Reduction of NOX and n2o in the exhaust gas of firing systems operated using nh3, in particular gas turbines

Abstract

The invention relates to the reduction of the content of NOX and N2O in the exhaust gas of a firing system operated using NH3, in particular a gas turbine operated using NH3.

Description

Reduction of NOx and N2O in the exhaust gases of NH3-fired combustion plants, in particular gas turbines

[0001] Priorities are claimed from European patent application No. 22 216 421.2, filed on 23 December 2022, and from European patent application No. 23 165 192.8, filed on 29 March 2023.

[0002] The invention relates to the reduction of the NOx and N2O content in the exhaust gas of a combustion plant operated with NH3, in particular of a gas turbine operated with NH3.

[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] 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.

[0007] EP 2 378 097 B1 relates to an engine driven by ammonia, wherein a NOx selective reduction catalyst is arranged in an exhaust passage of the engine, which catalyst can selectively reduce NOx contained in an exhaust gas in the presence of ammonia.

[0008] EP 3 517 757 A1 relates to a gas turbine which can be fired with NEE and / or EU and which is equipped with an exhaust gas treatment system.

[0009] EP 3 604 929 B1 relates to a combustion device of a gas turbine (A), comprising: a combustion chamber; an ammonia supply unit that supplies primary reducing ammonia as a nitrogen oxide reducing agent into the combustion chamber and mixes secondary reducing ammonia with combustion exhaust gas discharged from the combustion chamber to reduce nitrogen oxide contained in the combustion exhaust gas; and a control unit configured to control at least one of the amount of supply of the primary reducing ammonia and the amount of mixing of the secondary reducing ammonia with the combustion exhaust gas in accordance with the concentrations of remaining nitrogen oxide and remaining ammonia contained in the combustion exhaust gas after it has been discharged from the combustion chamber.

[0010] US 11 702 988 B2 relates to an ammonia decomposition system comprising a heating medium line configured to allow the flow of a heating medium heated by the heat generated by a gas turbine, an ammonia supply line configured to allow the flow of ammonia, an ammonia decomposition device, and an ammonia removal device. The ammonia decomposition device is configured to utilize the heat of the heating medium from the heating medium line, thermally decompose ammonia from the ammonia supply line, and generate a decomposition gas containing hydrogen, nitrogen, and residual ammonia.

[0011] US 2018 0355794 A1 relates to a gas turbine system having an ammonia source and a source of an oxygen-containing gas, a first combustion chamber connected to receive ammonia, a hydrogen-rich gas stream and oxygen-containing gas, a turbine connected to receive an exhaust gas stream from the first combustion chamber, and a second combustion chamber connected to receive an exhaust gas from the turbine, ammonia and a hydrogen-rich gas stream.

[0012] WO 2023 286516 A1 relates to a gas turbine plant comprising: a gas turbine; an ammonia supply device for supplying ammonia to a combustion chamber of the gas turbine; a flow channel forming frame forming an exhaust gas flow channel through which exhaust gas from the gas turbine flows; a water spray device including a water sprayer capable of spraying water into the exhaust gas flow channel; and a water spray controller for controlling the operation of the water spray device.

[0013] CD Avila et al., Applications in Energy and Combustion Science 13 (2023) 100104 concerns the experimental evaluation of the performance of a commercial micro gas turbine fueled by ammonia-methane mixtures.

[0014] L. Balling, Stationary Gas Turbines, Springer, VDI-Buch (2019) 31-65, concerns gas turbine power plants.

[0015] Th. Sattelmayer, Stationary Gas Turbines Springer, VDI Book (2019) 241-272 concerns the fundamentals of combustion in stationary gas turbines.

[0016] S. Mashruk et al., Combustion and Flame 244 (2022) 112299 concerns the evolution of MG production during lean combustion in premixed NFL / Fb / air vortex flames.

[0017] EC Okafor et al., Combustion and Flame 211 (2020) 406-416 concerns the control of NOx and other emissions in micro gas turbine combustors fired with methane-ammonia mixtures.

[0018] M. Zhang et al., Int. Journal of Hydrogen Energy 46 (2021) 21013-21025 concerns the regulatory effect of methane and hydrogen on emission behavior.

[0019] Operating limits for ammonia-fueled spark-ignition internal combustion engines were investigated. It was found that NFF emissions in the exhaust gas decrease with increasing engine speed, with the highest values ​​being reached under a rich mixture. NFF emissions can reach up to 1 vol. NOx emissions consist primarily 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 NOx and N2O, the highest emission values ​​are 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 gas 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).

[0020] CN 114 412 668 A relates to ammonia fuel engines, in particular to an ammonia-hydrogen fusion type hybrid energy system and an engine.

[0021] 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.

[0022] JP 2023 026798A, 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.

[0023] US 2003 / 0143142 Al and US 2017 / 0334722 Al describe processes for reducing the NOx concentration and the N2O concentration of the residual gas from nitric acid production.

[0024] Previous research has focused 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.

[0025] However, emissions of NOx, N2O, and possibly other components that may be present in combustion gases (e.g., CO, HCN, or NH3) must be avoided or at least reduced as much as possible to protect health, the environment, and the climate. Many industrialized countries have therefore issued corresponding regulations.

[0026] 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 gas 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 costs. Furthermore, these processes should convert HCN into non-toxic substances that do not require further post-treatment.

[0027] Another problem is the incomplete combustion of ammonia, which leads to the exhaust gases of combustion plants using ammonia as fuel containing significant amounts of unburned ammonia (so-called NFF slip, NH3 breakthrough). Since the permissible limits for ammonia released into the atmosphere are comparatively strict, it is necessary in such cases to ensure 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 lack selectivity (i.e., they may form NOx or N2O from NH3) and are susceptible to chlorine compounds and other catalyst poisons.

[0028] There is therefore a need for measures that are suitable - nitrogen oxides (especially N2O and NOx (ie NO and NO2)), - any excess NH3 present, and - to at least partially remove 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 combustion plants powered by NH3, in particular of internal combustion engines powered by NH3, gas turbines powered by NH3 or furnaces for splitting NH3 into N2 and H2, as a result of combustion, so that the exhaust gas can then be released into the ambient air in compliance with all environmental regulations.

[0029] In this context, the special circumstances resulting from the most efficient combustion of NH3 for the operation of combustion plants, preferably for powering internal combustion engines, driving gas turbines, or operating furnaces for splitting NH3 into N2 and H2, must be taken into account. In addition to the different composition of the exhaust gas, important 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 NOx and N2O removal measures have been developed to date.

[0030] 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. Typical water contents in the exhaust gas range from approximately 1 to 3 vol%.

[0031] In contrast, when NH3 is burned to operate combustion plants, preferably to drive internal combustion engines, to drive gas turbines or to operate furnaces for splitting NH3 into N2 and H2, the NH3 is preferably only oxidized to the N2 stage, for which no catalysts are usually necessary, and this conversion usually takes place at atmospheric pressure. The aim of the combustion is to achieve the lowest possible yield of NOx and N2O. Typical water contents in the exhaust gas 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 energy generation. Low nitrogen oxide levels in the flue gas produced 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 regulatory requirements regarding permissible emissions. Only then can sufficiently low residual concentrations be achieved using known nitrogen oxide reduction processes.

[0032] 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.

[0033] On the one hand, the comparatively low pressures, 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 moldings, etc., the pressure drops could potentially be excessive. 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 high temperatures, 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, whereas the removal of N2O by decomposition and / or chemical reduction is significantly impaired by the high water content.

[0034] A further difference between the exhaust gases to be treated according to the invention and 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 the NH3 content, any other combustible gases present (H2 and / or CH4 (natural gas)), and the air ratio X. 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 to NO2 due to the slow formation kinetics of NO2 at high temperatures. This means that the degree of oxidation (ß) of NOx, ie the molar fraction of NO2 in the total NOx (ß = 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 NOx reduction can actually only proceed very poorly or slowly, corresponding to the slow so-called normal SCR.

[0035] These are fundamental differences to the established exhaust gas purification in HNO; plants, in which the residual gas containing N2O and NOx is discharged under an overpressure of usually 4-10 bar after leaving of the absorption tower from a "cold" state (the thermodynamic NOx equilibrium here lies almost entirely on the side of NO2). Thus, the NOx oxidation level of residual gases in HNO production before entering the corresponding exhaust gas treatment system is typically between 30 and 70 vol.%, i.e., close to the ideal stoichiometric ratio for NOx reduction according to the very fast SCR.

[0036] The high NOx content, combined with a very low NOx oxidation level and high water content at a simultaneously low operating pressure (near atmospheric pressure), poses particular challenges to the effectiveness of the exhaust gas treatment system according to the invention in this case. Added to this is the challenge and necessity of removing the N2O also present in the exhaust gas, which cannot be reduced with conventional SCR processes based on V2O5 / TiO2 catalysts.

[0037] The objectives and the reaction products obtained during the combustion of NH3 therefore sometimes differ considerably.

[0038] In conventional plants for the production of nitric acid, the exhaust gas often has a comparatively high pressure - a comparatively low NOx content; - a comparatively high proportion of NO2; - a comparatively high content of N2O; - a comparatively low water content; and - no proportion of unburned NH3 (NH3 slip).

[0039] In contrast, in combustion plants, preferably for driving internal combustion engines, for driving gas turbines or for operating furnaces for splitting NH3 into N2 and H2, the exhaust gas often has a comparatively low pressure - a comparatively high NOx content; - a comparatively low proportion of NO2; - a comparatively low N2O content; - a significantly higher water content; - possibly a not insignificant proportion of unburned NH3 (NH3 slip); and - possibly a non-negligible proportion of HCN, if NH3 is burned together with CH4 (natural gas);

[0040] These special circumstances must be taken into account when removing NOx and N2O from exhaust gases, which presents a particular challenge.

[0041] Compared to existing industrial plants, so-called stationary plants, further challenges in the removal of NOx and N2O from exhaust gases arise from the use of NH3-fired combustion systems, particularly NH3-powered internal combustion engines, in vehicles, ships, and possibly even aircraft. 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. Furthermore, the operating mode of combustion systems, particularly 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 in the removal of NOx and N2O from exhaust gases.

[0042] It is an object of the invention to reduce the content of NOx (ie NO and NO2), N2O and optionally NH3, CO and / or HCN in exhaust gases which arise from combustion plants operated with NH3, preferably from internal combustion engines operated with NH3, from gas turbines operated with NH3 or from furnaces for splitting NH3 into N2 and H2.

[0043] This problem is solved by the subject matter of the patent claims.

[0044] A first aspect of the invention relates to a method for reducing the NOx and N2O content in the exhaust gas of a combustion plant operated with NH3, preferably an internal combustion engine powered by NH3, an NH3-powered gas turbine or a furnace for splitting NH3 into N2 and H2, the method comprising the following steps: (a) Combustion of NH3 (or of NH3 in a mixture with another combustible gas, in particular H2, CH4, etc.) to operate the combustion plant, preferably to drive the internal combustion engine, to drive the gas turbine or to operate the furnace for splitting NH3 into N2 and H2, producing an exhaust gas which comprises N2, H2O, NOx and N2O and optionally HCN and which leaves the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace; (b) transferring the exhaust gas from the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, to an exhaust gas treatment plant; (c) Reducing the N2O content in the exhaust gas by (ci) decomposition of N2O on a N2O decomposition catalyst and / or (C2) chemical reduction of N2O with a reducing agent on a N2O reduction catalyst; and (d) Reducing the NOx content in the exhaust gas by chemical reduction of NOx with a reducing agent on a NOx reduction catalyst.

[0045] The order of steps (c) and (d) is arbitrary; according to the invention, all possibilities are encompassed, from sequentially in any order to simultaneously or mixed forms thereof.

[0046] 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 the same or different depending on the given functionality or multiple functionality and may be present in common or separate reaction zones (catalyst beds).

[0047] In preferred embodiments, the exhaust gas treatment system according to the invention comprises - a N2O reduction catalyst; - a N2O decomposition catalyst; and - a NOx 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).

[0048] In preferred embodiments, the exhaust gas treatment system according to the invention additionally comprises at least one further catalyst or one of the above-mentioned N2O reduction, N2O decomposition or NOx reduction catalysts fulfills at least one further functionality selected from - NFF oxidation catalyst: - HCN degradation catalyst; and - CO oxidation catalyst.

[0049] The NH3 oxidation catalyst is preferably used when the proportion of unburned NH3 in the exhaust gas (NFF slip) is greater than the demand for NH3 as a reducing agent for NOx and / or N2O in the exhaust gas treatment system, so that the exhaust gas, after passing through steps (C1) and / or (C2) and (d), still contains residual amounts of NH3 that 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.

[0050] 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.

[0051] It was surprisingly found that HCN in water-containing exhaust gases, which simultaneously contain NOx and N2O in a molar amount which 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).

[0052] In contrast to known processes, this method allows complete removal of HCN, i.e. conversion into non-toxic substances, in a single step, i.e. in a single process step, without the need for expensive precious metal catalysts. To remove excess NOx and N2O, NH3 can be added to the exhaust gas containing HCN, NOx and N2O for NOx and N2O reduction and, if necessary, CO or hydrocarbons such as CH4 or propane for N2O reduction. 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.

[0053] 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. Any CO produced in this process can then be degraded to CO2 by oxidation with the help of the downstream CO oxidation catalyst.

[0054] If the exhaust gas treatment system according to the invention comprises an NH3 oxidation catalyst, it may be preferable according to the invention to first cool the exhaust gas within the exhaust gas treatment system using a heat exchanger to a lower 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 heat exchangers.

[0055] 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.

[0056] For the purpose of description, "NOx" includes nitrogen monoxide (NO) and nitrogen dioxide (NO2), but not nitrous oxide (N2O).

[0057] Catalysts accelerate certain chemical reactions by lowering their activation energies.

[0058] Unless expressly stated otherwise, all data are in ppm 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%.

[0059] Steps (a) and (b) of the process according to the invention are carried out successively in alphabetical order, followed by steps (c) and (d) in basically any desired order. Step (c) can therefore take place 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 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 proceeding in parallel.

[0060] Steps (C1) and (C2) are considered separately for the purpose of description, but both serve the common purpose of reducing the N2O content in the exhaust gas.

[0061] Steps (ci), (C2) and (d) can also be carried out in any order, whereby mixed forms of partial simultaneity are also possible.

[0062] In preferred embodiments, the process 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).

[0063] In preferred embodiments, the exhaust gas passes through the steps of the process 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) - (ci); (iv) (a) -> (b) -> (d) -> (C1+C2); or (v) (a) - (b) - (d) - ( C1 ).

[0064] Here (C1+C2) means that both step (ci) and step (C2) are executed, whereby the execution of these two steps (ci) and (C2) takes place at least partly simultaneously, ie both steps run in parallel.

[0065] Additional steps not explicitly mentioned may occur between these steps.

[0066] In step (a) of the process according to the invention, NH3 is burned to operate a combustion plant.

[0067] "Combustion plants" within the meaning of the invention generate heat through combustion processes. Heat is generated by burning fuels. Optionally, electricity can also be generated and / or machines driven. The term encompasses a wide variety of plants: from domestic heating, motors for driving vehicles, and industrial combustion plants for steam and process heat generation to large power plant combustion plants. "Combustion plants" within the meaning of the invention are any plants in which NH3 is oxidized with O2 (preferably from the air). with the aim of producing, in particular, N2 and H2O as the main products. 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, for example, in the production of nitric acid, are not combustion plants within the meaning of the invention.

[0068] 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). 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.

[0069] According to the invention, the combustion of NH3 preferably takes place in a mixture with H2 or fossil fuels, e.g. CH4.

[0070] In preferred embodiments, in step (a) of the process according to the invention, NH3 is burned to drive an internal combustion engine.

[0071] "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.

[0072] In preferred embodiments, in step (a) of the process according to the invention, NH3 is burned to drive a gas turbine.

[0073] "Gas turbines" within the meaning of the invention are, in particular, internal combustion engines in which an exhaust gas flow is generated, which can be used, for example, to generate (mechanical) rotational energy by means of an exhaust gas expansion turbine.

[0074] It has surprisingly been found that the process according to the invention is particularly suitable for gas turbines and offers several advantages over conventional processes. The process according to the invention is characterized by a lower air volume requirement and simplified gas turbine operation. Furthermore, high removal rates for N2O and NOx are ensured, and this with only low consumption of reducing agent (particularly NH3). Emissions of N2O and NOx can be reduced within the exhaust gas treatment system, particularly if the exhaust gas treatment system is equipped with two catalyst beds arranged in series. The advantages of so-called end-of-pipe technology come into play. The catalysts used are non-toxic and have a long service life. The pressure drop is minimal, and the catalysts and the process can be used over a wide temperature range.

[0075] In this context, it is relevant that modern gas turbines have turbine inlet temperatures of more than 1,500°C and, consequently, exhaust gas temperatures of more than 600°C. Conventional SCR catalysts based on vanadium oxide cannot be used at temperatures above 400°C due to irreversible damage. In contrast, the zeolite catalysts preferred according to the invention can be used in a wide temperature range from approximately 350 to 600°C, and thus also at higher temperatures. Therefore, according to the invention, complex pre-cooling of the exhaust gas can be dispensed with if necessary.

[0076] In preferred embodiments, in step (a) of the process according to the invention, NH3 is burned to operate a furnace for cracking NH3 into N2 and H2.

[0077] In step (b) of the inventive process, the exhaust gas is transferred to an exhaust gas treatment system, i.e., from the internal combustion engine or gas turbine to an exhaust gas treatment system. Steps (c) and (d) of the inventive process take place in the inventive exhaust gas treatment system. For this purpose, the exhaust gas treatment system is equipped with the N2O decomposition catalyst for step (c1) and / or with the N2O reduction catalyst for step (c2), as well as with the NOx reduction catalyst for step (d).

[0078] If the exhaust gas treatment system according to the invention additionally comprises at least one further catalyst or one of the above-mentioned N2O reduction, N2O decomposition or NOx reduction catalysts fulfils at least one further functionality, at least one of the following steps (ei) to (04) is preferably additionally carried out in the exhaust gas treatment system according to the invention: (ei) cooling the exhaust gas in at least one heat exchanger, which is preferably arranged within the exhaust gas treatment system; preferably upstream of the NFh oxidation catalyst in the flow direction of the exhaust gas; (62) reducing the content of NH3 in the exhaust gas by oxidation with an oxidizing agent on an NFh oxidation catalyst; wherein the oxidizing agent preferably comprises O2; (63) 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 (04) 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.

[0079] In step (c) of the process according to the invention, the N2O content in the exhaust gas is reduced. This can be achieved by (c1) decomposition of N2O on an N2O decomposition catalyst and / or (c2) chemical reduction of N2O with a reducing agent on an N2O reduction catalyst.

[0080] During the decomposition of N2O, N2 and O2 are formed according to the following overall reaction: 1 N2O 2 N2+ O2.

[0081] Decomposition of N2O therefore means decomposition into N2 and O2. An "N2O decomposition catalyst" within the meaning of the invention catalyzes the decomposition of N2O. The achievable reduction of N2O through catalytic decomposition depends not only on the type, i.e., the chemical nature and physical design of the N2O decomposition catalyst and the prevailing pressure and temperature conditions, but above all on the selected space velocity, i.e., the ratio of exhaust gas volume flow to catalyst volume. However, the catalytic activity of an N2O decomposition catalyst does not have to be limited exclusively to this conversion. Thus, it is entirely possible and, according to the invention, also preferred for the N2O decomposition catalyst to also catalyze other conversions, 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.

[0082] During the chemical reduction of N2O with a reducing agent, different reaction products are formed depending on the reducing agent.

[0083] In the case of the reducing agent NH3 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 NH34 N2 + 3 H2O or 4 N2O + 4 NH3+ O26 N2+ 6 H2O or in the joint reduction with NO according to 2NO + N2O + 2 NH33 N2+ 3 H2O.

[0084] In the case of hydrocarbons, which are also preferred as reducing agents according to the invention, CO and H2O are formed in particular during the chemical reduction of N2O, e.g. according to (2n+l) N2O + CnH2n+2 (2n+l) N2+ n CO + (n+1) H2O or CO2 and H2O according to 4n N2O + C n H2n+2 — * 4n N2 + n CO2 + 2n H2O.

[0085] CO is also preferred as a reducing agent according to the invention. It can react further with N2O to form CO2, e.g., according to: N2O + CO N2 + co2.

[0086] 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 conversion. Thus, it is entirely possible and, according to the invention, also preferred for the NOx reduction catalyst to also catalyze other conversions, for example, the decomposition of N2O, the chemical reduction of N2O and / or the establishment of NOx equilibrium or the selective oxidation of excess NH3 with free O2. Whether such further conversions 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.

[0087] In step (d) of the process according to the invention, the NOx content in the exhaust gas is reduced by chemical reduction of NOx with reducing agent on a NOx reduction catalyst.

[0088] Preference is given to NOx reduction catalysts which, if possible, enable the selective catalytic reduction (SCR) of the nitrogen oxides contained in the exhaust gas, in particular of NOx, ie the NOx reduction catalysts primarily catalyze the oxidation of NH3 with NOx and not, or only secondarily, the oxidation of NH3 with free oxygen (O2) which may be present in the exhaust gas.

[0089] During the chemical reduction of NOx with a reducing agent, different reaction products are formed depending on the reducing agent. In the case of the reducing agent NH3 preferred according to the invention, N2 and H2O are formed in particular 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 NO24 N2+ 6 H2O (so-called almost SCR) 4 NH3+ 4 NO + O24 N2+ 6 H2O (so-called normal SCR) 8 NH3+ 6 NO27 N2+ 12 H2O (so-called NO 2 SCR).

[0090] 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.

[0091] 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 further reactions, for example, the decomposition of N2O and / or the chemical reduction of N2O and / or the establishment of 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:

[0092] 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 decomposing N2O into N2 and O2, for example, in the temperature range of 350 to 600°C.

[0093] 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 using iron-loaded zeolite catalysts in the first catalyst bed, the NOx still present in the gas accelerates the desired N2O decomposition as expected through an activating effect (co-catalytic effect), as described for different N2O / NOx ratios by Kögel et al. in Catal. Comm. 2 (2001) 273-276.

[0094] 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 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 solid catalysts.

[0095] The catalytically active compounds themselves can be metallic and / or oxidic 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. -Sei. 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 and rhodium oxides, such as RI1O2 or Rh2O. CoO, CO2O3, Co-containing spinels such as CO3O4, Cu x Co3 x O4 or Co-containing perovskites such as LaCoO; or Co-containing perovskites substituted on A and B sites.

[0096] The catalytically active compounds can be contained in the catalysts in pure form or applied to or blended with suitable support materials. In the former case, these are so-called unsupported catalysts, which, in addition to active compounds, may also contain additives known to those skilled in the art, such as binders or other manufacturing-related additives such as plasticizers, pore-forming agents, fiber reinforcements, or pressing aids.

[0097] 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.

[0098] 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 ZrCE, TiCE, 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 also contain CcCE in addition to Rh. The proportion of CcCE is preferably 5 to 50 wt. %, in particular 10 to 30 wt.

[0099] 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 the person skilled in the art. In the case of magnesium oxide supports, they 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.

[0100] Particular preference is given to catalysts 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 1 257 347 B1. Furthermore, particular preference is given to using oxidic Co compounds as The active component is catalysts with a support consisting of at least 50 wt.% MgO or a mixed oxide consisting of at least 50 wt.% MgO, and with a cerium oxide functional layer applied to the support. Such catalysts and their preparation are described in DE 10 2007 038 71 1 A1.

[0101] 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.

[0102] N2O reduction catalysts and NOx reduction catalysts are also known per se, and a wide variety of materials 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.

[0103] Preferably, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOx reduction catalyst independently of one another contain 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, independently of one another, an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU and / or MEL.

[0104] 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-loaded zeolite; even more preferably, independently of one another, an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU and / or MEL.

[0105] 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 FER-type zeolite, can be present in the catalyst used according to the invention.

[0106] In addition, the catalyst used according to the invention may contain further additives known to the person skilled in the art, such as binders.

[0107] The iron content of the preferred zeolites can be up to 25% based on the mass of zeolite, but preferably 0.1 to 10%.

[0108] 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, 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.

[0109] 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 dealuminizes the zeolite lattice; this treatment is known per se to the person 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.

[0110] 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).

[0111] In preferred embodiments, the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material.

[0112] In preferred embodiments, the N2O decomposition catalyst and the NOx reduction catalyst are made of the same material.

[0113] In preferred embodiments, the N2O reduction catalyst and the NOx reduction catalyst are made of the same material.

[0114] In preferred embodiments, the N2O decomposition catalyst, the N2O reduction catalyst and the NOx reduction catalyst are made of the same material. Preferred catalysts for the degradation of N2O and NOx

[0115] The N2O decomposition catalysts, N2O reduction catalysts and NOx reduction catalysts according to the invention independently of one another preferably contain zeolitic materials (for the purpose of description also "zeolites") which are reacted with at least one transition metal (order- atomic numbers 21-30, 39-48, 57-80, 89-112) and / or loaded with at least one lanthanide (also called "lanthanide"; atomic numbers 57-71). For the purposes of this description, transition metals and lanthanides are referred to collectively as "transition metals" for simplicity. Preferably, the transition metals are iron ("Fe-Zeo / zFze"), copper ("Cu-zeolites"), and cobalt ("Co-zeolites"). Iron-loaded zeolitic materials (i.e., Fe-zeolites) are particularly preferred and, in addition to iron, may also be loaded with or contain other transition metals, for example manganese, vanadium, chromium, nickel, or mixtures.

[0116] The zeolitic materials according to the invention preferably exhibit high hydrothermal stability. 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.

[0117] 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 structure 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.

[0118] Particularly preferred N2O decomposition, N2O reduction, or NOx reduction catalysts according to the invention contain, independently of one another, 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.

[0119] 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, NFL 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 thus obtained loaded zeolitic materials are then 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 loaded zeolitic materials are then dried.The loaded zeolitic materials thus obtained are preferably admixed and mixed with suitable binders, such as aluminosilicates, boehmite, or silica sol, and optionally with auxiliary agents for plasticizing or for producing slurries. In preferred embodiments, The resulting mixtures are extruded into catalyst bodies (full catalysts) and finally calcined. In other preferred embodiments, the resulting mixtures are coated onto catalyst supports (supported catalysts) and finally calcined. These methods are also known to those skilled in the art and established in many technical applications.

[0120] The N2O decomposition, N2O reduction, NOx reduction, NFF 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. Particular preference is given to monolithic catalyst elements with parallel channels, e.g., monolithic honeycomb bodies, so-called "catalyst honeycombs," as are known, for example, from the purification or denitrification of power plant or automotive exhaust gases. Catalyst honeycombs, honeycomb bodies and honeycomb modules

[0121] 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, arranged parallel to one another in the exhaust gas duct, 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] The so-called cell density, ie, the density of the channels of a single catalyst honeycomb, is preferably 150 to 500 cpsi, more preferably 180 to 450 cpsi (cells per square inch). 100 cpsi, ie, 100 cells or honeycomb channels per square inch, correspond to approximately 15.5 catalyst channels per cm 2 .

[0126] The individual honeycomb modules are preferably stacked on top of and next to each other in the direction of flow and secured by suitable holders so that the inflow area, i.e. cross-sectional area of ​​the exhaust duct, is used as effectively as possible. 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%.

[0127] 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 sealed with blanking plates. This has the advantage that when replacing worn-out honeycomb modules, only standardized honeycomb modules need to be replaced, and no special adaptations are required.

[0128] 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 combine several honeycomb bodies parallel to one another to form honeycomb modules.

[0129] In preferred embodiments, the honeycomb bodies or honeycomb modules are arranged in several layers offset along the longitudinal axis in the direction of flow of the exhaust gas. The honeycomb bodies or honeycomb modules are preferably arranged in 2 to 5 layers, particularly preferably in 2 to 3 layers. Between the layers, i.e. between the end faces of the honeycomb bodies or honeycomb modules, a distance is preferably provided, 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 avoided 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.

[0130] The supply and distribution of the reducing agents for NOx and possibly N2O is preferably carried out via a multiply branched pipe system provided with a large number 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.

[0131] 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.

[0132] 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. NHs oxidation catalyst

[0133] NFL oxidation catalysts are known to experts.

[0134] Preferably, the NFL oxidation catalyst is platinum group metal-free, more preferably noble metal-free.

[0135] 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, "noble metal-free" means that it contains essentially no precious metals. However, analytically detectable traces of precious metals may be present.

[0136] Preferably, the NFL oxidation catalyst is an iron- or copper-loaded zeolite; preferably an iron- or copper-loaded zeolite of the structural type MFI, BEA, FER, MOR, FAU, AEI, and / or MEL (hereinafter referred to as "NH3 oxidation-active, iron- or copper-loaded zeolite catalyst").

[0137] Preferred platinum group metal-free NFL oxidation catalysts are selected from transition metal oxides (e.g. of Fe, Mn, Cu, Cr, Co, Ni ...), metal-loaded zeolites, e.g. described ben 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”.

[0138] Preferred NH3 oxidation catalysts include - cobalt-containing catalysts; in particular CO3O4; mixed oxides derived from CO3O4 (Co3- 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; in particular MnOx with x = 1-2; mixed oxides derived from MnOx (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 (Cu x y M y Ox), 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, TiCE, or SiCE, more preferably e.g. X% Ag / TiCE, X% Ag / AhCh, or X% Ag / SiCE, each with X=1-10.

[0139] In preferred embodiments, the device according to the invention contains no further NH3 oxidation catalyst besides the iron- or copper-loaded zeolite.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] In the synthesis of zeolites, the selected Si and Al starting materials are usually heated in an alkaline solution, often under elevated pressure, causing crystallization to form microporous aluminosilicates, the zeolites, composed of three-dimensionally linked AlO2 and SiCl units. Through the careful selection of 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.

[0145] 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 NH 2 , 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 AlCl units are compensated by cations, the so-called degree of exchange is 100%.

[0146] 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.

[0147] If the Al content of the underlying zeolitic material is to be subsequently determined on the finished molded body, it should 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 examination of the molded bodies, e.g., by means of 27Al solid-state NMR is required, which allows a distinction 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. l( 29 Si MAS NMR Spectroscopy of SiCC Tetrahedra in the Zeolite Framework) and 4.3.4.2 ( 27 Al NMR Spectroscopy of Framework and Non-Framework Aluminum in Zeolites)' ).

[0148] Preferably, the NfL oxidation catalyst, preferably the NfL oxidation-active zeolite catalyst loaded with iron, 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.%.

[0149] Preferably, the N fL oxidation catalyst, preferably the N fL oxidation-active, copper-loaded zeolite catalyst, has a total copper content (expressed as mass content CU2O) from less than 9.0 wt.% to greater than 1.5 wt.%; preferably from less than 6.5 wt.% to greater than 1.5 wt.%, more preferably from less than 4.5 wt.% to greater than 1.5 wt.% and even more preferably from less than 3.5 wt.% to greater than 1.5 wt.%.

[0150] In preferred embodiments, the N FE oxidation catalyst, preferably the NFfi oxidation-active zeolite catalyst loaded with iron or copper, 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 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 m 2 / m 3 up to 1500 m 2 / m 3in an amount of 8.0±0.5 mL in an isothermally operated, axial-flow 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 based on standard conditions (0°C; 1.01325 bara) 1 , a total pressure of 6±0.5 bara and a temperature of 380°C±5 K, a NEU 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%.

[0151] In preferred embodiments, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOx reduction catalyst and / or the NFE oxidation catalyst independently have a honeycomb monolithic structure.

[0152] In preferred embodiments, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOx reduction catalyst and / or the NFE oxidation catalyst independently have a honeycomb monolithic structure.

[0153] In preferred embodiments, the NFE oxidation catalyst and the N2O decomposition catalyst are made of the same material.

[0154] In preferred embodiments, the NEfi oxidation catalyst and the N2O reduction catalyst are made of the same material.

[0155] In preferred embodiments, the NFE oxidation catalyst and the NOx reduction catalyst are made of the same material.

[0156] In preferred embodiments, the NFfi oxidation catalyst, the NOx reduction catalyst and the N2O decomposition catalyst are made of the same material. Step (a):

[0157] In step (a) of the process according to the invention, NH3 is burned to operate a combustion plant, preferably to drive an internal combustion engine, to drive a gas turbine, or to operate a furnace for splitting NH3 into N2 and H2. During combustion, an exhaust gas is produced, which comprises N2, H2O, NOx, and N2O. The exhaust gas leaves the combustion plant, preferably the internal combustion engine, the gas turbine, or the furnace, and is subsequently fed to step (b) of the process according to the invention.

[0158] 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.

[0159] In preferred embodiments, in step (a) 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.

[0160] In preferred embodiments, the additional combustible gas is a fossil fuel.

[0161] 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.

[0162] In preferred embodiments, the further combustible gas is selected from alcohols, preferably methanol and / or ethanol.

[0163] In other preferred embodiments, the additional combustible gas is H2.

[0164] 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), the combustion of NH3 is preferably integrated into a process for thermal and / or catalytic cracking of NH3 into N2 and H2.

[0165] In preferred embodiments, in step (a) the combustion of NH3 takes place to drive a gas turbine in combination with a steam turbine.

[0166] Preferably, the combustion in the gas turbine with air or oxygen takes place as a single-stage combustion (i) of pure NH3; or (ii) of a mixture comprising NH3 and hydrocarbon, preferably natural gas or CIL; or (iii) of a mixture comprising NIL and IL.

[0167] The air ratio X (combustion air ratio) represents the actual available air mass in relation to the minimum air mass theoretically required for stoichiometrically complete combustion. Depending on the fuel composition, combustion in step (a) occurs preferentially at different air ratios X.

[0168] If the fuel consists essentially of pure NIL or the proportion of NIL in the fuel is at least 90 vol.% based on the total volume of the fuel, the Combustion preferably at an air ratio X in the range of 1.0 to 1.5, more preferably 1.1 to 1.4, even more preferably 1.1 to 1.3.

[0169] If the fuel consists essentially of mixtures of NH3 and CH4 and the proportion of CH4 is at most 50 vol.% based on the total volume of the fuel, combustion preferably takes place at an air ratio X in the range of 1.5 to 2.5, more preferably 1.6 to 2.4, even more preferably 1.7 to 2.3.

[0170] If the fuel consists essentially of mixtures of NH3 and CH4 and the proportion of CH4 is more than 50 vol.% based on the total volume of the fuel, combustion preferably takes place at an air ratio X in the range of 2.0 to 3.0, more preferably 2.1 to 2.9, even more preferably 2.2 to 2.8.

[0171] If the fuel consists essentially of mixtures of NH3 and H2 and the proportion of H2 is at most 50 vol.% based on the total volume of the fuel, the combustion preferably takes place at an air ratio X in the range of 2.0 to 3.0, more preferably 2.1 to 2.9, even more preferably 2.2 to 2.8.

[0172] If the fuel consists essentially of mixtures of NH3 and H2 and the proportion of H2 is more than 50 vol.% based on the total volume of the fuel, combustion preferably takes place at an air ratio X in the range of 2.5 to 3.5, more preferably 2.6 to 3.4, even more preferably 2.7 to 3.3.

[0173] Preferably, during the combustion in step (a), an exhaust gas is produced which preferably has a temperature in the range of 1000 to 1500 °C before entering the turbine.

[0174] Preferably, during the combustion in step (a), an exhaust gas is produced which preferably has a pressure in the range of 10 to 32 bar before entering the turbine.

[0175] Preferably, during the combustion in step (a), an exhaust gas is produced which preferably has an oxidation degree (n(NO2) / (n(NO)+n(NO2))) of NOx of at most 5.0%, more preferably at most 4.0%, even more preferably at most 3.0%, most preferably at most 2.0% and in particular at most 1.0%, optionally even at most 0.5%, before the turbine inlet.

[0176] According to the invention, combustion preferably takes place in a single stage, i.e., preferably neither as lean premixed combustion nor as staged rich-lean combustion. Single-stage combustion enables optimized operation and simplifies the design of the gas turbine plant. According to the invention, combustion takes place with a comparatively low excess air X, thereby deliberately accepting increased NOx concentrations. The equilibrium between NO2 and NO, i.e., the degree of oxidation of NOx, lies on the side of NO at the high combustion temperatures (e.g., >1,500 °C). Consequently, almost all of the NOx in the hot combustion exhaust gas is present as NO, i.e., only small amounts of NO2 are present.

[0177] The gas turbine according to the invention preferably has an annular combustion chamber. Preferably, several burners are arranged in a ring around a shaft in front of the turbine. A secondary air flow is directed around these burners and mixed in front of the turbine. Fuel premixing, complete combustion, and mixing must then take place within short distances.

[0178] Due to the high volume flows in gas turbines, exhaust gas purification can be very complex. Therefore, conventional gas turbine operating processes often attempt to control pollutant emissions at the point of origin through combustion-related measures. A comparatively high excess air X results in superstoichiometric combustion, so complete combustion can be assumed. Due to the limited thermal capacity of the gas turbine, the excess air X in stationary single-shaft machines typically cannot fall below values ​​for X of 2.5 to 3.5.

[0179] In conventional, natural gas-fired gas turbines, NOx is formed from atmospheric nitrogen (thermal NOx) at high-temperature locations with sufficiently long reaction times. In NH3-fired gas turbines, the majority of NOx is formed from the fuel (fuel NOx). Therefore, temperature and residence time in hot zones must be reduced to reduce NOx formation.

[0180] Cooling the flames by adding water or steam to the fuel (wet denitrification) has proven effective. A fuel / steam mixture ratio of 1:1 results in a reduction in NOx content of 80%. However, the necessary use of expensive demineralized water to prevent scaling and corrosion of the turbine blades leads to higher operating costs for this measure.

[0181] Newer burners utilize intensive premixing of superstoichiometric air and fuel to prevent localized overheating during combustion due to fuel concentration differences (dry denitrification). Uniform flow control is emphasized, for example, to avoid backflow zones where a long air residence time could occur. Different, successively arranged combustion zones, such as rich-lean zones, have also produced good results.

[0182] In general, the lower calorific value of the fuel NH3 vs. CH4 combined with a lower flame temperature can be expected to result in lower thermal load on the turbine. However, the lower flame temperature also promotes the formation of NOx and N2O.

[0183] Preferably, the exhaust gas produced by combustion in step (a) is then expanded in a gas turbine.

[0184] Preferably, the exhaust gas at the outlet from the gas turbine has a temperature in the range of 450 to 670 °C.

[0185] Preferably, the exhaust gas at the outlet from the gas turbine 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.

[0186] Preferably, the exhaust gas at the outlet from the gas turbine has a NOx content in the range of 500 to 3000 ppmv.

[0187] Preferably, the exhaust gas at the outlet from the gas turbine has an O2 content in the range of 1.0-6.0 vol.%

[0188] Preferably, the exhaust gas at the outlet from the gas turbine has a H2O content in the range of 20-30 vol.%

[0189] Preferably, the exhaust gas at the outlet from the gas turbine has an N2O content of at most 500 ppmv, more preferably at most 200 ppmv, even more preferably at most 100 ppmv.

[0190] Preferably, the exhaust gas at the outlet from the gas turbine has an N2O content of at least 5 ppmv, more preferably at least 20 ppmv, even more preferably at least 50 ppmv.

[0191] Preferably, the exhaust gas at the outlet from the gas turbine has an NH3 content of at most 800 ppmv, more preferably at most 500 ppmv, even more preferably at most 250 ppmv.

[0192] Preferably, the exhaust gas at the outlet from the gas turbine has an NH3 content of at least 10 ppmv, more preferably at least 50 ppmv, even more preferably at least 100 ppmv.

[0193] Preferably, the exhaust gas at the outlet from the gas turbine has an oxidation degree (n(NO2) / (n(NO)+n(NO2))) of NOx of at most 10%, more preferably at most 9.0%, even more preferably at most 8.0%, most preferably at most 7.0% and in particular at most 6.0%, possibly even at most 5.0%.

[0194] In preferred embodiments, in step (a) NH3 is burned in a mixture with CH4 and the exhaust gas therefore additionally contains CO and CO2 and preferably also HCN.

[0195] Preferably, the exhaust gas at the outlet from the gas turbine has an HCN content of at least 5 ppmv, more preferably at least 10 ppmv, even more preferably at least 50 ppmv.

[0196] Preferably, the exhaust gas at the outlet from the gas turbine has an HCN content of at most 1000 ppmv, more preferably at most 500 ppmv, even more preferably at most 200 ppmv, most preferably at most 100 ppmv.

[0197] In particularly preferred embodiments, step (a) of the process according to the invention comprises the substeps: (ai) 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; (ad burning of the fission gas or the mixture.

[0198] 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 MgAl2C>4, 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).

[0199] If the fission in sub-step (a3) ​​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).

[0200] When the fission in sub-step (a3) ​​is complete, the required amount of NH3 must be added to the fission gas in step (a2).

[0201] Preferably, by sub-step (ai) and optionally the optional sub-step (a2), a mixing ratio of NH3 and H2 is established 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%.

[0202] In particularly preferred embodiments, the molar ratio of H2:NH3 in the mixture is in the range of 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.

[0203] In sub-step (a3), the mixture is burned, typically with air. In preferred embodiments, the air ratio X for combustion in sub-step (a3) ​​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, and most preferably 1.2 to 1.4. The air ratio X (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 amount of substance (see, for example, P. Majumdar, Design of Thermal Energy Systems, Wiley 2021, page 66, no. 2.13.5.2).For the purposes of description, the ratio is based on mass. For a combustion process, a fuel other than air is used. If an oxygen-containing gas is used, "air" should strictly speaking be replaced by "oxygen carrier." However, the parameter X is still used in the above definition.

[0204] In preferred embodiments, the equivalence ratio NH3 / H2 (O) (not to be confused with the inverse of the air ratio 1 / X) is in the range of 0.55 to 1.40, more preferably 1.05 to 1.20.

[0205] In other preferred embodiments, in step (a) the combustion of NH3 alone occurs, ie NH3 is the only combustible gas that is burned.

[0206] In preferred embodiments, the combustion system, preferably the internal combustion engine, is mounted in a vehicle and serves to move the vehicle. The vehicle is preferably a ship. The vehicle is preferably a road vehicle; preferably selected from commercial vehicles, trucks, and passenger cars; or a rail vehicle.

[0207] In other preferred embodiments, the combustion plant, preferably the gas turbine, is part of a power plant. The power plant preferably generates electricity and / or district heating.

[0208] In further preferred embodiments, the combustion plant, preferably the furnace for splitting NH3 into N2 and H2, is integrated into a plant for the thermal and / or catalytic splitting of NH3 into N2 and H2. The combustion of NH3 is then integrated into a process for the thermal and / or catalytic splitting of NH3 into N2 and H2.

[0209] In preferred embodiments, the exhaust gas has a NOx content that is greater than the N2O content. 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 especially at least ten times as high as the N2O content. 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 especially at least 50:1.

[0210] In preferred embodiments, the exhaust gas has a NO content that is greater than the N2O content. 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.

[0211] In preferred embodiments, the exhaust gas has a NO2 content that is greater than the N2O content. 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 especially at least ten times as high as the N2O content.

[0212] Preferably, 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.

[0213] Preferably, 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.

[0214] Preferably, 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.

[0215] Preferably, 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.

[0216] Preferably, 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.

[0217] 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.

[0218] In other 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.%.

[0219] 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.%.

[0220] 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.%.

[0221] 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.%.

[0222] In preferred embodiments, 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.%.

[0223] 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.%.

[0224] 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.%.

[0225] 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.%.

[0226] Preferably, 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.%.

[0227] The exhaust gas preferably comprises further gaseous components; preferably selected from the group consisting of O2, CO, CO2, NH3, CH4 and mixtures thereof.

[0228] Preferably, the exhaust gas, when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, 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.

[0229] Preferably, the exhaust gas, when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, 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.

[0230] Preferably, the exhaust gas is cooled after leaving the combustion plant in the course of the process according to the invention, wherein steps (ci) and / or (C2) and / or (d) can introduce new heat. Preferred variants of combinations of steps (c) and (d):

[0231] 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.

[0232] Preferably, the exhaust gas upon leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has a pressure of at most 1.5 bar; preferably atmospheric pressure.

[0233] Preferably, the exhaust gas, when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, 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%.

[0234] Preferably, the exhaust gas, when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has an oxidation degree 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%.

[0235] Preferably, the exhaust gas leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has an O2 content of less than 2.0 vol.%.

[0236] Preferably, the exhaust gas leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has an O2 content of more than 4.0 vol.%.

[0237] In step (b) of the process according to the invention, the exhaust gas which has left the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, is transferred to an exhaust gas treatment plant.

[0238] This can be achieved, for example, by means of pipelines connecting the outlet of the combustion system, preferably the internal combustion engine, gas turbine, or furnace, to the inlet of the exhaust gas treatment system. Since the process according to the invention is preferably carried out at atmospheric pressure, such pipelines typically do not have any special requirements regarding possible pressure stress.

[0239] However, the pipes should be able to withstand the temperatures that the exhaust gas reaches when leaving the combustion plant, preferably the internal combustion engine, gas turbine or furnace, or when entering the exhaust gas treatment plant.

[0240] In preferred embodiments, the temperature of the exhaust gas at the outlet of the combustion plant, preferably the internal combustion engine, the gas turbine, or the furnace, is measured and, if necessary, modified using suitable devices so that the exhaust gas, upon entering the exhaust gas treatment plant, has a temperature which, under the given conditions, is optimized for carrying out steps (c) and (d) of the process according to the invention within the exhaust gas treatment plant. 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 NOx reduction catalyst. The optimized temperature depends on the selected configuration of steps (c) and (d), ie according to the type and sequence of the individual process steps for N2O reduction and NOx 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 NOx reduction catalyst.

[0241] Suitable devices for changing the temperature of the exhaust gas are known to a person skilled in the art and include, in particular, heat exchangers, which can be designed, for example, as plate heat exchangers or tube heat exchangers.

[0242] Preferably, at least one heat exchanger is arranged in the flow direction of the exhaust gas downstream of the gas turbine and upstream of the exhaust gas treatment system, in which the exhaust gas is cooled.

[0243] Preferably, the temperature of the exhaust gas at the outlet of the heat exchanger is at most 550°C, more preferably at most 525°C, even more preferably at most 500°C.

[0244] Preferably, the temperature of the exhaust gas at the outlet of the heat exchanger is at least 400°C, more preferably at least 425°C, even more preferably at least 450°C.

[0245] In order to avoid heat losses, it may be preferable according to the invention to choose the distance from the outlet of the combustion system, preferably the internal combustion engine, the gas turbine or the furnace, to the inlet into the exhaust gas treatment system as short as possible and in this way to achieve a compact design.

[0246] 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.

[0247] The exhaust gas treatment system according to the invention serves in particular to carry out steps (c) and (d) of the process according to the invention. 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.

[0248] This preferably concerns 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 a reducing agent). In such embodiments, the exhaust gas is preferably cooled before being introduced into the downstream catalyst bed, ie the oxidation of NH3 and / or CO preferably takes place at a lower temperature than steps (c) and (d).

[0249] 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.

[0250] 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.

[0251] 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.

[0252] Particularly preferred variants / embodiments include [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] (ci) the decomposition of N2O and (d) the chemical reduction of NOx with NH3, preferably together in one reaction zone; [d] (ci) 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] (ci) 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] (ci) the decomposition of N2O, preferably in a first reaction zone; and subsequently (d) the chemical reduction of NOx with NH3, preferably in a second reaction zone; [g] (ci) 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 NOx with NH3, preferably in a second reaction zone; [h] (ci) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (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; [i] (ci) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (cl*) the decomposition of residual N2O and (d) the chemical reduction of NOx with NH3, preferably in a second reaction zone; [j] (ci) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (cl*) the decomposition of residual N2O and (C2) the chemical reduction of residual N2O with NH3 (d) and the chemical reduction of NOx with NH3, preferably in a second reaction zone; [k] (ci) the incomplete decomposition of N2O, preferably in a first reaction zone; and subsequently (cl*) 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 (ci) 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 (ci) 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; followed by (ci) 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.

[0253] 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.

[0254] If NOx, N2O and NH3 are present in the mixture and the catalyst used catalyses both the chemical reduction of NOx with NEE and the chemical reduction of N2O with NH;, The chemical reduction of NOx with 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 typically overlaps the chemical reduction of N2O with NH; the extent of the chemical reduction of N2O can be increased by increasing the amount of NH3 added.

[0255] 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 reduced chemically in a first process sub-step (d), the fact that process sub-step (d*) is subsequently carried out does not necessarily mean 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*).

[0256] 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.

[0257] According to the invention, the method of introducing the reducing agent into the exhaust gas stream to be treated is freely configurable, as long as it 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. It is fed in 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.

[0258] When the catalyst beds are designed as a packing of catalyst honeycombs or honeycomb modules, the supply and distribution of the reducing agents for NOx and optionally N2O to the one or more reaction zones (catalyst beds) is preferably carried out via a multiply branched pipe 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.

[0259] The distributors are preferably designed in the form of grids, so-called "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).

[0260] 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.

[0261] 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. However, it should be noted that the kinetics of the individual reactions can be quite different. For example, depending on the catalyst material used, the chemical reduction of NOx with NH3 as the reducing agent can take place significantly faster than the chemical reduction of N2O with NH3. Therefore, if NOx and N2O are present in a mixture and NH3 is fed in as the 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.In the front section, due to the faster kinetics, the chemical reduction of NOx occurs predominantly, and only in the rear section, when the majority of the NOx has been removed, does the chemical reduction of N2O take place.

[0262] 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.

[0263] In preferred embodiments, the reaction zones are each spatially separated catalyst beds.

[0264] In preferred embodiments, the exhaust gas passes through the steps of the process according to the invention in one of the following sequences: (i) (a) — > (b) — > (ci) — > (d); wherein preferably step (ci) takes place in a first reaction zone; and step (d) takes place in a second reaction zone; (ii) (a) — > (b) — > (d) — > (C2); wherein preferably step (d) takes place in a first reaction zone; and step (C2) takes place in a second reaction zone; (iii) (a) — > (b) — > (d) — > (C2) — > (ci); wherein preferably step (d) takes place in a first reaction zone; step (C2) takes place in a second reaction zone; and step (ci) 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 step (c1) and step (c2) take place in a second reaction zone; (v) (a) —> (b) —> (d) —> (ci); wherein preferably step (d) takes place in a first reaction zone; and step (ci) takes place in a second reaction zone; (vi) (a) — > (b) — > (ci)+(d) — > (d*); wherein preferably step (ci) and incomplete 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 remainder of step (d*) take place in a second reaction zone; (viii) (a) —> (b) —> (ci)+(c2)+(d) —> (cl*)+(c2*)+(d*); wherein preferably incomplete step (ci) 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 (cl*) 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) —> (ci)+(c2)+(d) —> (cl*)+(c2*)+(d*); wherein preferably incomplete step (ci) 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 (cl*) 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) — > (ci) — > (cl*)+(c2)+(d); wherein step (ci) preferably takes place incompletely in a first reaction zone which preferably contains zeolitic material as catalyst; and the remaining step (cl*) 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) — > (ci) — > (cl*)+(c2)+(d); wherein step (ci) preferably takes place incompletely in a first reaction zone which preferably contains a NOx-sensitive N2O decomposition catalyst as catalyst; and the remaining step (cl*) as well as step (C2) and step (d) take place in a second reaction zone which preferably contains zeolitic material as catalyst.

[0265] 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. Upstream of the feed point, no reducing agent is then present, so that steps (C2) and (d) of the inventive process cannot take place in the absence of reducing agent. The decomposition of N2O then essentially takes place upstream according to step (ci) (first reaction zone). Downstream of the feed point, reducing agent is present, so that steps (C2) and (d) of the inventive process can take place, optionally overlaid by step (ci) of the inventive process (second reaction zone).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 each other in that, in the first reaction zone, in the absence of a reducing agent, no chemical reduction of N2O and no chemical reduction of NOx takes place.

[0266] 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.

[0267] 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 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.

[0268] 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).

[0269] Preferably, the temperature in the first reaction zone (in the first catalyst bed) 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 in particular at least 650°C.

[0270] 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.

[0271] 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).

[0272] 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).

[0273] 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.

[0274] 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.

[0275] In preferred embodiments, the temperature of the exhaust gas at the inlet into the first reaction zone (into the first catalyst bed) is relatively higher by at least 20K, more preferably by at least 40K, even more preferably by at least 60K, most preferably by at least 80K and in particular by at least 100K than the temperature of the exhaust gas at the inlet into the second reaction zone (into the second catalyst bed).

[0276] 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).

[0277] 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).

[0278] 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).

[0279] In other preferred embodiments, the first reaction zone and the second reaction zone are spatially connected. In this case, they preferably form a common catalyst bed, with external influences causing the catalyst bed to be divided 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.

[0280] Preferably, the first reaction zone and the second reaction zone are arranged in a common container.

[0281] 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, independently of one another, it is in the range from 350 to 450°C.

[0282] In preferred embodiments, the space velocity in the first reaction zone is greater than the space velocity in the second reaction zone. Preferably, the space velocity in the first reaction zone is at least a factor of 1.2, more preferably at least a factor of 1.4, 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.

[0283] In other preferred embodiments, the space velocity in the second reaction zone is greater than the space velocity in the first reaction zone. 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 especially at least a factor of 10.0 greater than the space velocity in the first reaction zone.

[0284] For the purposes of the invention, "space velocity" is 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 given in Nm 3 h -1 ) relative to the volume of the catalyst or catalyst bed. The space velocity can thus be adjusted via the gas flow rate and / or the amount of catalyst.

[0285] 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 plant.

[0286] 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 plant.

[0287] 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 when entering the exhaust gas treatment plant.

[0288] 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 when entering the exhaust gas treatment plant.

[0289] Preferably, the exhaust gas has a temperature on entry into the exhaust gas treatment plant 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 combustion plant, preferably the internal combustion engine, the gas turbine or the furnace.

[0290] Preferably, the exhaust gas has a pressure of at most 1.4 bara, preferably of at most 1.3 bara, more preferably of at most 1.2 bara when entering the exhaust gas treatment system.

[0291] Preferably, the exhaust gas upon entry into the exhaust gas treatment system 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%.

[0292] Preferably, the exhaust gas on entry into the exhaust gas treatment plant has an oxidation degree 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%.

[0293] 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%.

[0294] Preferably, the exhaust gas has an O2 content of less than 2.0 vol.% upon entry into the exhaust gas treatment system.

[0295] Preferably, the exhaust gas has an O2 content of more than 4.0 vol.% upon entry into the exhaust gas treatment system.

[0296] In step (c) of the process according to the invention, the N2O content in the exhaust gas is reduced. This can be achieved in various 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.

[0297] In preferred embodiments, step (c) comprises reducing the content of N2O in the exhaust gas by (ci) decomposing N2O on a N2O decomposition catalyst.

[0298] 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-loaded zeolite; even more preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU, and / or MEL.

[0299] 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.

[0300] Preferably, the N2O decomposition catalyst is arranged in a radial basket through which the flow is axial.

[0301] Preferably, the N2O decomposition catalyst is particulate and comprises at least 50 particles.

[0302] 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 an iron-loaded zeolite; even more preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU and / or MEL.

[0303] Preferably, the N2O reduction catalyst is arranged in a radial basket through which the flow is axial.

[0304] Preferably, the N2O reduction catalyst is particulate and comprises at least 50 particles.

[0305] In preferred embodiments, step (c) comprises reducing the content of N2O in the exhaust gas - both by (ci) decomposition of 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 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 and / or MEL; - thus also 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 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 and / or MEL.

[0306] Preferably, the reducing agent in step (C2) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

[0307] 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.

[0308] 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.

[0309] 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 amount of NH3 possibly required for NOx 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.

[0310] Likewise, the reducing agent may already be present in the exhaust gas, e.g., as residual fuels and / or their oxidation products. The process according to the invention then not only reduces the content of nitrogen oxides (NOx and N2O), but also the content of these contaminants (residual fuels and / or their oxidation products).

[0311] In step (d) of the inventive process, the NOx (i.e., NO and NO2) content in the exhaust gas is reduced. This is achieved by chemically reducing NOx with a reducing agent on a NOx reduction catalyst. Step (d) of the inventive process is also carried out in the exhaust gas treatment system.

[0312] Preferably, the NOx reduction catalyst 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 and / or MEL.

[0313] Preferably, the NOx reduction catalyst is arranged in a radial basket through which the flow is axial.

[0314] Preferably, the NOx reduction catalyst is particulate and comprises at least 50 particles.

[0315] Preferably, the reducing agent in step (d) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

[0316] 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.

[0317] In preferred embodiments, the reducing agent in step (C2) is the same as the reducing agent in step (d); preferably NH3.

[0318] 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. 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 a carbamate 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 the form of aqueous solutions. Ammonia or substances that release ammonia upon introduction, such as urea or ammonium carbamate, are particularly preferred.

[0319] Particularly preferred processes according to the invention are explained in more detail below: DeNOx-DeN2O - Variant 1

[0320] In preferred embodiments, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream of it, 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 (ci)) 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)).

[0321] Preferably, the NOx reduction catalyst in the first reaction zone comprises a conventional, preferably non-zeolitic SCR catalyst, e.g. based on V2O5-WO3- / TiO2.

[0322] Preferably, the temperature of the exhaust gas upon entry into the first reaction zone is at most 400°C, preferably at most 350°C.

[0323] 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU, and / or MEL structural type.

[0324] 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.

[0325] Preferably, the exhaust gas after leaving the first reaction zone and before entering the second reaction zone has a NOx content in the range from 0 to 200 ppmv, preferably 1 to 200 ppmv, and a N2O content in the range from 200 to 2000 ppmv. DeNOx-DeN2O - Variant 2

[0326] In other preferred embodiments, the exhaust gas treatment system also comprises a first reaction zone and a second reaction zone arranged downstream of it, 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 (ci)) 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)).

[0327] 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-loaded zeolite; even more preferably an iron-loaded zeolite of the structure type MFI, BEA, FER, MOR, FAU and / or MEL.

[0328] Preferably, the temperature of the exhaust gas upon entering 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 entering the first reaction zone is at most 600°C, more preferably at most 550°C.

[0329] Preferably, the N2O decomposition catalyst in the second reaction zone comprises a NOx-sensitive N2O decomposition catalyst according to the invention, which has already been described in more detail above.

[0330] Preferably, 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. Preferably, the temperature of the exhaust gas upon entering the second reaction zone is at most 600°C, more preferably at most 550°C.

[0331] 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 a N2O content in the range from 200 to 2000 ppmv. Particularly preferred embodiments of DeNOx-DeN2O - Variant 2

[0332] 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 (ci) 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) (NFE 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 NOx is chemically reduced with NH3.;

[0333] Preferably, the catalytic decomposition of N2O in the first catalyst bed is co-catalyzed by NOx present in the exhaust gas.

[0334] Preferably, the incomplete chemical reduction of NOx with NH3 in the first catalyst bed leads to a predetermined residual NOx content sufficient to cause a co-catalytic effect on the decomposition of N2O in the first catalyst bed. Since the chemical reduction of NOx with NH3 in the first catalyst bed typically proceeds significantly faster than the chemical reduction of N2O with NH3, and not the entire amount of NOx is chemically reduced in the first catalyst bed, the extent of any parallel chemical reduction of N2O with NH3 in the first catalyst bed is typically negligible.

[0335] Preferably, additional NH3 is metered into the exhaust gas via the first device for NOx reduction; preferably under feedforward control, i.e. a specific value for the NOx concentration at the outlet of the first catalyst bed is specified as the target value (setpoint) and the actual NOx concentration at the outlet of the first catalyst bed is measured (actual value). 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 target value 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 NH3 consumption 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 lower than the expected specific (mol / mol) NH3 consumption in the second catalyst bed.

[0336] Preferably, the temperature of the exhaust gas at the outlet from the first catalyst bed is in the range of 400 to 550°C.

[0337] 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.

[0338] 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%.

[0339] In preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation degree of NOx in the range of 30 to 50%.

[0340] In other preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation degree of NOx in the range of 15 to 35%, preferably 15 to 30%.

[0341] In further preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation degree of NOx in the range of 10 to 20%.

[0342] In other preferred embodiments, the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NOx in the range of 5 to 15%.

[0343] 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.

[0344] Preferably, residual NOx is decomposed in the second catalyst bed to a residual NOx 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.

[0345] Preferably, the additional NH3 is metered in with the second device under Fee / brwar control, ie the concentrations of NOx and optionally preferably of N2O are measured at the outlet of the first catalyst bed or optionally at the inlet to the second catalyst bed; under 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 amounts of NH3 required for NOx reduction and N2O reduction is calculated using stored ratios, e.g., molar ratios (mol / mol) of NH NOx and, optionally preferably, of NH3 / / N2O, or factors derived therefrom; and the control level of the second control valve is changed using the calculated result (control variable) in order to meter in the required amount of NH3.

[0346] 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.

[0347] For the Fee<7 / dnvar 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.

[0348] . For the Fee / bnvar 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.

[0349] Preferably, the additional NH3 is not metered in with the second device under FeetföacF control, since the aim is to achieve the most complete chemical reduction of NOx in the second catalyst bed, ie no or only very low residual concentrations of NOx and N2O result, which would be difficult to use as reference variables in terms of control technology.

[0350] 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.

[0351] Preferably, the amount of catalyst and the amount of additional NH3 are selected such that at the outlet of the first catalyst bed the molar ratio of NOX / N2O is at least 5, more preferably at least 10, even more preferably at least 20.

[0352] Preferably, the space velocity of the first catalyst bed is in the range of 5,000 h 1 up to 100,000 hours" 1 , preferably 10,000 h" 1 up to 50,000 hours" 1 , even more preferably 15,000 h" 1 up to 45,000 hours" 1 .

[0353] If the molar ratio of NOX / N2O at the outlet of the first catalyst bed is at least 10, then the addition of NH3 via the second device can preferably be carried out solely in relation to the amount of NOx entering.

[0354] Preferably, the temperature of the exhaust gas upon entering 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 entering 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 NH3 combustion conditions.

[0355] 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.

[0356] Preferably, the space velocity of the second catalyst bed is in the range of 5,000 h" 1 up to 100,000 hours" 1 , preferably 10,000 h" 1 up to 50,000 hours" 1 , even more preferably 15,000 h" 1 up to 45,000 hours" 1 .

[0357] Preferably, the ratio of the catalyst volumes (V 1 kat / V 2kat) of the first catalyst bed V 1kat to the second catalyst bed V 2kat 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.

[0358] 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, even more preferably at most 1.3 bara, most preferably at most 1.2 bara and in particular at most 1.1 bara; • the content of H2O in the exhaust gas upon 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 upon 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 upon 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, more preferably at least 10 ppmv, even more preferably at least 50 ppmv; • the exhaust gas contains unburned residues of NH3 from the combustion of NH3 when entering the first catalyst bed; • the N2O decomposition catalyst and / or the N2O reduction catalyst is in the form of a honeycomb body; • the NOx reduction catalyst is in the form of a honeycomb structure; • the first catalyst bed contains Fe zeolite; • the second catalyst bed contains Fe zeolite; • the exhaust gas flows through a heat exchanger before entering the first catalyst bed and is heated there; • 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, there is no intermediate cooling of the exhaust gas; • the molar ratio of N2O : NOx upon entry into 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 at the outlet of 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 direction of flow of the exhaust gas upstream of the first catalyst bed is optional; if injection occurs, it is preferably substoichiometric with regard to the NOx content at 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.

[0359] The process described above using Fe-zeolite catalysts in two catalyst beds enables, compared to classical DeNOx processes using V2O5 / TiO2 catalysts - the complete or almost complete removal of large quantities of NOx without the risk of NH slip; and - the simultaneous, complete or almost complete degradation of N2O at comparatively small catalyst volumes, i.e. at comparatively high space velocities.

[0360] This is achieved, in addition to the inventive operating mode, 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 position. Thus, the NOx oxidation level (molar ratio of NO2 / (NO + NO2)) before entering the first catalyst bed is, as expected, less than 5% due to the upstream NH combustion at very high temperatures and the slow establishment of equilibrium in the gas phase during cooling of the exhaust gas in the subsequent heat exchanger(s), if any. 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 NOx, since only a small part of the NOx present in the exhaust gas can be removed according to fast SCR and a large part of the NOx or the remaining NO must be removed according to the much slower normal SCR.

[0361] Due to the selected operating mode of limited NH 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, chemical reduction of NOx 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 chemical reduction of NOx in the second catalyst bed right from the start.

[0362] 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.

[0363] Furthermore, the chemical reduction of NOx itself is also inhibited by NH3 itself at sufficiently high NH3 dosages. This means that, depending on temperature, catalyst quantity, and NOx content, with increasing NH3 addition, no further increase in NOx reduction occurs beyond a certain amount of NH3. With further increases in the amount of NH3 added, a decrease in NOx reduction may even be observed, accompanied by a simultaneous NH slip.

[0364] By chemically reducing the NOx in the first catalyst bed, the amount of NH3 required for chemically reducing NOx in the second catalyst bed is significantly reduced.

[0365] 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.

[0366] The fact that this occurs according to the invention without or only with a negligible NH 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 added within the limits of the invention is selectively oxidized to N2 and H2O by the residual oxygen content of the exhaust gas.

[0367] All of these advantages cannot be realized when using conventional V2C>5 / 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 that 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 even a risk of undesirable N2O formation.

[0368] 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, whereby 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, whereby a first device with a first control valve for metering NH3 into the exhaust gas is preferably arranged upstream of this common catalyst bed. Additional NH3 is preferably metered into the exhaust gas via the first device; preferably under feedforward control, i.e.The concentration of NOx, N2O, and NH3 in the exhaust gas upstream of the common catalyst bed is 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 (manipulated 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 NFfi slip. Simultaneous combustion of NH3 and CEE - reduction of hydrogen cyanide content

[0369] 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.

[0370] In these cases, the first catalyst bed preferably assumes the additional function of catalytic decomposition of 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.

[0371] Due to its toxicity, its longevity in the atmosphere, and its absorption in the infrared spectrum, 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. Heat recovery steam generator

[0372] In preferred embodiments, the exhaust gas treatment plant according to the invention comprises a first heat recovery steam generator and preferably a second heat recovery steam generator, wherein the first heat recovery steam generator is arranged upstream of the second heat recovery steam generator in the flow direction of the exhaust gas.

[0373] Figures 1 to 3 schematically illustrate preferred embodiments according to the invention, showing how a first heat recovery steam generator (ADE1), a second heat recovery steam generator (ADE2), a first catalyst bed (K1), and a second catalyst bed (K2) can be positioned and brought into contact with the hot turbine exhaust gas after the turbine outlet. A generator (G) drives a compressor (V) in which air is compressed. In a combustion chamber (VK, combustion chamber, combustion chamber), ammonia is burned, optionally mixed with CH4 or H2, and the resulting exhaust gas flows into a gas turbine (GT) under expansion. After exiting the gas turbine (GT), the exhaust gas is fed into an exhaust gas treatment system (AB), which comprises the first heat recovery steam generator (ADE1), the second heat recovery steam generator (ADE2), the first catalyst bed (K1), and the second catalyst bed (K2).In the second heat recovery steam generator (ADE2) and subsequently in the first heat recovery steam generator (ADE1), steam absorbs heat from the exhaust gas. The heated steam is fed to a steam turbine driven by a generator (G). then flows through a heat exchanger (WT). After leaving the exhaust gas treatment system (AB), the exhaust gas is fed into a chimney (SS).

[0374] In preferred embodiments, the exhaust gas first flows through the first heat recovery steam generator, then the first catalyst bed, then the second catalyst bed and finally the second heat recovery steam generator (Figure 1).

[0375] In other preferred embodiments, the exhaust gas first flows through the first heat recovery steam generator, then the first catalyst bed, then the second heat recovery steam generator and finally the second catalyst bed (Figure 2).

[0376] In further preferred embodiments, the exhaust gas first flows through the first catalyst bed, then the first heat recovery steam generator, then the second catalyst bed and finally the second heat recovery steam generator (Figure 3).

[0377] In other embodiments, which are less preferred, only one catalyst bed is present and the combustion takes place in two stages as premixed combustion (Figure 4) or as rich-lean combustion (Figure 5). DeN2O-DeNOx

[0378] In further preferred embodiments, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone arranged downstream of it, 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 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)) (DeNOx stage); 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)).

[0379] Preferably, no reducing agent is added to the exhaust gas before the first reaction zone.

[0380] Such a process is particularly preferred according to the invention. It allows the relative NOx and N2O content 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 required to adjust the desired relative NOx and N2O content. For economic reasons, the amount of N2O decomposition catalyst is preferably not as large chosen so that a quantitatively complete reduction of the N2O content in the exhaust gas occurs through decomposition (0 ppmv), but a compromise is found between decomposition rate and dimensioning of the N2O decomposition catalyst.

[0381] 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU, and / or MEL structure type.

[0382] 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.

[0383] 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU, and / or MEL structural type.

[0384] Preferably, the first reaction zone and the second reaction zone are operated at different temperature levels.

[0385] Preferably includes - the N2O decomposition catalyst in the first reaction zone is a NOx-sensitive 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; 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 an iron-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU and / or MEL structural 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.

[0386] 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.

[0387] 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.

[0388] 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.

[0389] 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. 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)) and by chemical reduction with reducing agent on an N2O reduction catalyst (step (c2)).

[0390] 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)).

[0391] In addition, the NOx content is reduced in the second reaction zone by chemical reduction with a reducing agent on a NOx reduction catalyst. This reduction typically has rapid kinetics and, according to the invention, preferably proceeds virtually quantitatively. control

[0392] Regardless of the respective procedure, the process according to the invention is preferably regulated.

[0393] In preferred embodiments, depending on the design of the combustion system, preferably the internal combustion engine, the gas turbine, or the furnace, at least one parameter characteristic of the current operating state of the combustion system, preferably the internal combustion engine, the gas turbine, or the furnace, is measured as the first measured variable for controlling the method according to the invention. This first measured variable or parameter is preferably selected from the group consisting of combustion temperature, NFF consumption, possibly rotational speed, and noise level of the combustion system, preferably the internal combustion engine, the gas turbine, or the furnace.

[0394] Depending on the nature of the exhaust gas leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, in particular - 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; - exhaust gas temperature; - exhaust gas pressure; and - Volume flow of the exhaust gas; the process conditions can be optimized to achieve an efficient and economical reduction of the NOx and N2O content in the exhaust gas.

[0395] In preferred embodiments, therefore, for the control of the method according to the invention, at the outlet from the combustion system, preferably the internal combustion engine, the gas turbine or the furnace; and / or at the inlet to 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. This second 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.

[0396] 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. This third measured variable or 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.

[0397] In preferred embodiments, particularly 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, with reducing agent being fed between the first reaction zone and the second reaction zone, for the control of the method according to the invention, at least one parameter is measured 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, which is characteristic of the current state of the exhaust gas after leaving the first reaction zone and before entering the second reaction zone. This fourth 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.

[0398] 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. Therefore, the method is preferably regulated or controlled based on the first measured variable and / or the second measured variable and / or the third measured variable and / or the fourth measured variable by deliberately changing the manipulated variable (control variable), preferably by deliberately changing the metered amount of reducing agent.

[0399] With regard to preferred control variables, a distinction must be made between - Process conditions which cannot be changed at short notice or only with considerable equipment expenditure, and - Procedural conditions which can be changed at short notice and are therefore better suited to regulating the procedure.

[0400] According to the invention, preference is given to - the dimensioning of the exhaust gas treatment device; - the type, quantity and flow direction of the N2O decomposition catalyst and / or N2O reduction catalyst; - the type, quantity 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 injection; and - the arrangement of the first reaction zone and second reaction zone relative to each other does not require any control variables, ie these parameters preferably remain constant during the implementation of the process according to the invention.

[0401] However, these parameters can be selected or adjusted during the planning and design of the exhaust gas treatment system so that the process according to the invention can be controlled 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).

[0402] According to the invention, preferred manipulated variables (control variables) are: - the amount of reducing agent; - if applicable, the temperature of the exhaust gas; and - if applicable, the temperature of the catalysts.

[0403] Preferably, the exhaust gas leaves the exhaust gas treatment plant and has a residual NOx 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.

[0404] 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, even more preferably at most 7.5 ppmv, most preferably at most 5.0 ppmv, and in particular at most 2.5 ppmv.

[0405] A further aspect of the invention relates to a device comprising (i) a combustion plant powered by NH3; preferably an NH3-powered internal combustion engine, an NH3-powered gas turbine, or a furnace for cracking NH3 into N2 and H2; and (ii) an exhaust gas treatment system; wherein the device is configured to carry out the method according to any one of the preceding claims.

[0406] Particularly preferred embodiments of the invention are summarized below as sentences: Sentence 1 : A process for reducing the NOx and N2O content in the exhaust gas of a combustion plant operating with NH3, whereby Sentence 2: The method comprises the following steps: (a) burning NH3 to operate the combustion plant to produce an exhaust gas which comprises N2, H2O, NOx and N2O and which leaves the combustion plant; (b) transferring the exhaust gas to an exhaust gas treatment plant; (c) reducing the N2O content in the exhaust gas by (ci) 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 chemical reduction of NOx with reducing agent on an NOx reduction catalyst. Sentence 3: The process according to sentence 1, wherein the combustion plant operated with NH; is an internal combustion engine powered by NH; or a gas turbine powered by NH3. Sentence 4: The process according to sentence 1, wherein the combustion plant operated with NH; is a furnace for cracking NH3 into N2 and H2. Sentence 5: The process according to any one of the preceding sentences, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NOx reduction catalyst independently of one another comprises a zeolitic material; preferably a zeolite loaded with transition metal (including lanthanide), in particular with iron, cobalt or copper; more preferably a zeolite loaded with iron loaded zeolite; more preferably, independently, an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU and / or MEL type. Sentence 6: The process according to any one of the preceding sentences, wherein the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material. Sentence 7: 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 8: The process according to any one of the preceding sentences, wherein the N2O reduction catalyst and the NOx reduction catalyst are made of the same material. Sentence 9: The process according to any 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 10: The process according to any one of the preceding sentences, wherein in step (a) the combustion of NFL does not take place on a catalyst. Sentence 11: The process according to one of the preceding sentences, wherein in step (a) the combustion of NFL takes place in a mixture with a further combustible gas; preferably wherein the further combustible gas is selected from (i) FE; (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 12: The process according to any one of the preceding sentences, wherein in step (a) the combustion of NFL takes place in a mixture with FL. Sentence 13: The process according to sentence 11, wherein step (a) comprises the substeps: (ai) thermally and / or catalytically cracking NFL to produce a cracking gas comprising N2, FL, and optionally remaining NFL; (a2) optionally, mixing the cracking gas with further NFL to produce a mixture comprising FL and NFL; (as) combusting the cracking gas or the mixture. Sentence 14: The process according to sentence 11 or 12, wherein the proportion of FL in the mixture with NFL 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 15: The process according to any one of sentences 11 to 13, wherein the proportion of FL in the mixture with NFL 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 16: The process according to any one of sentences 11 to 14, wherein the molar ratio of FL:NFL in the mixture is in the range of 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 17: The process according to any one of sentences 11 to 15, wherein the air ratio X is in the range of 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 18: The process according to any one of Sentences 1 to 9, wherein in step (a) the combustion of NH3 occurs alone, so that NH3 is the only combustible gas which is combusted. Sentence 19: The method according to one of the preceding sentences, wherein the combustion plant, preferably the internal combustion engine, is mounted in a vehicle and serves to move the vehicle. Sentence 20: The procedure according to sentence 18, where the vehicle is a ship. Sentence 21: The method according to sentence 18, wherein the vehicle is a road vehicle; preferably selected from commercial vehicles, trucks and passenger cars; or a rail vehicle. Sentence 22: The process according to one of the preceding sentences, wherein the combustion plant, preferably the gas turbine, is part of a power plant. Sentence 23: The process according to sentence 21, whereby the power plant generates electricity and / or district heating. Sentence 24: The process according to one of the preceding sentences, wherein the combustion plant, preferably the furnace, is integrated into a plant for the thermal and / or catalytic decomposition of NH3 into N2 and H2. Sentence 25: 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 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. Sentence 26: The process according to any one of the preceding sentences, wherein the exhaust gas has a NO content which is greater than the N2O content; preferably wherein 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. Sentence 27: The process according to any one of the preceding sentences, wherein the exhaust gas has a NO2 content which is greater than the N2O content; preferably wherein 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. Sentence 28: The process according to any one of sentences 1 to 23, wherein the exhaust gas has an N2O content which is greater than the NOx 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 NOx content. Sentence 29: The process according to one of sentences 1 to 23 or 27, wherein the exhaust gas has a N2O content which is greater than the NO content; preferably wherein the N2O 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 NO content. Sentence 30: The process according to any one of sentences 1 to 23, 27 or 28, 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 31: The process according to any 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 32: The process according to any 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 33: 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 34: The process according to any one of the preceding sentences, wherein 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. Sentence 35: The process according to any one of the preceding sentences, wherein 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. Sentence 36: 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 37: The process according to any one of the preceding sentences, wherein the exhaust gas has a H2O content of less than 2.0 vol.%. Sentence 38: The process according to any 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 39: The process according to any 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 40: The process according to any one of the preceding sentences, wherein the exhaust gas has a 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%. Sentence 41: The process according to any one of the preceding sentences, wherein the exhaust gas has a 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 42: The process according to any one of the preceding sentences, wherein 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%, 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 43: The process according to any one of the preceding sentences, wherein the exhaust gas has a 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 44: The process according to any one of the preceding sentences, wherein the exhaust gas has a 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 45: 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 46: The process according to any 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 47: The process according to any one of the preceding sentences, wherein the exhaust gas comprises further gaseous components; preferably selected from the group consisting of O2, CO, CO2, NH3, CH4 and mixtures thereof. Sentence 48: The process according to any one of the preceding sentences, wherein the exhaust gas, when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, 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. Sentence 49: The process according to one of the preceding sentences, wherein the exhaust gas, when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, 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 50: The process according to one of the preceding sentences, wherein the exhaust gas, upon leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has a pressure of at most 1.5 bar; preferably atmospheric pressure. Sentence 51: The process according to one of the preceding sentences, wherein the exhaust gas on leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, 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 52: The process according to one of the preceding sentences, wherein the exhaust gas, on leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has an oxidation degree 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%. Sentence 53: The process according to one of the preceding sentences, wherein the exhaust gas on leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace, has an O2 content of less than 2.0 vol.%. Sentence 54: The process according to one of sentences 1 to 28, wherein the exhaust gas has an O2 content of more than 4.0 vol.% when leaving the combustion plant, preferably the internal combustion engine, the gas turbine or the furnace. Sentence 55: The process according to any one of the preceding sentences, wherein 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 plant. Sentence 56: 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 entering the exhaust gas treatment plant. Sentence 57: The process according to any 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 58: The process according to any 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 59: The method according to one of the preceding sentences, wherein the exhaust gas on entry into the exhaust gas treatment plant has a temperature 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 combustion plant, preferably the internal combustion engine, the gas turbine or the furnace. Sentence 60: The process according to any one of the preceding sentences, wherein the exhaust gas upon entering the exhaust gas treatment system has a pressure of at most 1.2 bar; preferably atmospheric pressure. Sentence 61: The process according to any one of the preceding sentences, wherein the exhaust gas upon entering the exhaust gas treatment system has a NOx oxidation level 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 62: 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 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 63: The process according to any one of the preceding sentences, wherein the exhaust gas has an O2 content of less than 2.0 vol.% upon entry into the exhaust gas treatment plant. Sentence 64: The process according to one of sentences 1 to 36, wherein the exhaust gas has an O2 content of more than 4.0 vol.% upon entry into the exhaust gas treatment plant. Sentence 65: The process according to any one of the preceding sentences, wherein step (c) comprises reducing the content of N2O in the exhaust gas by (ci) decomposing N2O on an N2O decomposition catalyst; preferably wherein 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-loaded zeolite; even more preferably an iron-loaded zeolite of the type MFI, BEA, FER, MOR, FAU and / or MEL. Sentence 66: The process according to any one of the preceding sentences, wherein step (c) comprises reducing the content of N2O 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 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 type MFI, BEA, FER, MOR, FAU and / or MEL. Sentence 67: 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 68: 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 part of N2O to be chemically reduced. Sentence 69: 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 part of N2O to be degraded. Sentence 70: 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 loaded zeolite; even more preferably an iron loaded zeolite of the type MFI, BEA, FER, MOR, FAU and / or MEL. Sentence 71: 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 72: 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 73: 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 74: 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 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)); 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 (ci)) and / or by chemical reduction of N2O with reducing agent on an N2O reduction catalyst (step (C2)); 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)). Sentence 75: The process according to sentence 73, wherein the NOx reduction catalyst in the first reaction zone comprises a conventional SCR catalyst, preferably based on V2O5-WC>3- / TiO2. Sentence 76: The process according to sentence 73 or 74, wherein the temperature of the exhaust gas on entry into the first reaction zone is at most 400°C, preferably at most 350°C. Clause 77: The process according to any one of clauses 73 to 75, wherein 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU, and / or MEL type. Sentence 78: The process according to any one of sentences 73 to 76, 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. Clause 79: The process according to any one of clauses 73 to 77, wherein 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU and / or MEL type. Clause 80: The process according to any one of clauses 73 to 78, 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. Clause 81: The process according to any one of clauses 73 to 79, 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. Clause 82: The process of any one of clauses 73 to 80, wherein the N2O decomposition catalyst in the second reaction zone comprises a NOx-sensitive N2O decomposition catalyst. Clause 83: The process according to any one of clauses 73 to 81, wherein 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. Clause 84: The process according to any one of clauses 73 to 82, wherein the temperature of the exhaust gas upon entry into the second reaction zone is at most 600°C, more preferably at most 550°C. Sentence 85: The process according to any one of sentences 73 to 83, wherein the exhaust gas after leaving the first reaction zone and before entering the second reaction zone has a NOx content in the range from 0 to 200 ppmv, preferably 1 to 200 ppmv, and a N2O content in the range from 200 to 2000 ppmv. Sentence 86: The process according to any one of sentences 73 to 84, wherein 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 a N2O content in the range from 200 to 2000 ppmv. Sentence 87: 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 of it, 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 content of N2O 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 content of NOx in the exhaust gas is reduced by chemical reduction of NOx with reducing agent on a NOx reduction catalyst (step (d)); wherein optionally in addition the content of N2O 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)). Clause 88: The process according to clause 86, wherein no reducing agent is added to the exhaust gas before the first reaction zone. Clause 89: The process according to clause 86 or 87, wherein 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU and / or MEL type. Clause 90: The process of any one of clauses 86 to 88, wherein the N2O decomposition catalyst in the first reaction zone comprises a NOx-sensitive N2O decomposition catalyst. Clause 91: The process according to any one of clauses 86 to 89, 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU and / or MEL type. Clause 92: The process according to any one of clauses 86 to 90, 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 93: The process according to any one of sentences 86 to 91, wherein in the second reaction zone a further reduction of the N2O content in the exhaust gas takes place 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 94: The process according to any one of clauses 86 to 92, 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)). Clause 95: The process according to any one of clauses 73 to 93, wherein the first reaction zone and the second reaction zone are spatially separated. Clause 96: The process according to any one of clauses 73 to 94, wherein the first reaction zone and the second reaction zone are spatially connected to one another. Clause 97: The process according to any one of clauses 73 to 95, wherein the first reaction zone and the second reaction zone are arranged in a common vessel. Clause 98: The process according to any one of clauses 73 to 96, 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. Clause 99: The process according to any one of clauses 73 to 97, 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 by at least a factor of 1.4, even more preferably by at least a factor of 1.6, most preferably by at least a factor of 1.8, and especially by at least a factor of 2.0. Clause 100: The process according to any one of clauses 73 to 98, wherein the space velocity in the first reaction zone is lower than in the second reaction zone; preferably by at least a factor of 1.5, more preferably by at least a factor of 2.0, even more preferably by at least a factor of 3.0, most preferably by at least a factor of 5.0, and especially by at least a factor of 10.0. Sentence 101: The process according to any one of Sentences 73 to 99, 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 102: The process according to any one of sentences 73 to 100, 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 especially at most 400°C. Clause 103: The process according to any one of clauses 73 to 101, wherein the temperature in the first reaction zone is relatively higher than the temperature in the second reaction zone 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 especially by at least 100°C. Clause 104: The process according to any one of clauses 73 to 102, wherein the temperature in the first reaction zone is relatively higher than the temperature in the second reaction zone 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 especially by at least 200°C. Sentence 105: The process according to any one of the preceding sentences, wherein the exhaust gas leaving the exhaust gas treatment plant has a residual NOx 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 106: The process according to any one of the preceding sentences, wherein the exhaust gas leaving the exhaust gas treatment plant 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 107: The process according to any one of the preceding sentences, wherein the N2O decomposition catalyst is arranged in a radial basket through which the flow is axial. Sentence 108: The process according to any one of the preceding sentences, wherein the N2O decomposition catalyst is particulate and comprises at least 50 particles. Sentence 109: The process according to any one of the preceding sentences, wherein the N2O reduction catalyst is arranged in a radial basket through which the flow is axial. Sentence 110: The process according to any one of the preceding sentences, wherein the N2O reduction catalyst is particulate and comprises at least 50 particles. Sentence 111: The method according to any one of the preceding sentences, wherein the NOx reduction catalyst is arranged in a radial basket through which the flow is axial. Sentence 112: The process according to any one of the preceding sentences, wherein the NOx reduction catalyst is particulate and comprises at least 50 particles. Sentence 113: The method according to one of the preceding sentences, wherein at least one parameter which is characteristic of the current operating state of the combustion plant is measured as a first measured variable in the combustion plant. Clause 114: The method according to clause 112, wherein the first measured variable is selected from the group consisting of combustion temperature, NFL consumption, rotational speed if applicable, and noise level of the combustion plant. Sentence 115: 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 which is characteristic of the current state of the exhaust gas before entering the exhaust gas treatment system. Sentence 116: The method according to sentence 114, wherein the second measured variable is 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. Sentence 117: The method according to one of the preceding sentences, wherein 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. Sentence 118: The method according to sentence 116, wherein the third measured variable is 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. Sentence 119: 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 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 120: The method according to sentence 118, wherein the fourth measured variable is 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. Sentence 121: The method according to one of the sentences 112 to 119, 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 targeted modification of a manipulated variable. Sentence 122: The method according to Sentence 120, where the manipulated variable is the added quantity of reducing agent. Sentence 123: A device comprising (i) a combustion plant powered by NH3; preferably an internal combustion engine powered by NH3, a gas turbine powered by NH3, or a furnace for splitting NH3 into N2 and FE; and (ii) an exhaust gas treatment plant; wherein the device is configured to carry out the method according to one of the preceding sentences. List of reference symbols: G: Generator V : Compressor GT: Gas turbine VK: Combustion chamber AB: Exhaust gas treatment system ADE 1 : first heat recovery steam generator ADE2: second heat recovery steam generator Kl: first catalyst bed K2: second catalyst bed WT: Heat exchanger DT: steam turbine SS: chimney

Claims

Patent claims:

1. A process for reducing the NOx and N2O content in the exhaust gas of a combustion plant operated with NH3, preferably a gas turbine, the process comprising the following steps: (a) burning NH3 to operate the combustion plant, preferably a gas turbine, producing an exhaust gas comprising N2, H2O, NOx and N2O, which leaves the combustion plant; (b) transferring the exhaust gas to an exhaust gas treatment plant; (c) Reducing the N2O content in the exhaust gas by (ci) decomposition of N2O on a N2O decomposition catalyst and / or (C2) chemical reduction of N2O with a reducing agent on a N2O reduction catalyst; and (d) Reducing the NOx content in the exhaust gas by chemical reduction of NOx with a reducing agent on a NOx reduction catalyst.

2. The method of claim 1, wherein the NH3-fired combustion plant is an NH3-fired gas turbine.

3. The method of claim 2, wherein the gas turbine is combined with a steam turbine.

4. The method according to claim 2 or 3, wherein the gas turbine is part of a power plant.

5. The method according to claim 4, wherein the power plant generates electrical power and / or district heating.

6. The process 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 independently comprise 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, independently of one another, an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU, and / or MEL structural type.

7. The process according to any one of the preceding claims, wherein in step (a) the combustion of NH3 does not take place on a catalyst.

8. The process according to any one of the preceding claims, wherein in step (a) the combustion of NH3 takes place in admixture with another combustible gas; preferably wherein the further combustible gas is selected from (1) 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.

9. The process according to any one of the preceding claims, wherein in step (a) the combustion of NH3 takes place in a mixture with H2.

10. The method according to claim 9, wherein step (a) comprises the substeps: (ai) 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; (ad burning of the fission gas or the mixture.

11. The process according to claim 9 or 10, wherein the proportion of H2 is at most 50 vol.% and wherein the combustion preferably takes place at an air ratio X in the range of 2.0 to 3.0, more preferably 2.1 to 2.9, even more preferably 2.2 to 2.

8.

12. The process according to claim 9 or 10, wherein the proportion of H2 is more than 50 vol.% and wherein the combustion preferably takes place at an air ratio X in the range of 2.5 to 3.5, more preferably 2.6 to 3.4, even more preferably 2.7 to 3.

3.

13. The process according to any one of the preceding claims, wherein in step (a) the combustion of NH3 takes place in admixture with CH4.

14. The process according to claim 13, wherein the proportion of CH4 is at most 50 vol.% and wherein the combustion takes place at an air ratio X in the range of 1.5 to 2.5, more preferably 1.6 to 2.4, even more preferably 1.7 to 2.

3.

15. The process according to claim 13, wherein the proportion of CH4 is more than 50 vol.% and wherein the combustion takes place at an air ratio X in the range of 2.0 to 3.0, more preferably 2.1 to 2.9, even more preferably 2.2 to 2.

8.

16. The process according to any one of claims 1 to 7, wherein in step (a) the combustion of NH3 occurs alone, so that NH3 is the only combustible gas which is burned.

17. The process according to claim 16, wherein the combustion takes place at an air ratio X in the range of 1.0 to 1.5, more preferably 1.1 to 1.4, even more preferably 1.1 to 1.

3.

18. The process according to any one of the preceding claims, wherein in step (a) an exhaust gas is produced which has a temperature in the range of 1000 to 1500 °C.

19. The process according to any one of the preceding claims, wherein in step (a) an exhaust gas is produced which has a pressure in the range of 10 to 32 bar.

20. The process according to any one of the preceding claims, wherein in step (a) an exhaust gas is produced which has an oxidation degree of NOx of at most 5.0%, more preferably at most 4.0%, even more preferably at most 3.0%, most preferably at most 2.0% and in particular at most 1.0%, optionally even at most 0.5%.

21. The method according to any one of the preceding claims, wherein the exhaust gas produced in step (a) is expanded via a gas turbine.

22. The method of claim 21, wherein the exhaust gas at the outlet from the gas turbine has a temperature in the range of 450 to 670 °C.

23. The method according to claim 21 or 22, wherein the exhaust gas at the outlet from the gas turbine 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.

24. The process according to any one of claims 21 to 23, wherein the exhaust gas at the outlet from the gas turbine has a NOx content in the range of 500 to 3000 ppmv.

25. The process according to any one of claims 21 to 24, wherein the exhaust gas at the outlet from the gas turbine has an O2 content in the range of 1.0-6.0 vol.%.

26. The process according to any one of claims 21 to 25, wherein the exhaust gas at the outlet from the gas turbine has a H2O content in the range of 20-30 vol.%.

27. The process according to any one of claims 21 to 26, wherein the exhaust gas at the outlet from the gas turbine has an N2O content of at most 500 ppmv, more preferably at most 200 ppmv, even more preferably at most 100 ppmv.

28. The process according to any one of claims 21 to 27, wherein the exhaust gas at the outlet from the gas turbine has an N2O content of at least 5 ppmv, more preferably at least 20 ppmv, even more preferably at least 50 ppmv.

29. The method according to any one of claims 21 to 28, wherein the exhaust gas at the outlet from the gas turbine has an NH3 content of at most 800 ppmv, more preferably at most 500 ppmv, even more preferably at most 250 ppmv.

30. The process according to any one of claims 21 to 29, wherein the exhaust gas at the outlet from the gas turbine has an NH3 content of at least 10 ppmv, more preferably at least 50 ppmv, even more preferably at least 100 ppmv.

31. The method according to any one of claims 21 to 30, wherein the exhaust gas at the outlet from the gas turbine has an oxidation degree (n(NO2) / (n(NO)+n(NO2))) of NOx of at most 10%, more preferably at most 9.0%, even more preferably at most 8.0%, most preferably at most 7.0% and in particular at most 6.0%, optionally even at most 5.0%.

32. The process according to any one of the preceding claims, wherein in step (a) NH3 is combusted in admixture with CH4 and the exhaust gas therefore additionally contains CO and CO2 and preferably also HCN.

33. The process of claim 32, wherein the exhaust gas at the outlet from the gas turbine has an HCN content of at least 5 ppmv, more preferably at least 10 ppmv, even more preferably at least 50 ppmv.

34. The process according to claim 32 or 33, wherein the exhaust gas at the outlet from the gas turbine has a HCN content of at most 1000 ppmv, more preferably at most 500 ppmv, even more preferably at most 200 ppmv, most preferably at most 100 ppmv.

35. The method according to any one of the preceding claims, wherein at least one heat exchanger is arranged in the flow direction of the exhaust gas downstream of the gas turbine and upstream of the exhaust gas treatment system, in which the exhaust gas is cooled.

36. The process according to claim 35, wherein the temperature of the exhaust gas at the outlet of the heat exchanger is at most 550°C, more preferably at most 525°C, even more preferably at most 500°C.

37. The process according to claim 35 or 36, wherein the temperature of the exhaust gas at the outlet of the heat exchanger is at least 400°C, more preferably at least 425°C, even more preferably at least 450°C.

38. The process according to any one of the preceding claims, wherein step (c) comprises reducing the N2O content in the exhaust gas by (ci) decomposing N2O on an N2O decomposition catalyst; preferably wherein 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU and / or MEL structure type.

39. The process according to any one of the preceding claims, wherein step (c) comprises reducing the N2O content in the exhaust gas by (C2) chemically reducing N2O with reducing agent over an N2O reduction catalyst; preferably wherein the N2O reduction catalyst comprises 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 MFI, BEA, FER, MOR, FAU and / or MEL structure type.

40. The process according to any one of the preceding claims, wherein the reducing agent in step (C2) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

41. The process according to any one of the preceding claims, 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 part of N2O to be chemically reduced.

42. The process according to any one of the preceding claims, 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 part of N2O to be degraded.

43. The process 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-loaded zeolite; even more preferably an iron-loaded zeolite of the MFI, BEA, FER, MOR, FAU, and / or MEL structural type.

44. The process according to any one of the preceding claims, wherein the reducing agent in step (d) is selected from NFL, hydrocarbons, CO, FL and mixtures thereof; preferably NFL.

45. The process according to any one of the preceding claims, wherein the reducing agent in step (d) is NFL, 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.

46. ​​The process according to any one of the preceding claims, wherein the reducing agent in step (C2) is the same as the reducing agent in step (d); preferably NFL.

47. The method according to any one of the preceding claims, wherein the exhaust gas treatment system 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; optionally, wherein preferably upstream of the first catalyst bed, a first device with a first control valve for metering NFL 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 NFL into the exhaust gas is arranged, with which further NFL 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 (ci) the N2O content in the exhaust gas is reduced by catalytic decomposition of N2O; and (d) the NOx content in the exhaust gas is incompletely reduced by catalytic chemical reduction of NOx with NFL, wherein at least part of the NFL originates from incomplete combustion of NFL in step (a) (NFL slip): and (ii) in the second catalyst bed (C2) the content of residual N2O is reduced by catalytic chemical reduction of N2O with NH3; (cl*) optionally, the residual N2O content is reduced by catalytic decomposition of N2O; and (d*) the residual NOx content is reduced by catalytic chemical reduction of NOx with NH3.

48. The process according to claim 47, wherein in the first catalyst bed the catalytic decomposition of N2O is co-catalyzed by NOx present in the exhaust gas.

49. The process according to claim 47 or 48, wherein the incomplete chemical reduction of NOx with NH3 in the first catalyst bed continues to a predetermined residual NOx content which is sufficient to cause a co-catalytic effect on the decomposition of N2O in the first catalyst bed.

50. The method according to any one of claims 47 to 49, wherein additional NH3 is metered into the exhaust gas via the first device; preferably under feedback control; wherein preferably a specific value for the NOx concentration at the outlet of the first catalyst bed is specified as a target value (setpoint value) and the actual NOx concentration at the outlet of the first catalyst bed is measured (actual value); and wherein, in the event of a difference between the setpoint value and the actual value (control difference), the control degree of the first control valve is changed in order to minimize the difference.

51. The process according to claim 50, wherein the amount of additional NH3 is selected such that the residual concentration of NOx at the outlet of the first catalyst bed is at most 1000 ppmv, preferably at most 500 ppmv, more preferably at most 100 ppmv.

52. The process according to claim 50 or 51, wherein the amount of additional NH3 is selected such that the residual concentration of NOx at the exit of the first catalyst bed is at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 40 ppmv.

53. The process according to any one of claims 47 to 52, wherein the temperature of the exhaust gas at the outlet from the first catalyst bed is in the range of 400 to 550°C.

54. The process according to any one of claims 47 to 53, wherein 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.

55. The process according to any one of claims 47 to 54, wherein 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%.

56. The process according to any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has an oxidation degree of NOx in the range of 30 to 50%.

57. The process according to any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NOx in the range of 15 to 35%.

58. The process according to any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NOx in the range of 10 to 20%.

59. The process according to any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has an oxidation level of NOx in the range of 5 to 15%.

60. The process according to any one of claims 47 to 59, wherein residual N2O in the second catalyst bed is decomposed 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.

61. The process according to any one of claims 47 to 60, wherein residual NOx is decomposed in the second catalyst bed to a residual NOx 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.

62. The method according to any one of claims 47 to 61, wherein the additional NH3 is metered in using the second device under feedforward control; wherein preferably the concentration of NOx and N2O is measured at the outlet of the first catalyst bed; the required amount of NH3 is calculated taking into account the amount of exhaust gas entering the second catalyst bed; and the control level of the second control valve is changed using the calculated result (control variable) in order to meter in the required amount of NH3.

63. The process according to any one of claims 47 to 62, wherein the molar ratio of NH 3 / fNO x +bh O) at the inlet to the second catalyst bed is in the range of 1.7 to 6.0; preferably 2.1 to 4.6; more preferably 2.7 to 3.

9.

64. The process according to any one of claims 47 to 63, wherein the molar ratio of NEE / NOx at the inlet to the second catalyst bed is in the range of 1.0 to 2.0; preferably 1.1 to 1.6; more preferably 1.2 to 1.

4.

65. The process according to any one of claims 47 to 64, wherein the molar ratio of NH3 / N2O at the inlet to the second catalyst bed is in the range of 0.7 to 4.0; preferably 1.0 to 3.0; more preferably 1.5 to 2.

5.

66. The method according to any one of claims 47 to 65, wherein the additional NH3 is added by the second device without FeetföacF control.

67. The process according to any one of claims 47 to 66, wherein the amount of catalyst is selected such that a degradation of N2O of at least 50%, 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 occurs in the first catalyst bed.

68. The process according to any one of claims 47 to 67, wherein the amount of catalyst and the amount of additional NH3 are selected such that at the outlet of the first catalyst bed the molar ratio of NOX / N2O is at least 5, more preferably at least 10, even more preferably at least 20.

69. The process according to any one of claims 47 to 68, wherein the space velocity of the first catalyst bed is in the range of 5,000 h" 1 up to 100,000 hours" 1 preferably 10,000 h" 1 up to 50,000 hours" 1 , even more preferably 15,000 h" 1 up to 45,000 hours" 1 .

70. The process according to any one of claims 47 to 69, wherein the molar ratio of NOX / N2O at the outlet of the first catalyst bed is at least 10 and the addition of further NH3 via the second device is carried out solely in relation to the amount of NOx entering.

71. The process according to any one of claims 47 to 70, wherein 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.

72. The process according to any one of claims 47 to 71, wherein 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.

73. The process according to any one of claims 47 to 72, wherein, 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 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.

74. The process according to any one of claims 47 to 73, wherein the space velocity of the second catalyst bed is in the range of 5,000 h" 1 up to 100,000 hours" 1 preferably 10,000 h" 1 up to 50,000 hours" 1 , even more preferably 15,000 h" 1 up to 45,000 hours" 1 .

75. The process according to any one of claims 47 to 74, wherein the ratio of the catalyst volumes (Vlkat / 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.

76. The method according to any one of claims 47 to 75, wherein 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, even more preferably at most 1.3 bara, most preferably at most 1.2 bara and in particular at most 1.1 bara; - the H2O content in the exhaust gas upon 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 upon 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 upon 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, more preferably at least 10 ppmv, even more preferably at least 50 ppmv; - the exhaust gas contains unburned residues of NH3 from the combustion of NEE when entering the first catalyst bed; - the N2O decomposition catalyst and / or the N2O reduction catalyst is in the form of a honeycomb body; - the NOx reduction catalyst is in the form of a honeycomb structure; - 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 tempered 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; - there is no intermediate cooling of the exhaust gas after leaving the first catalyst bed and until it enters the second catalyst bed; - the molar ratio of N2O : NOx upon entry into 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 at the outlet of the first catalyst bed is not more than 0.20, more preferably not more than 0.1, even more preferably not more than 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 NOx content at the inlet to the first catalyst bed; and / or - 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.

77. The method according to any one of the preceding claims, wherein the exhaust gas treatment plant comprises a first heat recovery steam generator and preferably a second heat recovery steam generator, wherein the first heat recovery steam generator is optionally arranged upstream of the second heat recovery steam generator in the flow direction of the exhaust gas.

78. The method according to any one of claims 47 to 77, wherein the exhaust gas treatment plant comprises a first heat recovery steam generator and a second heat recovery steam generator, wherein the first heat recovery steam generator is arranged upstream of the second heat recovery steam generator in the flow direction of the exhaust gas.

79. The method of claim 78, wherein the exhaust gas first flows through the first heat recovery steam generator, then through the first catalyst bed, then through the second catalyst bed, and finally through the second heat recovery steam generator.

80. The method of claim 78, wherein the exhaust gas first flows through the first heat recovery steam generator, then the first catalyst bed, then the second heat recovery steam generator, and finally the second catalyst bed.

81. The method of claim 78, wherein the exhaust gas first flows through the first catalyst bed, then the first heat recovery steam generator, then the second catalyst bed, and finally the second heat recovery steam generator.

82. The method according to any one of the preceding claims, wherein the exhaust gas leaving the exhaust gas treatment plant has a residual NOx 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.

83. The method according to any one of the preceding claims, wherein the exhaust gas leaving the exhaust gas treatment plant 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.

84. The process according to any one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and the NOx reduction catalyst are present independently of one another as monolithic catalyst elements traversed by parallel channels, preferably as monolithic honeycomb bodies.

85. A device comprising (i) a NH3-driven gas turbine; and (ii) an exhaust gas treatment system; wherein the device is configured to carry out the method according to any one of the preceding claims.

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