Reducing nox and n2O in exhaust gases of combustion systems operating with nh3, in particular gas turbines

Abstract

The invention relates to reducing the NOx and N2O content in the exhaust gases of combustion systems operated with NH3, in particular gas turbines operated with NH3.

Description

[0001] This application claims priority from European patent application No. 22216421.2 filed on December 23, 2022 and from European patent application No. 23165192.8 filed on March 29, 2023.

[0002] The present invention relates to reducing NO in exhaust gases from NH3-driven combustion systems, in particular NH3-driven gas turbines X and N2O content.

[0003] Ammonia is one of the most widely produced and distributed chemicals in the world and is famous for its use as fertilizer in agriculture. In recent years, there has been increasing interest in its use as a carbon-free fuel in advanced energy and 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). The use of ammonia in aircraft has also been discussed (A. Boretti et al., ACS Energy Lett. 2022, 7, 2557-2564).

[0004] Ammonia is carbon-free and has a global transport and storage infrastructure. It can be produced directly from renewable energy, water, and air, and is therefore currently considered a smart energy source and combustion fuel.

[0005] Ammonia has a relatively low calorific value and a low flame propagation speed, and there is a risk of flame extinction caused by incomplete combustion. In addition, the combustion of NH3 also carries the risk of increased emissions of nitrogen oxides (especially NO, NO2, N2O), which affects its suitability as a combustion gas. Gaseous ammonia / hydrogen / air mixtures have been proposed, in which a certain hydrogen content acts as a combustion promoter, which will be producible, for example, by catalytic or thermally 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 a system capable of treating NH3 and NO in the exhaust gas. X Exhaust gas treatment catalyst and exhaust gas treatment catalyst capable of controlling NH3 and NO in exhaust gas flowing into the exhaust gas treatment catalyst X Ratio flow gas control unit.

[0007] EP 2378097 B1 relates to an ammonia-driven engine, wherein an ammonia-driven ... X The catalyst can selectively reduce NO in the exhaust gas in the presence of ammonia. X .

[0008] EP 3517757 A1 relates to a gas turbine which can be fired with NH 3 and / or H 2 and is equipped with an exhaust gas treatment system.

[0009] EP 3604929 B1 relates to a combustion device of a gas turbine (A), comprising: a combustion chamber; an ammonia supply unit, which supplies primary reducing ammonia as a nitrogen oxide reducing agent into the combustion chamber and mixes secondary reducing ammonia with the combustion exhaust gas discharged from the combustion chamber to reduce nitrogen monoxide present in the combustion exhaust gas; and a control unit, which is designed so that it controls at least the amount of primary reducing ammonia supplied or the amount of secondary reducing ammonia mixed with the combustion exhaust gas according to the concentrations of residual nitrogen monoxide and residual ammonia present in the combustion exhaust gas after being discharged from the combustion chamber.

[0010] US Pat. No. 11702988 B2 relates to an ammonia decomposition apparatus comprising a heating medium conduit configured to flow a heating medium heated by heat generated by a gas turbine, an ammonia supply conduit configured to flow ammonia, an ammonia decomposition device, and an ammonia removal device. The ammonia decomposition device is configured to utilize heat from the heating medium in the heating medium conduit to thermally decompose ammonia from the ammonia supply conduit, thereby generating a decomposition gas containing hydrogen, nitrogen, and residual ammonia.

[0011] US20180355794 A1 relates to a gas turbine system comprising: an ammonia source and an oxygen-containing gas source, a first combustion chamber connected so as to accommodate ammonia, a hydrogen-rich gas stream and an oxygen-containing gas, a turbine connected so as to absorb an exhaust gas stream from the first combustion chamber, and a second combustion chamber connected so as to accommodate the exhaust gas from the turbine, ammonia and a hydrogen-rich gas stream.

[0012] WO 2023286516 A1 relates to a gas turbine apparatus, comprising: a gas turbine; an ammonia supply device for supplying ammonia to a combustion chamber of the gas turbine; a frame forming a flow channel, the flow channel forming an exhaust gas flow duct through which exhaust gas from the gas turbine flows; a water spray device comprising a water sprayer capable of spraying water into the exhaust gas flow duct; 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 relates to an experimental evaluation of the performance of a commercial microturbine operated with an ammonia-methane mixture.

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

[0015] Th.Sattelmayer, Gasturbinen, Springer, VDI-Buch (2019) 241-272 deals with the combustion principles of stationary gas turbines.

[0016] S. Mashruk et al., Combustion and Flame 244 (2022) 112299 relates to progress in N2O production in lean combustion in a premixed NH3 / H2 / air swirl flame.

[0017] ECOkafor et al., Combustion and Flame 211 (2020) 406-416, relates to NO in microturbine burners fired with methane-ammonia mixtures. X and other emissions control.

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

[0019] The operating limits of an ammonia-fueled spark-ignition engine have been examined. Here, it was found that NH3 emissions in the exhaust gas decrease with increasing engine speed, reaching maximum values ​​in rich mixtures. NH3 emissions can reach up to 1% by volume. NO XThe emissions consist mainly of NO, and the effect of engine speed appears to depend on the equivalence ratio. Although NH3 does not contribute to carbon content in the exhaust, it can emit N2O (one of the most potent greenhouse gases). X For both N2O and N2O, the highest emission values ​​are observed on the lean side, as they decrease with increasing equivalence ratio. Finally, even when burning pure ammonia under rich conditions, H2 is produced in the exhaust gas, indicating a partial decomposition of ammonia. The exhaust gas temperature was also monitored and appears to be high enough to allow NO to be degraded using the catalyst. X Selective catalytic reduction (SCR) to reduce NO X Emissions and N2O emissions are at least below 2000rpm (Ch. et al., Energies 2021, 14, 4141).

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

[0021] YK Park, Chemical Engineering Journal, Volume 461, 141958, published on April 1, 2023, is a review of the catalytic removal of nitrogen oxides (NO, NO2, N2O) from exhaust gases formed when ammonia is used as a fuel.

[0022] JP 2023 026798A published on March 1, 2023 relates to an exhaust gas treatment system for an ammonia engine, which includes an oxidation catalyst as a first catalyst and a denitration catalyst as a second catalyst, wherein the oxidation catalyst includes a catalyst layer containing Pt and zeolite, and the denitration catalyst includes a catalyst layer containing zeolite that has been ion-exchanged with Cu, Co or Fe ions.

[0023] US2003 / 0143142 A1 and US2017 / 0334722 A1 describe methods for reducing NO in tail gas from nitric acid production. X concentration and N2O concentration.

[0024] To date, the focus of research has been on the optimization of ammonia combustion itself, in particular with regard to energy yield and economic feasibility, but also with regard to the formation of undesirable nitrogen oxides. However, it can be assumed that it is not possible to completely suppress NO in the combustion process. X (i.e. the formation of NO and NO2) and the formation of N2O.

[0025] However, in order to protect health, the environment and the climate, NO should be avoided or at least reduced as much as possible. X, N2O and other components that may be present in the combustion gases (such as CO, HCN or even NH3). Therefore, many industrialized countries have implemented corresponding regulations.

[0026] Furthermore, the combustion of hydrocarbons (CH4, natural gas, etc.) in the presence of NH3 produces exhaust gases that may contain hydrogen cyanide (HCN, hydrocyanic acid). Even small amounts of HCN are problematic, as it is classified as highly toxic, and corresponding low limit values ​​for HCN emissions into the environment must be adhered to. HCN-contaminated exhaust gases can, in principle, be purified using various methods. Alkaline scrubbing operations can form and separate cyanides, but these, in turn, must be handled as highly toxic compounds. Specific oxidation catalysts based on precious metals can be used to convert HCN into CO2, H2O, N2, and various nitrogen oxides. However, this involves considerable procedural complexity and costs. For example, the nitrogen oxides formed must be decomposed in further process steps, such as with the aid of SCR. Treatment over specific catalysts, such as those based on TiO2, for the hydrolysis of HCN via the reaction HCN + H2O → CO + NH3 has also been described. In this case, subsequent further oxidation over a corresponding separate oxidation catalyst is also necessary. Therefore, there is a need for a cleaning process for HCN-contaminated exhaust gases that is characterized by a simple and inexpensive operating mode and low equipment expenditure. Furthermore, these processes should convert HCN into non-toxic substances that do not require further treatment.

[0027] Another problem is the incomplete combustion of ammonia, the effect of which is that the exhaust gases from a combustion system operating with ammonia as fuel may contain considerable amounts of unburned ammonia (known as NH3 slip, NH3 breakthrough). Since the permissible limits for ammonia that can be released into the atmosphere are relatively strict, it must be ensured in this case that the ammonia is oxidized to nitrogen before the exhaust gases can be released into the atmosphere. For this purpose, so-called ammonia slip catalysts (ASCs) have been developed, which are typically based on platinum group noble metals (i.e. Ru, Rh, Pd, Os, Ir, Pt). Such catalysts are not only expensive but also not very selective (i.e. they cannot form NO from NH3). X or N2O) and are sensitive to chlorine compounds and other catalyst poisons.

[0028] Therefore, measures are needed that can at least partially eliminate:

[0029] - Nitrogen oxides (especially N2O and NO X (i.e. NO and NO2)),

[0030] - any excess NH3, and

[0031] - any other components in the exhaust gas that are harmful to the environment (such as CO or HCN),

[0032] For combustion-related reasons, it is or may be present in the exhaust gases of NH3-driven combustion systems, in particular in the exhaust gases of NH3-driven internal combustion engines, NH3-driven gas turbines, or in the exhaust gases of furnaces for cracking NH3 into N2 and H2, so that the exhaust gases can then be discharged into the ambient air in compliance with all environmental regulations.

[0033] It is necessary to take into account the special circumstances arising from the maximum efficiency of the combustion of NH3 for operating a combustion system, preferably for driving an internal combustion engine, for driving a gas turbine or for driving a furnace for cracking NH3 into N2 and H2. Important parameters are not only the different compositions of the exhaust gases, but also, in particular, the pressure and temperature of the exhaust gases. These parameters can be compared with the methods that have been developed so far for the removal of NO X The parameters of other exhaust gases are very different from those of N2O measures.

[0034] For example, in the industrial production of nitric acid NH3, it is intentionally oxidized to NO X , so that nitric acid can be subsequently obtained from it by reaction with water in an absorption tower. Special catalysts made of precious metals are used for oxidation, and the reaction is often carried out under high pressure. The purpose of the combustion of NH3 is to achieve NO X Typical water contents in the off-gas range from about 1% to 3% by volume.

[0035] In contrast, in the combustion of NH3 for operating a combustion system, preferably for operating an internal combustion engine, for operating a gas turbine or for operating a furnace for cracking NH3 into N2 and H2, NH3 is preferably only oxidized to the level of N2, for which typically no catalyst is required and the conversion is usually carried out at atmospheric pressure. The purpose of the combustion is to achieve NO X and a minimum yield of N₂O. Typical water contents in exhaust gases are well above 3% by volume. For example, the combustion of pure NH₃ in air with a residual oxygen content of 3 mol% produces over 28 mol% water. The primary purpose of the NH₃ combustion here is to generate energy. The low levels of nitrogen oxides in the exhaust gases formed during combustion are advantageous because, in this case, only relatively small exhaust gas treatment systems are required to reduce the nitrogen oxide levels in the flue gases and thus comply with statutory requirements for permissible emissions, or because sufficiently low residual concentrations can only be achieved using known nitrogen monoxide reduction methods.

[0036] Compared to conventional exhaust gas treatment systems used (for example in the case of exhaust gases from plants for the production of HNO 3 ), the inventive combustion of NH 3 (preferably in a mixture with H 2 ) offers special features which require special measures.

[0037] On the one hand, a relatively low pressure, typically not exceeding 5 bar, and on the other hand a very high water content are essential. The term "low pressure" or "low pressure" means that when using conventional catalyst beds based on granular beds, for example, the pressure drop can be too great. Due to the hydrothermal load on the catalyst in the exhaust gas treatment system (especially in the case of zeolite materials), a high water content combined with simultaneously high temperatures can lead to a gradual deactivation of the catalyst. Therefore, the maximum temperature should be limited. In addition to aging, NO X The chemical reduction of N2O is hardly affected by high water content, whereas the decomposition of N2O by decomposition and / or chemical reduction is significantly impaired by high water content.

[0038] A further difference of the exhaust gas to be treated according to the invention is the relatively high NO X Content, NO X The content can be several thousand ppmv. X The content depends on the conditions of NH3 combustion, in particular on the NH3 content, the presence of any other combustible gases (H2 and / or CH4 (natural gas)) and the air ratio λ. Due to the high temperatures of up to 1000°C or more in combustion, NO X Initially, it is also almost entirely present as NO, i.e. the proportion of NO is very high and the proportion of NO2 is very low. Since the formation kinetics of NO2 are slow at high temperatures and due to the preferred cooling, only a small part of NO is converted into NO2. This means that when the exhaust gas enters the exhaust gas treatment system, NO X The degree of oxidation (β) (i.e. NO2 in the total NO X The molar ratio (β = n(NO2) / (n(NO) + n(NO2))) in the reaction is small, typically <5 vol%. This in turn means that the desired selective catalysis of NO is not sufficient, according to normal SCR, which occurs at a slow rate. X The restore may actually proceed very poorly or slowly.

[0039] There is a fundamental difference between these and the established exhaust gas cleaning in HNO3 systems, where exhaust gas is removed from the “cold” state (thermodynamic NO X After leaving the absorption tower, the mixture containing N2O and NO is gradually heated under a positive pressure of usually 4-10 bar. X For example, in the production of HNO3, the tail gas NO X The oxidation level before entering the corresponding exhaust gas treatment system is typically between 30% and 70% by volume, i.e. close to the NO in a very fast SCR. X The ideal stoichiometric ratio for reduction.

[0040] Therefore, in this case, high NO X Very low NO content XThe combination of oxidation levels and high water content with low operating pressures (near atmospheric pressure) presents particular challenges to the effectiveness of the exhaust gas treatment system of the present invention. Furthermore, there is the challenge or need to eliminate N2O, which is also present in the exhaust gas and cannot be reduced by conventional SCR methods based on V2O5 / TiO2 catalysts.

[0041] Therefore, the purpose and the resulting reaction products in the combustion of NH3 are sometimes very different from each other.

[0042] In conventional plants for the production of nitric acid, the waste gases often have at relatively high pressure:

[0043] - Relatively low levels of NO X ;

[0044] - Relatively high proportion of NO2;

[0045] - Relatively high content of N2O;

[0046] - relatively low levels of water; and

[0047] - Zero proportion of unburned NH3 (NH3 slip).

[0048] In contrast, in combustion plants (preferably for driving internal combustion engines, for driving gas turbines or for operating furnaces for cracking NH3 into N2 and H2), the exhaust gases generally have a relatively low pressure.

[0049] - Relatively high levels of NO X ;

[0050] - A relatively small proportion of NO2;

[0051] - Relatively low content of N2O;

[0052] - Significantly higher water content;

[0053] - a possibly non-negligible proportion of unburned NH3 (NH3 slip); and

[0054] - If NH3 is burned together with CH4 (natural gas), a non-negligible proportion of HCN may be produced.

[0055] Eliminating NO from exhaust gas X These special circumstances must be taken into account when analyzing N2O and NH3, which poses special challenges.

[0056] Compared with existing industrial plants (so-called stationary plants), the removal of NO from exhaust gas is XFurther challenges in terms of NO and N2O are caused by the use of NH3-operated combustion systems, especially NH3-driven internal combustion engines, in vehicles, ships and possibly aircraft. Therefore, these systems are not fixedly installed and operated at one location, but are mobile. However, special requirements are placed on mobile systems, for example with regard to weight, size, safety, impact stability, etc. In addition, the operating mode of the combustion system, preferably the operating mode of the internal combustion engine, can sometimes change spontaneously, for example when switching from partial load operation to full load operation, for example in the case of acceleration or braking at short notice. This is also the case for the removal of NO from the exhaust gas. X and a particular challenge for N2O.

[0057] One object of the present invention is to reduce NO in the exhaust gases obtained in NH3-operated combustion systems, preferably NH3-driven internal combustion engines, NH3-driven gas turbines or furnaces for cracking NH3 into N2 and H2. X (ie NO and NO2), N2O and, if necessary, NH3, CO and / or HCN content.

[0058] This object is achieved by the subject matter of the claims.

[0059] A first aspect of the present invention relates to the reduction of NO in the exhaust gas of an NH3-operated combustion system, preferably an NH3-driven internal combustion engine, an NH3-driven gas turbine or a furnace for cracking NH3 into N2 and H2. X and N2O content, wherein the method comprises the following steps:

[0060] (a) burning NH3 (or NH3 in a mixture with another combustible gas, in particular H2, CH4, etc.) for operating a combustion system, preferably for driving an internal combustion engine, for driving a gas turbine or for driving a furnace for cracking NH3 into N2 and H2, generating an exhaust gas containing N2, H2O, NO X and N2O and possibly HCN and exit the combustion system, preferably an internal combustion engine, a gas turbine or a furnace;

[0061] (b) diverting exhaust gases from a combustion system, preferably an internal combustion engine, a gas turbine or a furnace, to an exhaust gas treatment system;

[0062] (c) reducing the N2O content in the exhaust gas by the following steps

[0063] (c1) decomposing N2O on an N2O decomposition catalyst, and / or

[0064] (c2) chemically reducing N2O using a reducing agent on an N2O reduction catalyst;

[0065] (d) By XReduction of NO by using a reducing agent on a catalyst X Chemical reduction is performed to reduce NO in the exhaust gas X content.

[0066] The order of steps (c) and (d) is desired; according to the present invention, all options from sequential in time to simultaneous in any order or a mixture thereof are included.

[0067] The exhaust gas treatment system of the present invention comprises at least:

[0068] - N2O reduction catalyst and / or N2O decomposition catalyst; and

[0069] - NO X Reduction catalyst;

[0070] They may be identical or different depending on the given function or functions and may be present in common or separate reaction zones (catalyst beds).

[0071] In a preferred embodiment, the exhaust gas treatment device of the present invention comprises:

[0072] - N2O reduction catalyst;

[0073] - N2O decomposition catalyst; and

[0074] -NO X Reduction catalyst;

[0075] They may be identical or different depending on the given function or functions and may be present in common or separate reaction zones (catalyst beds).

[0076] In a preferred embodiment, the exhaust gas treatment system of the present invention further comprises at least one additional catalyst, or the aforementioned N2O reduction catalyst, N2O decomposition catalyst or NO having at least one additional function selected from the group consisting of: X One of the reduction catalysts:

[0077] - NH3 oxidation catalyst;

[0078] - HCN decomposition catalyst; and

[0079] - CO oxidation catalyst.

[0080] When the proportion of unburned NH3 in the exhaust gas (NH3 slip) is greater than the amount of NO in the exhaust gas treatment system XWhen NH3 is required as a reducing agent for the production of N2O and / or N2O, an NH3 oxidation catalyst is preferably used so that the exhaust gas still contains residual amounts of NH3 that should not or must not be released into the environment after passing through steps (c1) and / or (c2) and (d). This residual amount of NH3 can then be decomposed by oxidation of NH3 using a downstream NH3 oxidation catalyst.

[0081] When the fuel (in addition to NH3) contains hydrocarbons (CH4, natural gas, etc.) and the exhaust gas formed during the combustion contains a certain amount of HCN, an HCN decomposition catalyst is preferably used. The HCN decomposition catalyst can then be used by hydrolysis of HCN and oxidation of the hydrolysis products (hydrolysates) formed in the process (i.e. oxidation of NH3 and CO, preferably using NO present in the exhaust gas). X and N2O) to decompose (eliminate) the resulting HCN.

[0082] It was surprising to find that while containing NO X HCN in an aqueous exhaust gas containing N2 and N2O (each in a molar amount greater than or equal to the molar amount of HCN) can be decomposed into N2, H2O and CO2 by passing the exhaust gas over a transition metal-loaded zeolite catalyst (for example a package of catalyst pellets comprising an iron-loaded zeolite material of the BEA structure type) at a temperature of 300 to 600°C (preferably 350 to 550°C).

[0083] Thus, in contrast to known methods, the complete elimination of HCN (i.e., conversion into non-toxic substances) can be achieved in a one-stage process, i.e., in one process step without expensive noble metal catalysts. X and N2O, which can be additionally added for the reduction of NO X and NH3 of N2O, and optionally for reducing N2O to a mixture containing HCN, NO X and N2O in the exhaust gas of CO or hydrocarbons (such as CH4 or propane). In this case, the amount of reducing agent should be based on the amount of N2O and NO X If excess N2O is present in the exhaust gas and is reduced with NH3 or CO or hydrocarbons, in each case NO X The content should be reduced to zero (or close to zero) by means of NH3. If CO or hydrocarbons are used as additional reducing agents, any CO emissions can be eliminated by using an additional CO oxidation catalyst downstream of the zeolite catalyst.

[0084] A 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 decomposition catalyst is used to decompose HCN and CO is present in its degradation products. In each case, any CO obtained can then be decomposed by oxidation to CO2 with the aid of a downstream CO oxidation catalyst.

[0085] If the exhaust gas treatment system of the present invention includes an NH3 oxidation catalyst, it is preferred according to the present invention to first cool the exhaust gas to a lower temperature than when it enters the exhaust gas treatment system using a heat exchanger within the exhaust gas treatment system, so that the NH3 oxidation catalyst can optimally demonstrate its effectiveness. Therefore, in a preferred embodiment, the exhaust gas treatment system of the present invention further includes one or more heat exchangers.

[0086] For the purposes of this 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.

[0087] For descriptive purposes, "NO X ” includes nitric oxide (NO) and nitrogen dioxide (NO)2, but not nitrous oxide (N2O).

[0088] Catalysts speed up certain chemical reactions by lowering their activation energy.

[0089] Unless expressly stated otherwise, all figures in ppm are based on volume, i.e. ppmv. Unless expressly stated otherwise, all percentages relating to gas composition are based on volume, i.e. vol%. Unless expressly stated otherwise, all other percentages are based on weight, i.e. wt%.

[0090] The steps (a) and (b) of the inventive method are carried out in alphabetical order, and steps (c) and (d) are carried out in any order basically subsequently. Therefore, step (c) can be carried out before step (d) or after step (d) or simultaneously with step (d). It can also be a mixed form of part at the same time. When a kind of identical catalyst material is capable of catalyzing multiple reactions, this may be particularly relevant. According to the present invention, such embodiment is particularly preferred. Then, according to the present invention, these reactions may occur simultaneously, although the kinetics of each reaction can change, so that the first reaction can end earlier than the second reaction carried out in parallel or can reach a higher conversion rate.

[0091] For the purpose of description, steps (c1) and (c2) are considered separately, but both serve the common purpose of reducing the N2O content in the exhaust gas.

[0092] Steps (c1), (c2) and (d) can likewise be carried out in any order, although a partially simultaneous mixed form is also possible in this respect.

[0093] In a preferred embodiment, the method of the present invention comprises steps (a), (b), (c1) and (d); steps (a), (b), (c2) and (d); or steps (a), (b), (c1), (c2) and (d).

[0094] In a preferred embodiment, the exhaust gas undergoes the steps of the method of the present invention in one of the following orders:

[0095] (i)(a)→(b)→(c1)→(d):

[0096] (ii) (a)→(b)→(d)→(c2);

[0097] (iii)(a)→(b)→(d)→(c2)→(c1);

[0098] (iv) (a) → (b) → (d) → (c1 + c2); or

[0099] (v)(a)→(b)→(d)→(c1).

[0100] (c1+c2) means that both steps (c1) and (c2) are performed, although the two steps (c1) and (c2) are performed at least partially simultaneously, ie the two steps are performed in parallel.

[0101] Between these steps, there may be additional steps that are not explicitly specified.

[0102] In step (a) of the process of the present invention, combustion of NH3 is used for the operation of the combustion system.

[0103] In the context of the present invention, a "combustion system" is a system that generates heat by means of a combustion process. The combustion of a fuel generates heat. Optionally, power can also be generated and / or a machine can be driven here in addition. The term covers a wide range of different systems: from heating homes, electric motors for driving vehicles, industrial combustion systems for steam and process heat generation, to combustion systems in large power plants. In the context of the present invention, a "combustion system" is any system in which NH3 is oxidized by O2 (preferably from air) with the aim of producing N2 and H2O, in particular N2 and H2O as main products. Where NH3 is oxidized by O2 with the aim of producing nitrogen compounds with a higher oxidation number (e.g. NO X ) as the main product (such as is the case in nitric acid production) is not a combustion system in the context of the present invention.

[0104] Combustion of NH3 means oxidation of NH3 with O2, wherein, according to the invention, this reaction does not have to be complete, so that the exhaust gas may contain residual unburned (unoxidized, unconverted) NH3 (NH3 slip, NH3 breakthrough). This also applies if NH3 is not burned in pure form, but is burned 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, wherein the combustion air can optionally be enriched with O2.

[0105] According to the present invention, NH 3 is preferably combusted in a mixture with H 2 or fossil fuels (eg CH 4 ).

[0106] In a preferred embodiment, in step (a) of the process of the present invention, the combustion of NH3 is used to drive an internal combustion engine.

[0107] In the context of the present invention, an “internal combustion engine” (heat engine) is in particular a combustion engine, preferably a piston heat engine with internal combustion, such as a reciprocating piston engine or a rotary piston engine.

[0108] In a preferred embodiment, in step (a) of the process of the present invention, the combustion of NH3 is used to drive a gas turbine.

[0109] In the context of the present invention, a “gas turbine” is in particular an internal combustion engine in which an exhaust gas flow is generated and can be used to generate (mechanical) rotational energy, for example by means of an exhaust gas expansion turbine.

[0110] Surprisingly, it has been found that the method of the present invention is particularly suitable for gas turbines and has several advantages over conventional methods. For example, the method of the present invention is characterized by a lower air volume requirement and simplified gas turbine operation. In addition, the reduction of N2O and NO is ensured. X It can reduce the degradation rate of N2O and NO in the exhaust gas treatment system. X Emissions are reduced, particularly when the exhaust gas treatment system is equipped with two catalyst beds connected in series. The advantages of "end-of-pipe technology" are evident. The catalyst used is non-toxic and has a long service life. Pressure drops are minimal, and the catalyst and method can be used over a wide temperature range.

[0111] In this context, it is relevant that most modern gas turbines have turbine inlet temperatures exceeding 1500°C and therefore exhaust gas temperatures exceeding 600°C. Conventional SCR catalysts based on vanadium oxide cannot be used at temperatures above 400°C due to irreversible damage. In contrast, the preferred zeolite catalysts according to the invention can be used in a wide temperature range of approximately 350°C to 600°C and therefore also at higher temperatures. Therefore, the invention can dispense with complex exhaust gas cooling.

[0112] In a preferred embodiment, in step (a) of the process according to the invention, NH 3 is burned to operate a furnace for cracking NH 3 into N 2 and H 2 .

[0113] In step (b) of the method according to the invention, the exhaust gas is transferred to an exhaust gas treatment system, i.e., from an internal combustion engine or a gas turbine. Steps (c) and (d) of the method according to the invention are carried out in an exhaust gas treatment system according to the invention. For this purpose, the exhaust gas treatment system is equipped with an N2O decomposition catalyst for step (c1) and / or an N2O reduction catalyst for step (c2), and with a NOx reduction catalyst for step (d). X Reduction catalyst.

[0114] If the exhaust gas treatment system of the present invention additionally comprises at least one further catalyst, or the aforementioned N2O reduction catalyst, N2O decomposition catalyst or NO X Reducing one of the catalysts, at least one of the following steps (e1) to (e4) is preferably additionally carried out in the exhaust gas treatment system of the present invention:

[0115] (e1) cooling the exhaust gas in at least one heat exchanger, which is preferably arranged in the exhaust gas treatment system; preferably upstream of the NH3 oxidation catalyst in the flow direction of the exhaust gas;

[0116] (e2) reducing the NH 3 content in the exhaust gas by oxidation with an oxidant over an NH 3 oxidation catalyst; wherein the oxidant preferably comprises O 2 ;

[0117] (e3) reducing the HCN content in the exhaust gas by hydrolysis and oxidation of the hydrolysis product with an oxidant over an HCN decomposition catalyst; wherein the oxidant preferably comprises NO X and / or N2O; and

[0118] (e4) Reducing the CO content in the exhaust gas by chemical oxidation with an oxidant over a CO oxidation catalyst; wherein the oxidant preferably comprises O2.

[0119] In step (c) of the method according to the present invention, the N2O content in the exhaust gas is reduced. This can be achieved by (c1) decomposing N2O over an N2O decomposition catalyst and / or (c2) chemically reducing N2O with a reducing agent over an N2O reduction catalyst.

[0120] The decomposition of N2O forms N2 and O2 according to the following empirical reaction:

[0121] 2N2O→2N2+O2.

[0122] The decomposition of N2O therefore means the decomposition into N2 and O2. In the context of the present invention, an "N2O decomposition catalyst" catalyzes the decomposition of N2O. The decomposition of N2O achievable by catalytic decomposition depends not only on the type of N2O decomposition catalyst (i.e. chemical properties and physical configuration) and the pressure and temperature conditions present, but also, in particular, on the selected space velocity, i.e. the ratio of the exhaust gas volume flow rate to the catalyst volume. However, the catalytic activity of the N2O decomposition catalyst is not necessarily limited to this reaction. For example, according to the present invention, it is entirely possible and indeed preferred that the N2O decomposition catalyst can also additionally catalyze further reactions, such as the chemical reduction of N2O and / or NO X Whether this further reaction actually takes place depends on the conditions of the individual case, in particular the type of catalyst, and the kinetics of any processes occurring in parallel, for example on the presence or amount of reducing agent and the presence or amount of other co-reactants.

[0123] Depending on the reducing agent, the chemical reduction of N2O with the reducing agent forms different reaction products.

[0124] In the case of the NH 3 reducing agents preferred according to the invention, the chemical reduction of N 2 O forms N 2 and H 2 O, in particular, for example as follows:

[0125] 3N2O+2NH3→4N2+3H2O or

[0126] 4N2O+4NH3+O2→6N2+6H2O

[0127] or in a combined reduction with NO, as follows:

[0128] 2NO+N2O+2NH3→3N2+3H2O.

[0129] In the case of hydrocarbons, which are likewise preferred according to the invention as reducing agents, the chemical reduction of N2O to form CO and H2O is carried out, in particular, for example as follows:

[0130] (2n+1)N2O+C n H 2n+2 →(2n+1)N2+n CO+(n+1)H2O

[0131] Alternatively, CO2 and H2O are formed as follows:

[0132] 4n N2O+C n H 2n+2 →4n N2+n CO2+2n H2O.

[0133] According to the present invention, CO is also preferred as a reducing agent. It can further react with N2O to obtain CO2, for example according to:

[0134] N2O+CO→N2+CO2.

[0135] In the context of the present invention, "NO X Reduction catalyst" catalyzes the reduction of NO by a reducing agent X However, NO X The catalytic activity of the reduction catalyst is not necessarily limited to this reaction. For example, according to the present invention, it is entirely possible and indeed preferred that NO X The reduction catalyst may also additionally catalyze further reactions, such as the decomposition of N2O, the chemical reduction of N2O and / or NO X The establishment of equilibrium or the selective oxidation of excess NH 3 with free O 2 . Whether this further reaction actually occurs depends on the conditions of the individual case and on the kinetics of any processes occurring in parallel, for example on the presence or amount of reducing agent and the presence or amount of other co-reactants.

[0136] In step (d) of the method of the present invention, by X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction to reduce NO in exhaust gas X content.

[0137] It is preferred here to be able to reduce the nitrogen oxides (especially NO X ) for those NO that undergo selective catalytic reduction (SCR) X Reduction catalyst, i.e. NO X The reduction catalyst mainly catalyzes NO X The oxidation of NH3 is performed and does not catalyze or only to a minor extent catalyzes the oxidation of NH3 with any free oxygen (O2) present in the exhaust gas.

[0138] According to the reducing agent, the reducing agent is used to reduce NO X The chemical reduction carried out forms different reaction products. In the case of the NH3 reducing agent preferred according to the invention, NO X Chemical reduction to form N2 and H2O, especially depending on NO XThe type of reduction catalyst and the ratio of NO to NO2 are, for example, as follows:

[0139] 4NH3+2NO+2NO2→4N2+6H2O (fast SCR)

[0140] 4NH3+4NO+O2→4N2+6H2O (normal SCR)

[0141] 8NH3+6NO2→7N2+12H2O (NO2 SCR).

[0142] A common selective catalytic reduction is called "fast SCR" and is typically much faster than normal SCR or NO2 SCR.

[0143] In the context of the present invention, "NO X Reduction catalyst" catalyzes the reduction of NO by a reducing agent X However, NO X The catalytic activity of the reduction catalyst is not necessarily limited to this reaction. For example, according to the present invention, it is entirely possible and indeed preferred that NO X The reduction catalyst can additionally catalyze further reactions, such as the decomposition of N2O and / or the chemical reduction of N2O and / or NO X The establishment of equilibrium or the selective oxidation of excess NH 3 with free O 2 . Whether this further reaction actually occurs depends on the conditions of the individual case and on the kinetics of any processes occurring in parallel, for example on the presence or amount of reducing agent and the presence or amount of other co-reactants.

[0144] catalyst:

[0145] N2O decomposition catalysts are known per se, and a variety of material classes can be used. Preferred are N2O decomposition catalysts having high catalytic activity, for example, N2O decomposition catalysts having high catalytic activity in the temperature range of 350-600°C for decomposing N2O into N2 and O2.

[0146] Examples of preferred NO decomposition catalysts according to the invention are metal-loaded zeolite catalysts, for example copper- or cobalt-loaded or in particular iron-loaded zeolite catalysts, noble metal catalysts or other transition metal oxide catalysts, for example catalysts containing cobalt oxide. Examples of suitable catalysts are described in particular 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 an iron-loaded zeolite catalyst is used in the first catalyst bed, as expected, NO still present in the gas is X Accelerate the desired N2O decomposition through activation effect (promoter effect), such as et al. in Catal. Comm. 2 (2001) 273-276 for different N2O / NO X Ratio described.

[0147] Another example of a preferred N2O decomposition catalyst according to the present invention is a catalyst having an activity factor for N2O decomposition. X For the purpose of description, this N2O decomposition catalyst is also referred to as "NO X -sensitive N2O decomposition catalysts". These catalysts contain one or more catalytically active compounds of elements from groups 5 to 11 of the Periodic Table of the Elements (PTE). Particular preference is given to compounds of elements from groups 9 to 11 of the PTE. In particular, preference is given in that order to compounds of the elements Co, Pt, Pd, Ir, Rh, Ni and / or Cu, preferably compounds of Co, Rh, Ni and / or Cu, in particular compounds of Co or Rh. Preference is given to N2O decomposition catalysts based on noble metals, preferably supported on refractory oxides, or based on mixtures of transition metal oxides, in particular mixed oxides or simple transition metal oxides, in each case in supported form or preferably as unsupported catalysts.

[0148] The catalytically active compounds themselves can be metal and / or oxidic compounds, the latter in the form of single oxides or in the form of binary, ternary or multinary mixed oxides of different structural types, such as perovskites or spinels. These are described, for example, in Catalysis Letters 35 (1995) 372-382, Applied Catalysis 73 (1991) 165-171, Catal. Rev.-Sci. Eng.; 34 (4), 409-425 (1992) or Actes du 2ieme Congres International sur la Catalyse 97 (1961) 1937-1953. Mixtures of different catalytically active compounds can also be used. Examples of particularly preferred catalytically active compounds are metallic rhodium, rhodium oxides (e.g. RhO2 or Rh2O3), CoO, Co2O3, Co-containing spinels (e.g. Co3O4), Cu x Co 3-x O4 or Co-containing perovskite (such as LaCoO3) or Co-containing perovskite substituted at the A and B sites.

[0149] The catalytically active compounds may be present in pure form in the catalyst or may be applied to or mixed with a suitable support material. In the former case, these are so-called unsupported catalysts which, in addition to the active compounds, may also contain additives known to those skilled in the art, such as binders or other production-related additives, such as plasticizers, pore formers, fiber reinforcements or compression aids.

[0150] Methods for preparing such catalysts are known to those skilled in the art. In the case of a "supported catalyst," the catalytically active compound is already applied to a support material. As a result, the catalytically active compound undergoes dispersion and stabilization, resisting mechanical and thermal stresses. Methods for preparing such catalysts are also known to those skilled in the art. The support material is preferably a refractory oxide, such as SiO2, TiO2, ZrO2, or Al2O3, or a mixture of two or more of these, or a material that itself has some catalytic activity for the decomposition of NO, such as MgO, zeolite, hydrotalcite, or a mixture of two or more of these. Preferably, a catalyst that is substantially free of zeolite is used, and if zeolite is present, it preferably contains less than 15% by weight of zeolite, in particular less than 5% by weight of zeolite.

[0151] Preferred support materials for Rh-containing compounds are ZrO , TiO , Al 2 O , hydrotalcite or zeolite, for example, support materials having an MFI structure. These are described, for example, in Chemical Engineering and Technology 24 (2001) 281-285 or Catalysis Today 35 (1997) 113-120. Particularly preferred supports for Rh-containing compounds are ZrO , TiO , and hydrotalcite. The Rh content of these catalysts is preferably 0.1 to 10% by weight, preferably 0.5 to 5% by weight. In addition to Rh, the Rh-containing catalyst more preferably also contains CeO . The proportion of CeO is preferably 5 to 50% by weight, in particular 10 to 30% by weight.

[0152] Preferred supports for the Co-containing compound are zeolites, or preferably supports comprising magnesium oxide. In the case of zeolites, particularly preferred are Si-rich structures such as MFI, BEA, FER, MEL, or MOR. The production of such co-doped zeolites is known to those skilled in the art. The magnesium oxide support may be pure MgO or a compound containing MgO, such as hydrotalcite. Such catalysts are described, for example, in Appl. Catal. B: Environmental 7 (1996) 397-406 or Appl. Catal. B: Environmental 13 (1997) 69-79.

[0153] Particularly preferred are catalysts consisting essentially of at least one magnesium oxide compound and at least one cobalt oxide compound, wherein the content of the cobalt oxide compound is in the range of 0.1% to 50% by weight, and the content of the magnesium oxide compound is in the range of 50% to 99.9% by weight, in each case based on the total mass of the catalyst, and at least 30% by weight 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. When using a cobalt oxide compound as the active component, particularly preferred are catalysts having a support composed of at least 50% by weight of MgO or a support composed of a mixed oxide composed of at least 50% by weight of MgO, and wherein a cerium oxide functional layer has been applied to the support. Such catalysts and their preparation are described in DE 10 200 7 038 711 A1.

[0154] The N2O decomposition catalyst can take the form of shaped bodies of any size and geometry, preferably having a high surface area to volume ratio that produces a minimum pressure drop when traversed. All geometries known for catalysts are typical, such as cylinders, hollow cylinders, porous cylinders, rings, crushed particles, trilobes or honeycomb structures.

[0155] N2O reduction catalyst and NO X Reduction catalysts are likewise known per se, and various substance classes can likewise be used. Examples of these are metal-loaded zeolite catalysts, for example copper- or cobalt-loaded zeolite catalysts, or in particular iron-loaded zeolite catalysts, or noble metal catalysts or catalysts used in the known SCR (Selective Catalytic Reduction) process.

[0156] Preferably, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NO X The reduction catalyst independently comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an iron, cobalt or copper loaded zeolite; more preferably, an iron loaded zeolite; even more preferably, an iron loaded zeolite independently of the MFI, BEA, FER, MOR, FAU and / or MEL structure type.

[0157] Preferably, the N2O decomposition catalyst and / or the N2O reduction catalyst and the NO X The reduction catalysts both independently comprise a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an iron, cobalt or copper loaded zeolite; more preferably, an iron loaded zeolite; even more preferably, an iron loaded zeolite, independently of the MFI, BEA, FER, MOR, FAU and / or MEL structure type.

[0158] These can be different catalysts or the same catalyst. The iron-loaded zeolite catalyst used particularly preferably according to the invention essentially preferably contains >50% by weight, in particular >70% by weight, of one or more iron-loaded zeolites. For example, in addition to the Fe-ZSM-5 zeolite, further iron-containing zeolites, for example of the FER type, may be present in the catalyst used according to the invention.

[0159] Furthermore, the catalysts used according to the invention may comprise further additives known to those skilled in the art, such as binders.

[0160] The zeolites preferably used may have an iron content of up to 25%, but preferably from 0.1% to 10%, based on the mass of the zeolite.

[0161] The process of the present invention also includes the use of zeolites in which the lattice aluminum has been partially isomorphously substituted with one or more elements, for example with one or more elements selected from the group consisting of B, Be, Ga, Fe, Cr, V, As, Sb and Bi. It also includes the use of zeolites in which the lattice silicon has been isomorphously substituted with one or more elements, for example with one or more elements selected from the group consisting of Ge, Ti, Zr and Hf. The exact details of the formation or structure of the zeolites preferably used according to the present invention are given in Atlas of Zeolite Structure Types, Elsevier, 4th revised edition 1996, which is expressly incorporated herein by reference.

[0162] In the process of the present invention, very particular preference is given to the use of zeolite catalysts that have been treated with steam ("steamed" catalysts). This treatment results in dealumination of the zeolite lattice; such treatments are known per se to those skilled in the art. These hydrothermally treated zeolite catalysts have particularly high activity in the process of the present invention. Preference is given to using hydrothermally treated zeolite catalysts loaded with iron in which the ratio of extra-lattice aluminum to lattice aluminum is at least 1:2, preferably from 1:2 to 20:1.

[0163] Preferably, the N2O decomposition catalyst and / or the N2O reduction catalyst and the NO X The reduction catalysts each independently comprise a transition metal-loaded zeolite, preferably each comprise an iron-loaded zeolite (Fe zeolite), even more preferably each comprise an iron-loaded zeolite of the same structural type, most preferably having the same external shape (eg, honeycomb or pellet).

[0164] In a preferred embodiment, the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material.

[0165] In a preferred embodiment, the N2O decomposition catalyst and NO X The reduction catalyst is made of the same material.

[0166] In a preferred embodiment, the N2O reduction catalyst and the NO X The reduction catalyst is made of the same material.

[0167] In a preferred embodiment, the N2O decomposition catalyst, the N2O reduction catalyst and the NO X The reduction catalyst is made of the same material.

[0168] Used to decompose N2O and NO X The preferred catalyst

[0169] Preferably, the N2O decomposition catalyst, N2O reduction catalyst and NO XThe reduction catalyst independently comprises a zeolite-type material (also referred to as a "zeolite" for the purposes of this specification) loaded with at least one transition metal (atomic numbers 21-30, 39-48, 57-80, 89-112) and / or at least one lanthanide (also referred to as "lanthanide group elements", atomic numbers 57-71). For the purposes of description, for simplicity, transition metals and lanthanides are collectively referred to as "transition metals". The transition metals are preferably iron ("Fe zeolite"), copper ("Cu zeolite") and cobalt ("Co zeolite"). Zeolite materials loaded with iron (i.e., Fe zeolite) are particularly preferred and can be loaded or contain not only iron but also other transition metals, such as manganese, vanadium, chromium, nickel or a mixture thereof.

[0170] The zeolite material of the present invention preferably has high hydrothermal stability. Particularly preferred are SiO2-rich zeolites, known as "high silica zeolites," which have a [SiO2] and [AlO2] - ] units, thus having a Si / Al molar 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 in particular at least 13.

[0171] The preferred zeolitic materials according to the present invention essentially have a zeolitic structure of the BEA, MFI, MOR, MEL or FER structure type, more preferably the MFI and BEA structure types, even more preferably the BEA structure type. In the case of the MFI structure type, the ZSM-5 structure type is particularly preferred. More details on the structure types of zeolitic materials and their nomenclature can be found in Atlas of Zeolite Structure Types, Elsevier, 4th revised edition, 1996.

[0172] According to the present invention, particularly preferred N2O decomposition catalysts, N2O reduction catalysts or NO X The reduction catalyst independently comprises at least 50 wt. % of Fe zeolite, preferably at least 70 wt. % of Fe zeolite, relative to the total weight of the zeolitic material, wherein a single structure type or several structure types may be present. In a preferred embodiment, in addition to the Fe-BEA zeolite, another Fe zeolite of a different structure type, preferably an Fe-MOR zeolite, is present.

[0173] The zeolite material loaded (doped) with a transition metal / lanthanide element can be achieved by loading or doping zeolite with a transition metal / lanthanide element, as is known to those skilled in the art. Preferably, the zeolite material is loaded from a commercially available H form or preferably an NH4 form by ion exchange with an appropriate salt of a transition metal in an aqueous phase or by solid-state reaction. The loaded zeolite material thus obtained is then calcined, preferably calcined under air in a furnace at a temperature within the range of 400-650°C. After calcination, the loaded zeolite material is vigorously washed in distilled water, and the loaded zeolite material is filtered out and then dried. A suitable binder (such as aluminosilicate, boehmite or silica sol) and an optional auxiliary agent for plasticizing or for producing lubricants (slips) are preferably added to the loaded zeolite material thus obtained and mixed therewith. In a preferred embodiment, the mixture thus obtained is extruded into a catalyst body (unsupported catalyst) and finally calcined. In other preferred embodiments, the mixture thus obtained is applied to a catalyst support (supported catalyst) and finally calcined. These methods are also well known to those skilled in the art and have been established in many technical applications.

[0174] According to the present invention, the particularly preferred N2O decomposition catalyst, N2O reduction catalyst, NO X The reduction catalyst, the NH3 oxidation catalyst, the HCN decomposition catalyst and the CO oxidation catalyst can independently take the form of shaped bodies of any size and geometry, preferably having a large surface-to-volume ratio and generating a minimum pressure drop when the stream flows through them. Typical geometries are all those known in catalysis, such as cylinders, hollow cylinders, porous cylinders, rings, trilobes or star-shaped extrudates. Particularly preferred are monolithic catalyst elements permeated by parallel channels, such as monolithic honeycombs (referred to as "catalyst honeycombs"), as are known, for example, from the cleaning or denitrification of power plant exhaust gases or automobile exhaust gases.

[0175] Catalyst honeycombs, honeycomb bodies and honeycomb body modules

[0176] The exhaust gas treatment system of the present invention or the catalyst bed contained therein preferably comprises catalyst honeycombs arranged parallel to one another, preferably a plurality of catalyst honeycombs, wherein the honeycomb channels in the exhaust gas duct are longitudinally aligned with 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) can in principle be freely selected. 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. Therefore, according to the present invention, the term "honeycomb" is not limited to rectangular or square cross-sectional areas.

[0177] If the exhaust gas treatment system of the present invention includes 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 present invention), the first reaction zone and the second reaction zone (first catalyst bed and second catalyst bed) preferably have a plurality of catalyst honeycombs arranged parallel to each other, wherein the honeycomb channels in the exhaust gas duct are longitudinally aligned with the flow direction of the exhaust gas.

[0178] In a preferred embodiment, several catalyst honeycombs (i.e., several monolithic honeycomb bodies) are combined to form a honeycomb module, preferably using 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 optimal utilization of the available cross-sectional area of ​​the exhaust gas line and simple replacement of defective or inactivated honeycomb bodies.

[0179] The honeycomb body preferably has a rectangular cross-section. The rectangular cross-section preferably has a first edge length (perpendicular to the direction of exhaust gas flow) in the range of 5 to 20 cm, more preferably in the range of 10 to 15 cm, and a second edge length (also perpendicular to the direction of exhaust gas flow) in the range of 5 to 20 cm, preferably in the range of 10 to 15 cm. The height of the honeycomb body (in the direction of exhaust gas flow) is preferably in the range of 5 to 25 cm, preferably in the range of 7.5 to 15 cm.

[0180] The so-called cell density (i.e., the channel density of a single catalyst honeycomb) is preferably 150 to 500 cpsi, preferably 180 to 450 cpsi (cells per square inch). 100 cpsi (i.e., 100 cells or honeycomb channels per square inch) corresponds to approximately 15.5 catalyst channels per square centimeter.

[0181] The individual honeycomb modules are preferably stacked on top of each other and arranged side by side in the direction of flow and secured by suitable mounting means in such a manner as to maximize utilization of the inflow area (i.e., the cross-sectional area of ​​the exhaust gas duct). Bypass flows between individual honeycomb modules or in the outer edge regions between the outer edges of the honeycomb modules and the inner wall of the exhaust gas 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 spacings, cover plates are used, which are attached to the inner wall of the exhaust gas duct in the direction of flow, in front of and / or behind the charge of the honeycomb modules. The cover plates are preferably covered by seals at the points of contact with the honeycomb modules. The honeycomb modules are preferably arranged and dimensioned so that the available inflow area for the catalyst preferably represents at least 60%, more preferably at least 70%, and even more preferably at least 80% of the inner cross-sectional area of ​​the exhaust gas duct.

[0182] In the case of round exhaust gas ducts or exhaust gas pipes, gaps that occur in the edge region of the honeycomb module charge (unless they can be easily filled by rectangular honeycomb modules) are preferably not filled with specially customized honeycomb bodies, but rather closed with blanking plates. This has the advantage that when replacing a used honeycomb body, only a standardized honeycomb body needs to be replaced without any special adjustments.

[0183] When using an exhaust gas duct, it is also advantageous to use a single, larger honeycomb body adapted to the duct cross section with a circular inflow cross section, wherein a plurality of honeycomb bodies can also be arranged in series in the direction of flow in a preferred configuration. In this case, it is not necessary to combine a plurality of honeycomb bodies parallel to one another to form a honeycomb module.

[0184] In a preferred embodiment, the honeycomb bodies or honeycomb modules are arranged in several layers offset along the longitudinal axis in the direction of exhaust gas flow. The honeycomb bodies or honeycomb modules are preferably arranged in 2 to 5 layers, more preferably in 2 to 3 layers. Preferably, a margin is provided between the layers (i.e., between the end faces of the honeycomb bodies or honeycomb modules), preferably with a size of 3 to 30 mm, preferably 4 to 20 mm. This margin enables intermediate mixing, in particular radial mixing, of the gas flow exiting the first layer of the honeycomb body or honeycomb module. Furthermore, any possible escape of unreacted reducing agent and / or its incompletely oxidized reaction products from the first layer of the honeycomb body to the subsequent second layer of the honeycomb body can be prevented.

[0185] For NO X The reducing agent and optionally N2O are preferably supplied and distributed via a manifold pipe system having a plurality of openings or nozzles, which are arranged in the exhaust gas channel or in the exhaust gas duct in the flow direction or upstream of the corresponding catalyst bed, preferably in the exhaust gas channel or in the exhaust gas duct upstream of the filling material of the catalyst honeycombs as a honeycomb body or honeycomb body module.

[0186] The distributor pipes are preferably designed in the form of a grid, 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.

[0187] The specific design and dimensions of these distributors, including suitable outlet nozzles, are part of the know-how of catalytic exhaust gas cleaning technology and are widely used, for example, in the treatment of exhaust gases from coal-fired power plants.

[0188] NH3 oxidation catalyst

[0189] NH3 oxidation catalysts are known to those skilled in the art.

[0190] The Nh3 oxidation catalyst is preferably free of platinum group metals, preferably free of precious metals.

[0191] For the purposes of this description, "free of platinum group metals" means that platinum group metals (i.e., Ru, Rh, Pd, Os, Ir, Pt) are substantially absent. However, minimal analytically detectable traces of platinum group metals are possible. For the purposes of this description, "free of precious metals" means that precious metals are substantially absent. However, minimal analytically detectable traces of precious metals are possible.

[0192] The NH3 oxidation catalyst is preferably an iron- or copper-loaded zeolite; preferably an iron- or copper-loaded zeolite of the MFI, BEA, FER, MOR, FAU, AEI and / or MEL structure type (hereinafter referred to as "NH3 oxidation active iron- or copper-loaded zeolite catalyst").

[0193] Preferred platinum group metal-free NH oxidation catalysts are selected from transition metal oxides (e.g., Fe, Mn, Cu, Cr, Co, Ni, ...), metal-loaded zeolites, such as those described in Handbook of Heterogeneous Catalysis, Wiley-VCH, edited by Ertl, Schüth, Weitkamp, ​​2nd Ed. 2008, Volume 5, Chapter 11.5 "Solid Catalysts for the Oxidation of Volatile Organic Compounds".

[0194] Preferred NH3 oxidation catalysts include:

[0195] - cobalt catalysts; in particular Co3O4; Co3O4-derived mixed oxides (Co 3-y M y O4), preferably crystallized in a spinel structure like Co3O4, wherein M is preferably selected from Zn, Cu, Fe, Mn and V; a cobalt-loaded zeolite, preferably having an MFI, BEA, FER, MOR, FAU, CHA or AFI structure type;

[0196] - Manganese catalysts; especially MnO X , where x = 1-2; MnO X -derived mixed oxides (Mn x-y M y O x ), wherein M is preferably selected from Zn, Cu, Fe and Mn; a manganese-loaded zeolite preferably having an MFI, BEA, FER, MOR, FAU, CHA or AFI structure type;

[0197] - Copper catalysts; especially CuOX , where x = 0.5-1; CuO X -derived mixed oxides (Cu x-y M y O x ), wherein M is preferably selected from Zn, Co, Fe and Mn; copper-loaded zeolite, preferably having MFI, BEA, FER, MOR, FAU, CHA, AFI structure type;

[0198] - Silver catalyst; in particular in supported form, preferably on AAl2O3, TiO2 or SiO2, for example, more preferably X% Ag / TiO2, X% Ag / Al2O3 or X% Ag / SiO2, in each case X = 1-10.

[0199] In a preferred embodiment, the device of the invention contains no further NH3 oxidation catalyst other than the iron- or copper-loaded zeolite.

[0200] In a preferred embodiment, the NH3 oxidation catalyst, preferably the NH3 oxidation active iron-loaded zeolite catalyst, has a molar ratio of iron to zeolite 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.

[0201] In a preferred embodiment, the NH3 oxidation catalyst, preferably the NH3 oxidation active copper-loaded zeolite catalyst, has a molar ratio of copper to zeolite 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.

[0202] Thus, it was surprisingly found that iron- or copper-loaded zeolites in which only some of the potentially available cationic sites are occupied by Fe or Cu ions, leaving the remaining cationic sites essentially satisfied by protons, have significantly increased activity for the oxidation of NH 3 with free oxygen.

[0203] The ratio of iron or copper to zeolitic aluminum can be adjusted by selecting the Al content in the synthesis of the zeolitic material, in particular via the ratio of the selected Si and Al starting materials, and also by subsequent loading with iron or copper ions.

[0204] In the synthesis of zeolites, the selected Si and Al starting materials are usually heated in an alkaline solution, usually under elevated pressure, which causes crystallization to occur to obtain a zeolite consisting of three-dimensional chains of AlO2. -Zeolites are microporous aluminosilicates formed by SiO2 units. By controlling the selection of synthesis conditions, for example by adding structure-directing agents such as organic cations, not only the Si / Al ratio and thus the Al content, but also the structure type of the zeolite can be specifically adjusted or controlled. The synthesis method is industrially established. Zeolites of different structure types with different Si / Al ratios and loaded with different cations (e.g., in the form of Na or NH4) are commercially available.

[0205] Suitable methods known to those skilled in the art (such as liquid phase or solid state ion exchange) can result in the cations present in the zeolite (such as NH + ) for other cations (e.g., iron or copper ions) by targeted exchange (J. Weitkamp, ​​L. Puppe Catalysis and Zeolites—Fundamentals and Applications, Springer-Verlag Berlin Heidelberg New York, 1999 or Kucherov, A.V. Slinkin, A.A.: Solid state reactions as method of introducing transition metal cations into high-silicazeolites, Russ. Chem. Rev. 1992, vol. 61, no. 9, p. 925-943). If all the negative charges generated by the AlO2 units have been compensated by cations, the so-called exchange level is 100%.

[0206] It is known that the exact Al content and Fe content of zeolitic materials or catalyst shaped bodies produced therefrom can be determined by X-ray fluorescence analysis (XRF). This is suitably carried out according to DIN EN 169-2 (Section 5) after determining the loss on ignition and lithium tetraborate digestion.

[0207] If the intention is to subsequently determine the Al content of the parent zeolite material on finished shaped bodies, it should be noted that the shaped bodies may also contain Al-based binder components that cannot be distinguished from the zeolite Al by XRF. In this case, additional investigation of the shaped bodies is required, for example by 27Al solid-state NMR, which allows the distinction between Al bound in the zeolite structure and Al outside the lattice. Those skilled in the art will be familiar with the basic principles, implementation and evaluation details of these studies (J. Weitkamp, ​​L. Puppe Catalysis and Zeolites - Fundamentals and Applications, Springer-Verlag Berlin Heidelberg New York, 1999, Chapter 4.2 (NMR Spectroscopy; especially sections 4.2.4.1 ( 29 Si MAS NMR Spectroscopy of SiO4 Tetrahedra in the ZeoliteFramework)and 4.3.4.2( 27 Al NMR Spectroscopy of Framework and Non-FrameworkAluminum Zeolites)).

[0208] Preferably, the NH3 oxidation catalyst, preferably the NH3 oxidation active iron-loaded zeolite catalyst has a total iron content (reported as mass content of Fe2O3) of less than 10.0 wt% to more than 2.0 wt%, preferably less than 7.0 wt% to more than 2.0 wt%, more preferably less than 5.0 wt% to more than 2.0 wt%, even more preferably less than 4.0 wt% to more than 2.0 wt%.

[0209] Preferably, the NH3 oxidation catalyst, preferably the NH3 oxidation active copper-loaded zeolite catalyst, has a total copper content (reported as mass content of Cu2O) of less than 9.0 wt% to more than 1.5 wt%, preferably of less than 6.5 wt% to more than 1.5 wt%, more preferably of less than 4.5 wt% to more than 1.5 wt%, even more preferably of less than 3.5 wt% to more than 1.5 wt%.

[0210] In a preferred embodiment, the NH3 oxidation catalyst, preferably an NH3 oxidation active iron or copper loaded zeolite catalyst, is configured for the selective oxidation of NH3 with O2 to N2 and H2O and is introduced in the form of a bed of particles having an equivalent diameter (defined as the diameter of a spherical particle of equal volume) of 3.5 to 5.5 mm and wherein the ratio of the external geometrically detectable surface area of ​​the particles to the volume of the particle bed is 1000 m 2 / m 3 Up to 1500m 2 / m 3, in an isothermally operated tubular reactor with an axial flow having an inner diameter of 20±3 mm, in an amount of 8.0±0.5 ml with a gas mixture consisting of 500±50 ppmv of NH3, 2.5±0.1% by volume of O2 and 0.30±0.05% by volume of H2O in N2, at a volume flow rate of 10000±500 h -1 The conversion rate of NH3 produced is at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80%, and especially at least 90% under a space velocity based on standard conditions (0°C; 1.01325 bara), a total pressure of 6±0.5 bara, and a temperature of 380°C±5K.

[0211] In a preferred embodiment, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NO X The reduction catalyst and / or the NH 3 oxidation catalyst independently have a honeycomb monolithic structure.

[0212] In a preferred embodiment, the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NO X The reduction catalyst and / or the NH 3 oxidation catalyst independently have a honeycomb monolithic structure.

[0213] In a preferred embodiment, the NH 3 oxidation catalyst and the N 2 O decomposition catalyst are made of the same material.

[0214] In a preferred embodiment, the NH 3 oxidation catalyst and the N 2 O reduction catalyst are made of the same material.

[0215] In a preferred embodiment, the NH3 oxidation catalyst and NO X The reduction catalyst is made of the same material.

[0216] In a preferred embodiment, the NH3 oxidation catalyst, NO X The reduction catalyst and the N2O decomposition catalyst are made of the same material.

[0217] Step (a):

[0218] In step (a) of the process of the invention, NH3 is burned to operate a combustion system, preferably to drive an internal combustion engine, to drive a gas turbine or to operate a furnace for cracking NH3 into N2 and H2. The combustion produces a mixture containing N2, H2O, NO X and N2 O. The exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, are then fed to step (b) of the process according to the invention.

[0219] In step (a) or in an internal combustion engine configured according to the invention, the combustion of NH3 (or a mixture of NH3 with another combustible gas (such as H2, CH4, etc.)) (i.e. the oxidation of NH3 with O2) is preferably not carried out on a catalyst, i.e. the combustion is not carried out in the presence of a heterogeneous catalyst.

[0220] In a preferred embodiment, NH 3 is combusted in step (a) in a mixture with one or more further combustible gases, which means that NH 3 and at least one further combustible gas are oxidized with O 2 .

[0221] In a preferred embodiment, the additional combustible gas is a fossil fuel.

[0222] In a preferred embodiment, the additional combustible gas is selected from hydrocarbons and hydrocarbon mixtures, preferably methane, ethane, propane, butane, natural gas, gasoline and / or diesel.

[0223] In a preferred embodiment, the additional combustible gas is selected from alcohols, preferably methanol and / or ethanol.

[0224] In other preferred embodiments, the additional combustible gas is H2.

[0225] More preferably, the additional combustible gas is H2, which is formed by thermal and / or catalytic cracking of NH3. Preferably, the integrated combustion of NH3 and O2 preferably provides energy for the cracking. Therefore, preferably, in step (a), the combustion of NH3 is integrated into the process for thermal and / or catalytic cracking of NH3 into N2 and H2.

[0226] In a preferred embodiment, the NH3 is combusted in step (a) to drive a gas turbine in combination with a steam turbine.

[0227] Combustion in the gas turbine is preferably achieved with air or oxygen as (i) single-stage combustion of pure NH3; or (ii) single-stage combustion of a mixture comprising NH3 and hydrocarbons (preferably natural gas or CH4); or (iii) single-stage combustion of a mixture comprising NH3 and H2.

[0228] The air ratio λ (combustion air ratio) represents the actual mass of available air relative to the minimum necessary air mass required for theoretically stoichiometric complete combustion. Depending on the composition of the fuel, the combustion in step (a) is preferably carried out at different air ratios λ.

[0229] If the fuel consists essentially of pure NH3, or the proportion of NH3 in the fuel is at least 90% by volume, based on the total volume of the fuel, the combustion is preferably carried out at an air ratio λ in the range of 1.0 to 1.5, more preferably 1.1 to 1.4, even more preferably 1.1 to 1.3.

[0230] If the fuel consists essentially of NH3 and CH4 and the proportion of CH4 is not more than 50% by volume, based on the total volume of the fuel, the combustion is preferably carried out at an air ratio λ of 1.5 to 2.5, more preferably 1.6 to 2.4, even more preferably 1.7 to 2.3.

[0231] If the fuel consists essentially of NH3 and CH4 and the proportion of CH4 is more than 50% by volume based on the total volume of the fuel, the combustion is preferably carried out at an air ratio λ of 2.0 to 3.0, more preferably 2.1 to 2.9, even more preferably 2.2 to 2.8.

[0232] If the fuel consists essentially of NH3 and H2 and the proportion of H2 is not more than 50% by volume, based on the total volume of the fuel, the combustion is preferably carried out at an air ratio λ in the range of 2.0 to 3.0, more preferably 2.1 to 2.9, even more preferably 2.2 to 2.8.

[0233] If the fuel consists essentially of NH3 and H2 and the proportion of H2 is more than 50% by volume, based on the total volume of the fuel, the combustion is preferably carried out at an air ratio λ of 2.5 to 3.5, more preferably 2.6 to 3.4, even more preferably 2.7 to 3.3.

[0234] The combustion in step (a) preferably produces exhaust gases having a temperature in the range 1000°C to 1500°C before entering the turbine.

[0235] The combustion in step (a) preferably produces exhaust gas, preferably at a pressure in the range of 10 to 32 bar before entering the turbine.

[0236] The combustion in step (a) preferably produces an exhaust gas which, preferably before entering the turbine, has 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%, possibly even at most 0.5% NO X The degree of oxidation (n(NO2) / (n(NO)+n(NO2))).

[0237] According to the invention, combustion is preferably carried out in one stage, i.e. preferably neither as lean premixed combustion nor as staged rich-lean combustion. Single-stage combustion optimizes operation and simplifies the construction of the gas turbine system. According to the invention, combustion is carried out with a relatively small excess air λ, thereby deliberately accepting increased NO X Concentration. The balance of NO2 and NO (i.e. NO X The oxidation degree of NO is toward the NO side; therefore, almost all NO XAs NO in the hot combustion exhaust gas, there are at most small amounts of NO2.

[0238] The gas turbine of the present invention preferably has an annular combustion chamber. Multiple burners are preferably arranged in a ring around the shaft upstream of the turbine. The secondary air flow is directed around these burners and mixed upstream of the turbine. Fuel premixing, complete combustion, and mixing must then occur within a short distance.

[0239] Due to the high volumetric flow rates in gas turbines, exhaust gas cleaning can be very complex in some cases. Therefore, conventional methods of operating gas turbines often attempt to control pollutant emissions directly at the point of formation through combustion technology measures. A relatively high excess air λ leads to superstoichiometric combustion, thus assuming complete combustion. Due to the limited thermal durability of gas turbines, the excess air λ in stationary single-shaft machines typically cannot be lowered below a λ value of 2.5 to 3.5.

[0240] In conventional natural gas-operated gas turbines, atmospheric nitrogen (thermal NO X ) forms NO X In NH3-operated gas turbines, most NO X By fuel (fuel NO X ) formation. Therefore, in order to inhibit NO X To prevent the formation of ions, the temperature and residence time in the hot zone must be reduced.

[0241] It has been found that adding water or steam to the fuel to cool the flame is effective (wet denitrification). At a fuel / steam mixture ratio of 1:1, NO X However, this measure requires the use of expensive demineralized water to avoid fouling and corrosion of the turbine blades, leading to higher operating costs.

[0242] Newer burners utilize dense premixing of superstoichiometric air volumes and fuel to avoid localized excessive temperatures during combustion due to differences in fuel concentration (dry denitrification). Uniform flow conditions are crucial here, for example to avoid backflow zones where air can experience long residence times. Sequentially arranging different combustion zones, such as rich-lean zones, also yields positive results.

[0243] In general, the lower heating value of NH3 vs. CH4 fuel combined with the lower flame temperature can be assumed to result in a lower thermal load on the turbine. However, the reduced flame temperature additionally promotes NO X and the formation of N2O.

[0244] Preferably, the exhaust gases produced by the combustion in step (a) are subsequently expanded in a gas turbine.

[0245] Preferably, the exhaust gases at the outlet from the gas turbine are at a temperature in the range of 450 to 670°C.

[0246] Preferably, the exhaust gas at the outlet from the gas turbine is at a pressure greater than atmospheric pressure, ie ≥ 1.0 bara, but at most 1.2 bara, more preferably at most 1.1 bara.

[0247] Preferably, the exhaust gas at the outlet from the gas turbine has a NO in the range of 500 to 3000 ppmv X content.

[0248] Preferably, the exhaust gas at the outlet from the gas turbine has an O2 content in the range of 1.0% to 6.0% by volume.

[0249] Preferably, the exhaust gas at the outlet from the gas turbine has an H2O content in the range of 20% to 30% by volume.

[0250] 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.

[0251] 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.

[0252] 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.

[0253] 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.

[0254] Preferably, the exhaust gas at the outlet from the gas turbine has 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% NO X The degree of oxidation (n(NO2) / (n(NO)+n(NO2))).

[0255] Preferably, NH 3 is combusted in a mixture with CH 4 in step (a), and the exhaust gas therefore also comprises CO and CO 2 , preferably also HCN.

[0256] 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.

[0257] 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.

[0258] In a particularly preferred embodiment, step (a) of the method of the present invention comprises the following constituent steps:

[0259] (a1) thermal and / or catalytic cracking of NH3 to produce a cracked gas comprising N2, H2 and optionally residual NH3;

[0260] (a2) optionally mixing the cracked gas with additional NH3 to produce a mixture comprising H2 and NH3;

[0261] (a3) burning the cracked gas or the mixture.

[0262] Suitable methods for the thermal and / or catalytic cracking of NH to form N and H are known to those skilled in the art. Suitable catalysts for the cracking of NH to form N and H are, for example, AlO or SiO-supported Ru, MgAlO-supported Fe, Co, Ni, Cu or Ru, or CoMoN (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).

[0263] If the cracking in the composition step (a1) is not complete, the cracking gas (ie the cracking product) will still contain residual unconverted NH3 as well as N2 and H2. In this way, a mixture of NH3 and H2 is obtained, which can be burned directly as such or first enriched with further NH3 in an optional composition step (a2).

[0264] If the cracking is carried out to completion in constituent step (a1), the required amount of NH3 still has to be added to the cracking gas in step (a2).

[0265] Preferably, the composition step (a1) and the optional composition step (a2) establish a mixing ratio of NH3 and H2 that optimizes 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%.

[0266] In a particularly preferred embodiment, 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.

[0267] In the composition step (a3), the mixture is burned, typically with air. In a preferred embodiment, the air ratio λ for combustion in the composition step (a3) ​​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, and most preferably 1.2 to 1.4. The air ratio λ (i.e., the combustion air ratio) indicates the mass ratio of air to fuel relative to the stoichiometric ideal ratio of the theoretical complete combustion process. It is defined as the ratio of air to fuel containing enough 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 molar amount (see, for example, P.Majumdar, Design of Thermal Energy Systems, Wiley 2021, page 66, No.2.13.5.2). For the purpose of description, the ratio is based on mass. If another oxygen-containing gas than air is used for the combustion operation, strictly speaking, "air" should be changed to "oxygen carrier". However, the lambda parameter is still used in the above definition.

[0268] In a preferred embodiment, the equivalent ratio NH3 / H2 (Φ) (not to be confused with the inverse of the air ratio 1 / λ) is in the range of 0.55 to 1.40, more preferably 1.05 to 1.20.

[0269] In other preferred embodiments, NH 3 is combusted alone in step (a), that is, NH 3 is the only combustible gas combusted.

[0270] In a preferred embodiment, the combustion system, preferably an internal combustion engine, is installed in a vehicle and used to move the vehicle. The vehicle is preferably a watercraft. The vehicle is preferably a road vehicle; preferably selected from commercial vehicles, trucks and buses; or a rail vehicle.

[0271] In a further preferred embodiment, the combustion system, preferably the gas turbine, is part of a power plant. The power plant preferably generates electricity and / or district heating.

[0272] In a further preferred embodiment, a combustion system, preferably a furnace for cracking NH3 into N2 and H2, is integrated into a system for thermal and / or catalytic cracking of NH3 into N2 and H2. The combustion of NH3 is then integrated into a method for thermal and / or catalytic cracking of NH3 into N2 and H2.

[0273] In a preferred embodiment, the NO X The content is greater than the N2O content. Preferably, NO X The content is at least twice, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times the N2O content. X The molar ratio of NH:N2O is greater 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.

[0274] In a preferred embodiment, the NO content of the exhaust gas is greater than the N2O content. Preferably, the NO content is at least two times, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times, the N2O content.

[0275] In a preferred embodiment, the NO2 content of the exhaust gas is greater than the N2O content. Preferably, the NO2 content is at least two times, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times the N2O content.

[0276] Preferably, the exhaust gas NO X The content is 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.

[0277] Preferably, the exhaust gas NO X The content is 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.

[0278] Preferably, the exhaust gas NO XThe content is 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.

[0279] Preferably, the N2O content of the exhaust gas is 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.

[0280] Preferably, the N2O content of the exhaust gas is 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.

[0281] Preferred exhaust gases have NO in the range of 1500 to 3000 ppmv, preferably 2000 to 3000 ppmv. X content and N2O content in the range of 20 to 100 ppmv.

[0282] In other preferred embodiments, the H2O content of the offgas is greater 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%.

[0283] In a further preferred embodiment, the H2O content of the offgas is at least 10% by volume; preferably at least 12% by volume, more preferably at least 14% by volume, even more preferably at least 16% by volume, most preferably at least 18% by volume, and in particular at least 20% by volume.

[0284] In a preferred embodiment, the H2O content of the exhaust gas is 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.-%.

[0285] In a preferred embodiment, the H2O content of the exhaust gas is 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.-%.

[0286] In a preferred embodiment, the H2O content of the exhaust gas is 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.-%.

[0287] In a preferred embodiment, the H2O content of the exhaust gas is 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.-%.

[0288] In a preferred embodiment, the H2O content of the exhaust gas is 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.-%.

[0289] Preferably, the N2 content of the offgas is at most 95% by volume; preferably at most 90% by volume, more preferably at most 85% by volume, even more preferably at most 80% by volume, most preferably at most 75% by volume, and in particular at most 70% by volume.

[0290] Preferably, the N2 content of the exhaust gas is at least 40% by volume; preferably at least 50% by volume, more preferably at least 60% by volume, even more preferably at least 70% by volume, most preferably at least 80% by volume, and in particular at least 90% by volume.

[0291] Preferably, the exhaust gas comprises further gaseous components; preferably selected from the group consisting of O2, CO, CO2, NH3, CH4 and mixtures thereof.

[0292] Preferably, the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, are at 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.

[0293] Preferably, the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, are at 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.

[0294] Preferably, after leaving the combustion system, the exhaust gases are cooled during the process of the invention, although steps (c1) and / or (c2) and / or (d) may introduce new heat.

[0295] Preferred variants of the combination of steps (c) and (d):

[0296] In a preferred embodiment, steps (c1) and / or (c2) and / or (d) of the method of the present invention are carried out at different temperatures (i.e. at different temperature levels), wherein the step carried out earlier or upstream in the flow direction of the exhaust gas is preferably carried out at a higher temperature than the step carried out subsequently or downstream in the flow direction of the exhaust gas.

[0297] Preferably, the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, are at a pressure of at most 1.5 bar; preferably atmospheric pressure.

[0298] Preferably, the NO of the exhaust gases leaving a combustion system, preferably an internal combustion engine, a gas turbine or a furnace X The degree of oxidation is 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%.

[0299] Preferably, the NO of the exhaust gases leaving a combustion system, preferably an internal combustion engine, a gas turbine or a furnace X The degree of oxidation is 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%.

[0300] Preferably, the O2 content of the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, is less than 2.0% by volume.

[0301] Preferably, the O2 content of the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, is greater than 4.0% by volume.

[0302] In step (b) of the method of the invention, the exhaust gases which have left a combustion system, preferably an internal combustion engine, a gas turbine or a furnace, are transferred to an exhaust gas treatment system.

[0303] For example, this can be achieved by connecting the outlet pipe of the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, to the inlet of the exhaust gas treatment system.Since the method of the invention is preferably carried out at atmospheric pressure, there are typically no special requirements for such pipes with regard to possible compressive stresses.

[0304] However, the ducting should withstand the temperature of the exhaust gases as they leave the combustion system (preferably an internal combustion engine, a gas turbine or a furnace) or enter the exhaust gas treatment system.

[0305] In a preferred embodiment, the exhaust gas temperature is measured at the outlet of the combustion system (preferably an internal combustion engine, a gas turbine or a furnace) and optionally modified by suitable means so that the exhaust gas has an optimal temperature under given conditions when entering the exhaust gas treatment system in order to perform steps (c) and (d) of the method according to the invention in the exhaust gas treatment system. The optimized temperature depends in particular on the catalyst used for the N2O decomposition catalyst and / or the N2O reduction catalyst and the NO X The type of catalyst material of the reduction catalyst. The optimized temperature depends on the selected configuration of steps (c) and (d), i.e., N2O reduction and NO X The type and sequence of the individual process steps for the reduction, in particular for the N2O decomposition catalyst and / or N2O procatalyst and NO X The type of catalyst material of the reduction catalyst.

[0306] Suitable devices for changing the exhaust gas temperature are known to those skilled in the art and include, in particular, heat exchangers which can be designed, for example, as plate heat exchangers or tube heat exchangers.

[0307] Preferably, in the flow direction of the exhaust gas, at least one heat exchanger is provided downstream of the gas turbine and upstream of the exhaust gas treatment system, wherein the exhaust gas is cooled.

[0308] Preferably, the temperature of the exhaust gases at the outlet from the heat exchanger is at most 550°C, more preferably at most 525°C, even more preferably at most 500°C.

[0309] Preferably, the temperature of the exhaust gases at the outlet from the heat exchanger is at least 400°C, more preferably at least 425°C, even more preferably at least 450°C.

[0310] To avoid heat losses, it can be preferred according to the invention to select the shortest possible distance from the outlet of the combustion system (preferably an internal combustion engine, a gas turbine or a furnace) to the inlet of the exhaust gas treatment system and in this way achieve a compact design.

[0311] However, depending on the properties of the catalyst used, these steps may not be completely separated from one another locally or in time. If the catalyst used is simultaneously suitable for catalyzing two or more of steps (c1), (c2), and (d), these steps can be carried out simultaneously and / or sequentially. For this purpose, it is possible to consider, in the direction of exhaust gas flow, individual sections of one or the same catalyst through which the exhaust gas flows in sequence, and in which different reactions may predominate. Which reaction predominates in which section depends, in particular, on the respective reaction kinetics, the local temperature, and the local concentrations of the reactants, which may include the concentration of the reducing agent and, possibly, the concentration of the catalytically active substance.

[0312] The exhaust gas treatment system of the present invention is particularly useful for carrying out steps (c) and (d) of the method of the present invention. However, in addition to steps (c) and (d), further steps and chemical reactions may also be carried out within the exhaust gas treatment system.

[0313] This preferably involves a catalyst bed arranged downstream in the direction of exhaust gas flow for oxidizing incompletely converted reducing agent or its not yet completely oxidized reaction products, i.e., for example, for oxidizing NH 3 (NH 3 oxidation catalyst) or CO (CO oxidation catalyst; when hydrocarbons are used as reducing agent). In such an embodiment, the exhaust gas is preferably cooled before it is introduced into the downstream catalyst bed, i.e., the oxidation of NH 3 and / or CO is preferably carried out at a lower temperature than in steps (c) and (d).

[0314] In the embodiment of steps (c) and (d) of the process according to the invention, there are different preferred variants of the process scheme according to the invention, which can differ from one another with regard to the sequence of reactions carried out, the catalysts used, the reducing agents used, the space velocity and other reaction conditions.

[0315] In a preferred embodiment, these reactions are carried out in a common reaction zone (catalyst bed) which is equipped upstream with a device for metering the reducing agent into the exhaust gas.

[0316] In a further preferred embodiment, the reactions are carried out in two separate reaction zones (catalyst beds) arranged in series, wherein preferably at least one reaction zone, preferably both reaction zones, is independently equipped upstream with a device for metering the reducing agent into the exhaust gas. In this case, the exhaust gas first flows through the first reaction zone and then through the second reaction zone.

[0317] Particularly preferred variants / embodiments include

[0318] [a] (c2) chemical reduction of N2O with NH3 and (d) chemical reduction of NOx with NH3, preferably together in one reaction zone;

[0319] [b] (c2) Chemical reduction of N2O with hydrocarbons (CH4, natural gas, etc.) and (d) Chemical reduction of NO with NH3 X The chemical reduction is carried out, preferably together in one reaction zone;

[0320] [c] (c1) Decomposition of N2O and (d) Reaction of NO with NH3 X The chemical reduction is carried out, preferably together in one reaction zone;

[0321] [d] (c1) Decomposition of N2O and (c2) Chemical reduction of N2O with NH3 and (d) Chemical reduction of NO with NH3 XThe chemical reduction is carried out, preferably together in one reaction zone;

[0322] [e] (c1) Decomposition of N2O and (c2) Chemical reduction of N2O with hydrocarbons (CH4, natural gas, etc.) and (d) Reduction of NO with NH3 X The chemical reduction is carried out, preferably together in one reaction zone;

[0323] [f] (c1) decomposition of N2O, preferably in a first reaction zone; followed by (d) reaction of NO with NH3 X Chemical reduction is carried out, preferably in a second reaction zone;

[0324] [g] (c1) incomplete decomposition of N2O, preferably in a first reaction zone; followed by (c2) chemical reduction of residual N2O with NH3 and (d) chemical reduction of NO with NH3 X Chemical reduction is carried out, preferably in a second reaction zone;

[0325] [h] (c1) incomplete decomposition of N2O, preferably in a first reaction zone; followed by (c2) chemical reduction of residual N2O with hydrocarbons (CH4, natural gas, etc.) and (d) chemical reduction of NO with NH3 X Chemical reduction is carried out, preferably in a second reaction zone;

[0326] [i] (c1) incomplete decomposition of N2O, preferably in a first reaction zone; subsequently (c1 * ) Decomposition of residual N2O and (d) NH3 treatment of NO X Chemical reduction is carried out, preferably in a second reaction zone;

[0327] [j] (c1) incomplete decomposition of N2O, preferably in a first reaction zone; then (c1 * ) Decomposition of residual N2O and (c2) Chemical reduction of residual N2O with NH3 and (d) Chemical reduction of NO with NH3 X Chemical reduction is carried out, preferably in a second reaction zone;

[0328] [k] (c1) incomplete decomposition of N2O, preferably in a first reaction zone; subsequently (c1 * ) decomposition of residual N2O and (c2) chemical reduction of residual N2O with hydrocarbons (CH4, natural gas, etc.) and (d) reduction of NO with NH3 X Chemical reduction is carried out, preferably in a second reaction zone;

[0329] [l](d)NO X Incomplete chemical reduction, preferably in a first reaction zone; followed by (c1) decomposition of N2O and (d* ) Use NH3 to remove residual NO X Chemical reduction is carried out, preferably in a second reaction zone;

[0330] [m](d)NO X Incomplete chemical reduction, preferably in a first reaction zone; followed by (c1) decomposition of N2O and (c2) chemical reduction of N2O with NH3 and (d * ) chemical reduction of residual NOx with NH3, preferably in a second reaction zone;

[0331] [n](d)NO X Incomplete chemical reduction, preferably in a first reaction zone; followed by (c1) decomposition of N2O and (c2) chemical reduction of N2O with hydrocarbons (CH4, natural gas, etc.) and (d * ) Using NH3 to remove residual NO X Chemical reduction is carried out, preferably in a second reaction zone;

[0332] However, this does not mean that the reactions explicitly mentioned must be the only reactions occurring in the respective reaction zone. Depending on the catalyst used, it is preferred according to the invention that other reactions also occur simultaneously, which are not explicitly mentioned but can be carried out in parallel. Therefore, the reactions explicitly mentioned are only those reactions that occur at least in the respective variant / embodiment.

[0333] If NO X , N2O and NH3 are present in the mixture, and the catalyst used catalyzes the reaction of NO with NH3 X The chemical reduction of N2O is also catalyzed by NH3, and the chemical reduction of NO is catalyzed by NH3. X The chemical reduction that takes place is typically much faster than the chemical reduction of N2O with NH3. If the catalyst used additionally catalyzes the decomposition of N2O, the decomposition of N2O typically overlaps with the chemical reduction of N2O with NH3, wherein the extent of the chemical reduction of N2O can be increased by increasing the amount of NH3 metered in.

[0334] For the purposes of the description, a "*" indicates a component process step that has previously been carried out only partially in a component process step of the same type, wherein the component process step then identified by "*" continues the component process step that was previously carried out only partially, but possibly in a different reaction zone or in a different catalyst bed. As with all other process steps, the results obtained at the end of all component process steps are not quantified unless expressly stated otherwise. For example, if NO X In the first component process step (d) the chemical reduction is incomplete and then the component process step (d) *) does not necessarily mean that in the composition method step (d * ) End NO X The total amount of must have been completely chemically reduced (ie to 0.0 ppmv). On the contrary, it is entirely possible that in the composition process step (d * ) at the end of the experiment, there is still a residual amount of NO X .

[0335] The exhaust gas treatment system comprises at least one injection site for a reducing agent.The exhaust gas treatment system may comprise several injection sites for a reducing agent.

[0336] According to the invention, the mode of introduction of the reducing agent into the stream of the exhaust gas to be treated is freely configurable, provided that this is done in the direction of flow between the N2O reduction catalyst or the NO X The reducing agent can be introduced in the form of a gas or liquid or aqueous solution that evaporates in the stream of exhaust gas to be treated. The feeding is achieved by suitable means, such as a suitable pressure valve or a suitably designed nozzle, which leads to a mixer for the stream of exhaust gas to be treated and the supplied reducing agent. When using different X When using N2 as a reducing agent, they can be supplied and introduced into the exhaust gas separately or together.

[0337] In the case where the catalyst bed is constructed as a catalyst honeycomb or a filling material of a honeycomb module, the catalyst bed is used for NO X The supply and distribution of the reducing agent and optionally N2 to one or more reaction zones (catalyst beds) is preferably achieved by a manifold piping system having multiple openings or nozzles, which is arranged upstream of the corresponding reaction zone (catalyst bed) in the flow direction of the exhaust gas, i.e. upstream of the filling material of the catalyst honeycomb or honeycomb module.

[0338] The distributor is preferably designed in the form of a grid, or concentrically connected circles, which extends as far as possible over the cross-sectional area of ​​the exhaust gas duct or the inflow area of ​​the reaction zone (catalyst bed).

[0339] The specific design and dimensions of these distributors, including suitable outlet nozzles, are part of the know-how of catalytic exhaust gas cleaning technology and are widely used, for example, in the treatment of exhaust gases from coal-fired power plants.

[0340] The exhaust gas treatment system of the present invention may include a single reaction zone. In this case, the catalyst used in the single reaction zone acts as an N2O decomposition catalyst and / or an N2O reduction catalyst and acts as a NO XIn this case, steps (c) and (d) of the process of the invention are carried out essentially simultaneously in the reaction zone. However, it should be noted that the kinetics of the individual conversions can be very different. For example, depending on the catalyst material used, the reaction of NO with NH3 as a reducing agent may be very different. X The chemical reduction of NO can be much faster than the chemical reduction of N2O with NH3. X When N2O and NH3 are in a mixture and NH3 is fed as a reducing agent, different reactions will occur in the front of a single reaction zone than in the back of a single reaction zone. In the front, due to faster kinetics, NO X chemical reduction, and once most of the NO X It has been decomposed and only chemical reduction of N2O is carried out in the latter stage.

[0341] Alternatively, the exhaust gas treatment system may comprise several reaction zones, which is preferred according to the invention. If several reaction zones are comprised, they are preferably arranged in series, so that the exhaust gas flows through them one after another: first the first reaction zone, then the second reaction zone, and if appropriate, then the third reaction zone.

[0342] In a preferred embodiment, the reaction zones are each spatially separated catalyst beds.

[0343] In a preferred embodiment, the exhaust gas undergoes the steps of the method of the present invention in one of the following orders:

[0344] (i) (a) → (b) → (c1) → (d); wherein step (c1) is preferably carried out in a first reaction zone; and step (d) is carried out in a second reaction zone;

[0345] (ii) (a)→(b)→(d)→(c2); wherein step (d) is preferably carried out in the first reaction zone; and step (c2) is carried out in the second reaction zone;

[0346] (iii) (a) → (b) → (d) → (c2) → (c1); wherein step (d) is preferably carried out in the first reaction zone; step (c2) is carried out in the second reaction zone; and step (c1) is carried out in the third reaction zone;

[0347] (iv) (a) → (b) → (d) → (c1) + (c2); wherein step (d) is preferably carried out in a first reaction zone; and steps (c1) and (c2) are carried out in a second reaction zone;

[0348] (v) (a) → (b) → (d) → (c1); wherein step (d) is preferably carried out in the first reaction zone; and step (c1) is carried out in the second reaction zone;

[0349] (vi)(a)→(b)→(c1)+(d)→(d * ); wherein step (c1) is carried out in the first reaction zone and step (d) is not carried out completely and; step (d * ) is carried out in a second reaction zone;

[0350] (vii)(a)→(b)→(c1)+(d)→(d * )+(c2); wherein step (c1) is carried out in the first reaction zone and step (d) is preferably not carried out completely and; step (c2) and step (d * ) is carried out in a second reaction zone;

[0351] (viii)(a)→(b)→(c1)+(c2)+(d)→(c1 * )+(c2 * )+(d * ); wherein step (c1) and step (c2) and step (d) are preferably carried out incompletely in a first reaction zone, the first reaction zone preferably not containing zeolitic material as catalyst; and step (c1 * ) and the remainder of step (c2 * ) and the remainder of step (d * ) is carried out in a second reaction zone, which preferably contains a zeolitic material as a catalyst;

[0352] (ix)(a)→(b)→(c1)+(c2)+(d)→(c1 * )+(c2 * )+(d * ); wherein step (c1) and step (c2) and step (d) are preferably carried out incompletely in a first reaction zone, the first reaction zone preferably containing a zeolitic material as a catalyst; and step (c1 * ) and the remainder of step (c2 * ) and the remainder of step (d * ) is carried out in a second reaction zone, which preferably contains NO X -Sensitive N2O decomposition catalyst as catalyst;

[0353] (x)(a)→(b)→(c1)→(c1*)+(c2)+(d); wherein preferably step (c1) is not completely carried out in a first reaction zone, which preferably contains a zeolitic material as a catalyst; and step (c1 *) and step (c2) and step (d) are carried out in a second reaction zone, which preferably contains a zeolitic material as catalyst;

[0354] (xi)(a)→(b)→(c1)→(c1*)+(c2)+(d); wherein preferably step (c1) is not completely carried out in the first reaction zone, which preferably contains NO X - a sensitive N2O decomposition catalyst as a catalyst; and step (c1 * ) and step (c2) and step (d) are carried out in a second reaction zone, which preferably contains a zeolitic material as catalyst.

[0355] However, it is also possible to realize two or more reaction zones by means of a single catalyst bed. In particular, two reaction zones on a common catalyst bed can be formed by feeding the reducing agent in the middle of the catalyst bed (or at another position along the longitudinal extent). Upstream of the feeding point, there is no reducing agent, so that steps (c2) and (d) of the process according to the invention cannot be carried out due to the lack of reducing agent. What then takes place upstream is essentially the decomposition of N2O in step (c1) (first reaction zone). Downstream of the feeding point, there is a reducing agent, so that steps (c2) and (d) of the process according to the invention can be carried out, possibly overlapping with step (c1) (second reaction zone) of the process according to the invention. In this case as well, due to different reaction kinetics, different reactions may occur in the front section of each reaction zone and in the back section of each reaction zone; however, the first reaction zone and the second reaction zone will in any case differ from one another, since no chemical reduction of N2O and NO2 is carried out in the first reaction zone due to the lack of reducing agent. X Chemical reduction.

[0356] In a particularly preferred embodiment, the exhaust gas treatment system comprises a first reaction zone and a second reaction zone. Possibly, further reaction zones are present.

[0357] In a preferred embodiment, the first reaction zone and the second reaction zone are spatially separated from each other. In this case, they are preferably separate catalyst beds. In the case of spatial separation of the catalyst beds, the temperature of the second catalyst bed or the gas stream entering it can be adjusted by removing or supplying heat so that it is lower or higher than the temperature of the first catalyst bed. The temperature of a single catalyst bed can be appropriately determined as the arithmetic mean of the temperature of the gas stream at the inlet and outlet of the catalyst bed.

[0358] In a preferred embodiment, 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).

[0359] 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 especially at least 650°C.

[0360] 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.

[0361] Preferably, relatively speaking, the temperature in the first reaction zone (in the first catalyst bed) is at least 20°C higher than the temperature in the second reaction zone (in the second catalyst bed), more preferably at least 40°C, even more preferably at least 60°C, most preferably at least 80°C, and in particular at least 100°C.

[0362] Preferably, relatively speaking, the temperature in the first reaction zone (in the first catalyst bed) is at least 120°C higher than the temperature in the second reaction zone (in the second catalyst bed), more preferably at least 140°C, even more preferably at least 160°C, most preferably at least 180°C, and in particular at least 200°C.

[0363] Preferably, the temperature of the off-gas upon entering the first reaction zone (entering 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.

[0364] Preferably, the temperature of the off-gas on leaving the second reaction zone (leaving the second catalyst bed) is at most 600°C, more preferably at most 550°C, even more preferably at most 500°C.

[0365] In a preferred embodiment, relatively speaking, the temperature of the exhaust gas upon entering the first reaction zone (entering the first catalyst bed) is at least 20K higher than the temperature of the exhaust gas upon entering the second reaction zone (entering the second catalyst bed), more preferably at least 40K, even more preferably at least 60K, most preferably at least 80K, and in particular at least 100K.

[0366] In a preferred embodiment, relatively speaking, the temperature of the exhaust gas upon entering the second reaction zone (entering the second catalytic bed) is at least 10K higher than the temperature of the exhaust gas upon entering the first reaction zone (entering the first catalytic bed), more preferably at least 20K, even more preferably at least 30K, most preferably at least 40K, and in particular at least 50K.

[0367] In a preferred embodiment, the temperature in the first reaction zone (in the first catalyst bed) is, relatively speaking, at least 120 K higher than the temperature in the second reaction zone (in the first catalyst bed), more preferably at least 140 K higher, even more preferably at least 160 K higher, most preferably at least 180 K higher, and in particular at least 200 K higher.

[0368] In a preferred embodiment, the temperature in the second reaction zone (in the second catalyst bed) is, relatively speaking, at least 120 K higher than the temperature in the first reaction zone (in the first catalyst bed), more preferably at least 140 K, even more preferably at least 160 K, most preferably at least 180 K, and in particular at least 200 K higher.

[0369] In a further preferred embodiment, the first reaction zone and the second reaction zone are spatially connected to one another. In this case, the catalyst bed is preferably a common catalyst bed, wherein external influences lead to a division into a plurality of reaction zones, in particular by the injection points of the reducing agent, so that the reducing agent is present unevenly across the catalyst bed.

[0370] Preferably, the first reaction zone and the second reaction zone are provided in a common vessel.

[0371] Preferably, the temperature of the offgas in the first reaction zone and in the second reaction zone is in each case independently at most 500°C, preferably in each case independently in the range from 350°C to 450°C.

[0372] In a preferred embodiment, 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 1.2 times greater than the space velocity in the second reaction zone, more preferably at least 1.4 times, even more preferably at least 1.6 times, most preferably at least 1.8 times, and in particular at least 2.0 times greater.

[0373] 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 1.5 times greater than the space velocity in the first reaction zone, more preferably at least 2.0 times, even more preferably at least 3.0 times, most preferably at least 5.0 times, and in particular at least 10.0 times greater.

[0374] In the context of the present invention, "space velocity" means the quotient of the volumetric flow rates of the gas mixture through the catalyst bed, based on the volume of the catalyst or catalyst bed (measured at 0°C and 1.014 bara, typically in standard m / s). 3 ·h -1 Report). Thus, the space velocity can be adjusted by the volumetric flow rate of the gas and / or the amount of catalyst.

[0375] Preferably, the exhaust gas entering the exhaust gas treatment system is at 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 especially at least 450°C.

[0376] Preferably, the exhaust gas entering the exhaust gas treatment system is at 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 especially at least 650°C.

[0377] Preferably, the exhaust gas entering the exhaust gas treatment system is at 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.

[0378] Preferably, the exhaust gas entering the exhaust gas treatment system is at 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.

[0379] Preferably, the exhaust gas entering the exhaust gas treatment system is at a temperature which is relatively lower than the temperature of the exhaust gas leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, by at least 20°C, preferably by at least 40°C, more preferably by at least 60°C, even more preferably by at least 80°C, most preferably by at least 100°C and in particular by at least 120°C.

[0380] Preferably, the pressure of the exhaust gas entering the exhaust gas treatment system is at most 1.4 bara, preferably at most 1.3 bara, more preferably at most 1.2 bara.

[0381] Preferably, the NO of the exhaust gas entering the exhaust gas treatment system X The degree of oxidation is 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%.

[0382] Preferably, the NO of the exhaust gas entering the exhaust gas treatment system X The degree of oxidation is 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%.

[0383] Depending on the combustion temperature, the degree of oxidation can also be significantly lower, and the degree of oxidation decreases with increasing combustion temperature. Preferably, the exhaust gas NO X The degree of oxidation is at most 15%, more preferably at most 12.5%, even more preferably at most 10%, most preferably at most 7.5%, and in particular at most 5.0%.

[0384] Preferably, the O2 content of the exhaust gas when entering the exhaust gas treatment system is less than 2.0% by volume.

[0385] Preferably, the O2 content of the exhaust gas when entering the exhaust gas treatment system is greater than 4.0% by volume.

[0386] In step (c) of the method of the present invention, the NO content in the exhaust gas is reduced. This can be achieved in various ways, namely, by (c1) decomposing NO over an NO decomposition catalyst and / or (c2) chemically reducing NO with a reducing agent over an NO reduction catalyst. Step (c) of the method of the present invention is carried out in an exhaust gas treatment system.

[0387] In a preferred embodiment, step (c) comprises reducing the N2O content in the exhaust gas by (c1) decomposing N2O over an N2O decomposition catalyst.

[0388] In a preferred embodiment, the N2O decomposition catalyst comprises a zeolitic material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0389] In other preferred embodiments, the N2O decomposition catalyst is NO in the context of the present invention. X -sensitive N2O decomposition catalyst, which has been described in detail above. In this case, the exhaust gas is preferably first passed through step (d), i.e. first through the NO X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction to reduce NO in exhaust gas X content, preferably quantitatively, and then the exhaust gas is mixed with NO X -Contact with sensitive N2O decomposition catalyst.

[0390] Preferably, the N2O decomposition catalyst is arranged in a radial basket through which the flow passes axially.

[0391] The N2O decomposition catalyst is preferably in granular form and comprises at least 50 particles.

[0392] In a preferred embodiment, step (c) comprises reducing the N2O content in the exhaust gas by (c2) chemically reducing N2O with a reducing agent over a N2O reduction catalyst; preferably, wherein the N2O reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded 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 structure type.

[0393] Preferably, the N2O reduction catalyst is disposed in a radial basket through which the flow passes axially.

[0394] The N2O reduction catalyst is preferably in a granular form and comprises at least 50 particles.

[0395] In a preferred embodiment, step (c) comprises reducing the N2O content in the exhaust gas by:

[0396] - decomposing N2O by (c1) over an N2O decomposition catalyst; preferably, wherein the N2O decomposition catalyst is a zeolitic material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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;

[0397] - thereby chemically reducing N2O with a reducing agent over an N2O reduction catalyst by (c2); preferably, wherein the N2O reduction catalyst comprises a zeolitic material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0398] Preferably, the reducing agent in step (c2) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

[0399] In a preferred embodiment, the reducing agent in step (c2) is NH3, preferably, used in an amount of 0.5 to 2.0 parts by mole based on the molar ratio of N2O to be chemically reduced (i.e., based on the amount of N2O at the inlet of the catalyst bed entering the N2O reduction catalyst), preferably 0.8 to 1.8 parts by mole.

[0400] In a preferred embodiment, the reducing agent in step (c2) is NH3, preferably, the amount thereof is 0.5 to 2.0 parts by mole, preferably 0.8 to 1.8 parts by mole, based on the molar amount of N2O in the exhaust gas at the inlet to the catalyst bed of the N2O reduction catalyst. If step (d) is also carried out in the catalyst bed of the N2O reduction catalyst, this amount plus the amount for NO X Any desired amount of added NH3 for reduction.

[0401] In other preferred embodiments, the reducing agent is a hydrocarbon or a mixture of two or more hydrocarbons, and its amount is preferably 0.2 to 1.0 parts by mole, more preferably 0.2 to 0.7 parts by mole, based on the molar amount of NO in the exhaust gas at the inlet to the catalyst bed of the NO reduction catalyst. If step (e) is also carried out in the catalyst bed of the NO reduction catalyst, or the apparatus of the present invention is configured accordingly, this amount is also added to the amount for NO reduction. X Any desired amount of added NH3 for reduction.

[0402] The reducing agent may also already be present in the exhaust gas, for example in the form of residual fuel and / or its oxidation products. In this case, the method according to the invention not only reduces nitrogen oxides (NO X and N2O), and also reduce the content of these impurities (residual fuel and / or its oxidation products).

[0403] In step (d) of the method of the present invention, NO in the exhaust gas is reduced. X (i.e. NO and NO2) content. This is determined by the NO X Reduction of NO by using a reducing agent on a catalyst X The step (d) of the method of the present invention is also carried out in the exhaust gas treatment system.

[0404] NO X The reduction catalyst preferably comprises a zeolitic material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0405] Preferably, NO X The reduction catalyst is disposed in radial baskets through which the flow passes axially.

[0406] Preferably, NO X The reduction catalyst is in a granular form and comprises at least 50 particles.

[0407] Preferably, the reducing agent in step (d) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

[0408] Preferably, the reducing agent in step (d) is NH3, and its amount is based on the NO to be chemically reduced. X The molar ratio is 0.9 to 2.5 parts by mole, preferably 1.0 to 1.4 parts by mole, and preferably 1.0 to 1.2 parts by mole.

[0409] In a preferred embodiment, the reducing agent in step (c2) is the same as the reducing agent in step (d); preferably NH3.

[0410] In step (c2) and / or (d) of the inventive method, in addition to NH 3 , other nitrogen-containing reducing agents are also suitable in principle, for example nitrogen hydrogen compounds, such as azane, hydroxy derivatives of azane and amines, oximes, carbamates, ureas or urea derivatives. An example of an azane is hydrazine, and very particularly ammonia. An example of a hydroxy derivative of azane is hydroxylamine. An example of an amine is aliphatic primary amines, such as methylamine. An example of a carbamate is ammonium carbamate. An example of a urea derivative is N,N '-substituted urea, such as N,N '-dimethylurea. Urea and urea derivatives are preferably used in the form of an aqueous solution. Particularly preferred is ammonia or a substance that releases ammonia when introduced, such as urea or ammonium carbamate.

[0411] The particularly preferred process scheme of the present invention is described in detail below:

[0412] DeNO X -deN2O-transformer 1

[0413] In a preferred embodiment, the exhaust gas treatment system comprises a first reaction zone through which the exhaust gas passes in series and a subsequent second reaction zone;

[0414] wherein a reducing agent is added to the exhaust gas upstream of the first reaction zone;

[0415] Among them, in the first reaction zone, first by NO X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction to reduce NO in exhaust gas X Content (step (d)) (deNO X wherein, optionally, the N2O content in the exhaust gas is additionally reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with a reducing agent on an N2O reduction catalyst (step (c2));

[0416] wherein optionally, additional reducing agent is added to the exhaust gas upstream of the second reaction zone; and

[0417] wherein the N2O content in the exhaust gas is then reduced in a second reaction zone by decomposing N2O on an N2O decomposition catalyst (step (c1)) and / or by chemically reducing N2O with a reducing agent on an N2O reduction catalyst (step (c2)) (deN2O stage); wherein optionally, by X Chemical reduction of NOx on a reduction catalyst (step (d)) to additionally further reduce NO in the exhaust gas X content.

[0418] Preferably, the NO in the first reaction zone X The reduction catalyst comprises a conventional, preferably non-zeolitic SCR catalyst, for example based on V2O5-WO3- / TiO2.

[0419] Preferably, the temperature of the off-gas upon entering the first reaction zone is at most 400°C, preferably at most 350°C.

[0420] Preferably, the N2O decomposition catalyst in the second reaction zone comprises a zeolitic material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0421] Preferably, the temperature of the off-gas upon entering the second reaction zone is in the range of 300 to 550°C, preferably 350 to 500°C.

[0422] Preferably, the off-gas after leaving the first reaction zone and before entering the second reaction zone has a NO in the range of 0 to 200 ppmv, preferably 1 to 200 ppmv. X content and N2O content in the range of 200 to 2000 ppmv.

[0423] DeNO X -deN2O-transformer 2

[0424] In other preferred embodiments, the exhaust gas treatment system also comprises a first reaction zone and a subsequent second reaction zone through which the exhaust gas passes continuously;

[0425] wherein a reducing agent is added to the exhaust gas upstream of the first reaction zone;

[0426] Among them, in the first reaction zone, first by NO X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction to reduce NO in exhaust gas X Content (step (d)) (deNO Xwherein, optionally, the N2O content in the exhaust gas is additionally reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with a reducing agent on an N2O reduction catalyst (step (c2));

[0427] wherein optionally, additional reducing agent is added to the exhaust gas upstream of the second reaction zone; and

[0428] wherein the N2O content in the exhaust gas is then reduced in a second reaction zone by decomposing N2O on an N2O decomposition catalyst (step (c1)) and / or by chemically reducing N2O with a reducing agent on an N2O reduction catalyst (step (c2)) (deN2O stage); wherein optionally, by X NO reduction catalyst X Chemical reduction (step (d)) is performed to additionally further reduce NO in the exhaust gas. X content.

[0429] Preferably, the NO in the first reaction zone X The reduction catalyst comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0430] Preferably, the off-gas temperature 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 off-gas temperature upon entering the first reaction zone is at most 600°C, more preferably at most 550°C.

[0431] Preferably, the N2O decomposition catalyst in the second reaction zone comprises NO in the context of the present invention. X - a sensitive N2O decomposition catalyst, which has been described in detail above.

[0432] Preferably, the off-gas temperature 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 off-gas temperature upon entering the second reaction zone is at most 600°C, more preferably at most 550°C.

[0433] Preferably, the off-gas after leaving the first reaction zone and before entering the second reaction zone has a NO content of at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv. X content and N2O content in the range of 200 to 2000 ppmv.

[0434] DeNO X Particularly preferred embodiments of deN2O variant 2

[0435] In a particularly preferred embodiment, the exhaust gas treatment system of the present invention comprises a first catalyst bed and a spatially separated second catalyst bed; 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, a first device having a first control valve for metering NH3 into the exhaust gas is arranged upstream of the first catalyst bed; wherein a second device having a second control valve for metering NH3 into the exhaust gas is arranged downstream of the first catalyst bed and upstream of the second catalyst bed, the second device being used to meter additional NH3 into the exhaust gas; wherein both the first catalyst bed and the second catalyst bed each contain an iron-loaded zeolite catalyst; wherein (i) in the first catalyst bed (c1), N2O is decomposed; and (d) NO X incompletely chemically reduced with NH3, wherein optionally and preferably at least part of the NH3 comes from incomplete combustion of NH3 in step (a) (NH3 slip); and (ii) in the second catalyst bed (c2), residual N2O is chemically reduced with NH3, and (c1 * ) residual N2O is optionally decomposed; and (d * ) Residual NO X Chemically reduced with NH3.

[0436] Preferably, the catalytic decomposition of N2O in the first catalyst bed is carried out by the presence of NO in the exhaust gas. X Catalytic promoter.

[0437] Preferably, NH3 is used to convert NO into X Incomplete chemical reduction of NO leads to a predetermined residual NO X content, the residual NO X The content is sufficient to promote the decomposition of N2O in the first catalyst bed. X The chemical reduction is usually much faster than the chemical reduction of N2O with NH3, and the chemically reduced NO in the first catalyst bed X The amount is not the entire amount and the extent of any parallel chemical reduction of N2O with NH3 in the first catalyst bed is typically negligible.

[0438] Preferably, for NO X Reduction Additional NH3 is metered into the exhaust gas by the first device; preferably under feedback control; ie NO X A specific value of the concentration is defined as a target value (set point) and the NO Xand, in the event of a difference between the set point and the actual value (control difference), changing the output of the first control valve so as to minimize the difference. X The set point for the concentration and therefore the amount of additional NH3 is chosen so that upon leaving the first catalyst bed NO X The residual concentration of NO is at most 1000 ppmv, preferably at most 500 ppmv, more preferably at most 100 ppmv. X The set point for the concentration and therefore the amount of additional NH3 is chosen so that upon leaving the first catalyst bed NO X The residual concentration of NO in the first catalyst bed is at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 40 ppmv. X The expected specific consumption of chemically reduced NH3 is typically per mole of reduced NO X 0.9-1.1 mol of NH3 is used, thus significantly less than the expected specific (mol / mol) consumption of NH3 in the second catalyst bed.

[0439] Preferably, the temperature of the exhaust gas as it leaves the first catalyst bed is in the range of 400 to 550°C.

[0440] Preferably, the off-gas on leaving the first catalyst bed is at a pressure greater than atmospheric pressure, ie ≥ 1.0 bara, but at most 1.2 bara, more preferably at most 1.1 bara.

[0441] Preferably, the NO X The degree of oxidation is 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%.

[0442] In a preferred embodiment, the NO content of the exhaust gas leaving the first catalyst bed is X The degree of oxidation is in the range of 30% to 50%.

[0443] In other preferred embodiments, the NO content of the exhaust gas leaving the first catalyst bed is X The degree of oxidation is in the range of 15% to 35%, preferably 15% to 30%.

[0444] In a further preferred embodiment, the NO content of the exhaust gas leaving the first catalyst bed is X The degree of oxidation is in the range of 10% to 20%.

[0445] In other preferred embodiments, the NO content of the exhaust gas leaving the first catalyst bed isX The degree of oxidation is in the range of 5% to 15%.

[0446] Preferably, residual N2O is decomposed in the second catalyst bed such that the residual concentration of N2O leaving the second catalyst bed is at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv, most preferably at most 2 ppmv.

[0447] Preferably, residual NO X decomposed in the second catalyst bed so that NO X The residual concentration is at most 20 ppmv, more preferably at most 10 ppmv, even more preferably at most 5 ppmv, most preferably at most 2 ppmv.

[0448] Preferably, additional NH3 is metered in under feedforward control by a second means, namely NO X The concentration of N2O and optionally preferably N2O is measured in each case upon leaving the first catalyst bed or optionally in each case upon entering the second catalyst bed; the amount of exhaust gas entering the second catalyst bed is taken into account to calculate the amount of NO X The amount of reduced NH3 and optionally preferably by means of the stored ratio (ie for example NH3 / NO X The molar ratio (mol / mol) of NH3 / N2O and optionally preferably a factor derived therefrom) for NO X The sum of the required reduction and N2O reduction; and the calculation result (manipulated variable) is used to change the output of the second control valve in order to meter the required amount of NH3.

[0449] Preferably, according to the present invention, the molar NH3 concentration [NH3] of the exhaust gas entering the second catalyst bed is between 0.7x [N2O] and 1.0x [NO X ] to 4.0x[N2O] and 2.0x[NO X ], more preferably within the range of 1.0x[N2O] and 1.1x[NO X ] to 3.0x[N2O] and 1.6x[NO X ], even more preferably in the range of 1.5x[N2O] and 1.2x[NO X ] to 2.5x[N2O] and 1.4x[NO X ], where [N2O] is the molar concentration of N2O, and [NO X ] is NO X The molar concentrations of , both are the concentrations in the exhaust gas when entering the second catalyst bed.

[0450] Preferably, relative to NO XFor the feedforward control of the metered addition of NH3 to the second catalyst bed, an NH3 / NO ratio in the range of 1.0 to 2.0 is selected; preferably 1.1 to 1.6; more preferably 1.2 to 1.4. X molar ratio.

[0451] Preferably, for the feedforward control of the metered addition of NH 3 to the second catalyst bed relative to the N 2 O reduction, a molar ratio of NH 3 / N 2 O is selected in the range of 0.7 to 4.0; preferably 1.0 to 3.0; more preferably 1.5 to 2.5.

[0452] Preferably, additional NH3 is not metered with the second device under feedback control, since the aim is to maximize the chemical reduction of NO in the second catalyst bed. X , which means that the result is zero or only a very small residual concentration of NO X and N2O, which have limited utility as control variables.

[0453] Preferably, the amount of catalyst, i.e. the space velocity (= ratio of the exhaust gas volume flow rate under standard conditions to the catalyst volume) is selected so that the decomposition of N2O in the first catalyst bed is at least 50%, preferably at least 70%, more preferably at least 80%, based on the N2O concentration when entering the first catalyst bed.

[0454] Preferably, the amount of catalyst and the amount of additional NH3 are selected so that upon leaving the first catalyst bed, NO X The molar ratio of N2O to N2O is at least 5, more preferably at least 10, even more preferably at least 20.

[0455] Preferably, the space velocity of the first catalyst bed is 5000h -1 Up to 100,000 hours -1 In the range of 10000h, more preferably 10000h -1 Up to 50,000 hours -1 , even more preferably 15000h -1 Up to 45000h -1 .

[0456] If NO leaves the first catalyst bed X The molar ratio of NH3 to N2O is at least 10, and the NH3 metered in via the second device can preferably only react with the incoming NO X The amount is related.

[0457] Preferably, the exhaust gas temperature 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 exhaust gas temperature upon entering the first catalyst bed is not more than 550° C., more preferably not more than 525° C., even more preferably not more than 500° C. The temperature can be adjusted by measures known to those skilled in the art, in particular the design of the heat exchanger and the conditions of the NH combustion.

[0458] Depending on the exothermicity of the chemical reactions carried out in the first catalyst bed and in the second catalyst bed, the inlet temperature of the exhaust gas entering the first catalyst bed is preferably selected so that the temperature of the exhaust gas when leaving the second catalyst bed is at most 600°C, more preferably at most 550°C, even more preferably at most 520°C.

[0459] Preferably, the space velocity of the second catalyst bed is 5000h -1 Up to 100,000 hours -1 In the range of 10000h, more preferably 10000h -1 Up to 50,000 hours -1 , even more preferably 15000h -1 Up to 45000h -1 .

[0460] Preferably, the first catalyst bed V1 cat With the second catalyst bed V2 cat The catalyst volume ratio (V1 cat / V2 cat ) is in the range of 1 / 2 to 20 / 1, preferably 1 / 2 to 10 / 1, more preferably 1 / 1 to 4 / 1.

[0461] In a preferred embodiment, at least one, more than one, or all of the following conditions are met:

[0462] the pressure of the exhaust gas upon entering the first catalyst bed is at most 5 bara, preferably at most 4 bara, more preferably at most 1.3 bara, most preferably at most 1.2 bara, and in particular at most 1.1 bara;

[0463] - the H2O content of the off-gas upon entering the first catalyst bed is at least 5% by volume, more preferably at least 10% by volume, even more preferably at least 15% by volume, most preferably at least 20% by volume and in particular at least 25% by volume;

[0464] - NO in the exhaust gas entering the first catalyst bed X A content of 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;

[0465] - the N2O content in the off-gas upon entering the first catalyst bed is at most <500 ppmv, more preferably at most 200 ppmv, even more preferably at most 100 ppmv, but at least 5 ppmv, preferably at least 10 ppmv, more preferably at least 50 ppmv;

[0466] - the exhaust gas contains unburned NH3 residues from NH3 combustion when entering the first catalyst bed;

[0467] - The N2O decomposition catalyst and / or the N2O reduction catalyst is in the form of a honeycomb body;

[0468] - NO X The reduction catalyst is in the form of a honeycomb;

[0469] - the first catalyst bed comprises Fe zeolite;

[0470] - the second catalyst bed comprises Fe zeolite;

[0471] - the exhaust gas passes through a heat exchanger before entering the first catalyst bed and is heated therein;

[0472] - NO when leaving the first catalyst bed X The content 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;

[0473] - an NO2 content upon leaving the first catalyst bed of 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;

[0474] - There is no intermediate cooling of the exhaust gas between leaving the first catalyst bed and entering the second catalyst bed;

[0475] -N2O:NO upon entering the first catalyst bed X The molar ratio of is at most 0.5, more preferably at most 0.2, even more preferably at most 0.1;

[0476] -N2O:NO when leaving the first catalyst bed X The molar ratio of is at most 0.20, more preferably at most 0.1, even more preferably at most 0.05;

[0477] - NH3 feeding into the exhaust gas upstream of the first catalyst bed in the direction of exhaust gas flow is optional; if present, it is preferably relative to NO3 on entry into the first catalyst bed.X The content is substoichiometric;

[0478] - It is necessary to feed NH3 into the exhaust gas downstream of the first catalyst bed and upstream of the second catalyst bed in the direction of flow of the exhaust gas, and preferably relative to NO3 on entry into the second catalyst bed. X The total content of N2O is superstoichiometric.

[0479] Compared with conventional deNO using V2O5 / TiO2 catalyst X Compared to the above process, the above process using an Fe zeolite catalyst in two catalyst beds enables, at relatively low catalyst volumes (i.e. at relatively high space velocities):

[0480] - Complete or almost complete decomposition of large amounts of NO X , there is no risk of NH3 escape; and

[0481] - Simultaneous, complete or almost complete decomposition of N2O.

[0482] In addition to the inventive method of operation, this is achieved by the oxidizing properties of the Fe zeolite catalyst used according to the invention. Thus, in the first catalyst bed, according to the invention, the molar ratio of NO to NO2 is such that it is as close as possible to the thermodynamic equilibrium position. For example, due to the combustion of NH3 upstream at very high temperatures and the slow establishment of equilibrium in the gas phase as the exhaust gas cools in any downstream heat exchanger, the NO2 before entering the first catalyst bed is X The degree of oxidation (molar ratio of NO2 / (NO+NO2)) is lower than the expected 5% and is therefore well below the thermodynamic equilibrium applicable to the inlet temperature of the first catalyst bed. X This is very disadvantageous for efficient chemical reduction of NO, since as a result, only a small fraction of the NO present in the exhaust gas X It can be decomposed by fast SCR, and most of the NO X Or the remaining NO must be broken down by the significantly slower normal SCR.

[0483] The selected mode of operation of limited metered addition of NH3 in the first catalyst bed and the ability of the iron zeolite catalyst to oxidize NO or catalytically accelerate the establishment of equilibrium leads to a significantly faster (ie more efficient) NO X Chemical reduction, and at the same time the residual NO X NO X This allows NO to be oxidized from the outset in the second catalyst bed as well. X Perform efficient chemical reduction.

[0484] It has therefore been found that, similar to water, large amounts of NH3 (such as the complete chemical reduction of high concentrations of NO X required) to suppress NO on iron zeolite catalysts X Establishment of balance.

[0485] In addition, at relatively high doses of NH3, NO X The chemical reduction of NH3 is also inhibited by NH3 itself. As a result, depending on the temperature, the amount of catalyst and NO X As the amount of NH3 added increases and exceeds a certain amount of NH3, the NO X No further increase in decomposition occurred. With further increase in NH3 addition, it is even possible that in some cases NO2 can be observed simultaneously with NH3 slip. X Reduced decomposition.

[0486] The previous NO in the first catalyst bed X The chemical reduction of NO is significantly reduced in the second catalyst bed. X The amount of NH3 required.

[0487] According to the invention, in this way, together with the above-mentioned establishment or permanent readjustment of NO X Balance, a very efficient NO X Chemical reduction is also possible in the second catalyst bed even with superstoichiometric addition of NH 3 .

[0488] This is additionally achieved according to the invention with no or only negligible NH3 slip, preferably with an NH3 slip of at most 10 ppmv, more preferably at most 5 ppmv, even more preferably at most 3 ppmv, a fact also due to the oxidizing properties of the Fe zeolite catalyst 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., then within the limits of the invention, the excess NH3 is selectively oxidized to N2 and H2O by the residual oxygen content of the exhaust gas present.

[0489] When using conventional SCR catalysts based on V2O5 / TiO2 (typically also used for denitrification of exhaust gases from natural gas combustion reformers), all of these advantages cannot be achieved in a single-stage or multi-stage arrangement. Therefore, for stability reasons, these conventional SCR catalysts typically cannot be operated at temperatures above 400°C, which limits the achievable rate of the decomposition reaction. It is also the case that conventional SCR catalysts have only very limited oxidation activity, so NO XEstablishing an equilibrium or permanently resetting it is not possible, nor can these catalysts efficiently and selectively oxidize the stoichiometric excess of NH 3 . On the contrary, there is even the risk of the undesirable formation of N 2 O.

[0490] In a variant of the above-described preferred embodiment according to the invention, the first catalyst bed and the second catalyst bed contain the same catalyst. In a preferred embodiment, the second device with the second control valve for metering NH3 into the exhaust gas is omitted, and preferably the spatial separation of the first catalyst bed from the second catalyst bed is omitted - in that case, there is actually only a single common catalyst bed, the first device with the first control valve for metering NH3 into the exhaust gas being 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. NO X The concentrations of NO, N₂O, and NH₃ are measured in the exhaust gas upstream of the common catalyst bed; the amount of exhaust gas entering the common catalyst bed is taken into account to calculate the additional amount of NH₃ still required; and the result of the calculation (the manipulated variable) is used to change the output of the first control valve to meter the additional amount of NH₃ still required. Preferably, in such an embodiment, the NH₃ oxidation catalyst is disposed downstream of the common catalyst bed to reduce possible NH₃ slip.

[0491] Simultaneous combustion of NH3 and CH4 - reduction of hydrogen cyanide content

[0492] In a preferred embodiment, in step (a), a mixture of CH4 and NH3 is combusted with air and / or oxygen to produce a mixture containing additionally CO2, CO and HCN and NO X and N2O exhaust gases.

[0493] In these cases, the first catalyst bed preferably assumes the additional function of catalyzing the cracking of HCN to give CO and NH3 products by hydrolysis with water present in the exhaust gas, as follows: The CO and NH3 products formed can then be used, preferably (in the case of NH3), to reduce NO in the first catalyst bed. X , and preferably (for CO) used as a reducing agent to reduce N2O in the second catalyst bed to eliminate N2O and NO in the exhaust gas X .

[0494] As a pollutant and greenhouse gas, HCN content in exhaust gases must be limited or eliminated due to its toxicity, lifetime in the atmosphere, and absorption in the infrared. The cracking products formed when HCN is decomposed according to the invention with CO and NH3 in a first catalyst bed over a zeolite catalyst are suitable as catalysts for the second catalyst bed to remove NO. XThe fact that the vanadium oxide-based SCR catalysts are a reducing agent for further exhaust gas post-treatment with N2O completes the inventive concept of the present invention for exhaust gas treatment over zeolite catalysts. Conventional SCR catalysts based on vanadium oxide have virtually no HCN hydrolysis activity and are therefore unsuitable for HCN removal from exhaust gases. In this case, a downstream oxidation catalyst must be used.

[0495] Waste heat steam generator

[0496] In a preferred embodiment, the exhaust gas treatment system of the present invention comprises a first waste heat steam generator and preferably a second waste heat steam generator, wherein the first waste heat steam generator is arranged upstream of the second waste heat steam generator in the flow direction of the exhaust gas.

[0497] Figures 1 to 3 A preferred embodiment according to the present invention is schematically depicted, in which a first waste heat steam generator (ADE1), a second waste heat steam generator (ADE2), a first catalyst bed (K1), and a second catalyst bed (K2) can be positioned downstream of the turbine outlet and contacted with the hot turbine exhaust gas. A generator (G) drives a compressor (V), in which air is compressed. Ammonia is burned in a combustion chamber (VK, combustion chamber), possibly mixed with methane or hydrogen, and the resulting exhaust gas is expanded and flows into a gas turbine (GT). After leaving the gas turbine (GT), the exhaust gas is fed into an exhaust gas treatment system (AB), which includes a first waste heat steam generator (ADE1), a second waste heat steam generator (ADE2), a first catalyst bed (K1), and a second catalyst bed (K2). In the second waste heat steam generator (ADE2), and then also in the first waste heat steam generator (ADE1), water vapor absorbs heat from the exhaust gas. The heated steam is fed to a steam turbine driven by a generator (G) and then flows through a heat exchanger (WT).After leaving the exhaust gas treatment system (AB), the exhaust gas is fed to a stack (SS).

[0498] In a preferred embodiment, the exhaust gas first flows through the first waste heat steam generator, then flows through the first catalyst bed, then flows through the second catalyst bed, and finally flows through the second waste heat steam generator ( Figure 1 ).

[0499] In other preferred embodiments, the exhaust gas first flows through the first waste heat steam generator, then flows through the first catalyst bed, then flows through the second waste heat steam generator, and finally flows through the second catalyst bed ( Figure 2 ).

[0500] In a further preferred embodiment, the exhaust gas first flows through the first catalyst bed, then flows through the first waste heat steam generator, then flows through the second catalyst bed, and finally flows through the second waste heat steam generator ( Figure 3 ).

[0501] In other less preferred embodiments, there is only one catalyst bed and combustion is carried out in two stages, namely premixed combustion ( Figure 4 ) or rich-lean combustion ( Figure 5 ).

[0502] DeN2O-deNO X.

[0503] In a further preferred embodiment, the exhaust gas treatment system comprises a first reaction zone and a subsequent second reaction zone through which the exhaust gas passes continuously;

[0504] wherein a reducing agent is added to the exhaust gas between the first reaction zone and the second reaction zone;

[0505] wherein, in the first reaction zone, the N2O content in the exhaust gas is first reduced by decomposing N2O on an N2O decomposition catalyst (step (c1)) (deN2O stage); and

[0506] In the second reaction zone, the X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction to reduce NO in exhaust gas X Content (step (d)) (deNO X wherein optionally, the N2O content in the exhaust gas is additionally further reduced by further decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with a reducing agent on an N2O reduction catalyst (step (c2)).

[0507] Preferably, no reducing agent is added to the exhaust gas upstream of the first reaction zone.

[0508] According to the present invention, such a process scheme is particularly preferred. This makes it possible to first adjust the NO X and the relative content of N2O without consuming the reducing agent. The absolute NO in the first reaction zone X While the content remains almost unchanged, the N2O content in the exhaust gas is selectively reduced by decomposition. This can achieve the goal of establishing NO X The amount of N2O decomposition catalyst selected is preferably not too large to achieve a quantitative complete reduction of the N2O content in the exhaust gas by decomposition (0 ppmv) for economic reasons; rather, a compromise is found between the size of the N2O decomposition catalyst and the decomposition rate.

[0509] In a preferred embodiment, the N2O decomposition catalyst in the first reaction zone comprises a zeolitic material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0510] In other preferred embodiments, the N2O decomposition catalyst in the first reaction zone comprises NO in the context of the present invention. X - a sensitive N2O decomposition catalyst, which has been described in detail above.

[0511] In a preferred embodiment, the NO in the second reaction zone X The reduction catalyst comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0512] Preferably, in this context, the first reaction zone and the second reaction zone are operated at different temperature levels.

[0513] Preferably,

[0514] - The N2O decomposition catalyst in the first reaction zone contains NO X - a sensitive N2O decomposition catalyst; wherein the exhaust gas temperature 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

[0515] - NO in the second reaction zone X The reduction catalyst is a zeolitic material; preferably a zeolite loaded with a transition metal (including lanthanides), in particular 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 structure type; wherein the exhaust gas temperature 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 NO X In addition to the chemical reduction, preferably the (residual) N2O content is further reduced in the second reaction zone by decomposition and / or chemical reduction.

[0516] Preferably, in the first reaction zone, the space velocity is set such that the N2O content in the offgas is reduced in the first reaction zone by at most 95%, preferably at most 90%, preferably at most 85%, based on the N2O content in the offgas when entering the first reaction zone.

[0517] In a preferred embodiment, the N2O content in the offgas 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.

[0518] In a preferred embodiment, the N2O content in the offgas 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.

[0519] Preferably, in the second reaction zone, the space velocity is set so that the NO content in the exhaust gas is further reduced by at least 30%, preferably at least 40%, and more preferably at least 50%, based on the NO content in the exhaust gas upon entering the second reaction zone. Due to the presence of the reducing agent in the second reaction zone, further reduction of the NO content in the second reaction zone can be achieved by decomposition on the NO decomposition catalyst (step (c1)) and by chemical reduction with the reducing agent on the NO reduction catalyst (step (c2)).

[0520] Preferably, in the second reaction zone, the N2O content in the exhaust gas is further reduced by chemical reduction of N2O over an N2O reduction catalyst (step (c2)).

[0521] In addition, in the second reaction zone, by X Chemical reduction of NO by using a reducing agent on a reduction catalyst X This reduction typically has rapid kinetics and preferably proceeds practically quantitatively according to the invention.

[0522] Closed-loop control

[0523] Irrespective of the respective process scheme, the process according to the invention is preferably under closed-loop control.

[0524] In a preferred embodiment, depending on the configuration of the combustion system, preferably an internal combustion engine, a gas turbine, or a furnace, used for the closed-loop control of the method according to the invention, the first measured variable is at least one parameter characterizing the current operating state of the combustion system, preferably the internal combustion engine, the gas turbine, or the furnace. Preferably, the first measured variable or parameter is selected from the group consisting of combustion temperature, NH3 consumption, (if applicable) rotational speed, and noise emitted by the combustion system, preferably the internal combustion engine, the gas turbine, or the furnace.

[0525] Depending on the characteristics of the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, in particular:

[0526] - NO in exhaust gas X content;

[0527] - NO in exhaust gas X degree of oxidation;

[0528] - N2O content in exhaust gas;

[0529] - the content of other components in the exhaust gas, such as H2O, O2 and N2;

[0530] - exhaust gas temperature;

[0531] - exhaust gas pressure; and

[0532] - exhaust gas volume flow rate;

[0533] Process conditions can be optimized to achieve efficient and economically viable reduction of NO in exhaust gases X and N2O content.

[0534] Therefore, in a preferred embodiment, in addition to or instead of the first measured variable, for controlling the method according to the invention, at the outlet of the combustion system, preferably the internal combustion engine, the gas turbine or the furnace; and / or at the inlet into the exhaust gas treatment system, at least one characteristic parameter of the current state of the exhaust gas before entering the exhaust gas treatment system is measured as a second measured variable. Preferably, this second measured variable or parameter is selected from the group consisting of: NO in the exhaust gas; X Content; NO in exhaust gas X the degree of oxidation; the N2O content in the exhaust gas; the content of other components in the exhaust gas, such as H2O, O2 and N2; the exhaust gas temperature; the exhaust gas pressure; and the volume flow rate of the exhaust gas.

[0535] Therefore, in a preferred embodiment, for controlling the method according to the invention, in addition to or instead of the first measured variable and in addition to or instead of the second measured variable, at least one parameter characteristic of the current state of the exhaust gas when leaving the exhaust gas treatment system is measured as a third measured variable. Preferably, this third measured variable or parameter is selected from the group consisting of: NO in the exhaust gas; X Content; NO in exhaust gas X the degree of oxidation; the N2O content in the exhaust gas; the content of other components in the exhaust gas, such as H2O, O2 and N2; the exhaust gas temperature; the exhaust gas pressure; and the volume flow rate of the exhaust gas.

[0536] In a preferred embodiment, in particular when the exhaust gas treatment system comprises a first reaction zone and a second reaction zone through which the exhaust gas passes in sequence, wherein the reducing agent is fed between the first reaction zone and the second reaction zone, in order to control the method according to the invention, in addition to or instead of the first measured variable, and in addition to or instead of the second measured variable, and in addition to or instead of the third measured variable, at least one parameter characteristic of the current state of the exhaust gas after leaving the first reaction zone and before entering the second reaction zone is measured as a fourth measured variable. Preferably, this fourth measured variable or parameter is selected from the group consisting of: NO in the exhaust gas; X Content; NO in exhaust gas X the degree of oxidation; the N2O content in the exhaust gas; the content of other components in the exhaust gas, such as H2O, O2 and N2; the exhaust gas temperature; the exhaust gas pressure; and the volume flow rate of the exhaust gas.

[0537] Preferably, at least one manipulated variable is modified for the open-loop or closed-loop control of the method according to the invention as a function of the first measured variable and / or the second measured variable and / or the third measured variable and / or the fourth measured variable. Thus, preferably, the open-loop or closed-loop control of the method is 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 means of a controlled variation of the manipulated variable (control variable), preferably by means of a controlled variation of the amount of metered reducing agent.

[0538] In terms of preferred manipulated variables, it is necessary to distinguish:

[0539] - process conditions that can be changed at short notice only with relatively high plant complexity, if at all, and

[0540] - Process conditions that can be changed within a short time and are therefore better suited to the control of the process.

[0541] Preferably, according to the present invention,

[0542] - Dimensions of the exhaust gas treatment equipment;

[0543] - the nature, amount and flow direction of the N2O decomposition catalyst and / or N2O reduction catalyst;

[0544] - NO X the nature, amount and flow direction of the reduction catalyst;

[0545] - type of reducing agent;

[0546] - Exhaust gas pressure;

[0547] - the feeding location of the reducing agent; and

[0548] - Relative arrangement of the first reaction zone and the second reaction zone

[0549] These parameters are not manipulated variables, ie they are preferably kept constant during the performance of the method of the invention.

[0550] However, these parameters can be selected or adjusted during the planning and design of the exhaust gas treatment system so that control of the method according to the invention is possible within a wide range. In this way, changes, for example with respect to the exhaust gas to be treated, can also be reacted to within a short time. Efficient and economically viable reduction of NO in exhaust gases X and N2O content without causing an undesirable breakthrough of the reducing agent (known as slip).

[0551] The preferred manipulated variables (controlled variables) according to the present invention are:

[0552] - amount of reducing agent;

[0553] - exhaust gas temperature, if applicable; and

[0554] - If applicable, the temperature of the catalyst.

[0555] Preferably, the exhaust gas leaving the exhaust gas treatment system has a residual NO 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. X content.

[0556] Preferably, the exhaust gas leaving the exhaust gas treatment system 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.

[0557] Another aspect of the present invention relates to an apparatus comprising:

[0558] (i) an NH3-driven gas turbine; preferably an NH3-driven internal combustion engine, an NH3-driven gas turbine or a furnace for cracking NH3 into N2 and H2; and

[0559] (ii) exhaust gas treatment system;

[0560] The device is configured to perform the method according to any one of the preceding claims.

[0561] The particularly preferred embodiments of the present invention are summarized as follows:

[0562] Sentence 1: A method for reducing NO in the exhaust gas of an NH3-operated combustion system X and N2O content, wherein

[0563] Sentence 2: The method comprises the following steps: (a) burning NH3 to drive the combustion system to produce exhaust gas, the exhaust gas containing N2, H2O, NO X and N2O and leaves the combustion system; (b) transferring the exhaust gas to an exhaust gas treatment system; (c) reducing the N2O content in the exhaust gas by (c1) decomposing N2O on an N2O decomposition catalyst and / or (c2) chemically reducing N2O with a reducing agent on an N2O reduction catalyst; and (d) X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction is performed to reduce NO in the exhaust gas X content.

[0564] Clause 3: The method of clause 1, wherein the NH3-operated combustion system is an NH3-driven internal combustion engine or an NH3-driven gas turbine.

[0565] Clause 4: The method of clause 1, wherein the NH3-operated combustion system is a furnace for cracking NH3 into N2 and H2.

[0566] Clause 5: A method according to any one of the preceding clauses, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NO X The reduction catalyst independently comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an iron, cobalt or copper loaded zeolite; more preferably, an iron loaded zeolite; even more preferably, an iron loaded zeolite independently of the MFI, BEA, FER, MOR, FAU and / or MEL structure type.

[0567] Clause 6: The method of any preceding clause, wherein the N2O decomposition catalyst and the N2O reduction catalyst are made of the same material.

[0568] Clause 7: The method of any preceding clause, wherein the N2O decomposition catalyst and the NO X The reduction catalyst is made of the same material.

[0569] Clause 8: A method according to any one of the preceding clauses, wherein the N2O reduction catalyst and the NO X The reduction catalyst is made of the same material.

[0570] Clause 9: The method of any preceding clause, wherein the N2O decomposition catalyst, the N2O reduction catalyst, and the NO X The reduction catalyst is made of the same material.

[0571] Clause 10: The method of any preceding clause wherein in step (a), the combustion of NH3 is not over a catalyst.

[0572] Sentence 11: A method according to any of the preceding sentences, wherein NH3 is combusted in step (a) in a mixture with another combustible gas; preferably, wherein the other combustible gas is selected from: (i) H2; (ii) fossil fuels; preferably hydrocarbons and hydrocarbon mixtures, more preferably methane, ethane, propane, butane, natural gas, gasoline and / or diesel; (iii) alcohols, preferably methanol and / or ethanol; and mixtures thereof.

[0573] Clause 12: A method according to any preceding clause wherein NH3 is combusted in step (a) in a mixture with H2.

[0574] Sentence 13: The method of sentence 11, wherein step (a) comprises the following constituent steps: (a1) thermally and / or catalytically cracking NH3 to produce a cracked gas comprising N2, H2 and optionally residual NH3; (a2) optionally mixing the cracked gas with additional NH3 to produce a mixture comprising H2 and NH3; (a3) ​​burning the cracked gas or mixture.

[0575] Sentence 14: A method according to sentence 11 or 12, wherein the proportion of H2 in the mixture with NH3 is at most 80 mol%, more preferably at most 70 mol%, even more preferably at most 60 mol%, most preferably at most 50 mol%, and in particular at most 40 mol%.

[0576] Sentence 15: A process according to any of sentences 11 to 13, wherein the proportion of H2 in the mixture with NH3 is at least 10 mol%, more preferably at least 20 mol%, even more preferably at least 30 mol%, most preferably at least 40 mol%, and in particular at least 50 mol%.

[0577] Sentence 16: A method according to any of sentences 11 to 14, wherein 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.

[0578] Clause 17: A method according to any of clauses 11 to 15, wherein the air ratio λ 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.

[0579] Clause 18: A method according to any one of clauses 1 to 9, wherein NH3 is combusted alone in step (a), whereby NH3 is the only combustible gas combusted.

[0580] Clause 19: A method according to any preceding clause, wherein the combustion system, preferably an internal combustion engine, is installed in a vehicle and is used to move the vehicle.

[0581] Clause 20: The method of clause 18, wherein the vehicle is a watercraft.

[0582] Clause 21: The method of clause 18, wherein the vehicle is a road vehicle; preferably selected from commercial vehicles, trucks and buses; or a rail vehicle.

[0583] Clause 22: The method of any preceding clause, wherein said combustion system, preferably said gas turbine, is part of a power plant.

[0584] Clause 23: The method of clause 21 wherein the power plant generates electricity and / or district heating.

[0585] Clause 24: The method of any preceding clause, wherein the combustion system, preferably a furnace, is integrated into a system for thermal and / or catalytic cracking of NH3 into N2 and H2.

[0586] Clause 25: A method according to any preceding clause, wherein the NO X The content is greater than the N2O content; preferably, wherein NO XThe content is at least twice, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times the N2O content.

[0587] Sentence 26: A method according to any of the preceding sentences, wherein the NO content of the exhaust gas is greater than the N2O content; preferably, wherein the NO content is at least twice the N2O content, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times.

[0588] Sentence 27: A method according to any of the preceding sentences, wherein the NO2 content of the exhaust gas is greater than the N2O content; preferably, wherein the NO2 content is at least twice the N2O content, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times.

[0589] Paragraph 28: A method according to any one of paragraphs 1 to 23, wherein the N2O content of the exhaust gas is greater than NO X content; preferably, wherein the N2O content is NO X The amount is at least twice, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times greater.

[0590] Sentence 29: A method according to any one of sentences 1 to 23 and 27, wherein the N2O content of the exhaust gas is greater than the NO content; preferably, wherein the N2O content is at least twice the NO content, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times.

[0591] Sentence 30: A method according to any one of sentences 1 to 23, 27 and 28, wherein the N2O content of the exhaust gas is greater than the NO2 content; preferably, wherein the N2O content is at least twice the NO2 content, more preferably at least three times, even more preferably at least four times, most preferably at least seven times, and in particular at least ten times.

[0592] Clause 31: A method according to any preceding clause, wherein the NO X The content is 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.

[0593] Clause 32: A method according to any preceding clause, wherein the exhaust gas has NO X The content is 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.

[0594] Clause 33: A method according to any preceding clause, wherein the exhaust gas has NO X The content is 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.

[0595] Clause 34: A method according to any preceding clause, 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 especially at least 50 ppmv.

[0596] Clause 35: A method according to any preceding clause, 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 especially at least 250 ppmv.

[0597] Clause 36: A method according to any preceding clause, 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 especially at least 3500 ppmv.

[0598] Clause 37: The method of any preceding clause wherein the off-gas has an H2O content of less than 2.0 vol%.

[0599] Sentence 38: A method according to any of the preceding sentences, wherein the H2O content of the exhaust gas is greater 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%.

[0600] Sentence 39: A method according to any of the preceding sentences, wherein the H2O content of the off-gas is 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%.

[0601] Sentence 40: A method according to any of the preceding sentences, wherein the H2O content of the exhaust gas is in the range of 10±8 volume %; preferably in the range of 10±7 volume %, more preferably in the range of 10±6 volume %, even more preferably in the range of 10±5 volume %, most preferably in the range of 10±4 volume %, and in particular in the range of 10±3 volume %.

[0602] Sentence 41: A method according to any of the preceding sentences, wherein the H2O content of the exhaust gas is in the range of 15±8 volume %; preferably in the range of 15±7 volume %, more preferably in the range of 15±6 volume %, even more preferably in the range of 15±5 volume %, most preferably in the range of 15±4 volume %, and in particular in the range of 15±3 volume %.

[0603] Sentence 42: A method according to any of the preceding sentences, wherein the H2O content of the exhaust gas is in the range of 20±8 volume %; preferably in the range of 20±7 volume %, more preferably in the range of 20±6 volume %, even more preferably in the range of 20±5 volume %, most preferably in the range of 20±4 volume %, and in particular in the range of 20±3 volume %.

[0604] Sentence 43: A method according to any of the preceding sentences, wherein the H2O content of the exhaust gas is in the range of 25±8 volume %; preferably in the range of 25±7 volume %, more preferably in the range of 25±6 volume %, even more preferably in the range of 25±5 volume %, most preferably in the range of 25±4 volume %, and in particular in the range of 25±3 volume %.

[0605] Sentence 44: A method according to any of the preceding sentences, wherein the H2O content of the exhaust gas is in the range of 30±8 volume %; preferably in the range of 30±7 volume %, more preferably in the range of 30±6 volume %, even more preferably in the range of 30±5 volume %, most preferably in the range of 30±4 volume %, and in particular in the range of 30±3 volume %.

[0606] Sentence 45: A method according to any of the preceding sentences, wherein the N2 content of the exhaust gas is at most 95 volume %; preferably at most 90 volume %, more preferably at most 85 volume %, even more preferably at most 80 volume %, most preferably at most 75 volume %, and in particular at most 70 volume %.

[0607] Sentence 46: A method according to any of the preceding sentences, wherein the N2 content of the exhaust gas is at least 40 volume %; preferably at least 50 volume %, more preferably at least 60 volume %, even more preferably at least 70 volume %, most preferably at least 80 volume %, and in particular at least 90 volume %.

[0608] Clause 47: A method according to any preceding clause, wherein the exhaust gas comprises an additional gaseous component; preferably selected from O2, CO, CO2, NH3, CH4 and mixtures thereof.

[0609] Sentence 48: A method according to any of the preceding sentences, wherein the exhaust gases leaving the combustion system, preferably the internal combustion engine, the gas turbine or the furnace, are at 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.

[0610] Sentence 49: A method according to any of the preceding sentences, wherein the exhaust gases leaving the combustion system, preferably the internal combustion engine, the gas turbine or the furnace, are at 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.

[0611] Clause 50: A method according to any preceding clause, wherein the exhaust gases leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, are at a pressure of at most 1.5 bar; preferably atmospheric pressure.

[0612] Clause 51: A method according to any of the preceding clauses, wherein the exhaust gas leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, has a NO X The degree of oxidation is 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%.

[0613] Clause 52: A method according to any preceding clause, wherein the NO X The degree of oxidation is 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%.

[0614] Clause 53: The method of any preceding clause, wherein the exhaust gas exiting the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, has an O2 content of less than 2.0% by volume.

[0615] Clause 54: A method according to any of clauses 1 to 28, wherein the O2 content of the exhaust gas when leaving the combustion system, preferably an internal combustion engine, a gas turbine or a furnace, is greater than 4.0% by volume.

[0616] Sentence 55: A method according to any preceding sentence, wherein the exhaust gas entering the exhaust gas treatment system is at 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.

[0617] Sentence 56: A method according to any of the preceding sentences, wherein the exhaust gas entering the exhaust treatment system is at 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.

[0618] Sentence 57: A method according to any preceding sentence, wherein the exhaust gas entering the exhaust gas treatment system is at 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.

[0619] Sentence 58: A method according to any preceding sentence, wherein the exhaust gas entering the exhaust gas treatment system is at 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.

[0620] Sentence 59: A method according to any of the preceding sentences, wherein the exhaust gas entering the exhaust gas treatment system is at a temperature which is relatively lower than the temperature of the exhaust gas leaving the combustion system, preferably the internal combustion engine, gas turbine or furnace, by 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.

[0621] Clause 60: A method according to any preceding clause wherein the exhaust gas on entering the exhaust gas treatment system is at a pressure of at most 1.2 bar; preferably atmospheric pressure.

[0622] Clause 61: A method according to any preceding clause, wherein the NO X The degree of oxidation is 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%.

[0623] Clause 62: A method according to any preceding clause, wherein the NO X The degree of oxidation is 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%.

[0624] Clause 63: The method of any preceding clause wherein the O2 content of the exhaust gas entering the exhaust treatment system is less than 2.0% by volume.

[0625] Clause 64: The method of any one of clauses 1 to 36, wherein the O2 content of the exhaust gas entering the exhaust treatment system is greater than 4.0% by volume.

[0626] Sentence 65: A method according to any of the preceding sentences, wherein step (c) comprises reducing the N2O content in the exhaust gas by (c1) decomposing N2O over an N2O decomposition catalyst; preferably, wherein the N2O decomposition catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded 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 type.

[0627] Sentence 66: A method according to any of the preceding sentences, wherein step (c) comprises reducing the N2O content in the exhaust gas by (c2) chemically reducing the N2O with a reducing agent over an N2O reduction catalyst; preferably, wherein the N2O reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded 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 type.

[0628] Sentence 67: A method according to any of the preceding sentences, wherein the reducing agent in step (c2) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

[0629] Sentence 68: The method of any preceding sentence, wherein the reducing agent in step (c2) is NH3 in an amount of 0.5 to 2.0 parts by mole, preferably 0.8 to 1.8 parts by mole, based on the molar fraction of N2O to be chemically reduced.

[0630] Sentence 69: A method according to any of the preceding sentences, wherein the reducing agent in step (c2) is a hydrocarbon or a mixture of several hydrocarbons, and its amount is preferably 0.2 to 1.0 mol parts, more preferably 0.2 to 0.7 mol parts based on the molar proportion of N2O to be decomposed.

[0631] Clause 70: A method according to any preceding clause wherein the NO X The reduction catalyst comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0632] Sentence 71: A method according to any of the preceding sentences, wherein the reducing agent in step (d) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

[0633] Clause 72: A method according to any preceding clause, wherein the reducing agent in step (d) is NH3 in an amount based on the NO to be chemically reduced. X The molar fraction is 0.9 to 2.5 parts by mole, preferably 1.0 to 1.4 parts by mole, more preferably 1.0 to 1.2 parts by mole.

[0634] Clause 73: A process according to any preceding clause wherein the reducing agent in step (c2) is the same as the reducing agent in step (d); preferably NH3.

[0635] Sentence 74: The method of any of the preceding sentences, wherein the exhaust gas treatment system comprises a first reaction zone through which the exhaust gas passes in series and a subsequent second reaction zone; wherein a reducing agent is added to the exhaust gas upstream of the first reaction zone; wherein in the first reaction zone, the reducing agent is first added to the exhaust gas by the addition of a reducing agent to the exhaust gas upstream of the first reaction zone; X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction is performed to reduce NO in the exhaust gas X wherein optionally, the N2O content in the exhaust gas is additionally reduced by decomposing N2O on an N2O decomposition catalyst (step (c1)) and / or by chemically reducing N2O with a reducing agent on an N2O reduction catalyst (step (c2)); wherein optionally, a further reducing agent is added to the exhaust gas upstream of the second reaction zone; and wherein then, in the second reaction zone, the N2O content in the exhaust gas is further reduced by decomposing N2O on an N2O decomposition catalyst (step (c1)) and / or by chemically reducing N2O with a reducing agent on an N2O reduction catalyst (step (c2)); wherein optionally, the N2O content in the exhaust gas is additionally reduced by decomposing N2O on an N2O decomposition catalyst (step (c1)) and / or by chemically reducing N2O with a reducing agent on an N2O reduction catalyst (step (c2)); X Chemical reduction of NO on reduction catalysts X To further reduce NO in the exhaust gas X content (step (d)).

[0636] Clause 75: The method of clause 73, wherein the NO in the first reaction zone X The reduction catalyst comprises a conventional SCR catalyst, preferably based on V2O5-WO3- / TiO2.

[0637] Sentence 76: The method of sentence 73 or 74, wherein the temperature of the off-gas upon entering the first reaction zone is no greater than 400°C, preferably no greater than 350°C.

[0638] Sentence 77: A process according to any one of sentences 73 to 75, wherein the N2O decomposition catalyst in the second reaction zone comprises a zeolitic material; preferably, a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded 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 type.

[0639] Clause 78: The process of any of clauses 73 to 76 wherein the off-gas temperature upon entering the second reaction zone is in the range of 300 to 550°C, preferably 350 to 500°C.

[0640] Clause 79: A process according to any one of clauses 73 to 77 wherein the NO in the first reaction zone X The reduction catalyst comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0641] Clause 80: The process of any of clauses 73 to 78 wherein the off-gas temperature upon entering the first reaction zone is at least 300°C, more preferably at least 350°C, even more preferably at least 400°C.

[0642] Clause 81: The process of any of clauses 73 to 79 wherein the temperature of the off-gas upon entering the first reaction zone is no greater than 600°C, more preferably no greater than 550°C.

[0643] Clause 82: The process of any one of clauses 73 to 80, wherein the N2O decomposition catalyst in the second reaction zone comprises NO X -Sensitive N2O decomposition catalyst.

[0644] Clause 83: The process of any of clauses 73 to 81 wherein the off-gas temperature upon entering the second reaction zone is at least 300°C, more preferably at least 350°C, even more preferably at least 400°C.

[0645] Clause 84: The process of any one of clauses 73 to 82 wherein the temperature of the off-gas upon entering the second reaction zone is no greater than 600°C, preferably no greater than 550°C.

[0646] Clause 85: A process according to any one of clauses 73 to 83, wherein the off-gas after leaving the first reaction zone and before entering the second reaction zone has a NO in the range of 0 to 200 ppmv, preferably 1 to 200 ppmv. Xcontent and N2O content in the range of 200 to 2000 ppmv.

[0647] Clause 86: A process according to any one of clauses 73 to 84, wherein the off-gas after leaving the first reaction zone and before entering the second reaction zone has no more than 20 ppmv, more preferably no more than 10 ppmv, even more preferably no more than 5 ppmv of NO X content and N2O content in the range of 200 to 2000 ppmv.

[0648] Sentence 87: The method according to any of the preceding sentences, wherein the exhaust gas treatment system comprises a first reaction zone and a subsequent second reaction zone through which the exhaust gas passes continuously; wherein a reducing agent is added to the exhaust gas between the first reaction zone and the second reaction zone; wherein, in the first reaction zone, the NO content in the exhaust gas is first reduced by decomposing NO on an NO decomposition catalyst (step c1); and wherein, in the second reaction zone, the NO content in the exhaust gas is then reduced by decomposing NO on an NO decomposition catalyst (step c2). X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction is performed to reduce NO in the exhaust gas X wherein optionally, the N2O content in the exhaust gas is additionally reduced by decomposition of N2O on an N2O decomposition catalyst (step (c1)) and / or by chemical reduction of N2O with a reducing agent on an N2O reduction catalyst (step (c2)).

[0649] Clause 88: The method of clause 86 wherein no reducing agent is added to the exhaust gas upstream of the first reaction zone.

[0650] Sentence 89: A method according to sentence 86 or 87, wherein the N2O decomposition catalyst in the first reaction zone comprises a zeolitic material; preferably, a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded with iron, cobalt or copper; more preferably, a zeolite loaded with iron; even more preferably, a zeolite loaded with iron of the MFI, BEA, FER, MOR, FAU and / or MEL type.

[0651] Clause 90: The method of any one of clauses 86 to 88, wherein the N2O decomposition catalyst in the first reaction zone comprises NO X -Sensitive N2O decomposition catalyst.

[0652] Clause 91: The process of any one of clauses 86 to 89, wherein the NO in the second reaction zone XThe reduction catalyst comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

[0653] Sentence 92: A method according to any one of sentences 86 to 90, wherein in the first reaction zone and the second reaction zone, the space velocity is set so that the N2O content in the exhaust gas in the first reaction zone is reduced by at most 95%, preferably at most 90%, based on the N2O content in the exhaust gas when entering the first reaction zone.

[0654] Sentence 93: A method according to any one of sentences 86 to 91, wherein in the second reaction zone, the N2O content in the exhaust gas is reduced by at least 30%, preferably at least 40%, and more preferably at least 50% based on the N2O content in the exhaust gas when entering the second reaction zone.

[0655] Clause 94: The method of any of clauses 86 to 92, wherein in the second reaction zone, the N2O content in the exhaust gas is further reduced by chemically reducing the N2O with a reducing agent over an N2O reduction catalyst (step (c2)).

[0656] Clause 95: The method of any one of clauses 73 to 93 wherein the first reaction zone and the second reaction zone are spatially separated.

[0657] Clause 96: The method of any one of clauses 73 to 94 wherein the first reaction zone and the second reaction zone are spatially connected to each other.

[0658] Clause 97: The process of any one of clauses 73 to 95 wherein the first reaction zone and the second reaction zone are disposed in a common vessel.

[0659] Clause 98: A process according to any of clauses 73 to 96 wherein the off-gas temperature in the first reaction zone and in the second reaction zone does not exceed 500°C, preferably in the range of 350 to 450°C.

[0660] Sentence 99: A method according to any one of sentences 73 to 97, wherein the space velocity in the first reaction zone is greater than the space velocity in the second reaction zone; preferably at least 1.2 times greater, more preferably at least 1.4 times greater, even more preferably at least 1.6 times greater, most preferably at least 1.8 times greater, and in particular at least 2.0 times greater.

[0661] Sentence 100: A method according to any one of sentences 73 to 98, wherein the space velocity in the first reaction zone is less than the space velocity in the second reaction zone; preferably at least 1.5 times less, more preferably at least 2.0 times less, even more preferably at least 3.0 times less, most preferably at least 5.0 times less, and in particular at least 10.0 times less.

[0662] Sentence 101: The process of 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.

[0663] Sentence 102: A 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.

[0664] Sentence 103: A process according to any one of sentences 73 to 101, wherein the temperature in the first reaction zone is at least 20°C higher than the temperature in the second reaction zone, more preferably at least 40°C, even more preferably at least 60°C, most preferably at least 80°C, and in particular at least 100°C.

[0665] Sentence 104: A process according to any one of sentences 73 to 102, wherein the temperature in the first reaction zone is at least 120°C higher than the temperature in the second reaction zone, more preferably at least 140°C, even more preferably at least 160°C, most preferably at least 180°C, and in particular at least 200°C.

[0666] Clause 105: The method of any preceding clause, wherein the exhaust gas exits the exhaust gas treatment system and has a residual NO 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 especially at most 2.5 ppmv. X content.

[0667] Sentence 106: A method according to any preceding sentence, wherein the exhaust gas leaves the exhaust gas treatment system 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.

[0668] Clause 107: The method of any preceding clause wherein the N20 decomposition catalyst is disposed in radial baskets through which flow passes axially.

[0669] Clause 108: The method of any preceding clause wherein the N2O decomposition catalyst is granular and comprises at least 50 particles.

[0670] Clause 109: The method of any preceding clause wherein the N20 reduction catalyst is disposed in a radial basket through which flow is axially passed.

[0671] Clause 110: The method of any preceding clause wherein the N2O reduction catalyst is granular and comprises at least 50 particles.

[0672] Clause 111: The method of any preceding clause wherein the NO X The reduction catalyst is disposed in radial baskets through which the flow passes axially.

[0673] Clause 112: The method of any preceding clause wherein the NO X The reduction catalyst is in a granular form and comprises at least 50 particles.

[0674] Clause 113: The method of any of the preceding clauses, wherein at least one parameter characteristic of a current operating state of the combustion system is measured in the combustion system as a first measured variable.

[0675] Clause 114: The method of clause 112, wherein the first measured variable is selected from the group consisting of: combustion temperature, NH3 consumption, rotational speed (if applicable), and volume of the combustion system.

[0676] Clause 115: The method of any of the preceding clauses, wherein at least one parameter characteristic of a current state of the exhaust gas is measured before entering the exhaust gas treatment system as a second measured variable before entering the exhaust gas treatment system.

[0677] Clause 116: The method of clause 114, wherein the second measured variable is selected from the group consisting of: NO in the exhaust gas X Content; NO in exhaust gas X the degree of oxidation; the N2O content in the exhaust gas; the content of other components in the exhaust gas, such as H2O, O2 and N2; the exhaust gas temperature; the exhaust gas pressure; and the volume flow rate of the exhaust gas.

[0678] Clause 117: A method according to any of the preceding clauses, wherein at least one parameter characteristic of the current state of the exhaust gas upon leaving the exhaust gas treatment system is measured as a third measured variable upon leaving the exhaust gas treatment system.

[0679] Clause 118: The method of clause 116, wherein the third measured variable is selected from the group consisting of: NO in the exhaust gas X Content; NO in exhaust gas X the degree of oxidation; the N2O content in the exhaust gas; the content of other components in the exhaust gas, such as H2O, O2 and N2; the exhaust gas temperature; the exhaust gas pressure; and the volume flow rate of the exhaust gas.

[0680] Sentence 119: A method according to any of the preceding sentences, wherein the exhaust gas treatment system includes a first reaction zone and a second reaction zone through which the exhaust gas flows in sequence, wherein a 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 characteristic of the current state of the exhaust gas after leaving the first reaction zone and before entering the second reaction zone is measured as a fourth measurement variable.

[0681] Clause 120: The method of clause 118, wherein the fourth measured variable is selected from the group consisting of: NO in the exhaust gas X Content; NO in exhaust gas X the degree of oxidation; the N2O content in the exhaust gas; the content of other components in the exhaust gas, such as H2O, O2 and N2; the exhaust gas temperature; the exhaust gas pressure; and the volume flow rate of the exhaust gas.

[0682] Sentence 121: A method according to any of sentences 112 to 119, wherein control of the method is 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 means of a controlled change of a manipulated variable.

[0683] Clause 122: The method of clause 120, wherein the manipulated variable is the amount of metered reducing agent.

[0684] Sentence 123: An apparatus comprising: (i) an NH3-operated combustion system; preferably an NH3-driven internal combustion engine, an NH3-driven gas turbine or a furnace for cracking NH3 into N2 and H2; and (ii) an exhaust gas treatment system; wherein the apparatus is configured to perform a method according to any of the preceding sentences.

[0685] Reference Mark List:

[0686] G: Generator

[0687] V: compressor

[0688] GT: Gas Turbine

[0689] VK: Combustion Chamber

[0690] AB: Exhaust gas treatment system

[0691] ADE1: First waste heat steam generator

[0692] ADE2: Second waste heat steam generator

[0693] K1: first catalyst bed

[0694] K2: Second catalyst bed

[0695] WT: Heat exchanger

[0696] DT: Steam Turbine

[0697] SS: Chimney

Claims

1. A method for reducing NO in the exhaust gas of an NH3-operated combustion system, preferably a gas turbine X and N2O content, the method comprising the following steps: (a) burning NH3 for operating the combustion system, preferably a gas turbine, to produce an exhaust gas containing N2, H2O, NO X and N2O and leave the combustion system; (b) transferring the exhaust gas to an exhaust gas treatment system; (c) reducing the N2O content in the exhaust gas by the following steps: (c1) decomposing N2O on an N2O decomposition catalyst, and / or (c2) chemically reducing N2O using a reducing agent on an N2O reduction catalyst; (d) By X Reduction of NO by using a reducing agent on a catalyst X Chemical reduction is performed to reduce NO in the exhaust gas X content.

2. The method of claim 1, wherein the NH3-operated combustion system is an NH3-driven gas turbine.

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

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

5. The method of claim 4, wherein the power plant generates electricity and / or district heating.

6. The method according to any one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and / or the NO X The reduction catalyst independently comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an iron, cobalt or copper loaded zeolite; more preferably, an iron loaded zeolite; even more preferably, an iron loaded zeolite independently of the MFI, BEA, FER, MOR, FAU and / or MEL structure type.

7. The process according to any one of the preceding claims, wherein in step (a), the combustion of NH3 is not over a catalyst.

8. The process according to any one of the preceding claims, wherein NH3 is combusted in step (a) in a mixture with another combustible gas; preferably, wherein the other combustible gas is selected from: (i)H2; (ii) fossil fuels; preferably hydrocarbons and hydrocarbon mixtures, more preferably methane, ethane, propane, butane, natural gas, gasoline and / or diesel; (iii) alcohols, preferably methanol and / or ethanol; and mixtures thereof.

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

10. The method of claim 9, wherein step (a) comprises the following constituent steps: (a1) thermal and / or catalytic cracking of NH3 to produce a cracked gas comprising N2, H2 and optionally residual NH3; (a2) optionally mixing the cracked gas with additional NH3 to produce a mixture comprising H2 and NH3; (a3) burning the cracked gas or the mixture.

11. The method of claim 9 or 10, wherein the proportion of H2 is at most 50% by volume, and wherein the combustion is preferably carried out at an air ratio λ 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 method of claim 9 or 10, wherein the proportion of H2 is greater than 50% by volume, and wherein the combustion is preferably carried out at an air ratio λ 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 NH3 is combusted in step (a) in a mixture with CH4.

14. The process as claimed in claim 13, wherein the proportion of CH4 is at most 50% by volume, and wherein the combustion is carried out at an air ratio λ 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 of claim 13, wherein the proportion of CH4 is greater than 50% by volume, and wherein the combustion is carried out at an air ratio λ of 2.0 to 3.0, more preferably of 2.1 to 2.9, even more preferably of 2.2 to 2.

8.

16. The method of any one of claims 1 to 7, wherein NH3 is combusted alone in step (a), whereby NH3 is the only combustible gas combusted.

17. The method of claim 16, wherein the combustion is carried out at an air ratio λ 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 method of any one of the preceding claims, wherein in step (a) an offgas having a temperature in the range of 1000 to 1500°C is generated.

19. The method according to any one of the preceding claims, wherein in step (a) an offgas is generated at a pressure in the range of 10 to 32 bar.

20. The method of any one of the preceding claims, wherein in step (a) NO is produced X The degree of oxidation of the off-gas is 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%, possibly even at most 0.5%.

21. A method as claimed in any preceding claim, wherein the exhaust gas produced in step (a) is expanded through a gas turbine.

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

23. A method as claimed in claim 21 or 22, wherein the exhaust gas at the outlet from the gas turbine is at a pressure greater than atmospheric pressure, ie ≥ 1.0 bara, but at most 1.2 bara, preferably at most 1.1 bara.

24. The method of any one of claims 21 to 23, wherein the exhaust gas at the outlet from the gas turbine has a NO in the range of 500 to 3000 ppmv. X content.

25. The method of any one of claims 21 to 24, wherein the exhaust gas at the outlet from the gas turbine has a NO in the range of 1.0% to 6.0% by volume. X content.

26. The method of any one of claims 21 to 25, wherein the exhaust gas at the outlet from the gas turbine has an H2O content in the range of 20% to 30% by volume.

27. The method of 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 method of 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 of 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 method of 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 of any one of claims 21 to 30, wherein the exhaust gas at the outlet from the gas turbine has 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% NO X The degree of oxidation (n(NO2) / (n(NO)+n(NO2))).

32. The process of any one of the preceding claims, wherein NH3 is combusted in step (a) in a mixture with CH4, and the off-gas therefore also comprises CO and CO2, preferably also HCN.

33. The method 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 method of claim 32 or 33, wherein 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.

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

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

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

38. The method of any of the preceding claims, wherein step (c) comprises reducing the N2O content in the exhaust gas by (c1) decomposing N2O over an N2O decomposition catalyst; preferably, wherein the N2O decomposition catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded 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 structure type.

39. The method of any of the preceding claims, wherein step (c) comprises reducing the NO content in the exhaust gas by (c2) chemically reducing the NO with a reducing agent over an NO reduction catalyst; preferably, wherein the NO reduction catalyst comprises a zeolitic material; preferably a zeolite loaded with a transition metal (including a lanthanide), in particular a zeolite loaded 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 structure type.

40. The method of 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 in an amount of 0.5 to 2.0 parts by mole, preferably 0.8 to 1.8 parts by mole, based on the molar fraction of N2O to be chemically reduced.

42. The method according to any one of the preceding claims, wherein the reducing agent in step (c2) is a hydrocarbon or a mixture of several hydrocarbons, preferably in an amount of 0.2 to 1.0 mol parts, more preferably 0.2 to 0.7 mol parts, based on the molar fraction of NO to be decomposed.

43. The method of any one of the preceding claims, wherein the NO X The reduction catalyst comprises a zeolite material; preferably, a transition metal (including lanthanide) loaded zeolite, in particular an 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.

44. The method of any one of the preceding claims, wherein the reducing agent in step (d) is selected from NH3, hydrocarbons, CO, H2 and mixtures thereof; preferably NH3.

45. The method of any one of the preceding claims, wherein the reducing agent in step (d) is NH3 in an amount based on the NO to be chemically reduced. X The molar fraction is 0.9 to 2.5 parts by mole, preferably 1.0 to 1.4 parts by mole, more preferably 1.0 to 1.2 parts by mole.

46. ​​The process of any one of the preceding claims, wherein the reducing agent in step (c2) is the same as the reducing agent in step (d); preferably NH3.

47. The method of any of the preceding claims, wherein the exhaust gas treatment system comprises a first catalyst bed and a spatially separated second catalyst bed; wherein the first catalyst bed is arranged upstream of the second catalyst bed in the flow direction of the exhaust gas; Optionally, a first device having a first control valve for metering NH 3 to the exhaust gas is preferably arranged upstream of the first catalyst bed; wherein a second device having a second control valve for metering NH 3 into the exhaust gas is arranged downstream of the first catalyst bed and upstream of the second catalyst bed, wherein the second device is used to meter additional NH 3 into the exhaust gas; wherein both the first catalyst bed and the second catalyst bed each comprise an iron-loaded zeolite catalyst; in (i) in the first catalyst bed (c1) reducing the N2O content in the exhaust gas by catalytic decomposition of N2O; and (d) By using NH3 to NO X Catalytic chemical reduction is performed to incompletely reduce NO in the exhaust gas X a content, wherein at least some of the NH3 comes from incomplete combustion of NH3 in step (a) (NH3 slip); and (ii) in the second catalyst bed (c2) reducing the residual N2O content by catalytic chemical reduction of N2O with NH3; (c1 * ) optionally, reducing the residual N2O content by catalytic decomposition of N2O; and (d * ) by using NH3 to NO X Catalytic chemical reduction to reduce residual NO X content.

48. The method of claim 47, wherein the catalytic decomposition of N2O in the first catalyst bed is caused by the presence of NO in the exhaust gas. X Catalytic promoter.

49. The method of claim 47 or 48, wherein NH3 is used to convert NO into X Incomplete chemical reduction of NO leads to a predetermined residual NO X content, the residual NO X The content is sufficient to promote the decomposition of N2O in the first catalyst bed.

50. A process as claimed in any one of claims 47 to 49, wherein additional NH3 is metered into the exhaust gas by means of the first device; preferably under feedback control; wherein NO X A specific value of the concentration is preferably defined as a target value (set point) and the NO concentration is measured upon leaving the first catalyst bed. X The actual concentration (actual value) of In the event that there is a difference between the set point and the actual value (control difference), the output of the first control valve is varied so as to minimize the difference.

51. The method of claim 50, wherein the amount of additional NH3 is selected so that upon leaving the first catalyst bed NO X The residual concentration is at most 1000 ppmv, preferably at most 500 ppmv, more preferably at most 100 ppmv.

52. The process of claim 50 or 51, wherein the amount of additional NH3 is selected so that upon leaving the first catalyst bed NO X The residual concentration is at least 10 ppmv, preferably at least 20 ppmv, more preferably at least 40 ppmv.

53. The process of 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. A process as claimed in any one of claims 47 to 53, wherein the off-gas at the outlet from the first catalyst bed is at a pressure greater than atmospheric pressure, ie > 1.0 bara, but at most 1.2 bara, preferably at most 1.1 bara.

55. The process of any one of the preceding claims, wherein the exhaust gas leaving the first catalyst bed has 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% NO X degree of oxidation.

56. The process of any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has a NO in the range of 30% to 50%. X degree of oxidation.

57. The process of any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has a NO in the range of 15% to 35%. X degree of oxidation.

58. The process of any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has a NO in the range of 10% to 20%. X degree of oxidation.

59. The process of any one of claims 47 to 55, wherein the exhaust gas at the outlet from the first catalyst bed has a NO in the range of 5% to 15%. X degree of oxidation.

60. The process of any one of claims 47 to 59, wherein residual NO is decomposed in the second catalyst bed such that the residual concentration of NO upon exiting the second catalyst bed is 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 method of any one of claims 47 to 60, wherein the residual NO X decomposed in the second catalyst bed so that NO X The residual concentration is 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 of any one of claims 47 to 61, wherein the additional NH3 is metered by the second device under feedforward control; wherein NO is preferably measured upon leaving the first catalyst bed. X taking into account the amount of exhaust gas entering the second catalyst bed to calculate the required amount of NH3; and the calculation result (manipulated variable) is used to change the output of the second control valve to measure the required amount of NH3.

63. The process of any one of claims 47 to 62, wherein upon entering the second catalyst bed, NH3 / (NO X The molar ratio of N2O) 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 of any one of claims 47 to 63, wherein upon entering the second catalyst bed NH3 / NO X The molar ratio 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 of any one of claims 47 to 64, wherein the molar ratio of NH3 / N2O upon entry into 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 of any one of claims 47 to 65, wherein the additional NH3 is not metered with the second device under feedback control.

67. The process of any one of claims 47 to 66, wherein the amount of catalyst is selected such that the decomposition of N2O in the first catalyst bed is at least 50%, more preferably at least 70%, even more preferably at least 80%, based on the concentration of N2O upon entering the first catalyst bed.

68. The process of any one of claims 47 to 67, wherein the amount of catalyst and the amount of additional NH3 are selected so that upon leaving the first catalyst bed, NO X The molar ratio of N2O to N2O is at least 5, more preferably at least 10, even more preferably at least 20.

69. The process of any one of claims 47 to 68, wherein the space velocity of the first catalyst bed is between 5000 h / min and 5000 h / min. -1 Up to 100,000 hours -1 In the range of 10000h, more preferably 10000h -1 Up to 50,000 hours -1 , even more preferably 15000h -1 Up to 45000h -1 .

70. The process of any one of claims 47 to 69, wherein upon exiting the first catalyst bed, NO X The molar ratio of NH3 to N2O is at least 10, and the additional NH3 metered in via the second device is only combined with the incoming NO X The amount is related.

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

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

73. The method of any one of claims 47 to 72, wherein, depending on the exothermicity of the chemical reactions carried out in the first catalyst bed and in the second catalyst bed, the inlet temperature of the exhaust gas entering the first catalyst bed is selected so that the temperature of the exhaust gas when leaving 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 of any one of claims 47 to 73, wherein the space velocity of the second catalyst bed is between 5000 h / min and 5000 h / min. -1 Up to 100,000 hours -1 In the range of 10000h, more preferably 10000h -1 Up to 50,000 hours -1 , even more preferably 15000h -1 Up to 45000h -1 .

75. The process of any one of claims 47 to 74, wherein the first catalyst bed V1 cat With the second catalyst bed V2 cat The catalyst volume ratio (V1 cat / V2 cat ) is in the range of 1 / 2 to 20 / 1, more preferably 1 / 2 to 10 / 1, even more preferably 1 / 1 to 4 / 1.

76. The method of any one of claims 47 to 75, wherein at least one, more than one, or all of the following conditions are met: - the exhaust gas pressure upon entering the first catalyst bed is at most 5 bara, preferably at most 4 bara, 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 of the off-gas upon entering the first catalyst bed is at least 5% by volume, more preferably at least 10% by volume, even more preferably at least 15% by volume, most preferably at least 20% by volume and in particular at least 25% by volume; - NO in the exhaust gas entering the first catalyst bed X A content of 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 of the off-gas upon entering 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 NH3 residues from NH3 combustion when entering the first catalyst bed; - the N2O decomposition catalyst and / or the N2O reduction catalyst are in the form of a honeycomb; -NO X The reduction catalyst is in the form of a honeycomb; - the first catalyst bed comprises Fe zeolite; - the second catalyst bed comprises Fe zeolite; - the exhaust gas passes through a temperature control device before entering the first catalyst bed, and the temperature of the exhaust gas is adjusted in the temperature control device; - NO when leaving the first catalyst bed X The content 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; - an NO2 content upon leaving the first catalyst bed of 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; - no intermediate cooling of the exhaust gas between leaving the first catalyst bed and entering the second catalyst bed; -N2O:NO when entering the first catalyst bed X The molar ratio of is at most 0.5, more preferably at most 0.2, even more preferably at most 0.1; -N2O:NO when leaving the first catalyst bed X The molar ratio of is at most 0.20, more preferably at most 0.1, even more preferably at most 0.05; - NH3 feeding into the exhaust gas upstream of the first catalyst bed in the direction of flow of the exhaust gas is optional; if present, it is preferably fed relative to NO on entry into the first catalyst bed. X is substoichiometric in content; and / or - It is necessary to feed NH3 into the exhaust gas downstream of the first catalyst bed and upstream of the second catalyst bed in the direction of flow of the exhaust gas, and preferably relative to NO3 on entry into the second catalyst bed X The total content of N2O is superstoichiometric.

77. The method of any of the preceding claims, wherein the exhaust gas treatment system comprises a first waste heat steam generator and preferably comprises a second waste heat steam generator, wherein the first waste heat steam generator can be arranged upstream of the second waste heat steam generator in the flow direction of the exhaust gas.

78. The method of any one of claims 47 to 77, wherein the exhaust gas treatment system comprises a first waste heat steam generator and a second waste heat steam generator, wherein the first waste heat steam generator is arranged upstream of the second waste heat 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 waste heat steam generator, then flows through the first catalyst bed, then flows through the second catalyst bed, and finally flows through the second waste heat steam generator.

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

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

82. The method of any preceding claim, wherein the exhaust gas exits the exhaust gas treatment system and has a residual NO 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 X content.

83. The method of any of the preceding claims, wherein the exhaust gas leaves the exhaust gas treatment system 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.

84. The method of any one of the preceding claims, wherein the N2O decomposition catalyst and / or the N2O reduction catalyst and the NO X The reduction catalyst is independently in the form of a monolithic catalyst element permeated by parallel channels, preferably in the form of a monolithic honeycomb.

85. A device comprising (i) NH3-driven gas turbines; and (ii) exhaust gas treatment system; in, The apparatus is configured to perform the method of any one of the preceding claims.

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