Catalyst for a selective catalytic reduction or decomposition of nitrous oxide

Abstract

The invention relates to a catalyst in the form of a molded body for decomposing or selectively catalytically reducing N2O and / or NOx using a reducing agent, comprising: an active material containing a zeolite of the CHA structure type which is loaded with an iron component, the zeolite having an SiO2 / Al2O3 ratio of between 5 and 20, and a binder. The catalyst is characterized in that the iron component is present in an amount of 1 wt.% to 10 wt.% Fe2O3, based on the total weight of the catalyst, and the iron component is introduced into the zeolite of the CHA structure type by means of a solid-state ion exchange process. The invention also relates to a method for producing a catalyst according to the invention, having the steps of: a) mixing a zeolite of the CHA structure type with an iron precursor present as a solid in order to obtain a precursor mixture, b) calcining the precursor mixture from step a) in order to obtain the active material, c) mixing the active material from step b) with a binder and optionally other components in order to obtain an extrudable mixture, d) extruding the mixture from step c) in order to obtain molded bodies, and e) calcining the molded bodies from step d).

Description

[0001] Clariant International Ltd 2024DE605-WO-PCT

[0002] Catalyst for the selective catalytic reduction or decomposition of nitrous oxide

[0003] The invention relates to a catalyst for the decomposition or selective catalytic reduction of N2O and / or NO. X comprising a reducing agent in the form of a shaped body, comprising: an active material containing a zeolite of structure type CHA loaded with an iron component, wherein the zeolite has a SiCL / AhOs ratio between 5 and 20 and a binder, characterized in that the iron component contains an amount of 1 wt.% to 10 wt.% Fe20s based on the total weight of the catalyst and the iron component has been introduced into the zeolite of structure type CHA by solid ion exchange.

[0004] The synthesis of nitric acid is carried out on an industrial scale using the so-called Ostwald process, in which ammonia is oxidized to nitrogen oxide with oxygen over heated noble metal catalysts. The nitrogen dioxide produced by further oxidation reacts with water to form nitric acid. A characteristic of this process is that unwanted NO₂ is produced. x Exhaust gases containing carbon monoxide and nitrous oxide (N2O) are produced, which pose a burden on the environment. Nitrous oxide is also known for its particularly high climate impact, as it is 300 times more harmful to the climate than carbon dioxide.

[0005] Therefore, avoiding nitrous oxide emissions is just as important as avoiding NO. X Emissions have increasingly become the focus of scientific and technical considerations. It is now common practice to measure NOₓ. Xand nitrous oxide-containing exhaust gases to be catalytically decomposed or treated using selective catalytic reduction (SCR) to minimize emissions. Zeolite catalysts doped with the active metals copper or iron have proven particularly suitable for this purpose. The reduction of NO X SCR from stationary or mobile sources using metal-doped zeolites is known. The use of metal-doped CHA, especially iron-doped CHA (FeCHA), is also described.

[0006] FeCHA is described in the literature and in patents as an active catalyst for the purification of exhaust gases from diesel engines by DeNOx. x , e.g. in automotive applications, as described.

[0007] WO 2016070090 A1 discloses catalytically active articles with at least one washcoat, comprising a first molecular sieve promoted with copper and a second molecular sieve promoted with iron, wherein the first and second molecular sieves have a d6r unit and the first molecular sieve has cubic crystals with a mean crystal diameter between about 0.5 and about 2 pm. The weight ratio of the copper-containing molecular sieve to the iron-containing molecular sieve can be about 1:1 to about 4:1. The catalytically active articles are disclosed in Clariant International Ltd 2024DE605-WO-PCT

[0008] Methods and systems for the catalytic reduction of nitrogen oxides in the presence of a reducing agent are useful.

[0009] WO 20190141 15 A1 discloses a catalyst for the conversion of nitrogen and N₂O, consisting of an iron chabazite and an iron beta-zeolite. A process for the simultaneous reduction of NO₂ is also disclosed. X - and iX^O concentration in a process gas stream comprising contacting the process gas stream with a catalyst comprising iron chabazite and an iron beta-zeolite under suitable conditions.

[0010] US 9,242,238 B2 discloses compositions and catalytically active articles comprising a copper-promoted 8-ring molecular sieve and an iron-promoted 8-ring molecular sieve. The catalytically active articles are useful in processes and systems for catalyzing the reduction of nitrogen oxides in the presence of a reducing agent.

[0011] US 9,999,877 B2 discloses a catalyst that can be used in selective catalytic reduction (SCR). This catalyst comprises one or more zeolites of structural type BEA, one or more zeolites of structural type CHA, and optionally one or more zeolites of structural type MFI, wherein at least a portion of the one or more zeolites of structural type BEA contains iron (Fe), wherein at least a portion of the one or more zeolites of structural type CHA contains copper (Cu), and wherein at least a portion of the optional one or more zeolites of structural type MFI contains iron (Fe). The disclosure further relates to an exhaust gas treatment system comprising the catalyst, as well as a method for treating a gas stream containing NOₓ. X includes and in which the catalyst is used.

[0012] WO 2023203203 A1 discloses a catalyst for the selective catalytic reduction of NO X, comprising a substrate with an inlet end, an outlet end, an axial substrate length extending from the inlet end to the outlet end, and several passages defined by the inner walls of the substrate and extending through them, as well as a coating comprising a zeolitic material, copper, and a first non-zeolitic oxide material comprising iron and aluminum, wherein at least 25 wt. % of the first non-zeolitic oxide material consists of iron, calculated as Fe20s.

[0013] WO 2019014119 A1 discloses a catalyst for the conversion of NO X comprehensive iron chabazite and iron beta zeolite and a method for reducing NO x -Concentration in a process gas stream, encompassing contacting the process gas stream with the Clariant International Ltd 2024DE605-WO-PCT

[0014] Catalyst. The catalyst is particularly suitable for high-temperature deNOx conversions.

[0015] Methods were developed specifically for the aftertreatment of exhaust gases from nitric acid plants to reduce NO. X and especially to remove nitrous oxide from the process exhaust gases; such processes are described, for example, in US 2002 / 0127163 A1, US 2002 / 127163 A1 and WO 2001051415 A1. Catalysts based on iron-promoted zeolites have proven particularly suitable for these processes.

[0016] US 2014 / 01 12854 A1 describes a catalyst for selective catalytic reduction comprising an iron-containing, eight-ring molecular sieve with small pores. Systems and methods for using these iron-containing eight-ring molecular sieves as catalysts in a variety of processes are also described, for example, for reducing pollutants in exhaust gases and in conversion processes. The iron-containing, eight-ring molecular sieve with small pores is selected from the group consisting of iron-promoted zeolites with a structure type selected from AEI, AFT, AFX, CHA, EAB, ERI, KFI, LEV, SAS, SAT, and SAV.

[0017] CN 109701635 A discloses an iron-based molecular sieve catalyst for the decomposition of nitrous oxide, as well as a process for its preparation and application. The iron-based molecular sieve catalyst comprises Fe as its active components. 3+ -ions and an Fe x O yThe molecular sieve is an oligomer, with a support carrying the active components. The support on which the active components are applied is the molecular sieve. The iron-based molecular sieve catalyst is produced by applying a solid or liquid ion exchange process, wherein a solid ion exchange process proceeds as follows: mixing a precursor of the active components with the molecular sieve and performing a milling and calcining process; and a liquid ion exchange process proceeds as follows: dissolving the precursor of the active components in water, subsequently mixing the resulting solution with the molecular sieve and performing an ultrasonic treatment, drying, and calcining. The disclosed iron-based molecular sieve catalyst serves for the decomposition of nitrous oxide and is used for the removal of nitrous oxide from the exhaust gas of stationary sources and / or from the exhaust gas of motor vehicles.

[0018] EP 2043783 A2 discloses a process for the production of metal-doped zeolites, including in particular ZSM-5, Y and Beta, comprising the steps of i) providing a dry Clariant International Ltd 2024DE605-WO-PCT

[0019] A mixture of a) a zeolite, b) a compound of a catalytically active metal, ii) intimate milling of the mixture, ill) heating of the mixture in a reactor to a defined temperature, iv) holding of the mixture at the defined temperature, v) cooling to room temperature and recovery of the metal-doped zeolite, characterized in that during heating the internal pressure of the reactor is maintained in a pressure range of 0 to -200 millibar.

[0020] The object of the invention is to provide a catalyst for the decomposition or selective catalytic reduction of N2O and / or NO. Xto provide a catalyst that exhibits increased performance (activity and / or selectivity) and / or increased stability. In particular, it is an object of the invention to provide a catalyst for the selective catalytic reduction of N₂O and / or NO. X to provide one that exhibits increased hydrothermal stability.

[0021] The object of the invention is achieved by a catalyst for the decomposition or selective catalytic reduction of N2O and / or NO. Xcomprising a reducing agent in the form of a shaped body, comprising: an active material containing a zeolite of structure type CHA loaded with an iron component, wherein the zeolite has a SiCL / AhOs ratio between 5 and 20 and a binder, characterized in that the iron component contains Fe20s in an amount of 1 to 10 wt% based on the total weight of the catalyst and the iron component has been introduced into the zeolite of structure type CHA by solid ion exchange.

[0022] The active material contains a zeolite of the CHA structure type, i.e., chabazite or SSZ-13. The CHA structure type zeolite can be prepared by any method known to those skilled in the art. Typically, the synthesis of the CHA structure type zeolite is carried out by hydrothermal synthesis, in which a suitable silicon source and aluminum source are reacted in the presence of a template at elevated temperature and pressure. Suitable templates include, for example, quaternary alkyl amines, in particular N,N,N-trimethyl-1-adamantyl ammonium salts (hydroxide, carbonate, halides, sulfates). However, the hydrothermal synthesis of the CHA structure type zeolite can also be carried out without a template under certain circumstances. The CHA-type zeolite has a SiO2 / Al2Os ratio (also referred to as "modulus") of 5 to 20, preferably 8 to 15, and particularly 10 to 14. Typically, the CHA-type zeolite has a specific surface area in the range of 100 m². 2 / g and 1000 m 2 / g, preferably 400 m 2 / g and 800 m 2 / G.

[0023] The active material must contain 0.5 wt% to 10 wt% iron component, calculated as Fe2Os, based on the weight of the catalyst. Preferably, the catalyst contains a Clariant International Ltd 2024DE605-WO-PCT

[0024] The iron content ranges from 1 wt.% to 9 wt.%, 3 wt.% to 8 wt.%, or 5 wt.% to 7 wt.%, calculated as Fe₂O₃, based on the total weight of the catalyst. The iron component is preferably present as a promoter of the CHA-type zeolite. It is particularly preferred that the iron component is partially present as iron(II) and / or iron(III) cations, which, as cations, represent the charge balance to the negatively charged Si / Al zeolite framework. This is achieved by replacing the cations present in the original zeolite with the iron component, e.g., iron(II) and / or iron(II) cations. The iron component is preferably introduced into the zeolite, which has been exchanged with ammonium ions, by solid-state ion exchange.The exchange with the iron cations does not have to be complete; additional proportions of the iron component may be present as iron compounds such as Fe20s or FeO after the exchange.

[0025] The active material comprises the zeolite of structure type CHA according to the invention and the iron component; however, it may also include other zeolites or other activity-influencing metals or metalloids. Preferably, the zeolite of structure type CHA is the only zeolite contained in the active material; particularly preferably, the active material consists of the zeolite of structure type CHA and the iron component.

[0026] The catalyst is in the form of an extruded body, with a binder, i.e., a binding agent, forming the body together with at least the active material to ensure dimensional stability. Suitable binders according to the invention include all materials that maintain the zeolite's dimensional stability and are stable under reaction conditions. Metal oxides, for example, based on or consisting of SiO₂, Al₂O₃, TiO₂, ZrO₂, MgO, or clay, are particularly suitable. Attapulgite, montmorillonite, kaolin, or bentonite are also preferred as binders, but silica gel (amorphous SiO₂ and Al₂O₃, especially γ-Al₂O₃ (particularly the product Pural SB)) is especially suitable. These binders can be used individually or as a mixture of different binders. Typically, the binder is present in the catalyst in an amount of 5 wt.% to 70 wt.%, preferably 10 wt.% to 40 wt.%, based on the total weight of the catalyst.In addition to the active material and the binder, other components may be present in the catalyst, such as porosity-forming agents.

[0027] The catalyst according to the invention is characterized by the fact that certain absorption bands are visible in the FTIR spectrum when absorption is carried out with NO as the sample molecule. The adsorption of NO as the sample molecule (NO adsorption) takes place at a temperature of 77 K and an NO pressure greater than 0.1 mbar or in the range between 0.1 mbar and 20 mbar, preferably at an NO partial pressure of 1 mbar or 10 mbar. Under these conditions, the catalyst exhibits absorption bands with maxima at 1770 cm⁻¹. 1 and 1830 cm -1 with + / - 10 cm' 1 In particular, the catalyst according to the invention is also characterized in that, in addition to the bands at 1770 cm', during NO adsorption 1 and 1830 cm' 1Simultaneously no, or virtually no, absorption band at 1920 cm' 1 Visible within a range of +-10 cm.

[0028] The shaped body according to the invention, in which the catalyst is located, has a minimum size and must be such that it cannot be inserted into an imaginary cube with an edge length of 1 mm without protruding from the cube at least at one point. Preferably, the shaped body is at least 4 mm long and at least 1.6 mm wide at its narrowest point.

[0029] The shaped body according to the invention, in which the catalyst is present, preferably has a maximum size such that it can be placed inside an imaginary cube with an edge length of 5 cm without protruding from the cube at any point. Preferably, the catalyst according to the invention should be present as a packed bed in the reactor, i.e., the shaped body is preferably not present as a honeycomb structure through which the reactant gas flows individually.

[0030] The molded body is preferably an extruded body, i.e., a mixture of zeolite and binder, and optionally other components. The molded body is continuously extruded from a forming die under high pressure in a moist or plastically deformable state. To limit the length of the extrudate, the extrudate strand is typically cut at regular intervals. Therefore, the molded body is typically in the form of an extrudate strand, the cross-sectional profile of which (i.e., the cross-section perpendicular to the direction of extrusion) can be round, rectangular, square, or U-shaped.

[0031] The molded body according to the invention is preferably produced by extrusion, i.e., the components of the molded body are continuously forced out of a forming die under high pressure in a moist or plastically deformable state. It is preferred that all components of the molded body form a homogeneous mass and are already present during extrusion. If all components of the molded body according to the invention are present during extrusion, no coating (for example, by a washcoat) with an active compound is necessary; therefore, it is preferred that the molded body according to the invention is not coated after production by extrusion. Clariant International Ltd 2024DE605-WO-PCT

[0032] Preferred are shaped bodies in the form of trilobes, a shape shown in Figure 4b, in which the lobes of the shaped body extend in the axial direction and the shaped body has, for example, a diameter of 2.5 mm to 2.8 mm (when measured against the outer surface) and a length of 3 mm to 12 mm, preferably 5 mm to 10 mm.

[0033] Also preferred are shaped bodies in the form of quadlobes, a shape shown in Figure 4c, in which the lobes of the shaped body extend in the axial direction and the shaped body has, for example, a diameter of 2.5 mm to 2.8 mm (when measured against the outer surface) and a length of 3 mm to 12 mm, preferably 5 mm to 10 mm.

[0034] Particularly preferred are cylindrical molded bodies, a shape shown in Figure 4a, with substantially round bases, wherein the respective cylindrical molded body has one or more, preferably three, axial bores (an axial bore is a channel leading from one base of the cylinder to the opposite base of the cylinder). The axial bores can be located so close to the cylindrical surface that they are open lengthwise on one side. This so-called "CDS molded body" is shown in Figure 4d and preferably has an outer diameter of 2.5 mm to 2.8 mm (measured at the outer surface of the cylinder) and a length of 3 mm to 12 mm, preferably 5 mm to 10 mm. A particularly preferred molded body is an extruded strand with a round cross-sectional profile having a diameter of 2.5 mm to 3.5 mm and a length of 3.5 mm to 4.5 mm.

[0035] The catalyst according to the invention is particularly suitable for the decomposition of nitrogen oxides, whereby NO X and / or N2O decomposes directly into nitrogen and oxygen without the involvement of a reducing agent.

[0036] The catalyst according to the invention is particularly suitable for the selective catalytic reduction of N2O and / or NO. X with a reducing agent, wherein the reducing agent is preferably NH3 or CH4 or another hydrocarbon.

[0037] The invention also relates to a process for producing a catalyst according to the invention, comprising the steps: a) mixing a zeolite of the CHA structural type with an iron precursor in solid form to obtain a precursor mixture, b) calcining the precursor mixture from step a) to obtain the active material, Clariant International Ltd 2024DE605-WO-PCT, c) mixing the active material from step b) with a binder and optionally further components to obtain an extrudable mixture, d) extruding the mixture from step c) to obtain shaped bodies, and e) calcining the shaped bodies from step d).

[0038] The zeolite of structure type CHA (hereinafter referred to as zeolite) used in step a) is in powder form and can be used in its Na or NH4 form. The zeolite has a SiO2 / Al2O3 ratio between 5 and 20, preferably a SiO2 / Al2O3 ratio between 8 and 15, particularly between 12 and 14. The iron component is introduced into the zeolite, which is in solid form (regardless of moisture content), by solid-state ion exchange. For this to occur, the iron precursor containing the iron to be exchanged must also be in solid form. Preferably, the iron precursor is in powder form, and more preferably, the iron precursor is FeCl2, Fe(NOs)2, Fe(NO3)3, Fe2(SO4)s, or FeSO4.It is preferred that the mixing of the zeolite and the iron precursor be carried out intensively, for example in a stirring apparatus, to ensure thorough mixing of both components, which facilitates the subsequent exchange reaction and leads to a homogeneous product after calcination. It is also preferred that the mixing of the zeolite and the iron precursor be carried out by joint milling.

[0039] Preferably, water is present in an amount of 10 wt.% to 50 wt.%, based on the total weight of the mixture, during the mixing process according to step a). In this process, the zeolite of structure type CHA is preferably first mixed with water in a first step, and then the iron precursor is added in a second step. The amounts of zeolite and iron precursor used in step a) are selected such that, after calcination in step b), the active material contains an iron content of 0.5 wt.% to 10 wt.%, 2 wt.% to 9 wt.%, 3 wt.% to 8 wt.%, or preferably 5 wt.% to 7 wt.%, iron, calculated as Fe₂O₃s, based on the total weight of the catalyst.

[0040] The mixture obtained from step a) is calcined in step b), preferably at a temperature between 300 °C and 700 °C for at least 15 minutes, preferably at least 30 minutes, for example in air. It is particularly preferred that the calcination after step b) is carried out at a temperature between 400 °C and 600 °C for 1 to 6 hours in air. During this step, the iron precursor combines with the CHA-type zeolite, and the exchange reaction takes place, resulting in the formation of a CHA-type zeolite loaded with an iron component, which constitutes the active material. Clariant International Ltd 2024DE605-WO-PCT

[0041] The active material obtained in step b) is mixed in a subsequent step c) with at least one binder according to the invention. Optionally, components can also be added that improve the extrusion properties of the mixture, increase the mechanical stability of the finished catalyst, or influence its porosity. For example, liquids such as water, oil, glycerin, or liquid acids such as acetic acid or nitric acid can be added to form an extrudable paste. Components that burn during calcination, such as cellulose, particularly Tylose, increase the porosity of the catalyst obtained after calcination.

[0042] The mixture obtained in step c) is extruded in step d) to obtain shaped bodies according to the invention; commercially available extruders, such as a strand extruder, are suitable for this purpose.

[0043] The shaped bodies obtained in step d) are calcined in step e) to obtain the finished catalyst. This calcination according to step e) is typically carried out at 450 °C to 650 °C for at least 15 minutes, preferably more than 1 hour, particularly preferably 3 to 8 hours, in an inert gas or preferably in air.

[0044] The preferred use of the catalysts according to the invention is the decomposition or catalytic reduction of NO. X and / or N2O with a reducing agent in a plant for the production of nitric acid. The reduction of N2O, as produced in a nitric acid plant, with the catalyst according to the invention is particularly preferred.

[0045] In particular, the catalyst according to the invention can be used to implement a process for the selective catalytic reduction of NO. XThe process is carried out with a reducing agent, in which the catalyst according to the invention is brought into contact with a reactant gas at a temperature of 300 °C to 600 °C, which typically contains between 100 ppmv and 10000 ppmv NO. X , containing approximately the same amount of gaseous reducing agent, more than 1000 ppmv H₂O and more than 10000 ppmv O₂. It is particularly preferred that the reactant gas contains between 500 ppmv and 5000 ppmv NO₂. X contains and approximately the same amount of gaseous reducing agent. The gaseous reducing agent is preferably ammonia, methane, or a hydrocarbon that can be used as a gaseous reducing agent in the reaction.

[0046] Furthermore, the catalyst according to the invention can be used in the process for the catalytic decomposition of N2O, in which the catalyst according to the invention is brought into contact with a reactant gas, typically containing between 100 ppmv and 1000 ppmv NO, at a temperature of 420 °C to 520 °C, preferably 480 °C to 520 °C. X Contains up to 2000 ppmv N₂O, more than 1000 ppmv H₂O, and more than 10,000 ppmv O₂. Clariant International Ltd 2024DE605-WO-PCT

[0047] It is particularly preferred that the reactant gas contains between 600 ppmv and 1300 ppmv N2O.

[0048] Figure 1: Results of the decomposition test with the samples according to Examples 1 and 5.

[0049] Figure 2: Results of the decomposition test with the samples according to examples 4 to 6.

[0050] Figure 3: Results of the SCR test with the samples according to examples 2, 5 and 6.

[0051] Figure 4: Preferred cross-sections of the extruded molded bodies a) round molded body, b) trilobe, c) quadlobe, d) CDS shape.

[0052] Figure 5: Results of the reduction test with the samples from examples 3 and 5.

[0053] Figure 6: FTIR spectra of the samples from Examples 1, 2, 5, 7 and 8 with adsorbed NO at 77K and 10 mbar NO.

[0054] Measurement methods

[0055] Elemental analysis using ICP:

[0056] Inductively coupled plasma atomic emission spectroscopy (ICP-AES) to determine the elemental composition and the SiO₂ / Al₂O₃ ratio was performed using the ICP Spectro Modula / Arcos instrument. The following chemicals were used: sulfuric acid 98% pA, hydrofluoric acid 37% pA, and hydrochloric acid 37% pA. The sample was finely ground.

[0057] For the determination of the elements silicon (Si) and ammonium (Al), 100 mg of sample was weighed into a 100 ml plastic beaker and mixed with 1 ml of sulfuric acid and 4 ml of hydrofluoric acid. The mixture was digested in a water bath at 85°C for 5 minutes until a clear solution was obtained. The beaker was then tempered, filled to the required volume, and shaken. All elements were measured by ICP, as were corresponding standards. Si was measured with the following settings: wavelengths of 288 nm and 158 nm. Al was measured with the following settings: wavelengths of 396 nm and 152 nm.

[0058] All standards were adjusted with HF and HCl or H₂SO₄. The evaluation followed the calculation: w(E* in percent) = β(E* measurement value in mg / L) x V(volumetric flask in L) x 100 / m(sample weight in mg) (E* = respective element). Clariant International Ltd 2024DE605-WO-PCT

[0059] BET measurement method:

[0060] The specific surface area of ​​the materials was determined according to the BET method as per DIN 66131; a publication of the BET method can also be found in J. Am. Chem. Soc. 60, 309 (1938). The sample to be determined was dried in a quartz tube at 350 °C under vacuum (F = 50 ml / min for 1.5 h). The reactor was then cooled to room temperature, evacuated, and immersed in a Dewar flask containing liquid nitrogen. Nitrogen adsorption was carried out at 77 K using an RXM 100 sorption system (Advanced Scientific Design, Inc.).

[0061] FTIR spectroscopy, NO adsorption:

[0062] The samples for FTIR spectroscopy (short for "Fourier-transform infrared spectroscopy") were prepared as self-supporting pellets and vacuum-sealed (3.0 x 10" 8Samples were heated to 450 °C (10 mbar) at a heating rate of 10 K / min and activated for 1 hour. They were then cooled to 30 °C. For NO adsorption measurements, the samples were completely cooled to 77 K with liquid nitrogen. FTIR spectra were recorded after dosing 10% NO in helium (10 mbar) and a waiting period of 20 minutes. Measurements were performed using a Vertex 70 spectrometer (Bruker Optics).

[0063] Example 1 (Comparison)

[0064] A commercial Envicat®-DeN2O-1 catalyst is provided, which is produced by solid-state ion exchange of a zeolite of the MFI structural type with iron (FeMFI). The FeMFI bodies are trilobes with a diameter of 2.6 mm and a length between 5 mm and 10 mm and contain 20 wt% binder and an iron content of 4.9 wt% Fe2Os, both based on the total weight of the catalyst.

[0065] Example 2 (Comparison)

[0066] A commercial Envicat® DeNOx catalyst is provided, produced by solid-state ion exchange of an MFI-type zeolite with iron (FeMFI). The FeMFI bodies are trilobes with a diameter of 2.6 mm and a length between 5 mm and 10 mm, containing 20 wt% binder and 4.9 wt% Fe20s, based on the total weight of the catalyst. Clariant International Ltd 2024DE605-WO-PCT

[0067] Example 3 (Comparison)

[0068] A commercial Envicat®-DeN2O-2 catalyst is provided, which is produced by solid-state ion exchange of a BEA-type zeolite with iron (FeBEA). The FeBEA bodies are in the form of round extrudates with a diameter of 2.6 mm and a length between 5 mm and 10 mm, and contain 20 wt% binder and an iron content of 4.9 wt% Fe2Os, both based on the total weight of the catalyst.

[0069] Example 4 (Invention)

[0070] 450 g of ammonium ion-exchanged chabazite with a modulus of 13 (NH4CHAI3) were placed in a mixer and, during a mixing process of 1 hour, first mixed with 180 g of water (total water absorption 40%) and then slowly with 10.26 g of FeCl2. The resulting material was calcined in air at 500 °C for 5 hours in a calcining furnace, yielding calcined powdered FeCHA13 material. 400 g of the calcined powdered FeCHA13 material was successively mixed with 177.3 g of Pural SB, 160 g of water, 49.8 g of acetic acid, another 200 g of water, and 36 g of Exxol oil and extruded into round extrudates with a diameter of 1 / 8 inch and a length of 5 mm to 10 mm. The resulting extrudates were calcined in air at 550 °C for 5 hours. The resulting sample 1 FeCHA contained 20 wt% binder and a calculated 1 wt% Fe20s, based on the total weight of the sample.

[0071] Example 5 (Invention)

[0072] 457.18 g of ammonium ion-exchanged chabazite with a modulus of 13 (NH4CHAI3) were placed in a mixer and, during a mixing process of 1 hour, first mixed with 197 g of water (total water absorption 40%) and then slowly with 46.16 g of FeCl2. The resulting material was calcined in air at 500 °C for 5 hours in a calcining furnace, yielding calcined powdered FeCHA13 material. 393 g of the calcined powdered FeCHA13 material was mixed with 13.1 g of nitric acid, 78.6 g of Pural SB, 104.8 g of water, 8.4 g of glycerol, and 332 g of Tylose solution and extruded into round extrudates with a diameter of 1 / 8 inch and a length of 5 mm to 10 mm. The resulting extrudates were calcined in air at 550 °C for 5 hours. The resulting 4FeCHA sample contained 20 wt% binder and a calculated 4 wt% Fe20s, based on the total sample weight.

[0073] Example 6 (Invention) Clariant International Ltd 2024DE605-WO-PCT

[0074] 450 g of ammonium ion-exchanged chabazite with a modulus of 13 (NH4CHAI 3) were placed in a mixer and, during a 30-minute mixing process, first mixed with 180 g of water (total water absorption 40%) and then slowly with 61.7 g of FeCh. The resulting material was calcined in air at 500 °C for 5 hours, yielding calcined powdered FeCHA13 material. 388 g of the calcined FeCHA13 material was mixed with 46.7 g of acetic acid, 166.6 g of Pural SB, 155.5 g of water, and 35 g of Exxol oil and extruded into round extrudates with a diameter of 1 / 8 inch and a length of 5 mm to 10 mm. The resulting extrudates were calcined in air at 550 °C for 5 hours. The obtained sample 6FeCHA contained 20 wt% binder and, calculated, 6 wt% Fe20s, each based on the total weight of the sample.

[0075] Example 7 (Comparison)

[0076] 19.86 g of ammonium ion-exchanged chabazite with a modulus of 13 (NH4CHA13) was added to a beaker containing 80 g of water and 2.62 g of iron(II) sulfate and stirred for 1 hour at room temperature. The suspension was then filtered, washed, and dried at 120 °C. The Fe20s content of the sample was 0.16 wt%.

[0077] Example 8 (Comparison)

[0078] 10 g of the iron-exchanged chabazite from Example 7 were calcined in air at 500 °C for 5 h.

[0079] Test reactions

[0080] To test the performance of the catalysts, the samples were each subjected to three different test reactions under different conditions:

[0081] 1. The reduction test is an experiment to test the catalytic reduction of N2O in the simultaneous presence of NO. X with the reducing agent ammonia and methane in the gas stream to nitrogen and water.

[0082] 2. The SCR test is an experiment to test the usual selective catalytic reduction (“SCR”), in which NO was used. X (without N2O) reduced to nitrogen and water with ammonia in the gas stream as a reducing agent.

[0083] 3. The decomposition test is an experiment to test the decomposition reaction of N₂O. No reducing agent such as ammonia is present in the gas stream; N₂O (in the presence of traces of NOx) is catalytically decomposed into nitrogen and oxygen. Clariant International Ltd 2024DE605-WO-PCT

[0084] For the test reactions, the extrudates were ground and a sieve fraction was removed. The test conditions are shown in the following tables (Table 1: Decomposition test, Table 2: SCR test, Table 3: Reduction test).

[0085] Decomposition test

[0086] For the decomposition test, the samples were ground, and the particle fraction between 0.8 mm and 1.0 mm was sieved out. For each test, 6 g of the sieved sample were placed in the reactor. In each test, the reactor temperature was first increased to 425 °C and then, for some tests, gradually cooled to 325 °C. The temperature was maintained for 30 minutes at each step to ensure stable conditions. For the decomposition tests with different temperatures (Figures 1 and 2), the test duration was extended, with measurements taken every 20 °C.

[0087] Table 1: Test conditions for the decomposition test

[0088] 1 initiated as NO

[0089] SCR test

[0090] For the SCR test, the samples were ground and the particle fraction between 0.8 mm and 1.0 mm was sieved out. For each test, 2.5 g of the sieved sample was added to the reactor. In each test, the reactor temperature was first increased to 550 °C and then gradually cooled to 150 °C. The temperature was maintained for 30 minutes at each step to ensure stable conditions. The gas compositions are shown in Table 3.

[0091] Catalyst aging: The crushed samples were heated to 750 °C under nitrogen, held at this temperature for 16 hours under an atmosphere of 10 vol% H₂O, and then cooled under nitrogen. Clariant International Ltd 2024DE605-WO-PCT

[0092] Table 2: Test conditions for the SCR test (Figure 3)

[0093] 1 initiated as NO

[0094] Reduction test

[0095] For the reduction test (Figure 5), the samples were ground and the particle fraction between 0.8 mm and 1.0 mm was sieved out. For each test, 6 g of the sieved sample was added to the reactor. In each test, the reactor temperature was first increased to 360 °C and then, for some tests, gradually cooled to 260 °C. The temperature was maintained for 30 minutes at each step to ensure stable conditions. Table 3: Test conditions for the reduction test

[0096] Summary of results

[0097] Table 4: Results of the aging tests Clariant International Ltd 2024DE605-WO-PCT

Claims

Clariant International Ltd 2024DE605-WO-PCT Claims:

1. Catalyst for the decomposition or selective catalytic reduction of N2O and / or NOx with a reducing agent in the form of a shaped body, comprising: - an active material comprising a zeolite of the CHA structural type, which is bonded to an iron- The component is loaded, containing the zeolite having a SiO2 / Al2O3 ratio between 5 and 20 and - a binder characterized in that the iron component contains an amount of 1 wt.% to 10 wt.% Fe2Os, based on the total weight of the catalyst, and the iron component has been introduced into the zeolite of structure type CHA by solid ion exchange.

2. Catalyst according to claim 1, characterized in that the iron component has been introduced into the zeolite exchanged with ammonium ions by solid ion exchange.

3. Catalyst according to claim 1 or 2, wherein the only zeolite in the active material is a zeolite of the CHA structural type.

4. Catalyst according to one of the preceding claims, characterized in that, during NO adsorption by the catalyst at a temperature of 77 K and an NO pressure of more than 0.1 mbar, the FTIR spectrum shows adsorption bands with maxima at 1770 cm⁻¹ -1 and 1830 cm -1 with + / - 10 cm -1 shows.

5. Catalyst according to one of the preceding claims, characterized in that, during NO adsorption by the catalyst at a temperature of 77 K and an NO pressure of more than 0.1 mbar, the FTIR spectrum shows no adsorption band with a maximum at 1920 cm⁻¹ -1 with + / - 10 cm -1 shows.

6. Catalyst according to one of the preceding claims, characterized in that the binder contains a metal oxide and is present in more than 10 wt.%, based on the weight of the catalyst.

7. Catalyst according to one of the preceding claims, characterized in that the binder contains Al2Os or amorphous SiO2. Clariant International Ltd 2024DE605-WO-PCT 8. Catalyst according to one of the preceding claims, characterized in that the zeolite of structure type CHA has a SiCL / A^Os ratio between 1 and 15.

9. Catalyst according to one of the preceding claims, characterized in that the molded body is an extruded molded body.

10. Catalyst according to one of the preceding claims, characterized in that the shaped body can be placed in an imaginary cube with an edge length of 5 cm without protruding from the cube at any point.

11. Catalyst according to one of the preceding claims, characterized in that the shaped body is at least 4 mm long and at its narrowest point is at least 2 mm wide.

12. Catalyst according to one of the preceding claims, characterized in that the reducing agent is NH3 or an alkane, in particular CH4.

13. Catalyst according to one of the preceding claims, characterized in that the iron component is contained in an amount of 3 wt.% to 8 wt.%, preferably 5 wt.% to 7 wt.%, calculated as Fe20s, in each case based on the total weight of the catalyst.

14. A process for producing a catalyst according to any one of claims 1 to 13, comprising the steps of: a) mixing a zeolite of the CHA structural type with a solid iron precursor to obtain a precursor mixture, b) calcining the precursor mixture from step a) to obtain the active material, c) mixing the active material from step b) with a binder and optionally further components to obtain an extrudable mixture, d) extruding the mixture from step c) to obtain shaped bodies, and e) calcining the shaped bodies from step d).

15. Method according to claim 14, characterized in that in step a) between 10 and 50 wt.% water is present, based on the total weight of the mixture from step a). Clariant International Ltd 2024DE605-WO-PCT 16. Method according to claim 14 or 15, characterized in that in step a) the iron precursor is FeCl2 or Fe(NOs)2.

17. Method according to one of claims 14 to 16, characterized in that water, porosity-forming agents or lubricants are present as optional components during the mixing according to step b).

18. Method according to one of claims 14 to 17, characterized in that the calcination according to step b) takes place at a temperature between 400 °C and 600 °C for at least 15 minutes.

19. Method according to one of claims 14 to 18, characterized in that the calcination of the molded bodies after step e) takes place in air at a temperature between 450 °C and 650 °C for at least 15 minutes.

20. Method according to one of claims 14 to 19, characterized in that the calcination according to step b) takes place in air at a temperature between 400 °C and 600 °C for at least 1 hour.

21. Use of a catalyst according to any one of claims 1 to 13, for the decomposition or selective catalytic reduction of NO Xand / or N2O with a reducing agent in a plant for the production of nitric acid.

22. Methods for the decomposition or selective catalytic reduction of NO X with a reducing agent, wherein the catalyst according to one of claims 1 to 10 is brought into contact with a reactant gas at a temperature of 300 °C to 600 °C, which contains between 100 ppmv and 10000 ppmv NO X , approximately the same amount of gaseous reducing agent, more than 1000 ppmv H2O and more than 10,000 ppmv O2.

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