at the inlet into the first reaction zone (into the first catalyst bed), or the device according to the invention is configured accordingly.

[0262] In preferred embodiments, the temperature in the first reaction zone (in the first catalyst bed) is relatively higher by at least 120K, more preferably by at least 140K, even more preferably by at least 160K, most preferably by at least 180K and in particular by at least 200K than the temperature in the second reaction zone (in the first catalyst bed), or the device according to the invention is configured accordingly.

[0263] In preferred embodiments, the temperature in the second reaction zone (in the second catalyst bed) is relatively higher by at least 120K, more preferably by at least 140K, even more preferably by at least 160K, most preferably by at least 180K and in particular by at least 200K than the temperature in the first reaction zone (in the first catalyst bed), or the device according to the invention is configured accordingly.

[0264] In other preferred embodiments, the first reaction zone and the second reaction zone are spatially connected to one another. In this case, they preferably comprise a common catalyst bed, with external influences causing a division into reaction zones, in particular by the location of the reducing agent feed, so that reducing agent is not present equally throughout the catalyst bed, or the device according to the invention is configured accordingly.

[0265] Preferably, the first reaction zone and the second reaction zone are arranged in a common container.

[0266] Preferably, the temperature of the exhaust gas in the first reaction zone and in the second reaction zone is, independently of one another, at most 500°C, preferably it is, independently of one another, in the range from 350 to 450°C, or the device according to the invention is configured accordingly.

[0267] In preferred embodiments, the space velocity in the first reaction zone is greater than the space velocity in the second reaction zone, or the device according to the invention is configured accordingly. Preferably, the space velocity in the first reaction zone is zone by at least a factor of 1.2, more preferably at least a factor of 1.4, even more preferably at least a factor of 1.6, most preferably at least a factor of 1.8, and in particular at least a factor of 2.0 greater than the space velocity in the second reaction zone.

[0268] In other preferred embodiments, the space velocity in the second reaction zone is greater than the space velocity in the first reaction zone, or the device according to the invention is configured accordingly. Preferably, the space velocity in the second reaction zone is at least a factor of 1.5, more preferably at least a factor of 2.0, even more preferably at least a factor of 3.0, most preferably at least a factor of 5.0, and in particular at least a factor of 10.0 greater than the space velocity in the first reaction zone.

[0269] For the purposes of the invention, "space velocity" is understood as the quotient of the volume flow of the gas mixture passed through the catalyst bed (measured at 0 °C and 1.014 bara and usually expressed in Nm3 h-1) relative to the volume of the catalyst or catalyst bed. The space velocity can thus be adjusted via the volume flow of the gas and / or the amount of catalyst.

[0270] Preferably, the exhaust gas has a temperature of at least 300°C, more preferably at least 350°C, even more preferably at least 400°C, most preferably at least 425°C, and in particular at least 450°C upon entering the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0271] Preferably, the exhaust gas has a temperature of at least 500°C, more preferably at least 550°C, even more preferably at least 600°C, most preferably at least 625°C, and in particular at least 650°C when entering the exhaust gas treatment plant.

[0272] Preferably, the exhaust gas has a temperature of at least 500°C, more preferably at least 550°C, even more preferably at least 600°C, most preferably at least 625°C, and in particular at least 650°C upon entering the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0273] Preferably, the exhaust gas has a temperature of at most 825°C, more preferably at most 800°C, even more preferably at most 775°C, most preferably at most 750°C, and in particular at most 725°C, or the device according to the invention is configured accordingly.

[0274] Preferably, the exhaust gas has a temperature of at most 700°C, more preferably at most 650°C, even more preferably at most 600°C, most preferably at most 550°C, and in particular at most 500°C, or the device according to the invention is configured accordingly.

[0275] Preferably, the exhaust gas has a temperature in the range of 320 to 600°C upon entering the exhaust gas treatment system; more preferably 350 to 600°C.

[0276] Preferably, the exhaust gas has a temperature on entering the exhaust gas treatment system which is relatively at least 20°C, preferably at least 40°C, more preferably at least 60°C, even more preferably at least 80°C, most preferably at least 100°C, and in particular at least 120°C below the temperature which the exhaust gas has on leaving the internal combustion engine, or the device according to the invention is configured accordingly.

[0277] Preferably, the exhaust gas has a pressure of at most 5 bara, preferably at most 4 bara, upon entering the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0278] Preferably, the exhaust gas has an oxidation level of NOX of at least 10%, more preferably at least 20%, even more preferably at least 30%, most preferably at least 40%, and in particular at least 50% upon entering the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0279] Preferably, the exhaust gas has an oxidation level of NOX of at most 90%, more preferably at most 80%, even more preferably at most 70%, most preferably at most 60%, and in particular at most 50%, or the device according to the invention is configured accordingly.

[0280] Depending on the combustion temperature, the degree of oxidation can also be significantly lower, with the degree of oxidation decreasing with increasing combustion temperature. Preferably, the exhaust gas entering the exhaust gas treatment system has a NOX oxidation degree of no more than 15%, more preferably no more than 12.5%, even more preferably no more than 10%, most preferably no more than 7.5%, and in particular no more than 5.0%.

[0281] Preferably, the exhaust gas has an O2 content of less than 2.0 vol.% upon entry into the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0282] Preferably, the exhaust gas has an O2 content of at least 3.0 vol.% upon entry into the exhaust gas treatment system; preferably at least 3.1 vol.%, more preferably at least 3.2 vol.%, even more preferably at least 3.3 vol.%, most preferably at least 3.4 vol.% and in particular at least 3.5 vol.%, or the device according to the invention is configured accordingly.

[0283] Preferably, the exhaust gas has an O2 content of more than 4.0 vol.% upon entry into the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0284] In step (c) of the process according to the invention, the N2O content in the exhaust gas is reduced, or the device according to the invention is configured accordingly. This can be done in different ways, namely by (c1) decomposition of N2O on an N2O decomposition catalyst and / or by (c2) chemical reduction of N2O with a reducing agent on an N2O reduction catalyst. Step (c) of the process according to the invention is carried out in the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0285] In preferred embodiments, step (c) comprises reducing the content of N2O in the exhaust gas by (c1) decomposition of N2O on an N2O decomposition catalyst, or the device according to the invention is configured accordingly.

[0286] In preferred embodiments, the N2O decomposition catalyst comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI, and / or MEL.

[0287] In other preferred embodiments, the N2O decomposition catalyst is a NOX-sensitive N2O decomposition catalyst within the meaning of the invention, which has already been described in more detail above. In this case, the exhaust gas preferably first undergoes step (d), i.e., the NOX content in the exhaust gas is first reduced, preferably quantitatively, by chemical reduction of NOX with a reducing agent on a NOX reduction catalyst before the exhaust gas subsequently comes into contact with the NOX-sensitive N2O decomposition catalyst, or the device according to the invention is configured accordingly.

[0288] Preferably, the N2O decomposition catalyst is arranged in a radial basket through which the flow is axial, or the device according to the invention is configured accordingly.

[0289] Preferably, the N2O decomposition catalyst is particulate and comprises at least 50 particles.

[0290] In preferred embodiments, step (c) comprises reducing the N2O content in the exhaust gas by (c2) chemically reducing N2O with reducing agent on an N2O reduction catalyst; preferably wherein the N2O reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably an iron or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL, or the device according to the invention is configured accordingly.

[0291] Preferably, the N2O reduction catalyst is arranged in a radial basket through which the flow is axial, or the device according to the invention is configured accordingly.

[0292] Preferably, the N2O reduction catalyst is particulate and comprises at least 50 particles.

[0293] In preferred embodiments, step (c) comprises reducing the content of N2O in the exhaust gas - both by (c1) decomposition of N2O on an N2O decomposition catalyst; preferably wherein the N2O decomposition catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably an iron-loaded zeolite; even more preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL, orthe device according to the invention is configured accordingly; - as well as by (c2) chemical reduction of N2O with reducing agent on an N2O reduction catalyst; preferably wherein the N2O reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably a zeolite loaded with iron or copper of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL, or the device according to the invention is configured accordingly.

[0294] Preferably, the reducing agent in step (c2) is selected from NH3, hydrocarbons, CO, H2, and mixtures thereof; preferably NH3, or the device according to the invention is configured accordingly.

[0295] In preferred embodiments, the reducing agent in step (c2) is NH3, which is preferably used in an amount of 0.5 to 2.0 molar parts, preferably in an amount of 0.8 to 1.8 molar parts, based on a molar proportion of N2O to be chemically reduced, ie based on the amount of N2O at the inlet into the catalyst bed of the N2O reduction catalyst, or the device according to the invention is configured accordingly.

[0296] In preferred embodiments, the reducing agent in step (c2) is NH3, which is preferably used in an amount of 0.5 to 2.0 molar fractions, more preferably in an amount of 0.8 to 1.8 molar fractions, based on the molar amount of N2O in the exhaust gas at the inlet to the catalyst bed of the N2O reduction catalyst. This amount is additive to any amount of NH3 required for NOX reduction, provided that step (d) also takes place in the catalyst bed of the N2O reduction catalyst.

[0297] In other preferred embodiments, the reducing agent is a hydrocarbon or a mixture of several hydrocarbons, which are preferably used in an amount of 0.2 to 1.0 molar fractions, more preferably 0.2 to 0.7 molar fractions, based on the molar amount of N2O in the exhaust gas at the inlet to the catalyst bed of the N2O reduction catalyst. This amount is also additive to the possibly required amount of NH3 for NO. X -reduction, provided that step (d) also takes place in the catalyst bed of the N2O reduction catalyst, or the device according to the invention is configured accordingly.

[0298] The reducing agent may also already be present in the exhaust gas, e.g. as residual fuels and / or their oxidation products. The process according to the invention then reduces not only the content of nitrogen oxides (NO Xand N2O), but also the content of these impurities (residual fuels and / or their oxidation products, in particular NH3 slip), or the device according to the invention is configured accordingly.

[0299] In step (d) of the process according to the invention, the content of NO X (ie NO and NO2) in the exhaust gas, or the device according to the invention is configured accordingly. This is achieved by chemical reduction of NO X with reducing agent on a NO X Reduction catalyst. Step (d) of the process according to the invention is also carried out in the exhaust gas treatment system, or the device according to the invention is configured accordingly.

[0300] The NOX reduction catalyst preferably contains a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt or copper-loaded zeolite; more preferably an iron-loaded zeolite; even more preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL.

[0301] Preferably, the NOX reduction catalyst is arranged in a radial basket through which the flow is axial, or the device according to the invention is configured accordingly.

[0302] Preferably, the NOX reduction catalyst is particulate and comprises at least 50 particles.

[0303] Preferably, the reducing agent in step (d) is selected from NH3, hydrocarbons, CO, H2, and mixtures thereof; preferably NH3, or the device according to the invention is configured accordingly.

[0304] Preferably, the reducing agent in step (d) is NH3, which is used in an amount of 0.9 to 2.5 molar parts, preferably 1.0 to 1.4 molar parts, more preferably 1.0 to 1.2 molar parts, based on a molar part of NOX to be chemically reduced, or the device according to the invention is configured accordingly.

[0305] In preferred embodiments, the reducing agent in step (c2) is the same as the reducing agent in step (d); preferably NH3, or the device according to the invention is configured accordingly.

[0306] In addition to NH3, other nitrogen-containing reducing agents are also suitable in steps (c2) and / or (d) of the process according to the invention, for example hydrogen compounds of nitrogen, such as azanes, hydroxyl derivatives of azanes, as well as amines, oximes, carbamates, urea or urea derivatives, or the device according to the invention is configured accordingly. Examples of azanes are hydrazine and especially ammonia. Examples of hydroxyl derivatives of azanes are hydroxylamine. Examples of amines are primary aliphatic amines, such as methylamine. An example of carbamates is ammonium carbamate. Examples of urea derivatives are N,N'-substituted ureas, such as N,N'-dimethylurea. Ureas and urea derivatives are preferably used in Used in the form of aqueous solutions. Ammonia or substances that release ammonia upon introduction, such as urea or ammonium carbamate, are particularly preferred.

[0307] Particularly preferred process procedures according to the invention or corresponding configurations of the device according to the invention are explained in more detail below: Single reaction zone

[0308] In preferred embodiments, the exhaust gas treatment system contains a single reaction zone (optionally apart from a further reaction zone comprising an NH3 oxidation catalyst, preferably an NH3 oxidation-active zeolite catalyst loaded with iron or copper, see below), which comprises - as N2O decomposition catalyst and / or N2O reduction catalyst and - as NH3 reduction catalyst, a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably a zeolite loaded with iron or copper of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL; and wherein in the flow direction of the exhaust gas, a device for metering reducing agent for N2O and / or NOX into the exhaust gas is arranged upstream of the single reaction zone.

[0309] Preferably, the device for dosing reducing agent is a device for dosing NH3.

[0310] In preferred embodiments, a further device for metering reducing agent for N2O and / or NOX into the exhaust gas is arranged upstream of the single reaction zone in the flow direction of the exhaust gas. Preferably, the further device for metering reducing agent is a device for metering natural gas.

[0311] In preferred embodiments, a further reaction zone is arranged upstream of the single reaction zone in the flow direction of the exhaust gas, which further reaction zone comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration.

[0312] For the purposes of this description, "zone configuration" means that the catalysts are in the form of honeycomb bodies, which may be combined to form honeycomb modules, whereby several honeycomb bodies or honeycomb modules may be arranged one behind the other in the direction of flow of the exhaust gas. Honeycomb bodies or honeycomb modules arranged upstream then form a first "zone," which serves as the first reaction zone. Honeycomb bodies or honeycomb modules arranged downstream then form a second "zone," which serves as the second reaction zone. In this way, two, three, four or more zones can be configured one after the other and form a zone configuration according to the invention.

[0313] For the purpose of the description, "layer configuration" means, in contrast to and in addition to the zone configuration, that the catalytically active material is present as a bifunctional two-layer catalyst (bi-functional dual-layer catalyst), wherein preferably the NH3 oxidation catalyst according to the invention is in the lower of the two layers (lower washcoat) and the N2O decomposition, N2O reduction and / or NO X -reduction catalyst is present in the upper of the two layers. The bifunctional two-layer catalyst is preferably designed as a honeycomb body or honeycomb body module.

[0314] If steps (c) and (d) of the process according to the invention are carried out in a first reaction zone and a second reaction zone arranged downstream therefrom (zone configuration), the layered configuration of the NH3 oxidation catalyst described above is possible in both reaction zones. In preferred embodiments, the NH3 oxidation catalyst is present in a layered configuration only in the first reaction zone. In other preferred embodiments, the NH3 oxidation catalyst is present in a layered configuration only in the second reaction zone. In further preferred embodiments, the NH3 oxidation catalyst is present in a layered configuration in both the first reaction zone and the second reaction zone.

[0315] In preferred embodiments, the device has a controllable bypass around the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst, preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst. Preferably, a device for measuring the concentration of NH3, NOX, or N2O in the exhaust gas; preferably of NH3, NOX, and N2O; is arranged upstream of the single reaction zone in the flow direction of the exhaust gas, and the opening of the bypass is controllable or regulatable.

[0316] In preferred embodiments, a further reaction zone is arranged downstream of the single reaction zone in the flow direction of the exhaust gas, which further reaction zone comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration.

[0317] In preferred embodiments, the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst is arranged upstream of an exhaust gas turbine in the flow direction of the exhaust gas. In other preferred embodiments, the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst is arranged downstream of an exhaust gas turbine in the flow direction of the exhaust gas. The single reaction zone is preferably arranged upstream of the exhaust gas turbine in the flow direction of the exhaust gas. At least two reaction zones arranged one behind the other

[0318] In preferred embodiments, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream in the flow direction of the exhaust gas, which are configured such that the exhaust gas flows through them one after the other; wherein the first reaction zone and the second reaction zone each independently comprise a zeolitic material as an N2O decomposition catalyst and / or N2O reduction catalyst and / or as an NH3 reduction catalyst; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably a zeolite loaded with iron or copper of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL;and wherein, in the flow direction of the exhaust gas, a device for metering reducing agent for N2O and / or NOX into the exhaust gas is arranged downstream of the first reaction zone and upstream of the second reaction zone. ;

[0319] Preferably, the device for dosing reducing agent is a device for dosing NH3.

[0320] In preferred embodiments, a further device for metering reducing agent for N2O and / or NOX into the exhaust gas is arranged upstream of the single reaction zone in the flow direction of the exhaust gas. Preferably, the further device for metering reducing agent is a device for metering natural gas.

[0321] In preferred embodiments, an additional device for metering reducing agent for N2O and / or NOX into the exhaust gas is arranged upstream of the first reaction zone in the direction of flow of the exhaust gas. Preferably, the additional device for metering reducing agent is a device for metering NH3.

[0322] In preferred embodiments, the first reaction zone comprises a copper-loaded zeolite; preferably a copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL; and the second reaction zone comprises an iron-loaded zeolite; preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL.

[0323] In preferred embodiments, a device for measuring the concentration in the exhaust gas of NH3, NOX or N2O; preferably NH3 and NO X and N2O. Preferably, at least one device selected from the device for metering reducing agent, the optionally present further device for metering reducing agent, and the optionally present additional device for metering reducing agent is controllable or regulatable; preferably by feedforward control; depending on the measured concentration in the exhaust gas of NH3, NO X or N2O; preferably NH3 and NO X and N2O.

[0324] In preferred embodiments, a device for measuring the concentration in the exhaust gas of NH3, NO X or N2O; preferably NH3 and NO Xand N2O. Preferably, at least one device selected from the device for metering reducing agent, the optionally present further device for metering reducing agent, and the optionally present additional device for metering reducing agent is controllable or regulatable; preferably by feedforward control; depending on the measured concentration in the exhaust gas of NH3, NO X or N2O; preferably NH3 and NO X and N2O.

[0325] In preferred embodiments, a further reaction zone is arranged downstream of the first reaction zone and upstream of the second reaction zone in the flow direction of the exhaust gas, said further reaction zone comprising an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration.

[0326] In preferred embodiments, a further reaction zone is arranged in the flow direction of the exhaust gas downstream of the first reaction zone and upstream of the second reaction zone, as well as upstream of the device for metering reducing agent and any further device for metering reducing agent that may be present, which further reaction zone comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration.

[0327] In preferred embodiments, a further reaction zone is arranged downstream of the second reaction zone in the flow direction of the exhaust gas, which further reaction zone comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration.

[0328] In preferred embodiments, the device has a controllable bypass around the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst, preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst. Preferably, a device for measuring the concentration of NH3 and NO in the exhaust gas is arranged upstream of the first reaction zone or upstream of the second reaction zone in the flow direction of the exhaust gas. X or N2O; preferably NH3 and NOX and N2O; and wherein the opening of the bypass is controllable or adjustable.

[0329] In preferred embodiments, the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron or copper-loaded zeolite catalyst is arranged in the flow direction of the exhaust gas upstream of an exhaust gas turbine. In other preferred embodiments, the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst is arranged downstream of an exhaust gas turbine in the flow direction of the exhaust gas. The first reaction zone is preferably arranged upstream of the exhaust gas turbine in the flow direction of the exhaust gas. The second reaction zone is preferably arranged upstream of the exhaust gas turbine in the flow direction of the exhaust gas.

[0330] In preferred embodiments, the exhaust gas treatment system comprises at least one additional component selected from diesel oxidation catalysts, lean NO X -Trap catalysts, NO X Absorption components, non-catalytic particulate filters, and catalytic particulate filters; preferably, all additional components are arranged upstream of the second reaction zone in the direction of exhaust gas flow. DeNOX-DeN2O - Variant 1

[0331] In preferred embodiments, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream thereof, through which the exhaust gas flows one after the other; wherein reducing agent is added to the exhaust gas upstream of the first reaction zone; wherein initially in the first reaction zone the NOX content in the exhaust gas is reduced by chemical reduction of NOX with reducing agent on a NOX reduction catalyst (step (d)), (DeNOX stage); wherein optionally additionally the N2O content in the exhaust gas is reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)); wherein optionally further reducing agent is added to the exhaust gas upstream of the second reaction zone;and wherein the N2O content in the exhaust gas is subsequently reduced in the second reaction zone by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)) (DeN2O stage); wherein optionally, the NOX content in the exhaust gas is additionally further reduced by chemical reduction of NOX on an NOX reduction catalyst (step (d)), or the device according to the invention is configured accordingly.

[0332] Preferably, the NO X -Reduction catalyst in the first reaction zone is a classic, preferably non-zeolitic SCR catalyst, e.g. based on V2O5-WO3- / TiO2.

[0333] Preferably, the temperature of the exhaust gas upon entry into the first reaction zone is at most 400°C, preferably at most 350°C, or the device according to the invention is configured accordingly.

[0334] Preferably, the N2O decomposition catalyst in the second reaction zone comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structural type.

[0335] Preferably, the temperature of the exhaust gas upon entry into the second reaction zone is in the range from 300 to 550°C, preferably 350 to 500°C, or the device according to the invention is configured accordingly.

[0336] Preferably, the exhaust gas after leaving the first reaction zone and before entering the second reaction zone has a NOx content in the range of 0 to 200 ppmv, preferably 1 to 200 ppmv, and an N2O content in the range of 200 to 2000 ppmv, or the device according to the invention is configured accordingly. DeNOX-DeN2O - Variant 2

[0337] In other preferred embodiments, the exhaust gas treatment system also comprises a first reaction zone and a second reaction zone arranged downstream thereof, through which the exhaust gas flows one after the other; wherein reducing agent is added to the exhaust gas upstream of the first reaction zone; wherein initially in the first reaction zone the NOX content in the exhaust gas is reduced by chemical reduction of NOX with reducing agent on a NOX reduction catalyst; (step (d)) (DeNOX stage); wherein optionally additionally the N2O content in the exhaust gas is reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)); wherein optionally further reducing agent is added to the exhaust gas upstream of the second reaction zone;and wherein subsequently, in the second reaction zone, the N2O content in the exhaust gas is reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)) (DeN2O stage); wherein optionally additionally the NOX content in the exhaust gas is reduced by chemical reduction of NOX on an NO; X -reduction catalyst is further reduced (step (d)), or the device according to the invention is configured accordingly.

[0338] Preferably, the NOX reduction catalyst in the first reaction zone comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structure type.

[0339] Preferably, the temperature of the exhaust gas upon entry into the first reaction zone is at least 300°C, more preferably at least 350°C, even more preferably at least 400°C. Preferably, the temperature of the exhaust gas upon entry into the first reaction zone is at most 600°C, more preferably at most 550°C, or the device according to the invention is configured accordingly.

[0340] Preferably, the N2O decomposition catalyst in the second reaction zone comprises a NO X - sensitive N2O decomposition catalyst according to the invention, which has already been described in more detail above.

[0341] Preferably, the temperature of the exhaust gas upon entry into the second reaction zone is at least 300°C, more preferably at least 350°C, even more preferably at least 400°C. Preferably, the temperature of the exhaust gas upon entry into the second reaction zone is at most 600°C, more preferably at most 550°C, or the device according to the invention is configured accordingly.

[0342] Preferably, the exhaust gas after leaving the first reaction zone and before entering the second reaction zone has a NOx content of at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv, and an N2O content in the range of 200 to 2000 ppmv, or the device according to the invention is configured accordingly. Particularly preferred embodiments of DeNOX-DeN2O - Variant 2

[0343] In particularly preferred embodiments, the exhaust gas treatment system according to the invention comprises a first catalyst bed and a second catalyst bed spatially separated therefrom; wherein the first catalyst bed is arranged upstream of the second catalyst bed in the flow direction of the exhaust gas; wherein optionally and preferably upstream of the first catalyst bed, a first device with a first control valve for metering NH3 into the exhaust gas is arranged; wherein downstream of the first catalyst bed and upstream of the second catalyst bed, a second device with a second control valve for metering NH3 into the exhaust gas is arranged, with which further NH3 is metered into the exhaust gas; wherein both the first catalyst bed and the second catalyst bed each contain an iron-loaded zeolite catalyst; wherein (i) in the first catalyst bed (c1) N2O is decomposed;and (d) NOX is incompletely chemically reduced with NH3, wherein optionally and preferably at least a portion of the NH3 originates from incomplete combustion of NH3 in step (a) (NH3 slip); and (ii) in the second catalyst bed (c2) residual N2O is chemically reduced with NH3 and optionally (c1*) residual N2O is decomposed; and (d*) residual NO; X chemically reduced with NH3.

[0344] Preferably, the catalytic decomposition of N2O in the first catalyst bed is co-catalyzed by NO present in the exhaust gas X .

[0345] Preferably, the incomplete chemical reduction of NO X with NH3 in the first catalyst bed up to a specified residual NO content X , which is sufficient to produce a co-catalytic chemical effect on the decomposition of N2O in the first catalyst bed. Since the chemical reduction of NO Xwith NH3 is typically much faster than the chemical reduction of N2O with NH3 and in the first catalyst bed not the entire amount of NO X is chemically reduced, the extent of any parallel chemical reduction of N2O with NH3 in the first catalyst bed is typically negligible.

[0346] Preferably, additional NH3 is added to the NO via the first device. X -reduction is added to the exhaust gas; preferably under feedback control, ie a certain value for the concentration of NO Xat the outlet of the first catalyst bed is specified as a target value (setpoint) and the actual NOX concentration at the outlet of the first catalyst bed is measured (actual value) and in the event of a difference between the setpoint and actual value (control difference) the control level of the first control valve is changed in order to minimize the difference. Preferably, the setpoint of the NOX concentration at the outlet of the first catalyst bed and thus the amount of additional NH3 is selected such that the residual NOX concentration at the outlet of the first catalyst bed is at most 1000 ppmv, preferably at most 500 ppmv, more preferably at most 100 ppmv. Preferably, the setpoint of the NOX concentration at the outlet of the first catalyst bed and thus the amount of additional NH3 is selected such that the residual NOX concentration at the outlet of the first catalyst bed is at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 40 ppmv.The expected specific consumption of NH3 for the chemical reduction of NOX in the first catalyst bed is typically in the range of 0.9 to 1.1 mol NH3 per mol reduced NOX and is thus significantly smaller than the expected specific (mol / mol) consumption of NH3 in the second catalyst bed.

[0347] Preferably, the temperature of the exhaust gas at the outlet from the first catalyst bed is in the range of 400 to 550°C.

[0348] Preferably, the exhaust gas at the outlet from the first catalyst bed has a pressure which is greater than atmospheric pressure, ie ≥ 1.0 bara, but at most 1.2 bara, more preferably at most 1.1 bara.

[0349] Preferably, the exhaust gas at the outlet from the first catalyst bed has an oxidation degree of NOX of at least 5.0%, preferably at least 7.5%, more preferably at least 10%, even more preferably at least 12.5%, most preferably at least 15%, and in particular at least 17.5%.

[0350] In preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NOX in the range of 30 to 50%.

[0351] In other preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NO X in the range of 15 to 35%, preferably 15 to 30%.

[0352] In further preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NO X in the range of 10 to 20%.

[0353] In other preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NO X in the range of 5 to 15%.

[0354] Preferably, residual N2O is decomposed in the second catalyst bed to a residual N2O concentration at the outlet of the second catalyst bed of at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv, most preferably at most 2 ppmv.

[0355] In the second catalyst bed, residual NO X to a residual concentration of NOX at the outlet of the second catalyst bed of at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv, most preferably at most 2 ppmv.

[0356] Preferably, the additional NH3 is added with the second device under feedforward control, ie the concentration of NO Xand optionally preferably of N2O and optionally preferably of NH3, each at the outlet of the first catalyst bed or optionally at the inlet to the second catalyst bed is measured; taking into account the amount of exhaust gas entering the second catalyst bed, the amount of NH3 required for NOX reduction and optionally preferably the sum of the amount of NH3 required for NOX reduction and N2O reduction is calculated using stored molar ratios (mol / mol) of NH3 / NOX and optionally preferably of NH3 / / N2O or factors derived therefrom; and using the calculated result (manipulated variable), the control level of the second control valve is changed in order to meter in the required amount of NH3.

[0357] According to the invention, the molar NH3 concentration [NH3] of the exhaust gas at the inlet to the second catalyst bed is preferably in the range from the sum of 0.7 x [N2O] and 1.0 x [NOX] to the sum of 4.0 x [N2O] and 2.0 x [NOX], more preferably in the range from the sum of 1.0 x [N2O] and 1.1 x [NOX] to the sum of 3.0 x [N2O] and 1.6 x [NOX], even more preferably in the range from the sum of 1.5 x [N2O] and 1.2 x [NOX] to the sum of 2.5 x [N2O] and 1.4 x [NOX], where [N2O] is the molar concentration of N2O and [NOX] is the molar concentration of NOX in the exhaust gas at the inlet to the second catalyst bed.

[0358] For feedforward control of the NH3 dosage into the second catalyst bed with regard to NOX reduction, a molar ratio of NH3 / NOX in the range of 1.0 to 2.0; preferably 1.1 to 1.6; more preferably 1.2 to 1.4 is selected.

[0359] For feedforward control of the NH3 dosage into the second catalyst bed with regard to N2O reduction, a molar ratio of NH3 / N2O in the range of 0.7 to 4.0; preferably 1.0 to 3.0; more preferably 1.5 to 2.5 is preferably selected.

[0360] Preferably, the additional NH3 is not added with the second device under feedback control, since the most complete chemical reduction of NO X in the second catalyst bed, ie no or only very low residual concentrations of NO X and N2O, which would be difficult to use as control variables.

[0361] Preferably, the amount of catalyst, ie the space velocity (= ratio of exhaust gas volume flow under standard conditions to catalyst volume) is selected such that in the first catalyst bed a degradation of N2O of at least 50% takes place, more preferably at least 70%, even more preferably at least 80%, based on the concentration of N2O at the inlet to the first catalyst bed.

[0362] Preferably, the amount of catalyst and the amount of additional NH3 are selected so that at the outlet of the first catalyst bed the molar ratio of NO X / N2O is at least 5, more preferably at least 10, even more preferably at least 20.

[0363] Preferably, the space velocity of the first catalyst bed is in the range of 5,000 h-1 to 100,000 h-1, more preferably 10,000 h-1 to 50,000 h-1, even more preferably 15,000 h-1 to 45,000 h-1.

[0364] If the molar ratio of NO X / N2O at the outlet of the first catalyst bed is at least 10, then the addition of NH3 into the second catalyst bed via the second device can preferably be carried out solely in relation to the amount of NOX entering.

[0365] Preferably, the temperature of the exhaust gas upon entry into the first catalyst bed is at least 400°C, more preferably at least 425°C, even more preferably at least 450°C. Preferably, the temperature of the exhaust gas upon entry into the first catalyst bed is at most 550°C, more preferably at most 525°C, even more preferably at most 500°C. The temperature can be adjusted by measures known to those skilled in the art, in particular the design of heat exchangers and conditions for the combustion of NH3.

[0366] Depending on the heat of the chemical reactions taking place in the first catalyst bed and in the second catalyst bed, the inlet temperature of the exhaust gas into the first catalyst bed is preferably selected such that the temperature of the exhaust gas at the outlet of the second catalyst bed is at most 600°C, more preferably at most 550°C, even more preferably at most 520°C.

[0367] Preferably, the space velocity of the second catalyst bed is in the range of 5,000 h-1 to 100,000 h-1, more preferably 10,000 h-1 to 50,000 h-1, even more preferably 15,000 h-1 to 45,000 h-1.

[0368] Preferably, the ratio of the catalyst volumes (V1kat / V2kat) of the first catalyst bed V1kat to the second catalyst bed V2kat is in the range from 1 / 2 to 20 / 1, more preferably 1 / 2 to 10 / 1, even more preferably 1 / 1 to 4 / 1.

[0369] In preferred embodiments, at least one, several or all of the following conditions are met: ^ the pressure of the exhaust gas upon entry into the first catalyst bed is at most 5 bara, more preferably at most 4 bara; ^ the H2O content in the exhaust gas on entry into the first catalyst bed is at least 5 vol.%, more preferably at least 10 vol.%, even more preferably at least 15 vol.%, most preferably at least 20 vol.% and in particular at least 25 vol.%; ^ the NOX content in the exhaust gas on entry into the first catalyst bed is at least 500 ppmv, more preferably at least 1000 ppmv, even more preferably at least 1500 ppmv, most preferably at least 2000 ppmv, and in particular at least 2500 ppmv; ^ the N2O content in the exhaust gas on entry into the first catalyst bed is at most < 500 ppmv, more preferably at most 200 ppmv, even more preferably at most 100 ppmv, but at least 5 ppmv, preferably at least 10 ppmv, more preferably at least 50 ppmv; ^ the exhaust gas contains unburned residues of NH3 from the combustion of NH3 on entry into the first catalyst bed; ^ the N2O decomposition catalyst and / or the N2O reduction catalyst is present as a honeycomb body; ^ the NO X-reduction catalyst is in the form of a honeycomb body; ^ the first catalyst bed contains Fe zeolite; ^ the second catalyst bed contains Fe zeolite; ^ the exhaust gas flows through a temperature control device before entering the first catalyst bed and is temperature-controlled therein; ^ the NOX content at the outlet of the first catalyst bed is at most 1000 ppmv, more preferably at most 500 ppmv, even more preferably at most 300 ppmv, most preferably at most 100 ppmv; but preferably at least 10 ppmv, more preferably at least 20 ppm, even more preferably at least 40 ppmv, most preferably at least 100 ppmv, and in particular at least 250 ppmv; ^ the N2O content at the outlet of the first catalyst bed is at most 20 ppmv, more preferably at most 15 ppmv, even more preferably at most 10 ppmv, most preferably at most 5 ppmv and in particular at most 2 ppmv;^ after leaving the first catalyst bed and until entering the second catalyst bed, no intermediate cooling of the exhaust gas takes place; ^ the molar ratio of N2O:NOX on entering the first catalyst bed is at most 0.5, more preferably at most 0.2, even more preferably at most 0.1; ^ the molar ratio of N2O:NOX on leaving the first catalyst bed is at most 0.20, more preferably at most 0.1, even more preferably at most 0.05; ^ The injection of NH3 into the exhaust gas in the flow direction of the exhaust gas upstream of the first catalyst bed is optional; if injection is carried out, it is preferably substoichiometric with regard to the NO content Xat the inlet to the first catalyst bed; ^ the feeding of NH3 into the exhaust gas in the flow direction of the exhaust gas downstream of the first catalyst bed and upstream of the second catalyst bed is mandatory, preferably over-stoichiometric with regard to the total content of NOX and N2O at the inlet to the second catalyst bed.

[0370] The process described above using Fe-zeolite catalysts in two catalyst beds enables the complete or almost complete removal of large amounts of NO compared to classical DeNOX processes using V2O5 / TiO2 catalysts. X , without the risk of NH3 slippage; and - the simultaneous, complete or almost complete degradation of N2O at comparatively small catalyst volumes, ie at comparatively high space velocities.

[0371] This is achieved not only by the inventive operating mode but also by the oxidative properties of the Fe-zeolite catalysts used in the invention. Thus, in the first catalyst bed, the molar ratio of NO to NO2 is brought as close as possible to the thermodynamic equilibrium. Thus, the NO X The degree of oxidation (molar ratio of NO2 / (NO + NO2)) before entering the first catalyst bed is expected to be less than 5% due to the upstream NH3 combustion at very high temperatures and the slow establishment of equilibrium in the gas phase upon cooling of the exhaust gas. This is significantly below the thermodynamic equilibrium applicable for the inlet temperature of the first catalyst bed. However, this is very disadvantageous for efficient chemical reduction of NO. X , as this only removes a small part of the NO present in the exhaust gas Xcan be reduced according to an almost SCR and a large part of the NO X or the remaining NO must be removed according to the significantly slower normal SCR.

[0372] Due to the selected operating mode of limited NH3 dosing in the first catalyst bed and the ability of the Fe-zeolite catalysts to oxidize NO and to catalytically accelerate the equilibrium process, a significantly faster, i.e. more efficient, chemical reduction of NO is achieved in the first catalyst bed. X and at the same time the maximum possible NO X The oxidation level of the remaining NOX escaping is adjusted. This enables efficient chemical reduction of NOX in the second catalyst bed right from the start.

[0373] It was found that large amounts of NH3, which are necessary for the complete chemical reduction of high concentrations of NOX, inhibit the establishment of the NOX equilibrium on the Fe-zeolite catalyst, similar to water.

[0374] In addition, the chemical reduction of NO X as such, even at sufficiently high NH3 dosages, it is inhibited by NH3 itself. This means that, depending on temperature, catalyst quantity and NO content, X with increasing addition of NH3from a certain amount of NH3no further increase in NO X -degradation no longer occurs. With further increases in NH3 addition, a decrease in NOX degradation may even be observed, with a simultaneous occurrence of NH3 slip.

[0375] By chemical reduction of NO X Previously in the first catalyst bed, the chemical reduction of NO Xnecessary amount of NH3in the second catalyst bed is significantly reduced.

[0376] In this way, together with the above-described adjustment or permanent tracking of the NOX equilibrium, a very efficient chemical reduction of NOX is also possible in the second catalyst bed, even with the overstoichiometric dosing of NH3 according to the invention.

[0377] The fact that this occurs according to the invention without or only with a negligible NH3 slip of preferably at most 10 ppmv, more preferably at most 5 ppmv, even more preferably at most 3 ppmv, is also due to the oxidative properties of the Fe-zeolite catalysts used according to the invention. If the inlet temperature of the exhaust gas into the second catalyst bed is preferably at least 400°C, more preferably at least 425°C, even more preferably at least 450°C, the excess NH3 metered in within the limits of the invention is selectively oxidized to N2 and H2O by the residual oxygen content of the exhaust gas.

[0378] All of these advantages cannot be realized when using conventional V2O5 / TiO2-based SCR catalysts, such as those typically used for denitrification of exhaust gases from natural gas-fired reformers, in a single or multi-stage configuration. For stability reasons, these conventional SCR catalysts typically cannot be operated at temperatures above 400°C, which limits the achievable reaction rates of the degradation reaction. Furthermore, conventional SCR catalysts exhibit only very limited oxidation activity, so neither adjustment nor permanent tracking of the NOX balance is possible, nor do these catalysts enable effective and N2-selective oxidation of excess NH3. In fact, there is a risk of undesirable N2O formation.

[0379] In a preferred variant of the embodiments described above, the first catalyst bed and the second catalyst bed contain the same catalyst. In preferred embodiments, the second device with a second control valve for metering NH3 into the exhaust gas is omitted, wherein the spatial separation of the first catalyst bed from the second catalyst bed is preferably omitted - there is then in fact only one common catalyst bed, wherein preferably upstream of this common catalyst bed a first device with a first control valve for metering NH3 into the exhaust gas is arranged. the first device doses additional NH3 into the exhaust gas; preferably under feedforward control, ie the concentration of NO X, N2O, and NH3 in the exhaust gas upstream of the common catalyst bed are measured; taking into account the amount of exhaust gas entering the common catalyst bed, the additional amount of NH3 still required is calculated; and the calculated result (control variable) is used to change the control level of the first control valve in order to meter in the additional amount of NH3 still required. In such embodiments, an NH3 oxidation catalyst is preferably arranged downstream of the common catalyst bed to reduce possible NH3 slip. Simultaneous combustion of NH3 and CH4 - reduction of the hydrogen cyanide content

[0380] In preferred embodiments, in step (a) a mixture of CH4 and NH3 is burned with air and / or oxygen to produce an exhaust gas which, in addition to NOX and N2O, also contains CO2, CO and HCN.

[0381] In these cases, the first catalyst bed preferably assumes the additional function of catalytically splitting HCN by hydrolysis with water present in the exhaust gas into the products CO and NH3 according to HCN + H2O ↔ CO + NH3. The resulting products CO and NH3 can then be used as reducing agents for the removal of N2O and NOX in the exhaust gas, with NH3 being preferentially used for NOX reduction in the first catalyst bed and with CO being preferentially used for N2O reduction in the second catalyst bed.

[0382] Due to its toxicity, longevity in the atmosphere, and absorption in the infrared, HCN as a pollutant and greenhouse gas must be limited or eliminated in its concentration in exhaust gases. The fact that the inventive degradation of HCN on zeolite catalysts in the first catalyst bed with CO and NH3 produces decomposition products that are suitable as reducing agents for the further exhaust gas aftertreatment of NOX and N2O in the second catalyst bed completes the uniqueness of the inventive exhaust gas treatment on zeolite catalysts. Conventional SCR catalysts based on vanadium oxide exhibit almost no activity for HCN hydrolysis and are therefore unsuitable for removing HCN from exhaust gases. In this case, a downstream oxidation catalyst would have to be used. DeN2O-DeNO X

[0383] In further preferred embodiments, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream thereof, through which the exhaust gas flows one after the other; wherein reducing agent is added to the exhaust gas between the first reaction zone and the second reaction zone; wherein firstly in the first reaction zone, the N2O content in the exhaust gas is reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) (DeN2O stage); and In the second reaction zone, the NO content X in the exhaust gas by chemical reduction of NO X with reducing agent on a NO X -reduction catalyst (step (d)) (DeNO X-stage); wherein optionally the N2O content in the exhaust gas is further reduced by further decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)), or the device according to the invention is configured accordingly.

[0384] Preferably, no reducing agent is added to the exhaust gas before the first reaction zone, or the device according to the invention is configured accordingly.

[0385] Such a process is particularly preferred according to the invention. It allows the relative content of NOX and N2O to be initially adjusted without consuming reducing agent. While the absolute NOX content remains virtually unchanged in the first reaction zone, the N2O content in the exhaust gas is selectively reduced by decomposition. This can be done to the extent necessary to adjust the desired relative content of NOX and N2O. For economic reasons, the amount of N2O decomposition catalyst is preferably not selected so large that a quantitatively complete reduction of the N2O content in the exhaust gas occurs through decomposition (0 ppmv), but rather a compromise is found between the decomposition rate and the dimensioning of the N2O decomposition catalyst.

[0386] In preferred embodiments, the N2O decomposition catalyst in the first reaction zone comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structural type.

[0387] In other preferred embodiments, the N2O decomposition catalyst in the first reaction zone comprises a NOX-sensitive N2O decomposition catalyst according to the invention, which has already been described above.

[0388] In preferred embodiments, the NOx reduction catalyst in the second reaction zone comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structural type.

[0389] Preferably, the first reaction zone and the second reaction zone are operated at different temperature levels, or the device according to the invention is configured accordingly.

[0390] Preferably includes - the N2O decomposition catalyst in the first reaction zone produces a NO Xsensitive N2O decomposition catalyst; wherein the temperature of the exhaust gas in the first reaction zone is preferably at least 450°C, more preferably at least 500°C, even more preferably at least 550°C, most preferably at least 600°C, orthe device according to the invention is configured accordingly; and - the NOX reduction catalyst in the second reaction zone is a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably an iron or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI and / or MEL structure type; wherein the temperature of the exhaust gas in the second reaction zone is preferably at most 550°C, more preferably at most 500°C, even more preferably at most 450°C, most preferably at most 400°C; and wherein, in addition to the chemical reduction of NOX, a further reduction of the (residual) N2O content preferably takes place in the second reaction zone, by decomposition and / or chemical reduction, or the device according to the invention is configured accordingly.

[0391] Preferably, the space velocity in the first reaction zone is adjusted such that in the first reaction zone the N2O content in the exhaust gas is reduced by at most 95%, preferably by at most 90%, more preferably by at most 85%, based on the N2O content in the exhaust gas upon entry into the first reaction zone, or the device according to the invention is configured accordingly.

[0392] In preferred embodiments, the N2O content in the exhaust gas after leaving the first reaction zone and before entering the second reaction zone is at least 20 ppmv, more preferably at least 40 ppmv, even more preferably at least 60 ppmv, most preferably at least 80 ppmv and in particular at least 100 ppmv, or the device according to the invention is configured accordingly.

[0393] In preferred embodiments, the N2O content in the exhaust gas after leaving the first reaction zone and before entering the second reaction zone is at most 400 ppmv, more preferably at most 300 ppmv, even more preferably at most 200 ppmv, most preferably at most 100 ppmv and in particular at most 50 ppmv, or the device according to the invention is configured accordingly.

[0394] Preferably, the space velocity in the second reaction zone is adjusted such that a further reduction of the N2O content in the exhaust gas occurs in the second reaction zone by at least 30%, preferably by at least 40%, more preferably by at least 50%, based on the N2O content in the exhaust gas upon entry into the second reaction zone, or the device according to the invention is configured accordingly. Since reducing agent is present in the second reaction zone, the further reduction of the N2O content in the second reaction zone can be achieved both by decomposition on an N2O decomposition catalyst (step (c1)) as well as by chemical reduction with reducing agent on an N2O reduction catalyst (step (c2)), or the device according to the invention is configured accordingly.

[0395] Preferably, in the second reaction zone, a further reduction of the N2O content in the exhaust gas takes place by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)), or the device according to the invention is configured accordingly.

[0396] In addition, the NOX content is reduced in the second reaction zone by chemical reduction with a reducing agent on a NOX reduction catalyst, or the device according to the invention is configured accordingly. This reduction typically has rapid kinetics and, according to the invention, preferably proceeds practically quantitatively.

[0397] Regardless of the respective process control, the process according to the invention is preferably controlled or the device according to the invention is configured accordingly.

[0398] In preferred embodiments, depending on the design of the internal combustion engine, at least one parameter characteristic of the current operating state of the internal combustion engine is measured as the first measured variable for controlling the method according to the invention, or the device according to the invention is configured accordingly. This first measured variable or parameter is preferably selected from the group consisting of combustion temperature, NH3 consumption, rotational speed, and noise level of the internal combustion engine.

[0399] Depending on the nature of the exhaust gas leaving the internal combustion engine, in particular - NOX content in the exhaust gas; - degree of oxidation of the NOX in the exhaust gas; - N2O content in the exhaust gas; - content of other components in the exhaust gas, such as H2O, O2, and N2; - temperature of the exhaust gas; - pressure of the exhaust gas; and - volume flow of the exhaust gas; the process conditions can be optimized in order to bring about an efficient and economical reduction in the NOX and N2O content in the exhaust gas, or the device according to the invention is configured accordingly.

[0400] In preferred embodiments, therefore, for the control of the method according to the invention, at the outlet from the internal combustion engine and / or at the inlet into the exhaust gas treatment system, at least one parameter is measured as a second measured variable, either in addition to the first measured variable or instead of the first measured variable, which is characteristic of the current state of the exhaust gas before entering the exhaust gas treatment system, or the device according to the invention is accordingly configured. Preferably, this second measured variable or parameter is selected from the group consisting of NO content X in the exhaust gas; degree of oxidation of NO X in the exhaust gas; content of N2O in the exhaust gas; content of other components in the exhaust gas, such as H2O, O2, and N2; temperature of the exhaust gas; pressure of the exhaust gas; and volume flow of the exhaust gas, or the device according to the invention is configured accordingly.

[0401] In preferred embodiments, for the control of the method according to the invention, at least one parameter which is characteristic of the current state of the exhaust gas at the outlet of the exhaust gas treatment system is measured as a third measured variable at the outlet of the exhaust gas treatment system, either in addition to the first measured variable or instead of the first measured variable, and either in addition to the second measured variable or instead of the second measured variable, or the device according to the invention is configured accordingly. This third measured variable or the parameter is preferably selected from the group consisting of NOX content in the exhaust gas; degree of oxidation of NOX in the exhaust gas; N2O content in the exhaust gas; content of other components in the exhaust gas, such as H2O, O2, and N2; temperature of the exhaust gas; pressure of the exhaust gas; and volume flow of the exhaust gas, or the device according to the invention is configured accordingly.

[0402] In preferred embodiments, in particular when the exhaust gas treatment system comprises a first reaction zone and a second reaction zone through which the exhaust gas flows one after the other, wherein reducing agent is fed between the first reaction zone and the second reaction zone, for the control of the method according to the invention at the outlet from the first reaction zone and before entering the second reaction zone as a fourth measured variable, either in addition to the first measured variable or instead of the first measured variable, and either in addition to the second measured variable or instead of the second measured variable, and either in addition to the third measured variable or instead of the third measured variable, at least one parameter is measured which is characteristic of the current state of the exhaust gas after leaving the first reaction zone and before entering the second reaction zone, or the device according to the invention is configured accordingly.Preferably, this fourth measured variable or parameter is selected from the group consisting of NO content. X in the exhaust gas; degree of oxidation of NO X in the exhaust gas; content of N2O in the exhaust gas; content of other components in the exhaust gas, such as H2O, O2, and N2; temperature of the exhaust gas; pressure of the exhaust gas; and volume flow of the exhaust gas, or the device according to the invention is configured accordingly.

[0403] Depending on the first measured variable and / or the second measured variable and / or the third measured variable and / or the fourth measured variable, at least one manipulated variable is preferably changed to regulate or control the method according to the invention, or the device according to the invention is configured accordingly. Therefore, the method is preferably regulated or controlled based on the first measured variable and / or based on the second measured variable and / or based on the third measured variable. and / or based on the fourth measured variable by targeted change of the manipulated variable (control variable), preferably by targeted change of the added quantity of reducing agent, or the device according to the invention is configured accordingly.

[0404] With regard to preferred control variables, a distinction must be made between - conditions which cannot be changed at short notice or can only be changed with greater equipment expenditure, and - conditions which can be changed at short notice and are therefore better suited for control.

[0405] According to the invention, the following are preferred: - the dimensioning of the exhaust gas treatment device; - the type, amount and flow direction of the N2O decomposition catalyst and / or N2O reduction catalyst; - the type, amount and flow direction of the NOX reduction catalyst; - the type of reducing agent; - the pressure of the exhaust gas; - the position of the reducing agent feed; and - the arrangement of the first reaction zone and second reaction zone relative to one another are not manipulated variables, ie these parameters preferably remain constant during implementation of the method according to the invention, or the device according to the invention is configured accordingly.

[0406] However, these parameters can be selected or adjusted during the planning and design of the exhaust gas treatment system to allow for control within wide limits. This allows for responses to even short-term changes, for example, with regard to the exhaust gas to be treated. An efficient and economical reduction of the NOX and N2O content in the exhaust gas is ensured without undesirable breakthrough of reducing agent (so-called slip).

[0407] Preferred control variables according to the invention are: - the amount of reducing agent; - if applicable, the temperature of the exhaust gas; and - if applicable, the temperature of the catalysts.

[0408] Preferably, the exhaust gas leaves the exhaust gas treatment plant and has a residual content of NO Xof at most 20 ppmv, preferably at most 15 ppmv, more preferably at most 10 ppmv, even more preferably at most 7.5 ppmv, most preferably at most 5.0 ppmv, and in particular at most 2.5 ppmv, or the device according to the invention is configured accordingly.

[0409] Preferably, the exhaust gas leaves the exhaust gas treatment plant and has a residual N2O content of at most 20 ppmv, preferably at most 15 ppmv, more preferably at most 10 ppmv, more preferably at most 7.5 ppmv, most preferably at most 5.0 ppmv, and in particular at most 2.5 ppmv, or the device according to the invention is configured accordingly.

[0410] Preferred embodiments of the invention are schematically illustrated by Figures 1 to 5.

[0411] Figure 1 shows a particularly preferred DeN2O-DeNO XVariant with two catalyst beds without an additional NH3 oxidation catalyst. The internal combustion engine comprises, for example, a turbocharged reciprocating piston engine which, in the embodiment shown in the figure, is operated exclusively with ammonia as fuel (single fuel). Combustion air is supplied through an air manifold (1) to the suction side of the turbo compressor (2). Compressed air is fed to the cylinders of the reciprocating piston engine (8) via the air charge cooler (3) and the collector (4). Similarly, fuel from the ammonia tank (7) is supplied to the engine via the collector (6). Ammonia combustion takes place in the engine compartment, and the exhaust gas flows into the exhaust duct to the exhaust gas aftertreatment system essentially at the pressure built up by the exhaust turbine (14).

[0412] The exhaust gas treatment system comprises two spatially separated catalyst beds (12 and 13), preferably each containing an “Fe-zeolite catalyst”.

[0413] In the first catalyst bed (12) (located upstream of the second catalyst bed), a reduction of NOX and catalytic decomposition of N2O takes place, co-catalyzed by the (residual) NOX content present in the exhaust gas.

[0414] The reduction of NOX occurs through NH3 present in the exhaust gas (originates from the incomplete combustion of NH3 in the furnace or combustion device) and optionally additional NH3 added via the dosing device (10), up to a maximum of a predetermined residual value of NOX (sufficient to cause a co-catalytic effect on the decomposition of N2O that also takes place in the first bed). The addition of NH3 for NOX reduction is controlled using a so-called feedback control (11a). This means that a certain value for the NOX outlet concentration is specified as the target value (setpoint) and the actual outlet concentration of NOX after the first bed is measured (actual value). If there is a difference between the setpoint and actual value (control difference), the control level of a corresponding NH3 dosing valve (actuator) is adjusted to minimize the difference.In the case of relatively high residual ammonia concentrations in the exhaust gas flowing from the reciprocating engine (8) to the first catalyst bed (12) due to incomplete combustion, the exhaust gas metering device (10) closes completely. In borderline cases of engine design (incomplete combustion of the corresponding magnitude at all relevant engine operating points), it may also be obsolete and then omitted.

[0415] In the second catalyst bed (13) (located downstream of the first catalyst bed), (i) further, preferably practically complete, reduction of the residual concentration of NO X (originating from the first catalyst bed) by further addition of NH3 (dosing device (9)), whereby prefers the NO X-Degradation to a residual concentration of < 20 ppmv, preferably < 10 ppmv, more preferably < 5 ppmv, even more preferably < 2 ppmv. In addition, a further, also preferably practically complete N2O degradation takes place in the second catalyst bed by chemical reduction of the N2O with NH3 (this takes place in parallel or preferably after the complete NO X -reduction), wherein the N2O degradation preferably takes place to a residual concentration of < 20 ppmv, preferably < 10 ppmv, more preferably < 5 ppmv, even more preferably < 2 ppmv.

[0416] Preferably, the additional NH3 is added with the second device under feedforward control, ie the concentration of NO Xand optionally preferably of N2O and optionally preferably of NH3, each at the outlet of the first catalyst bed or optionally at the inlet to the second catalyst bed is measured; taking into account the amount of exhaust gas entering the second catalyst bed, the amount of NH3 required for NOX reduction and optionally preferably the sum of the amount of NH3 required for NOX reduction and N2O reduction is calculated using stored molar ratios (mol / mol) of NH3 / NOX and optionally preferably of NH3 / / N2O or factors derived therefrom; and using the calculated result (manipulated variable), the control level of the second control valve is changed in order to meter in the required amount of NH3.

[0417] According to the invention, the molar NH3 concentration [NH3] of the exhaust gas at the inlet to the second catalyst bed is preferably in the range from the sum of 0.7 x [N2O] and 1.0 x [NOX] to the sum of 4.0 x [N2O] and 2.0 x [NOX], more preferably in the range from the sum of 1.0 x [N2O] and 1.1 x [NOX] to the sum of 3.0 x [N2O] and 1.6 x [NOX], even more preferably in the range from the sum of 1.5 x [N2O] and 1.2 x [NOX] to the sum of 2.5 x [N2O] and 1.4 x [NOX], where [N2O] is the molar concentration of N2O and [NOX] is the molar concentration of NOX in the exhaust gas at the inlet to the second catalyst bed.

[0418] For feedforward control of the NH3 dosage into the second catalyst bed with regard to NOX reduction, a molar ratio of NH3 / NOX in the range of 1.0 to 2.0; preferably 1.1 to 1.6; more preferably 1.2 to 1.4 is selected.

[0419] For feedforward control of the NH3 dosage into the second catalyst bed with regard to N2O reduction, a molar ratio of NH3 / N2O in the range of 0.7 to 4.0; preferably 1.0 to 3.0; more preferably 1.5 to 2.5 is preferably selected.

[0420] A conventional feedback control of the NH3 addition, as in the first catalyst bed, is not preferred in the second catalyst bed according to the invention, since a complete NO X -reduction in the second catalyst bed is aimed for and thus no or only very small residual concentrations of NOX and N2O result, which would be very difficult to use as control variables.

[0421] The amount of NH3 added to the first catalyst bed is preferably selected according to the invention so that the NO X -Concentration at the outlet of the first catalyst bed is <1000 ppmv, preferably <500 ppmv, especially <100 ppmv. The minimum concentration of NO X at the exit of the first catalyst bed should preferably be >10 ppmv, preferably >20 ppmv, particularly preferably >40 ppmv. The expected specific NH3 consumption for NO X -Reduction in the first catalyst bed is 0.9 - 1.1 mol NH3 per mol reduced NO under the operating mode according to the invention X and is thus significantly smaller than the expected specific NH3 consumption in the second catalyst bed.

[0422] In the preferred embodiment of the invention shown here, no other NH3 oxidation catalysts are used apart from oxidation-active Fe-(Cu) zeolite catalysts. The operating mode of the internal combustion engine (8), which is preferably a reciprocating piston engine for marine propulsion, is therefore configured at the main operating point such that the exhaust gas flowing from the internal combustion engine (8) has maximum residual NH3 concentrations such that the above-mentioned molar ratios of NH3 / NOX and NH3 / N2O can be adjusted. In addition to the preferred lean combustion mode, further internal engine measures are conceivable, for example, advantageous control of the charge air cooling (3).

[0423] The amount of catalyst, ie the space velocity (= ratio of exhaust gas volume flow under standard conditions to catalyst volume) of the first catalyst bed is selected such that an N2O degradation of preferably >50%, particularly preferably >70% and most preferably >80% results.

[0424] In particular, the space velocity of the first catalyst bed and the added amount of NH3 are selected such that a molar ratio of NOX / N2O of > 5, preferably > 10, in particular > 20 results at the outlet of the first catalyst bed.

[0425] The space velocity of the first catalyst bed is preferably 5,000 h-1 to 100,000 h-1, in particular 10,000 h-1 to 50,000 h-1, very particularly preferably 15,000 h-1 to 45,000 h-1.

[0426] If the ratio of NOX / N2O at the outlet of the first catalyst bed is >10, in a preferred embodiment the total addition of NH3 into the second catalyst bed can be carried out solely in relation to the amount of NOX entering.

[0427] According to the invention, the temperature of the exhaust gas upon entry into the first catalyst bed is preferably set (by operating the internal combustion engine and / or additional cooling / heating measures) to a value greater than 300°C, preferably greater than 400°C, in particular greater than 450°C and at the same time less than 550°C, preferably less than 525°C and in particular less than 500°C.

[0428] Depending on the heat of the chemical reactions taking place in the catalyst beds, the inlet temperature of the exhaust gas into the first catalyst bed is selected so that the temperature of the exhaust gas at the outlet of the second catalyst bed does not exceed a value of 600°C, preferably 550°C, in particular 520°C.

[0429] The space velocity of the second catalyst bed is preferably 5,000 h-1 to 100,000 h-1, in particular 10,000 h-1 to 50,000 h-1, very particularly preferably 15,000 h-1 to 45,000 h-1.

[0430] The ratio of the catalyst volumes of the first to the second catalyst bed (V1 kat / V2 kat ) is preferably 1 / 2 to 20 / 1, particularly preferably 1 / 2 to 10 / 1, most particularly preferably 1 / 1 to 4 / 1.

[0431] The process described above using Fe-zeolite catalysts enables, compared to classical DeNO X-Process using V2O5 / TiO2 catalysts ^ the complete or almost complete decomposition of large quantities of NOX without the risk of NH3 slip, ^ the simultaneous, complete or almost complete decomposition of N2O contained in the exhaust gas; or whereby this can take place within the specified limits with the lowest possible supply of additional ammonia; ie the proportion of the N2O decomposition reaction can also be maximized. ^ and all this with relatively small catalyst volumes, ie at relatively high space velocities.

[0432] This is achieved, in addition to the above-described inventive operation, by the oxidative properties of the Fe-zeolite catalysts used in the invention. Thus, in the first catalyst bed, the molar ratio of NO to NO2 is brought as close as possible to the thermodynamic equilibrium. Thus, the NO X-Oxidation level (molar ratio of NO2 / (NO + NO2) before entering the first catalyst bed (due to the upstream NH3 combustion at very high temperatures and the slow establishment of equilibrium in the gas phase during cooling of the exhaust gas, as expected <5% and is therefore significantly below the thermodynamic equilibrium valid for the inlet temperature into the first catalyst bed. However, this is very disadvantageous for efficient NOX reduction, since only a small part of the NOX present in the exhaust gas can be removed according to an fast SCR and a large part of the NOX or the remaining NO must be removed according to the significantly slower normal SCR.

[0433] Due to the selected operating mode of limited NH3 dosing in the first catalyst bed and the ability of the Fe-zeolite catalysts to oxidize NO and catalytically accelerate the equilibrium process, a significantly faster, i.e., more efficient, NOX reduction is achieved in the first catalyst bed, while simultaneously adjusting the maximum possible NOX oxidation level of the escaping residual NOX. This also enables efficient NOX reduction in the second catalyst bed right from the start.

[0434] It was found that large amounts of NH3, such as these, lead to the complete reduction of high concentrations of NO X necessary, similar to water, the adjustment of the NO X -equilibrium on the Fe-zeolite catalyst.

[0435] In addition, the NO X-reduction as such is also inhibited by NH3 itself at sufficiently high dosages. This means that, depending on temperature, catalyst quantity and NO X -content with increasing addition of NH3from a certain amount of NH3no further increase of NO X -degradation no longer takes place. If the NH3 addition is further increased, a reduction in NO X -degradation can be observed with simultaneous NH3 slip.

[0436] By pre-reducing NOX in the first catalyst bed, the amount of NH3 required for NOX reduction in the second bed is significantly reduced.

[0437] In this way, together with the above-described adjustment or permanent tracking of the NOX equilibrium, a very efficient NOX reduction is also possible in the second bed, even with the over-stoichiometric dosing of NH3 according to the invention.

[0438] Figure 2 shows a particularly preferred DeN2O-DeNOX variant with two catalyst beds and an additional NH3 oxidation catalyst in an upstream, separate 3rd reaction zone as well as a bypass around the upstream oxidation catalyst.

[0439] In the preferred embodiment of the invention shown here, in addition to the oxidation-active Fe-(Cu) zeolite catalysts, another Pt group metal-free, particularly preferably noble metal-free, ammonia oxidation catalyst (16) is used. Such a variant is preferred when the operating mode of the internal combustion engine (8) (preferably a reciprocating piston engine for ship propulsion) cannot be configured in such a way that the previously mentioned advantageous molar ratios of NH3 / NOX and NH3 / N2O can be adjusted in the relevant operating conditions.

[0440] If, on the contrary, higher stoichiometric ammonia excesses already emerge from the internal combustion engine in relevant operating conditions and an inhibiting effect on the first reaction zone DeN2O-DeNOX cannot be excluded in relevant operating conditions, an upstream Pt group metal-free, particularly preferably noble metal-free oxidation catalyst (16), optionally with adjustable bypass (17), can be used:

[0441] Figure 3 shows a particularly preferred DeN2O-DeNOX variant with two catalyst beds and an additional NH3 oxidation catalyst in layered configuration, integrated into the second zone (the second catalyst bed) of the DeN2O-DeNO X -System.

[0442] Such a variant is preferred when the operating mode of the internal combustion engine (8) (preferably a reciprocating piston engine for ship propulsion) cannot be configured in such a way that the previously mentioned advantageous molar ratios of NH3 / NO X and NH3 / N2O NO X in the relevant operating conditions are adjustable, but an inhibiting effect due to high ammonia concentrations on the first reaction zone DeN2O-DeNO X can be excluded or is negligibly small in relevant operating conditions.

[0443] The integration of the Pt group metal-free, particularly preferably noble metal-free NH3 oxidation catalyst ultimately results in a broadening of the preferred ratios of NH3 / NO X and NH3 / N2O at the inlet to the second catalyst bed.

[0444] If the Pt group metal-free, particularly preferably noble metal-free NH3 oxidation catalyst is to represent the last reaction zone (the second catalyst bed) or be integrated into it for the purpose of better ammonia utilization, implementation in layered configuration is preferred, since an overall better selectivity of the oxidation of excess ammonia to nitrogen (instead of NOX and N2O) can be achieved.

[0445] Figure 4 shows a variant with a catalyst bed without an NH3 oxidation catalyst.

[0446] The internal combustion engine comprises, for example, a turbocharged reciprocating piston engine, which in the embodiment shown in the figure is operated exclusively with ammonia as fuel (single fuel):

[0447] Combustion air is supplied to the intake side of the turbocompressor (2) through an air manifold (1). Compressed air is fed to the cylinders of the reciprocating engine (8) via the air charge cooler (3) and the manifold (4). Similarly, fuel is supplied to the engine from the ammonia tank (7) via the manifold (6). Ammonia combustion takes place in the engine compartment, and the exhaust gas flows into the exhaust duct to the exhaust aftertreatment system at the pressure built up by the exhaust turbine (14).

[0448] The exhaust gas treatment system comprises a single catalyst bed (12), preferably containing an Fe-zeolite catalyst.

[0449] Figure 5 shows a variant with a catalyst bed containing a Pt group metal-free, preferably noble metal-free, additional NH3 oxidation catalyst.

[0450] The internal combustion engine comprises, for example, a turbocharged reciprocating piston engine which, in the embodiment shown in the figure, is operated exclusively with ammonia as fuel (single fuel). Combustion air is supplied through an air manifold (1) to the intake side of the turbo compressor (2). Compressed air is fed to the cylinders of the reciprocating piston engine (8) via the air charge cooler (3) and the collector (4). Similarly, fuel from the ammonia tank (7) is supplied to the engine via the collector (6). Ammonia combustion takes place in the engine compartment, and the exhaust gas flows into the exhaust duct to the exhaust aftertreatment system at the pressure built up by the exhaust turbine (14).

[0451] The exhaust gas treatment system comprises a single catalyst bed (12), preferably containing an Fe-zeolite catalyst, and a Pt-metal group-free NH3 oxidation catalyst, which are arranged in a layer configuration, wherein preferably the DeNO X-The N2O catalyst in the flow channel shape.

[0452] Particularly preferred embodiments of the invention are compiled below as sentences: Sentence 1: A method for reducing the content of NOX and N2O in the exhaust gas of an internal combustion engine powered by NH3, the method comprising the following steps: (a) burning NH3 to operate the internal combustion engine to produce an exhaust gas which comprises N2, H2O, NOX and N2O and which leaves the internal combustion engine; (b) transferring the exhaust gas to an exhaust gas treatment system; (c) reducing the content of N2O in the exhaust gas by (c1) decomposition of N2O on an N2O decomposition catalyst and / or (c2) chemical reduction of N2O with reducing agent on an N2O reduction catalyst; and (d) reducing the content of NOX in the exhaust gas by chemical reduction of NOX with reducing agent on an NOX reduction catalyst.Sentence 2: The process according to sentence 1, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOX reduction catalyst independently of one another comprise a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt, or copper; more preferably an iron- or copper-loaded zeolite; even more preferably, independently of one another, an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structural type. Sentence 3: The process according to sentence 1 or 2, wherein the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material. Sentence 4: The process according to any one of the preceding sentences, wherein the N2O decomposition catalyst and the NOX reduction catalyst are made of the same material. Sentence 5: The process according to any one of the preceding sentences, wherein the N2O reduction catalyst and the NO. X-reduction catalyst are made of the same material. Sentence 6: The process according to one of the preceding sentences, wherein the N2O decomposition catalyst, the N2O reduction catalyst and the NOX reduction catalyst are made of the same material. Sentence 7: The process according to one of the preceding sentences, wherein in step (a) the combustion of NH3 does not take place over a catalyst. Sentence 8: The process according to one of the preceding sentences, wherein in step (a) the combustion of NH3 takes place in a mixture with another combustible gas; preferably wherein the another combustible gas is selected from (i) H2; (ii) fossil fuels; preferably hydrocarbons and hydrocarbon mixtures, more preferably methane, ethane, propane, butane, natural gas, gasoline and / or diesel; (iii) alcohols, preferably methanol and / or ethanol; and mixtures thereof. Sentence 9: The process according to one of the preceding sentences, wherein in step (a) the combustion of NH3 takes place in a mixture with H2. Sentence 10: The process according to sentence 9, wherein step (a) comprises the substeps: (a1) thermal and / or catalytic cracking of NH3 to produce a cracked gas comprising N2, H2, and optionally residual NH3; (a2) optionally, mixing the cracked gas with further NH3 to produce a mixture comprising H2 and NH3; (a3) ​​combusting the cracked gas or the mixture. Sentence 11: The process according to sentence 9 or 10, wherein the proportion of H2 in the mixture with NH3 is at most 80 mol%, more preferably at most 70 mol%, even more preferably at most 60 mol%, most preferably at most 50 mol%, and in particular at most 40 mol%. Sentence 12: The process according to any one of sentences 9 to 11, wherein the proportion of H2 in the mixture with NH3 is at least 10 mol%, more preferably at least 20 mol%, even more preferably at least 30 mol%, most preferably at least 40 mol.-%, and in particular at least 50 mol%. Sentence 13: The process according to any one of sentences 9 to 12, wherein the molar ratio of H2:NH3 in the mixture is in the range from 45:55 to 90:10, preferably 50:50 to 85:15, more preferably 55:45 to 80:20, even more preferably 60:40 to 75:25, most preferably 65:35 to 70:30. Sentence 14: The process according to any one of sentences 9 to 13, wherein the air ratio λ is in the range from 0.9 to 1.7, more preferably 1.0 to 1.6, even more preferably 1.1 to 1.5, most preferably 1.2 to 1.4. Sentence 15: The method according to any one of Sentences 1 to 7, wherein in step (a), the combustion of NH3 occurs alone, so that NH3 is the only combustible gas that is burned. Sentence 16: The method according to any one of the preceding Sentences, wherein the internal combustion engine is mounted in a vehicle and serves to move the vehicle. Sentence 17: The method according to Sentence 16, wherein the vehicle is a ship.Sentence 18: The process according to any one of the preceding sentences, wherein the exhaust gas has a NOX content which is greater than the N2O content; preferably wherein the NOX content is at least twice as great, more preferably at least three times as great, even more preferably at least four times as great, most preferably at least seven times as great and in particular at least ten times as great as the N2O content; preferably wherein the molar ratio of NOX:N2O is more than 10:1, more preferably at least 20:1, even more preferably at least 30:1, most preferably at least 40:1, and in particular at least 50:1.Sentence 19: The process according to one of the preceding sentences, wherein the exhaust gas has an NO content which is greater than the N2O content; preferably wherein the NO content is at least twice as great, more preferably at least three times as great, even more preferably at least four times as great, most preferably at least seven times as great and in particular at least ten times as great as the N2O content. Sentence 20: The process according to one of the preceding sentences, wherein the exhaust gas has an NO2 content which is greater than the N2O content; preferably wherein the NO2 content is at least. twice as large, more preferably at least three times as large, even more preferably at least four times as large, most preferably at least seven times as large and in particular at least ten times as large as the N2O content. Sentence 21: The process according to one of the preceding sentences, wherein the exhaust gas has an N2O content which is greater than the NO content X; preferably wherein the N2O content is at least twice as high, more preferably at least three times as high, even more preferably at least four times as high, most preferably at least seven times as high and in particular at least ten times as high as the NOX content. Sentence 22: The process according to one of the preceding sentences, wherein the exhaust gas has an N2O content which is greater than the NO content; preferably wherein the N2O content is at least twice as high, more preferably at least three times as high, even more preferably at least four times as high, most preferably at least seven times as high and in particular at least ten times as high as the NO content.Sentence 23: The process according to one of the preceding sentences, wherein the exhaust gas has an N2O content which is greater than the NO2 content; preferably wherein the N2O content is at least twice as high, more preferably at least three times as high, even more preferably at least four times as high, most preferably at least seven times as high, and in particular at least ten times as high as the NO2 content. Sentence 24: The process according to one of the preceding sentences, wherein the exhaust gas has a NOX content of at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 30 ppmv, even more preferably at least 40 ppmv, and in particular at least 50 ppmv. Sentence 25: The process according to one of the preceding sentences, wherein the exhaust gas has a NOX content of at least 75 ppmv, preferably at least 100 ppmv, more preferably at least 150 ppmv, even more preferably at least 200 ppmv, and in particular at least 250 ppmv.Sentence 26: The process according to any one of the preceding sentences, wherein the exhaust gas has a NOX content of at least 500 ppmv, preferably at least 1000 ppmv, more preferably at least 2000 ppmv, even more preferably at least 3000 ppmv, and in particular at least 3500 ppmv. Sentence 27: The process according to any one of the preceding sentences, wherein the exhaust gas has a N2O content of at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 30 ppmv, even more preferably at least 40 ppmv, and in particular at least 50 ppmv. Sentence 28: The process according to any one of the preceding sentences, wherein the exhaust gas has a N2O content of at least 75 ppmv, preferably at least 100 ppmv, more preferably at least 150 ppmv, even more preferably at least 200 ppmv, and in particular at least 250 ppmv.Sentence 29: The process according to any one of the preceding sentences, wherein the exhaust gas has an N2O content of at least 500 ppmv, preferably at least 1000 ppmv, more preferably at least 2000 ppmv, even more preferably at least 3000 ppmv, and in particular at least 3500 ppmv. Sentence 30: The process according to one of the preceding sentences, wherein the exhaust gas has an H2O content of less than 2.0 vol.%. Sentence 31: The process according to one of the preceding sentences, wherein the exhaust gas has an H2O content of more than 4.0 vol.%; preferably at least 5.0 vol.%, more preferably at least 6.0 vol.%, even more preferably at least 7.0 vol.%, most preferably at least 8.0 vol.%, and in particular at least 9.0 vol.%. Sentence 32: The process according to one of the preceding sentences, wherein the exhaust gas has an H2O content of at least 10 vol.%; preferably at least 12 vol.%, more preferably at least 14 vol.%, even more preferably at least 16 vol.%, most preferably at least 18 vol.%, and in particular at least 20 vol.%. Sentence 33: The process according to one of the preceding sentences, wherein the exhaust gas has an H2O content in the range of 10±8 vol.%; preferably in the range of 10±7 vol%, more preferably in the range of 10±6 vol.-%, more preferably in the range of 10±5 vol.%, most preferably in the range of 10±4 vol.%, and in particular in the range of 10±3 vol.%. Sentence 34: The process according to any one of the preceding sentences, wherein the exhaust gas has an H2O content in the range of 15±8 vol.%; preferably in the range of 15±7 vol.%, more preferably in the range of 15±6 vol.%, even more preferably in the range of 15±5 vol.%, most preferably in the range of 15±4 vol.%, and in particular in the range of 15±3 vol.% Sentence 35: The process according to any one of the preceding sentences, wherein the exhaust gas has an H2O content in the range of 20±8 vol.%; preferably in the range of 20±7 vol.%, more preferably in the range of 20±6 vol.%, even more preferably in the range of 20±5 vol.%, most preferably in the range of 20±4 vol.%, and in particular in the range of 20±3 vol.%. Sentence 36: The process according to any one of the preceding sentences, wherein the exhaust gas has an H2O content in the range of 25±8 vol.%; preferably in the range of 25±7 vol.-%, more preferably in the range of 25±6 vol.%, even more preferably in the range of 25±5 vol.%, most preferably in the range of 25±4 vol.%, and in particular in the range of 25±3 vol.%. Sentence 37: The process according to any one of the preceding sentences, wherein the exhaust gas has an H2O content in the range of 30±8 vol.%; preferably in the range of 30±7 vol.%, more preferably in the range of 30±6 vol.%, even more preferably in the range of 30±5 vol.%, most preferably in the range of 30±4 vol.%, and in particular in the range of 30±3 vol.%. Sentence 38: The process according to any one of the preceding sentences, wherein the exhaust gas has an N2 content of at most 95 vol.%, preferably at most 90 vol.%, more preferably at most 85 vol.%, even more preferably at most 80 vol.%, most preferably at most 75 vol.%, and in particular at most 70 vol.%. Sentence 39: The process according to one of the preceding sentences, wherein the exhaust gas has an N2 content of at least 40 vol.%, preferably at least 50 vol.%, more preferably at least 60 vol.%, even more preferably at least 70 vol.%, most preferably at least 80 vol.%, and in particular at least 90 vol.%. Sentence 40: The process according to one of the preceding sentences, wherein the exhaust gas comprises further gaseous constituents; preferably selected from the group consisting of O2, CO, CO2, NH3, CH4, and mixtures thereof. Sentence 41: The process according to one of the preceding sentences, wherein the exhaust gas has a temperature of at least 500°C, more preferably at least 600°C, even more preferably at least 700°C, most preferably at least 800°C, and in particular at least 900°C upon leaving the internal combustion engine.Sentence 42: The method according to one of the preceding sentences, wherein the exhaust gas from the internal combustion engine has a temperature of at most 1100°C, more preferably at most 1000°C, even more preferably at most 900°C, most preferably at most 800°C, and in particular at most 700°C. Sentence 43: The method according to one of the preceding sentences, wherein the exhaust gas has a pressure of at most 1.5 bar upon leaving the internal combustion engine; preferably atmospheric pressure. Sentence 44: The method according to one of the preceding sentences, wherein the exhaust gas has an oxidation level of NOX of at least 10%, more preferably at least 20%, even more preferably at least 30%, most preferably at least 40%, and in particular at least 50% upon leaving the internal combustion engine.Sentence 45: The method according to one of the preceding sentences, wherein the exhaust gas, upon leaving the internal combustion engine, has a NOX oxidation level of at most 90%, more preferably at most 80%, even more preferably at most 70%, most preferably at most 60%, and in particular at most 50%. Sentence 46: The method according to one of the preceding sentences, wherein the exhaust gas, upon leaving the internal combustion engine, has an O2 content of less than 2.0 vol.%. Sentence 47: The method according to one of sentences 1 to 28, wherein the exhaust gas, upon leaving the internal combustion engine, has an O2 content of more than 4.0 vol.%. Sentence 48: The method according to one of the preceding sentences, wherein the exhaust gas, upon entering the exhaust gas treatment system, has a temperature of at least 300°C, more preferably at least 350°C, even more preferably at least 400°C, most preferably at least 425°C, and in particular at least 450°C.Sentence 49: The process according to any one of the preceding sentences, wherein the exhaust gas has a temperature of at least 500°C, more preferably at least 550°C, even more preferably at least 600°C, most preferably at least 625°C, and in particular at least 650°C upon entry into the exhaust gas treatment plant. Sentence 50: The method according to one of the preceding sentences, wherein the exhaust gas has a temperature of at most 825°C, more preferably at most 800°C, even more preferably at most 775°C, most preferably at most 750°C, and in particular at most 725°C upon entering the exhaust gas treatment plant. Sentence 51: The method according to one of the preceding sentences, wherein the exhaust gas has a temperature of at most 700°C, more preferably at most 650°C, even more preferably at most 600°C, most preferably at most 550°C, and in particular at most 500°C upon entering the exhaust gas treatment plant.Sentence 52: The method according to one of the preceding sentences, wherein the exhaust gas, upon entering the exhaust gas treatment system, has a temperature which is at least 20°C, preferably at least 40°C, more preferably at least 60°C, even more preferably at least 80°C, most preferably at least 100°C, and in particular at least 120°C lower than the temperature which the exhaust gas has upon leaving the internal combustion engine. Sentence 53: The method according to one of the preceding sentences, wherein the exhaust gas, upon entering the exhaust gas treatment system, has a pressure of at most 1.4 bara, preferably of at most 1.3 bara, more preferably of at most 1.2 bara. Sentence 54: The process according to any one of the preceding sentences, wherein the exhaust gas on entry into the exhaust gas treatment plant has an oxidation degree of NOX of at least 10%, more preferably at least 20%, even more preferably at least 30%, most preferably at least 40%, and in particular at least 50%.Sentence 55: The process according to one of the preceding sentences, wherein the exhaust gas, upon entering the exhaust gas treatment plant, has an NOX oxidation level of at most 90%, more preferably at most 80%, even more preferably at most 70%, most preferably at most 60%, and in particular at most 50%. Sentence 56: The process according to one of the preceding sentences, wherein the exhaust gas, upon entering the exhaust gas treatment plant, has an O2 content of less than 2.0 vol.%. Sentence 57: The process according to one of sentences 1 to 36, wherein the exhaust gas, upon entering the exhaust gas treatment plant, has an O2 content of more than 4.0 vol.%.Sentence 58: The process according to any one of the preceding sentences, wherein step (c) comprises reducing the content of N2O in the exhaust gas by (c1) decomposing N2O on an N2O decomposition catalyst; preferably wherein the N2O decomposition catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably an iron or copper loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL. Sentence 59: The process according to any one of the preceding sentences, wherein step (c) comprises reducing the N2O content in the exhaust gas by (c2) chemically reducing N2O with a reducing agent on an N2O reduction catalyst; preferably wherein the N2O reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL. Sentence 60: The process according to any one of the preceding sentences, wherein the reducing agent in step (c2) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.Sentence 61: The process according to any one of the preceding sentences, wherein the reducing agent in step (c2) is NH3, which is used in an amount of 0.5 to 2.0 molar parts, preferably 0.8 to 1.8 molar parts, based on a molar proportion of N2O to be chemically reduced. Sentence 62: The process according to any one of the preceding sentences, wherein the reducing agent in step (c2) is a hydrocarbon or a mixture of several hydrocarbons, which are preferably used in an amount of 0.2 to 1.0 molar parts, more preferably 0.2 to 0.7 molar parts, based on a molar proportion of N2O to be degraded.Sentence 63: The process according to any one of the preceding sentences, wherein the NOX reduction catalyst comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structure type. Sentence 64: The process according to any one of the preceding sentences, wherein the reducing agent in step (d) is selected from NH3, hydrocarbons, CO, H2, and mixtures thereof; preferably NH3. Sentence 65: The process according to any one of the preceding sentences, wherein the reducing agent in step (d) is NH3, which is used in an amount of 0.9 to 2.5 molar parts, preferably 1.0 to 1.4 molar parts, more preferably 1.0 to 1.2 molar parts, based on a molar part of NOX to be chemically reduced.Sentence 66: The process according to any one of the preceding sentences, wherein the reducing agent in step (c2) is the same as the reducing agent in step (d); preferably NH3. Sentence 67: The process according to any one of the preceding sentences, wherein the exhaust gas treatment plant comprises a first reaction zone and a second reaction zone arranged downstream thereof, through which the exhaust gas flows one after the other; wherein reducing agent is added to the exhaust gas upstream of the first reaction zone; wherein initially in the first reaction zone the NO content is X in the exhaust gas by chemical reduction of NO X with reducing agent on a NO X reduction catalyst; (step (d)); optionally additionally reducing the N2O content in the exhaust gas by decomposition of N2O on a N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)); wherein optionally further reducing agent is added to the exhaust gas upstream of the second reaction zone; and wherein subsequently in the second reaction zone the content of N2O in the exhaust gas is reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)); wherein optionally additionally the content of NO X in the exhaust gas by chemical reduction of NO X at a NO X-reduction catalyst is further reduced (step (d)). Sentence 68: The process according to sentence 67, wherein the NOX reduction catalyst in the first reaction zone comprises a classic SCR catalyst, preferably based on V2O5-WO3- / TiO2. Sentence 69: The process according to sentence 67 or 68, wherein the temperature of the exhaust gas on entry into the first reaction zone is at most 400°C, preferably at most 350°C. Sentence 70: The process according to any one of sentences 67 to 69, wherein the N2O decomposition catalyst in the second reaction zone comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; more preferably an iron or copper loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL.Sentence 71: The process according to any one of sentences 67 to 70, wherein the temperature of the exhaust gas on entry into the second reaction zone is in the range from 300 to 550°C, preferably 350 to 500°C. Sentence 72: The process according to any one of sentences 67 to 71, wherein the NOX reduction catalyst in the first reaction zone comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably a zeolite loaded with iron or copper of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL. Sentence 73: The process according to any one of Sentences 67 to 72, wherein the temperature of the exhaust gas upon entry into the first reaction zone is at least 300°C, more preferably at least 350°C, even more preferably at least 400°C.Sentence 74: The process according to any one of sentences 67 to 73, wherein the temperature of the exhaust gas upon entry into the first reaction zone is at most 600°C, more preferably at most 550°C. Sentence 75: The process according to any one of sentences 67 to 74, wherein the N2O decomposition catalyst in the second reaction zone comprises a NO. X Sentence 76: The process according to any one of Sentences 67 to 75, wherein the temperature of the exhaust gas upon entering the second reaction zone is at least 300°C, more preferably at least 350°C, even more preferably at least 400°C. Sentence 77: The process according to any one of Sentences 67 to 76, wherein the temperature of the exhaust gas upon entering the second reaction zone is at most 600°C, more preferably at most 550°C. Sentence 78: The process according to one of the sentences 67 to 77, wherein the exhaust gas after leaving the first reaction zone and before entering the second reaction zone has a content of NO Xin the range of 0 to 200 ppmv, preferably 1 to 200 ppmv, and an N2O content in the range of 200 to 2000 ppmv. Sentence 79: The process according to one of Sentences 67 to 78, wherein the offgas, after leaving the first reaction zone and before entering the second reaction zone, has an NO Xof at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv and an N2O content in the range of 200 to 2000 ppmv.Sentence 80: The method according to one of the preceding sentences, wherein the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream thereof, through which the exhaust gas flows one after the other; wherein reducing agent is added to the exhaust gas between the first reaction zone and the second reaction zone; wherein firstly in the first reaction zone the N2O content in the exhaust gas is reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)); and wherein subsequently in the second reaction zone the NOX content in the exhaust gas is reduced by chemical reduction of NOX with reducing agent on an NOX reduction catalyst (step (d)); wherein optionally in addition the N2O content in the exhaust gas is further reduced by further decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)).Sentence 81: The process according to sentence 80, wherein no reducing agent is added to the exhaust gas upstream of the first reaction zone. Sentence 82: The process according to sentence 80 or 81, wherein the N2O decomposition catalyst in the first reaction zone comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably a zeolite loaded with iron or copper of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL. Sentence 83: The process according to any one of sentences 80 to 82, wherein the N2O decomposition catalyst in the first reaction zone comprises a NO. XSentence 84: The process according to any one of Sentences 80 to 83, wherein the NOX reduction catalyst in the second reaction zone comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structure type. Sentence 85: The process according to any one of sentences 80 to 84, wherein the space velocities in the first reaction zone and in the second reaction zone are adjusted such that in the first reaction zone the N2O content in the exhaust gas is reduced by at most 95%, preferably at most 90%, based on the N2O content in the exhaust gas upon entry into the first reaction zone. Sentence 86: The process according to any one of sentences 80 to 85, wherein in the second reaction zone the N2O content in the exhaust gas is further reduced by at least 30%, preferably at least 40%, more preferably at least 50%, based on the N2O content in the exhaust gas upon entry into the second reaction zone. Clause 87: The process according to any one of clauses 80 to 86, wherein in the second reaction zone a further reduction of the N2O content in the exhaust gas takes place by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (c2)).Sentence 88: The process according to any one of sentences 67 to 87, wherein the first reaction zone and the second reaction zone are spatially separated. Sentence 89: The process according to any one of sentences 67 to 88, wherein the first reaction zone and the second reaction zone are spatially connected to one another. Sentence 90: The process according to any one of sentences 67 to 89, wherein the first reaction zone and the second reaction zone are arranged in a common vessel. Sentence 91: The process according to any one of sentences 67 to 90, wherein the temperature of the exhaust gas in the first reaction zone and in the second reaction zone is at most 500°C, preferably in the range from 350 to 450°C.Sentence 92: The process according to any one of sentences 67 to 91, wherein the space velocity in the first reaction zone is greater than in the second reaction zone; preferably by at least a factor of 1.2, more preferably at least a factor of 1.4, even more preferably at least a factor of 1.6, most preferably at least a factor of 1.8, and in particular at least a factor of 2.0. Sentence 93: The process according to any one of sentences 67 to 92, wherein the space velocity in the first reaction zone is smaller than in the second reaction zone; preferably by at least a factor of 1.5, more preferably at least a factor of 2.0, even more preferably at least a factor of 3.0, most preferably at least a factor of 5.0, and in particular at least a factor of 10.0. Sentence 94: The process according to any one of Sentences 67 to 93, wherein the temperature in the first reaction zone is at least 450°C, more preferably at least 500°C, even more preferably at least 550°C, most preferably at least 600°C, and especially at least 650°C.Sentence 95: The process according to any one of sentences 67 to 94, wherein the temperature in the second reaction zone is at most 600°C, more preferably at most 550°C, even more preferably at most 500°C, most preferably at most 450°C and in particular at most 400°C. Sentence 96: The process according to any one of sentences 67 to 95, wherein the temperature in the first reaction zone is relatively higher by at least 20°C, more preferably by at least 40°C, even more preferably by at least. 60°C, most preferably at least 80°C and in particular at least 100°C higher than the temperature in the second reaction zone. Sentence 97: The process according to any one of sentences 67 to 96, wherein the temperature in the first reaction zone is relatively higher by at least 120°C, more preferably by at least 140°C, even more preferably by at least 160°C, most preferably by at least 180°C and in particular by at least 200°C higher than the temperature in the second reaction zone. Sentence 98: The process according to any one of the preceding sentences, wherein the exhaust gas leaves the exhaust gas treatment plant and has a residual content of NO Xof at most 20 ppmv, preferably at most 15 ppmv, more preferably at most 10 ppmv, even more preferably at most 7.5 ppmv, most preferably at most 5.0 ppmv, and in particular at most 2.5 ppmv. Sentence 99: The process according to one of the preceding sentences, wherein the exhaust gas leaves the exhaust gas treatment plant and has a residual N2O content of at most 20 ppmv, preferably at most 15 ppmv, more preferably at most 10 ppmv, even more preferably at most 7.5 ppmv, most preferably at most 5.0 ppmv, and in particular at most 2.5 ppmv. Sentence 100: The process according to one of the preceding sentences, wherein the N2O decomposition catalyst is arranged in a radial basket through which flow is axial. Sentence 101: The process according to any one of the preceding sentences, wherein the N2O decomposition catalyst is particulate and comprises at least 50 particles.Sentence 102: The method according to one of the preceding sentences, wherein the N2O reduction catalyst is arranged in a radial basket through which flow occurs axially. Sentence 103: The method according to one of the preceding sentences, wherein the N2O reduction catalyst is particulate and comprises at least 50 particles. Sentence 104: The method according to one of the preceding sentences, wherein the NOX reduction catalyst is arranged in a radial basket through which flow occurs axially. Sentence 105: The method according to one of the preceding sentences, wherein the NOX reduction catalyst is particulate and comprises at least 50 particles. Sentence 106: The method according to one of the preceding sentences, wherein at least one parameter which is characteristic of the current operating state of the internal combustion engine is measured as a first measured variable in the internal combustion engine.Sentence 107: The method according to Sentence 106, wherein the first measured variable is selected from the group consisting of combustion temperature, NH3 consumption, rotational speed, and noise level of the internal combustion engine. Sentence 108: The method according to one of the preceding sentences, wherein, before entering the exhaust gas treatment system, at least one parameter is measured as a second measured variable that is characteristic of the current state of the exhaust gas before entering the exhaust gas treatment system. Sentence 109: The method according to sentence 108, wherein the second measured variable is selected from the group consisting of NO content X in the exhaust gas; degree of oxidation of NO Xin the exhaust gas; N2O content in the exhaust gas; content of other components in the exhaust gas, such as H2O, O2, and N2; temperature of the exhaust gas; pressure of the exhaust gas; and volume flow of the exhaust gas. Sentence 110: The method according to one of the preceding sentences, wherein at least one parameter is measured as a third measured variable at the outlet of the exhaust gas treatment system, which is characteristic of the current state of the exhaust gas at the outlet of the exhaust gas treatment system. Sentence 111: The method according to Sentence 110, wherein the third measured variable is selected from the group consisting of NO content X in the exhaust gas; degree of oxidation of NO Xin the exhaust gas; N2O content in the exhaust gas; content of other components in the exhaust gas, such as H2O, O2, and N2; temperature of the exhaust gas; pressure of the exhaust gas; and volume flow of the exhaust gas. Sentence 112: The method according to one of the preceding sentences, wherein the exhaust gas treatment plant comprises a first reaction zone and a second reaction zone, through which the exhaust gas flows one after the other, wherein reducing agent is fed between the first reaction zone and the second reaction zone, and wherein after leaving the first reaction zone and before entering the second reaction zone, at least one parameter is measured as a fourth measured variable, which is characteristic of the current state of the exhaust gas after leaving the first reaction zone and before entering the second reaction zone.Sentence 113: The method according to sentence 112, wherein the fourth measured variable is selected from the group consisting of NOX content in the exhaust gas; degree of oxidation of the NOX in the exhaust gas; N2O content in the exhaust gas; content of other components in the exhaust gas, such as H2O, O2, and N2; temperature of the exhaust gas; pressure of the exhaust gas; and volume flow of the exhaust gas. Sentence 114: The method according to one of sentences 106 to 113, wherein the control of the method is carried out on the basis of the first measured variable and / or on the basis of the second measured variable and / or on the basis of the third measured variable and / or on the basis of the fourth measured variable by specifically changing a manipulated variable. Sentence 115: The method according to sentence 114, wherein the manipulated variable is the metered amount of reducing agent. Sentence 116: A device comprising (i) an NH3-powered internal combustion engine; and (ii) an exhaust gas treatment system; wherein the device is configured to carry out the method according to one of the preceding sentences.

Claims

Claims:

1. A device comprising (i) an internal combustion engine configured to be driven by combustion of NH3, mounted in a ship and configured to move the ship; and (ii) an exhaust gas treatment system configured to reduce the NO X and N2O in an exhaust gas produced by combustion of the NH3 and which contains N2, H2O, NO Xand N2O; wherein the exhaust gas treatment system comprises - an N2O decomposition catalyst configured to decompose N2O; and / or an N2O reduction catalyst configured to chemically reduce N2O with a reducing agent; and - a NOX reduction catalyst configured to chemically reduce NOX with a reducing agent.

2. The device according to claim 1, wherein the exhaust gas comprises NH3 and wherein the exhaust gas treatment system is configured to reduce the content of NH3 in the exhaust gas.

3. The device according to claim 1 or 2, wherein the exhaust gas treatment system comprises an NH3 oxidation catalyst configured to chemically oxidize NH3 with O2; preferably to chemically oxidize NH3 with O2 to N2 and H2O. 4.The device according to any one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOX reduction catalyst and / or the NH3 oxidation catalyst independently of one another comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably, independently of one another, an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structure type.

5. The device according to claim 3 or 4, wherein the NH3 oxidation catalyst is an iron- or copper-loaded zeolite; preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structure type.

6. The device according to claim 5, which contains no further NH3 oxidation catalyst besides the iron- or copper-loaded zeolite.

7. The device according to claim 5 or 6, wherein the NH3 oxidation catalyst is an iron-loaded zeolite catalyst and has a molar ratio of iron to zeolitic aluminum n(Fe) / n(Al) of less than 0.50 to greater than 0.05; preferably less than 0.40 to greater than 0.05, more preferably less than 0.25 to greater than 0.05, even more preferably less than 0.15 to greater than 0.

05.

8. The device according to any one of claims 5 to 7, wherein the NH3 oxidation catalyst is a copper-loaded zeolite catalyst and has a molar ratio of copper to zeolitic aluminum n(Cu) / n(Al) of less than 1.00 to greater than 0.10; preferably less than 0.80 to greater than 0.10, more preferably less than 0.50 to greater than 0.10, even more preferably less than 0.30 to greater than 0.

10. 9.The device according to one of claims 3 to 8, wherein the NH3 oxidation catalyst is configured for the selective oxidation of NH3 with O2 to N2 and H2O and is filled as a particulate bed, the particles of which have an equivalent diameter, which is defined as the diameter of a spherical particle of the same volume, of 3.5 to 5.5 mm and wherein the ratio of the outer, geometrically detectable surface of the particles to the volume of the particulate bed is 1000 m2 / m3 to 1500 m2 / m3, in an amount of 8.0±0.5 mL in an isothermally operated, axially flowing tubular reactor with an inner diameter of 20±3 mm, subjected to a volume flow of a gas mixture consisting of 500±50 ppmv NH3, 2.5±0.1 vol% O2 and 0.30±0.05 vol% H2O in N2 at a space velocity of 10 based on standard conditions (0°C; 1.01325 bara).000 ± 500 h-1, a total pressure of 6 ± 0.5 bara and a temperature of 380°C ± 5 K, an NH3 conversion of at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80%, in particular at least 90%.

10. The device according to one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOX reduction catalyst and / or the NH3 oxidation catalyst independently of one another have a honeycomb-shaped monolithic structure.

11. The device according to one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NO. X -reduction catalyst and / or NH3 oxidation catalyst are independently present in the form of pellets; preferably in the form of extruded pellets.

12. The device according to any one of the preceding claims, wherein the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material.

13. The device according to any one of the preceding claims, wherein the N2O decomposition catalyst and the NOx reduction catalyst are made of the same material.

14. The device according to any one of the preceding claims, wherein the N2O reduction catalyst and the NO X-reduction catalyst are made of the same material.

15. The device according to any one of the preceding claims, wherein the N2O decomposition catalyst, the N2O reduction catalyst, and the NOX reduction catalyst are made of the same material.

16. The device according to any one of claims 3 to 15, wherein the NH3 oxidation catalyst and the N2O decomposition catalyst are made of the same material.

17. The device according to any one of claims 3 to 16, wherein the NH3 oxidation catalyst and the N2O reduction catalyst are made of the same material.

18. The device according to any one of claims 3 to 17, wherein the NH3 oxidation catalyst and the NOX reduction catalyst are made of the same material.

19. The device according to any one of claims 3 to 18, wherein the NH3 oxidation catalyst, the NOx reduction catalyst, and the N2O decomposition catalyst are made of the same material. 20.The device according to one of the preceding claims, which, in addition to the N2O decomposition catalyst and / or N2O reduction catalyst and the NOX reduction catalyst, comprises an NH3 oxidation catalyst.

21. The device according to claim 20, wherein the NH3 oxidation catalyst is selected from noble metal-containing catalysts, wherein the noble metals are preferably selected from platinum group metals.

22. The device according to claim 20 or 21, wherein the NH3 oxidation catalyst is platinum group metal-free, more preferably noble metal-free; preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst.

23. The device according to any one of claims 20 to 22, wherein the NH3 oxidation catalyst is selected from - cobalt-containing catalysts; in particular Co3O4; mixed oxides derived from Co3O4 (Co 3-yMyO4), where M is preferably selected from Zn, Cu, Fe, Mn and V; cobalt-loaded zeolites, preferably of the structure type MFI, BEA, FER, Mor, FAU, CHA, or AFI; - manganese-containing catalysts; in particular MnO X with x = 1-2; of MnO X derived mixed oxides (Mn x-y M y O x), where M is preferably selected from Zn, Cu, Fe and Mn; manganese-loaded zeolites, preferably of the structure type MFI, BEA, FER, Mor, FAU, CHA or AFI; - copper-containing catalysts; in particular CuOX with x = 0.5-1; mixed oxides derived from CuOX (Cux-yMyOx), where M is preferably selected from Zn, Co, Fe and Mn; copper-loaded zeolites, preferably of the structure type MFI, BEA, FER, Mor, FAU, CHA, AFI; - silver-containing catalysts; in particular supported, preferably supported on Al2O3, TiO2, or SiO2.

24. The device according to one of the preceding claims, wherein the combustion of NH3 does not take place on a catalyst.

25. The device according to one of the preceding claims, wherein the internal combustion engine comprises a reciprocating piston engine; preferably a reciprocating piston engine with compression ignition. 26.Device according to one of the preceding claims, wherein the internal combustion engine comprises a reciprocating piston engine, preferably a reciprocating piston engine with a turbocharger comprising a turbocompressor and an exhaust gas turbine.

27. The device according to claim 26, wherein, in the flow direction of the exhaust gas, all components of the exhaust gas treatment system are arranged upstream of the exhaust gas turbine.

28. The device according to one of the preceding claims, wherein the internal combustion engine is an ammonia dual-fuel engine.

29. The device according to one of the preceding claims, wherein the internal combustion engine comprises an emission gas recirculation system.

30. The device according to one of the preceding claims, wherein the internal combustion engine is configured to burn NH3 in a mixture with another combustible gas; preferably wherein the another combustible gas is selected from (i) H2; (ii) fossil fuels; preferably hydrocarbons and hydrocarbon mixtures, more preferably methane, ethane, propane, butane, natural gas, gasoline and / or diesel; (iii) alcohols, preferably methanol and / or ethanol; and mixtures thereof.

31. The device according to one of the preceding claims, wherein the internal combustion engine is configured to burn NH3 in a mixture with H2 and / or natural gas; preferably NH3 in a mixture with H2.

32. The device according to claim 30 or 31, wherein the proportion of H2 in the mixture with NH3 is at most 80 mol%, more preferably at most 70 mol%, even more preferably at most 60 mol%, most preferably at most 50 mol%, and in particular at most 40 mol%. 33.The device according to any one of claims 30 to 32, wherein the proportion of H2 in the mixture with NH3 is at least 10 mol%, more preferably at least 20 mol%, even more preferably at least 30 mol%, most preferably at least 40 mol%, and in particular at least 50 mol%.

34. The device according to any one of claims 30 to 33, wherein the molar ratio of H2:NH3 in the mixture is in the range from 45:55 to 90:10, preferably 50:50 to 85:15, more preferably 55:45 to 80:20, even more preferably 60:40 to 75:25, most preferably 65:35 to 70:

30.

35. The device according to any one of claims 30 to 34, which comprises a cracking device for the thermal and / or catalytic cracking of NH3.

36. The apparatus of claim 35, wherein the cracking device and the internal combustion engine are configured such that the combustion of NH3 in the internal combustion engine provides the energy for the cracking of NH3 in the cracking device. 37.The apparatus of claim 35 or 36, wherein the cracking device and the internal combustion engine are configured such that the cracking of NH3 in the cracking device provides the further combustible gas for combustion in admixture with NH3 in the internal combustion engine.

38. The device according to any one of claims 35 to 37, wherein the splitting device is arranged downstream of an NH3 reservoir and upstream of an NH3 injection of the internal combustion engine in the flow direction of NH3.

39. The device according to any one of claims 1 to 29, wherein the combustion of NH3 occurs alone, so that NH3 is the only combustible gas that is burned.

40. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the combustion of NH3 accounts for at least 90% of the total energy recovered; preferably at least 95%, more preferably at least 96%, even more preferably at least 97%, most preferably at least 98%, and in particular at least 99%. 41.The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the air ratio λ during combustion is in the range from 0.9 to 1.7, preferably 1.05 to 1.7, more preferably 1.0 to 1.6, even more preferably 1.1 to 1.5, most preferably 1.2 to 1.

4.

42. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the air ratio λ during combustion is at least 1.05; preferably at least 1.10, more preferably at least 1.15, even more preferably at least 1.20, most preferably at least 1.25, and in particular at least 1.

20.

43. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the air ratio λ during combustion is at least 1.25; preferably at least 1.30, more preferably at least 1.35, even more preferably at least 1.40, most preferably at least 1.45, and especially at least 1.

50. 44.The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas comprises further gaseous components; preferably selected from the group consisting of O2, CO, CO2, NH3, CH4 and mixtures thereof.

45. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas comprises NH3.

46. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a molar ratio of NH3:NO. X of at most 5.0; preferably at most 4.5, more preferably at most 4.0, even more preferably at most 3.5, most preferably at most 3.0, and in particular at most 2.

5.

47. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a molar ratio of NH3: NO Xof at most 2.3; preferably at most 2.1, more preferably at most 1.9, even more preferably at most 1.7, most preferably at most 1.5, and in particular at most 1.

3.

48. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a content of NO X which is greater than the content of N2O; preferably wherein the content of NO Xat least twice as large, more preferably at least three times as large, even more preferably at least four times as large, most preferably at least seven times as large, and in particular at least ten times as large as the N2O content; preferably wherein the molar ratio of NOX:N2O is more than 10:1, more preferably at least 20:1, even more preferably at least 30:1, most preferably at least 40:1, and in particular at least 50:

1.

49. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has an NO content which is greater than the N2O content; preferably wherein the NO content is at least twice as large, more preferably at least three times as large, even more preferably at least four times as large, most preferably at least seven times as large, and in particular at least ten times as large as the N2O content. 50.The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a NO2 content which is greater than the N2O content; preferably wherein the NO2 content is at least twice as great, more preferably at least three times as great, even more preferably at least four times as great, most preferably at least seven times as great, and in particular at least ten times as great as the N2O content.

51. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a NOX content of at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 30 ppmv, even more preferably at least 40 ppmv, and in particular at least 50 ppmv.

52. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a NO content. Xof at least 75 ppmv, preferably at least 100 ppmv, more preferably at least 150 ppmv, even more preferably at least 200 ppmv, and in particular at least 250 ppmv.

53. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has a content of NO Xof at least 500 ppmv, preferably at least 1000 ppmv, more preferably at least 2000 ppmv, even more preferably at least 3000 ppmv, and in particular at least 3500 ppmv.

54. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has an N2O content of at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 30 ppmv, even more preferably at least 40 ppmv, and in particular at least 50 ppmv.

55. The device according to any one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has an N2O content of at least 75 ppmv, preferably at least 100 ppmv, more preferably at least 150 ppmv, even more preferably at least 200 ppmv, and in particular at least 250 ppmv. 56.The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has an NH3 content of at most 35,000 ppmv; preferably at most 30,000 ppmv, more preferably at most 25,000 ppmv, even more preferably at most 20,000 ppmv, most preferably at most 15,000 ppmv, and in particular at most 10,000 ppmv.

57. The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has an NH3 content of at most 9,000 ppmv; preferably at most 8,000 ppmv, more preferably at most 7,000 ppmv, even more preferably at most 6,000 ppmv, most preferably at most 5,000 ppmv, and in particular at most 4,000 ppmv. 58.The device according to one of the preceding claims, wherein the internal combustion engine is configured such that the exhaust gas has an NH3 content of at most 3500 ppmv; preferably at most 3000 ppmv, more preferably at most 2500 ppmv, even more preferably at most 2000 ppmv, most preferably at most 1500 ppmv, and in particular at most 1000 ppmv 59. The device according to one of the preceding claims, wherein the device is configured such that the exhaust gas has an oxidation level of NO upon entering the exhaust gas treatment system. X of at least 10%, more preferably at least 20%, even more preferably at least 30%, most preferably at least 40%, and in particular at least 50%.

60. The device according to any one of the preceding claims, wherein the device is configured such that the exhaust gas, upon entering the exhaust gas treatment system, has an oxidation level of NO X of at most 90%, more preferably at most 80%, even more preferably at most 70%, most preferably at most 60%, and in particular at most 50%; preferably at most 15%, more preferably at most 12.5%, even more preferably at most 10%, most preferably at most 7.5%, and in particular at most 5.0%.

61. The device according to any one of the preceding claims, wherein the device is configured such that the exhaust gas has an O2 content of less than 2.0 vol.% upon entering the exhaust gas treatment system.

62. The device according to any one of the preceding claims, wherein the device is configured such that the exhaust gas has an O2 content of at least 3.0 vol.% upon entering the exhaust gas treatment system; preferably at least 3.1 vol.%, more preferably at least 3.2 vol.%, even more preferably at least 3.3 vol.%, most preferably at least 3.4 vol.%, and especially at least 3.5 vol.%. 63.The device according to any one of the preceding claims, wherein the device is configured such that the exhaust gas has an O2 content of more than 4.0 vol.% upon entering the exhaust gas treatment system.

64. The device according to any one of the preceding claims, wherein reducing the N2O content in the exhaust gas comprises decomposing N2O over an N2O decomposition catalyst; preferably wherein the N2O decomposition catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular iron, cobalt, or copper; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI, and / or MEL. 65.The device according to any one of the preceding claims, wherein reducing the N2O content in the exhaust gas comprises chemical reduction of N2O with reducing agent on an N2O reduction catalyst; preferably wherein the N2O reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL.

66. The device according to any one of the preceding claims, wherein the reducing agent for N2O is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

67. The device according to any one of the preceding claims, wherein the reducing agent for N2O is NH3, which is used in an amount of 0.5 to 2.0 molar parts, preferably 0.8 to 1.8 molar parts, based on a molar part of N2O to be chemically reduced.

68. The device according to any one of the preceding claims, wherein the reducing agent for N2O is a hydrocarbon or a mixture of several hydrocarbons, which are preferably used in an amount of 0.2 to 1.0 molar parts, more preferably 0.2 to 0.7 molar parts, based on a molar part of N2O to be degraded. 69.The device according to any one of the preceding claims, wherein the NOx reduction catalyst comprises a zeolitic material; preferably a transition metal (including lanthanide), in particular iron, cobalt, or copper-loaded zeolite; more preferably an iron- or copper-loaded zeolite; even more preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI, and / or MEL structural type.

70. The device according to any one of the preceding claims, wherein the reducing agent for NOx is selected from NH3, hydrocarbons, CO, H2, and mixtures thereof; preferably NH3.

71. The device according to any one of the preceding claims, wherein the reducing agent for NOX is NH3, which is used in an amount of 0.9 to 2.5 molar parts, preferably 1.0 to 1.4 molar parts, more preferably 1.0 to 1.2 molar parts, based on a molar part of NOX to be chemically reduced. 72.The device according to any one of the preceding claims, wherein the reducing agent for N2O is the same as the reducing agent for NOX; preferably NH3.

73. The device according to any one of the preceding claims, wherein the exhaust gas treatment plant contains a single reaction zone which comprises - as N2O decomposition catalyst and / or N2O reduction catalyst and - as NH3 reduction catalyst, a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron or copper; even more preferably an iron or copper loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL; and. wherein in the flow direction of the exhaust gas upstream of the single reaction zone a device for dosing reducing agent for N2O and / or NO Xinto the exhaust gas.

74. The device according to claim 73, wherein the device for metering reducing agent is a device for metering NH3.

75. The device according to claim 73 or 74, wherein in the flow direction of the exhaust gas upstream of the single reaction zone there is a further device for metering reducing agent for N2O and / or NO Xinto the exhaust gas.

76. The device according to claim 75, wherein the further device for metering reducing agent is a device for metering natural gas.

77. The device according to one of claims 73 to 76, wherein in the flow direction of the exhaust gas upstream of the single reaction zone there is arranged a further reaction zone which comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration; Most preferably defined as in any one of claims 3 to 13.

78. The device according to claim 77, wherein the device comprises a controllable bypass around the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst, preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst. 79.The device according to claim 78, wherein, upstream of the single reaction zone in the flow direction of the exhaust gas, a device is arranged for measuring the concentration of NH3, NOX, or N2O in the exhaust gas; preferably of NH3, NOX, and N2O; and wherein the opening of the bypass is controllable or regulatable.

80. The device according to any one of claims 73 to 79, wherein, downstream of the single reaction zone in the flow direction of the exhaust gas, a further reaction zone is arranged, which comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron- or copper-loaded zeolite catalyst; even more preferably in a layered configuration; most preferably defined as in any one of claims 3 to 13.

81. The device according to claim 80, wherein the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst is arranged upstream of an exhaust gas turbine in the flow direction of the exhaust gas.

82. The device according to claim 80, wherein the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst;A preferred NH3-oxidation-active, iron- or copper-loaded zeolite catalyst is arranged downstream of an exhaust gas turbine in the flow direction of the exhaust gas.

83. The device according to claim 81 or 82, wherein the single reaction zone is arranged upstream of the exhaust gas turbine in the flow direction of the exhaust gas.

84. The device according to any one of claims 1 to 72, wherein the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream of the exhaust gas in the flow direction, which are configured such that the exhaust gas flows through them one after the other; wherein the first reaction zone and the second reaction zone each independently comprise a zeolitic material as an N2O decomposition catalyst and / or N2O reduction catalyst and / or as an NH3 reduction catalyst; preferably a zeolite loaded with a transition metal (including lanthanide), in particular with iron, cobalt, or copper;more preferably a zeolite loaded with iron or copper; even more preferably a zeolite loaded with iron or copper of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL; and wherein, in the flow direction of the exhaust gas, downstream of the first reaction zone and upstream of the second reaction zone, a device for metering reducing agent for N2O and / or NOX into the exhaust gas is arranged.

85. The device according to claim 84, wherein the device for metering reducing agent is a device for metering NH3.

86. The device according to claim 84 or 85, wherein, in the flow direction of the exhaust gas, upstream of the single reaction zone, a further device for metering reducing agent for N2O and / or NO; X is arranged in the exhaust gas.

87. The device according to claim 86, wherein the further device for metering reducing agent is a device for metering natural gas.

88. The device according to one of claims 84 to 87, wherein in the flow direction of the exhaust gas upstream of the first reaction zone an additional device for dosing reducing agent for N2O and / or NO Xis arranged in the exhaust gas.

89. The device according to claim 88, wherein the additional device for dosing reducing agent is a device for dosing NH3.

90. The device according to one of claims 84 to 89, wherein - the first reaction zone comprises a copper-loaded zeolite; preferably a copper-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL; and - the second reaction zone comprises an iron-loaded zeolite; preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, AEI and / or MEL.

91. The device according to one of claims 84 to 90, wherein in the flow direction of the exhaust gas, downstream of the first reaction zone and upstream of the second reaction zone, a device for measuring the concentration in the exhaust gas of NH3, NOX or N2O is arranged; preferably by NH3 and NOX and N2O. 92.The device according to claim 91, wherein at least one device selected from the device for metering reducing agent, the optionally present further device for metering reducing agent, and the optionally present additional device for metering reducing agent is controllable or regulatable; preferably by feedforward control; as a function of the measured concentration in the exhaust gas of NH3, NOX or N2O; preferably of NH3 and NOX and N2O.

93. The device according to one of claims 84 to 92, wherein in the flow direction of the exhaust gas upstream of the first reaction zone there is arranged a device for measuring the concentration in the exhaust gas of NH3, NOX or N2O; preferably of NH3 and NOX and N2O.

94. The device according to claim 93, wherein at least one device selected from the device for metering reducing agent, the optionally present further device for metering reducing agent, and the optionallyexisting additional device for dosing reducing agent is controllable or adjustable; preferably by feedforward control; depending on the measured concentration of NH3, NO in the exhaust gas. X or N2O; preferably NH3 and NO X and N2O.

95. The device according to one of claims 84 to 94, wherein in the flow direction of the exhaust gas downstream of the first reaction zone and upstream of the second reaction zone there is arranged a further reaction zone which comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron or copper-loaded zeolite catalyst; even more preferably in a layer configuration; most preferably defined as in one of claims 3 to 9.

96. The device according to one of claims 84 to 95, wherein in the flow direction of the exhaust gas downstream of the first reaction zone and upstream of the second reaction zone and upstream of the device for metering reducing agent and anyexisting further device for dosing reducing agent, a further reaction zone is arranged which comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron or copper-loaded zeolite catalyst; even more preferably in a layered configuration; most preferably defined as in one of claims 3 to 9.

97. The device according to one of claims 84 to 96, wherein in the flow direction of the exhaust gas downstream of the second reaction zone there is arranged a further reaction zone which comprises an NH3 oxidation catalyst; preferably a platinum group metal-free, more preferably noble metal-free NH3 oxidation catalyst; more preferably an NH3 oxidation-active, iron or copper-loaded zeolite catalyst; even more preferably in a layered configuration; most preferably as defined in any one of claims 3 to 9. 98.The device according to any one of claims 95 to 97, wherein the device comprises a controllable bypass around the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst, preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst.

99. The device according to claim 98, wherein a device for measuring the concentration of NH3 and NO in the exhaust gas is arranged upstream of the first reaction zone or upstream of the second reaction zone in the flow direction of the exhaust gas. X or N2O; preferably NH3 and NO X and N2O; and wherein the opening of the bypass is controllable or adjustable.

100. The device according to any one of claims 95 to 99, wherein the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst is arranged upstream of an exhaust gas turbine in the flow direction of the exhaust gas.

101. The device according to claims 95 to 99, wherein the preferably platinum group metal-free, preferably noble metal-free NH3 oxidation catalyst; preferably NH3 oxidation-active, iron- or copper-loaded zeolite catalyst is arranged downstream of an exhaust gas turbine in the flow direction of the exhaust gas.

102. The device according to claim 100 or 101, wherein the first reaction zone is arranged upstream of the exhaust gas turbine in the flow direction of the exhaust gas.

103. The device according to any one of claims 100 to 102, wherein the second reaction zone is arranged upstream of the exhaust gas turbine in the flow direction of the exhaust gas. 104.The device according to one of the preceding claims, wherein the exhaust gas treatment system comprises at least one additional component selected from diesel oxidation catalysts, lean NOX trap catalysts, NOX absorption components, non-catalytic particulate filters, and catalytic particulate filters; preferably wherein all additional components are arranged upstream of the second reaction zone in the flow direction of the exhaust gas.

105. The method according to one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst as well as the NOX reduction catalyst and any NH3 oxidation catalyst present are present independently of one another as monolithic catalyst elements with parallel channels, preferably as monolithic honeycomb bodies.

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