Method for producing catalyst composition

Abstract

To provide a method for producing a catalyst composition for selective catalytic reduction of NOx in exhaust gas using hydrogen as a reducing agent, the method allowing production of the catalyst composition having enhanced activity and N2 selectivity.SOLUTION: The present invention provides a method for producing a catalyst composition for selective catalytic reduction of NOx in exhaust gas using hydrogen as a reducing agent, the catalyst composition comprising a catalyst component including zeolite particles, Zr, P, and Pt, the method comprising the following steps: (1) a step of preparing the zeolite particles; and (2) a step of supporting Zr, P, and Pt on surfaces of the zeolite particles to obtain the catalyst component.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for preparing a catalyst composition. [Background technology]

[0002] Due to growing interest in carbon neutrality, technologies that use hydrogen as an energy source instead of fossil fuels, such as hydrogen engines that use hydrogen as fuel, are attracting attention.

[0003] Exhaust gases emitted from hydrogen engines contain thermal NOx, which is generated by the high-temperature oxidation of N2 in the air. Therefore, technology to purify thermal NOx is required.

[0004] Known techniques for purifying NOx include a technique for converting NOx into N2 by selective catalytic reduction (H2-SCR) using hydrogen as a reducing agent (for example, Patent Document 1).

[0005] Patent Document 1 describes a catalyst for H2-SCR that is composed of a carrier with high solid acid strength (e.g., a phosphate-based compound such as SnP2O7, CeP2O7, ZrP2O7, or TiP2O7) and a precious metal element (e.g., Pt) supported on the carrier. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-440 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the catalyst described in Patent Document 1 has room for improvement in terms of activity and N2 selectivity.

[0008] Therefore, an object of the present invention is to provide a method for producing a catalyst composition for selective catalytic reduction of NOx in exhaust gas using hydrogen as a reducing agent, which can produce a catalyst composition with improved activity and N2 selectivity. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides the following method. [1] A method for producing a catalyst composition for selective catalytic reduction of NOx in exhaust gases using hydrogen as a reducing agent, comprising: the catalyst composition comprises a catalyst component comprising zeolite particles, Zr, P, and Pt; The method comprises the steps of: (1) providing zeolite particles; and (2) A step of supporting Zr, P, and Pt on the surface of the zeolite particles to obtain the catalyst component. The method comprising: [2] Step (2) is the following step: (2a) a step of supporting Zr and P on the surface of the zeolite particles to obtain a first intermediate; (2b) calcining the first intermediate to obtain a second intermediate; and (2c) A step of supporting Pt on the second intermediate The method according to [1], comprising: [3] The method according to [2], wherein in step (2b), the first intermediate is subjected to a hydrothermal treatment before being calcined. [4] The method according to [2] or [3], wherein in step (2b), the first intermediate is fired at a temperature of 800°C or higher and 1000°C or lower. [5] The method according to any one of [1] to [4], wherein the maximum ring of the zeolite constituting the zeolite particles is an eight-membered ring. [6] The method according to [5], wherein the zeolite constituting the zeolite particles is selected from the group consisting of AEI type, AFX type, ANA type, CHA type, DDR type, ERI type, GIS type, KFI type, LTA type, MRT type, PAU type and YUG type. [Effects of the Invention]

[0010] According to the present invention, there is provided a method for producing a catalyst composition for selective catalytic reduction of NOx in exhaust gas using hydrogen as a reducing agent, which can produce a catalyst composition with improved activity and N2 selectivity. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention relates to a method for preparing a catalyst composition for the selective catalytic reduction of NOx in exhaust gases using hydrogen as a reducing agent.

[0012] Examples of NOx include NO, NO2, NO3, N2O, N2O3, N2O4, N2O5, etc. The main component of NOx in exhaust gas is usually NO.

[0013] The exhaust gas is not particularly limited as long as it contains NOx. The exhaust gas is, for example, exhaust gas emitted from an internal combustion engine. Examples of internal combustion engines include hydrogen engines and engines that use carbon-containing fuels (e.g., diesel engines, gasoline engines, etc.). Engines that use carbon-containing fuels may be lean-burn engines (e.g., diesel engines, lean-burn gasoline engines, etc.). Exhaust gas emitted from a hydrogen engine may contain thermal NOx generated by the high-temperature oxidation of N2 in the air. Examples of carbon-containing fuels include fossil fuels (e.g., gasoline, diesel, natural gas, etc.), biofuels (e.g., ethanol and fatty acid esters obtained from biological resources), and synthetic fuels (e.g., carbon compounds artificially synthesized from carbon dioxide and hydrogen). Exhaust gas emitted from an engine that uses carbon-containing fuels may contain fuel NOx generated from nitrogen-containing components in the fuel (e.g., pyridine, pyrrole, etc.) in addition to thermal NOx.

[0014] The catalyst composition may be in the form of, for example, a powder, or may be formed into a desired shape such as pellets or layers.

[0015] The catalyst composition includes a catalyst component including zeolite particles, elemental zirconium (Zr), phosphorus (P), and platinum (Pt), where Zr, P, and Pt are contained outside the framework structure of the zeolite that constitutes the zeolite particles.

[0016] The catalyst composition is used for selective catalytic reduction of NOx in exhaust gases using hydrogen as a reducing agent. Selective catalytic reduction using hydrogen as a reducing agent (H2-SCR) converts NOx in exhaust gases to N2 (e.g., 2NO + 4H2 + O2 → N2 + 4H2O).

[0017] The method of the present invention makes it possible to produce a catalyst composition with improved activity and N selectivity. The catalyst composition with improved activity and N selectivity can achieve a high N production rate over a wide temperature range.

[0018] In a hydrogen engine, the temperature fluctuates depending on the operating conditions, so it is important to achieve a high N2 production rate over a wide temperature range. Therefore, the catalyst composition produced by the method of the present invention is preferably used for the selective catalytic reduction of NOx in exhaust gas emitted from a hydrogen engine.

[0019] As used herein, "activity" refers to the ability to convert NOx into other chemical species (e.g., 2NO + 4H2 + O2 → N2 + 4H2O, NO + 5 / 2H2 → NH3 + H2O). "Activity" includes the ability to convert NO into other NOx (e.g., NO 2、 This also includes the ability to convert NO into N2O (e.g., NO + 1 / 2O2 → NO2, 2NO + 3H2 + O2 → N2O + 3H2O, 2NO + H2 → N2O + H2O).

[0020] As used herein, "N2 selectivity" refers to the proportion of N2 among products produced from NOx.

[0021] The mechanism by which the present invention achieves the desired effects is presumed to be as follows, but is not limited to this.

[0022] Pt exhibits high activity and high N2 selectivity, and therefore contributes to improving the activity and N2 selectivity of the catalyst composition.

[0023] Zeolite particles are H + The NH3 produced from NOx and H2 due to the activity of Pt (for example, NO + 5 / 2H2 → NH3 + H2O) is transferred to the zeolite particles via the H + By NH4 + and converted to NH4 + The zeolite particles react with the remaining NOx, converting the remaining NOx to N2. This reaction pathway improves the activity and N2 selectivity. Therefore, the zeolite particles contribute to improving the activity and N2 selectivity of the catalyst composition.

[0024] In order for Pt to exhibit high activity and high N selectivity, it is necessary for electrons to be donated to Pt. When Zr and P are present on the zeolite particles together with Pt (i.e., Zr and P are present in close proximity to each other and to Pt), Zr and P donate electrons to Pt. Therefore, Zr and P contribute to improving the activity and N selectivity of the catalyst composition. However, when Zr and P are both present in the zeolite framework of the zeolite particles, or when one of Zr and P is present in the zeolite framework of the zeolite particles and the other is present on the zeolite particles, the condition that Zr and P are present in close proximity to each other and to Pt is not met, and therefore the desired effects of the present invention are not achieved.

[0025] From the viewpoint of more effectively improving the activity and N selectivity of the catalyst composition, the content of the zeolite particles is preferably 50% by mass or more and 98% by mass or less, more preferably 70% by mass or more and 97% by mass or less, and even more preferably 85% by mass or more and 96% by mass or less, based on the mass of the catalyst composition.

[0026] From the viewpoint of more effectively improving the activity and N selectivity of the catalyst composition, the content of Zr, calculated as ZrO, based on the mass of the catalyst composition, is preferably 1 mass% or more and 20 mass% or less, more preferably 1.5 mass% or more and 10 mass% or less, and even more preferably 2 mass% or more and 6 mass% or less.

[0027] From the viewpoint of more effectively improving the activity and N selectivity of the catalyst composition, the P content in terms of P2O5 is preferably 1 mass % or more and 20 mass % or less, more preferably 1.5 mass % or more and 10 mass % or less, and even more preferably 2 mass % or more and 7 mass % or less, based on the mass of the catalyst composition.

[0028] From the viewpoint of more effectively improving the activity and N selectivity of the catalyst composition, the content of Pt in terms of metal, based on the mass of the catalyst composition, is preferably 0.01 mass% or more and 1 mass% or less, more preferably 0.05 mass% or more and 0.6 mass% or less, and even more preferably 0.1 mass% or more and 0.45 mass% or less.

[0029] From the viewpoint of more effectively improving the activity and N2 selectivity of the catalyst composition, the ratio of the Zr content in terms of ZrO2 to the P content in terms of P2O5 (Zr content in terms of ZrO2 / P content in terms of P2O5) is preferably 0.3 or more and 2.5 or less, more preferably 0.5 or more and 2.0 or less, and even more preferably 0.7 or more and 1.6 or less.

[0030] From the viewpoint of more effectively improving the activity and N2 selectivity of the catalyst composition, the ratio of the Pt content in terms of metal to the sum of the Zr content in terms of ZrO2 and the P content in terms of P2O5 (Pt content in terms of metal / (Zr content in terms of ZrO2+P content in terms of P2O5)) is preferably 0.0005 or more and 0.2 or less, more preferably 0.001 or more and 0.15 or less, and even more preferably 0.002 or more and 0.11 or less.

[0031] When the composition of the raw materials used in the production of the catalyst composition is known, the content of zeolite particles in the catalyst composition can be determined from the composition of the raw materials.

[0032] When the composition of the raw materials used in the production of the catalyst composition is unknown, the content of zeolite particles in the catalyst composition can be measured by a conventional method such as scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX).

[0033] (1) A sample obtained from the catalyst composition is subjected to elemental analysis using a conventional method such as SEM-EDX to identify the types of constituent elements of the entire sample and to determine the content (mass%) of each identified element. (2) The sample obtained from the catalyst composition is subjected to elemental mapping using a conventional method such as SEM-EDX to identify the types of particles (zeolite particles and other particles) contained in the sample. (3) For each type of particle, randomly selected particles (e.g., 50 particles) are subjected to elemental analysis using SEM-EDX to identify the types of constituent elements of the particles and determine the content (mass%) of each identified element. The average content (mass%) of each element is then calculated for each type of particle. (4) An equation is created and solved to represent the relationship between the content (mass%) of each element in the sample, the content (mass%) of each element in each type of particle, and the content (mass%) of each type of particle in the sample, thereby calculating the content (mass%) of each type of particle in the sample, and this is the content (mass%) of each type of particle in the catalyst composition.

[0034] When the composition of the raw materials used in the production of the catalyst composition is known, the content of each element in the catalyst composition in terms of metal or oxide can be determined from the composition of the raw materials.

[0035] When the composition of the raw materials used in the production of the catalyst composition is unknown, the content of each element in the catalyst composition in terms of metal or oxide can be measured by a conventional method such as SEM-EDX. Specifically, it is as follows.

[0036] A sample obtained from the catalyst composition is subjected to elemental analysis using a conventional method such as SEM-EDX to identify the types of constituent elements of the entire sample and to determine the content (mass%) of each identified element. The content (mass%) of each element is determined for each of 10 SEM fields of view, and the average value of the content (mass%) of each element in the 10 fields of view is taken as the content (mass%) of each element in the catalyst composition.

[0037] In this specification, the "mass of the catalyst composition" refers to a calculated mass obtained by calculating the mass of precious metal elements in terms of metal and the mass of elements other than precious metal elements in terms of oxide, among all elements other than O contained in the catalyst composition, and then adding these up.

[0038] In this specification, the term "noble metal element" includes Au, Ag, Pt, Pd, Rh, Ru, Ir, and Os.

[0039] In this specification, oxides of rare earth elements other than Ce, Pr, and Tb are referred to as sesquioxides (M2O3, where M represents a rare earth element other than Ce, Pr, and Tb), oxides of Ce are referred to as CeO2, and oxides of Pr are referred to as Pr6O 11 Tb oxide is Tb4O7, Al oxide is Al2O3, Zr oxide is ZrO2, Si oxide is SiO2, Cu oxide is CuO, B oxide is B2O3, Cr oxide is Cr2O3, Mg oxide is MgO, Ca oxide is CaO, Sr oxide is SrO, Ba oxide is BaO, Fe oxide is Fe3O4, Mn oxide is Mn3O4, Ni oxide is NiO, Ti oxide is TiO2 , Zn oxide is ZnO, Sn oxide is SnO2, Li oxide is Li2O, Na oxide is Na2O, K oxide is K2O, Rb oxide is Rb2O, Cs oxide is Cs2O, Ag oxide is Ag2O, V oxide is V2O5, Co oxide is Co3O4, Nb oxide is Nb2O5, Mo oxide is MoO3, Ga oxide is Ga2O3, Ge oxide is GeO2, and P oxide is P2O5.

[0040] The method of the present invention comprises the following steps: (1) providing zeolite particles; and (2) A step of supporting Zr, P, and Pt on the surface of the zeolite particles prepared in step (1) to obtain a catalyst component. Includes.

[0041] According to the method of the present invention, it is possible to effectively realize a state in which Zr and P are present in close proximity to each other and to Pt.

[0042] The zeolite particles prepared in step (1) will be described below.

[0043] The zeolite particles may be primary particles, secondary particles, or a mixture thereof. Secondary particles are aggregated particles formed by aggregation of primary particles.

[0044] Examples of the shape of the primary particles include spherical, flake, columnar, needle, polyhedral, and irregular shapes. Spherical shapes include true spheres and ellipsoidal spheres. Flake shapes include scales, thin flakes, and flat shapes. Cylinder shapes include not only cylindrical, elliptical, and polygonal columns, but also shapes with a portion missing from the cylindrical, elliptical, and polygonal columns.

[0045] The average primary particle diameter of the zeolite particles is, for example, 0.5 μm to 30 μm, preferably 1 μm to 20 μm. The primary particle diameter of the zeolite particles is the equivalent circle diameter, i.e., the diameter of a circle having an area equal to that of the zeolite particles when viewed in an observation image (e.g., an SEM image) of the zeolite particles.

[0046] The specific surface area of ​​zeolite particles is, for example, 200 m 2 / g or more 800m 2 / g or less. The specific surface area of ​​zeolite particles is determined by the BET method based on the nitrogen adsorption isotherm measured in accordance with ISO 9277 (JIS Z8330:2013). The static volumetric method is used to measure the amount of adsorbed gas. The multipoint method is used to analyze the adsorption data.

[0047] The zeolite constituting the zeolite particles will be described below.

[0048] Zeolites are porous crystalline compounds with open, regular micropores, and have a structure in which TO4 units (where T represents an atom that constitutes the zeolite) with a tetrahedral structure are three-dimensionally connected by sharing O atoms.

[0049] The T atom is, for example, selected from metal atoms and metalloid atoms. Examples of metal atoms include Al, Ti, Fe, Zn, Ga, Sn, and Cu. Examples of metalloid atoms include B, Si, and Ge. The T atom may be composed of one type of atom, or two or more types of atoms.

[0050] In one embodiment, the T atoms are composed of Si and Al. Zeolites according to this embodiment include, for example, aluminosilicates.

[0051] In another embodiment, the T atoms are composed of Si and Al and one or more atoms other than Si and Al. Examples of zeolites according to this embodiment include aluminosilicates in which part of the Si atoms and / or part of the Al atoms in the framework are substituted with one or more atoms other than Si and Al (for example, metalloaluminosilicates such as boroaluminosilicate, titanoaluminosilicate, vanadoaluminosilicate, manganoaluminosilicate, iron aluminosilicate, zinc aluminosilicate, galloaluminosilicate, and tin aluminosilicate).

[0052] In yet another embodiment, the T atoms are composed of Si and one or more atoms other than Si and Al. Examples of zeolites according to this embodiment include silicates in which part of the Si atoms in the framework is substituted with one or more atoms other than Si and Al (for example, metallosilicates such as borosilicate, titanosilicate, vanadosilicate, manganosilicate, iron silicate, zinc silicate, gallosilicate, and tin silicate).

[0053] The viewpoint of stabilizing the crystalline structure of zeolite and H + From the viewpoint of sufficiently supplying, the T atoms are preferably composed of Si and Al, or composed of Si and Al and one or more atoms other than Si and Al, and more preferably composed of Si and Al.

[0054] For information on the pore size, skeletal structure, etc. of zeolite, reference can be made to "ATLAS OF ZEOLITE STRUCTURES TYPES" published by the International Zeolite Society and databases published by the International Zeolite Society.

[0055] The framework structures of zeolites are compiled into a database by the International Zeolite Society, and are assigned framework codes consisting of three capital letters. The framework structure of zeolites can be identified, for example, based on X-ray diffraction (XRD) patterns.

[0056] The zeolite can be selected from, for example, zeolites having a maximum ring size of 8 members, zeolites having a maximum ring size of 10 members, zeolites having a maximum ring size of 12 members, and the like.

[0057] In this specification, "8-membered ring" means a ring having 8 oxygen atoms in the ring structure, and "a zeolite having an 8-membered ring as the largest ring" means, when the zeolite has one type of pore, a zeolite in which the ring structure of the one type of pore is an 8-membered ring, and when the zeolite has two or more types of pores, a zeolite in which the ring structure of the largest pore of the two or more types of pores is an 8-membered ring. For example, an MRT-type zeolite having 8-, 6-, and 4-membered ring pores corresponds to "a zeolite having an 8-membered ring as the largest ring." Note that "MRT type" means a zeolite whose skeleton code is MRT. The same applies to other types.

[0058] Examples of zeolites having a maximum ring size of 8 include AEI, AFX, ANA, CHA, DDR, ERI, GIS, KFI, LTA, MRT, PAU, and YUG types.

[0059] In this specification, the term "10-membered ring" refers to a ring having 10 O atoms in the ring structure, and the term "zeolite having a 10-membered ring as the largest ring" refers to a zeolite having one type of pore, in which the ring structure of the one type of pore is a 10-membered ring, when the zeolite has two or more types of pores, and refers to a zeolite having a 10-membered ring as the largest pore of the two or more types of pores.

[0060] Examples of zeolites having a maximum ring size of 10 include AEL type, EUO type, FER type, HEU type, MEL type, MFI type, NES type, TON type, and WEI type.

[0061] In this specification, the term "12-membered ring" refers to a ring having 12 O atoms in the ring structure, and the term "zeolite having a maximum ring of 12-membered ring" refers to a zeolite having one type of pore, in which the ring structure of the one type of pore is a 12-membered ring, when the zeolite has two or more types of pores, in which the ring structure of the maximum pore of the two or more types of pores is a 12-membered ring.

[0062] Examples of zeolites having a maximum ring size of 12 include AFI, ATO, BEA, CON, FAU, GME, LTL, MOR, MTW, OFF, and MSE types.

[0063] H donated by zeolite particles + by NH3 NH4 + To ensure that the conversion to Pt is effectively carried out, it is preferable to prevent Pt from entering the pores of the zeolite. Considering the ionic radius of Pt, if the maximum ring of the zeolite is an eight-membered ring, Pt can be effectively prevented from entering the pores of the zeolite. Therefore, it is preferable that the maximum ring of the zeolite is an eight-membered ring.

[0064] The stability of the zeolite crystal structure and H + From the viewpoint of realizing a good balance between the supply of SiO2 and the amount of Al2O3, the SiO2 / Al2O3 molar ratio of the zeolite (the ratio of the amount (moles) of SiO2 to the amount (moles) of Al2O3) is preferably 5 or more and 200 or less, more preferably 7 or more and 150 or less, and even more preferably 10 or more and 40 or less.

[0065] The SiO2 / Al2O3 molar ratio of the zeolite can be determined by a conventional method such as X-ray fluorescence analysis (XRF).

[0066] Zeolites usually have a negative charge and have counter cations to cancel this negative charge. Zeolites may have one type of counter cation, or two or more types of counter cations. Examples of counter cations include alkali metal ions, alkaline earth metal ions, rare earth metal ions, transition metal ions, Group 13 element ions, and ammonium ions (NH 4+ ), proton (H +) and the like. Examples of alkali metals include Li, Na, K, Rb, and Cs. Examples of alkaline earth metals include Mg, Ca, Sr, and Ba. Examples of rare earth metals include Ce, Y, Pr, Sc, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Examples of transition metals include Cu, Fe, Mn, Ni, Zn, Ag, Ti, V, Cr, Co, Zr, Nb, and Mo. Examples of Group 13 elements include B, Al, and Ga. Zeolites containing alkali metal ions (e.g., sodium ions) as counter cations are called alkali metal types (e.g., sodium types), zeolites containing copper ions as counter cations are called copper types, zeolites containing iron ions as counter cations are called iron types, zeolites containing ammonium ions as counter cations are called ammonium types (NH4 types), and zeolites containing protons as counter cations are called proton types (H + It may be called a type.

[0067] H donated by zeolite particles + by NH3 NH4 + In order to ensure that the conversion to ammonium zeolite is effectively carried out, the zeolite constituting the zeolite particles contained in the catalyst component is preferably a proton type. By calcining ammonium zeolite, the ammonium type zeolite is converted to proton type zeolite. Therefore, when the method of the present invention includes a calcination treatment of zeolite particles, the zeolite constituting the zeolite particles prepared in step (1) is preferably an ammonium type. On the other hand, when the method of the present invention does not include a calcination treatment of zeolite particles, the zeolite constituting the zeolite particles prepared in step (1) is preferably a proton type.

[0068] The zeolite constituting the zeolite particles prepared in step (1) may be a commercially available zeolite or a zeolite prepared according to a known method.

[0069] Alkali metal zeolites can be prepared according to known methods. From the viewpoint of effectively synthesizing a zeolite with a desired structure, the alkali metal / Al molar ratio of the alkali metal zeolite is preferably 0.1 or more and 50 or less, more preferably 1 or more and 25 or less, and even more preferably 10 or more and 15 or less. When the alkali metal zeolite contains one alkali metal, the "alkali metal / Al molar ratio" means the ratio of the amount (moles) of the alkali metal to the amount (moles) of Al. When the alkali metal zeolite contains two or more alkali metals, the "alkali metal / Al molar ratio" means the ratio of the total amount (moles) of the alkali metals to the amount (moles) of Al. The alkali metal / Al molar ratio can be determined in the same manner as the SiO2 / Al2O3 molar ratio.

[0070] A desired ion-type zeolite can be prepared by ion-exchanging an alkali metal zeolite and exchanging the alkali metal ions with the desired ions. For example, an ammonium zeolite can be prepared by ion-exchanging an alkali metal zeolite using an aqueous solution containing ammonium ions (e.g., an ammonium chloride aqueous solution, an ammonium nitrate aqueous solution, etc.) to exchange the alkali metal ions with ammonium ions. When preparing an ammonium zeolite by ion-exchanging an alkali metal zeolite and exchanging the alkali metal ions with ammonium ions, the ion-exchange rate of the alkali metal ions is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more. The upper limit is 100 mol%. The ion-exchange rate of the alkali metal ions can be calculated using the following formula: Ion exchange rate of alkali metal ions (mol%) = (number of moles (mol) of alkali metals contained in zeolite before ion exchange treatment - number of moles (mol) of alkali metals contained in zeolite after ion exchange treatment) / number of moles (mol) of alkali metals contained in zeolite before ion exchange treatment

[0071] In one embodiment, proton-type zeolite can be prepared by calcining ammonium-type zeolite. The calcination temperature is preferably 400°C or higher and 1100°C or lower, more preferably 700°C or higher and 1000°C or lower. The calcination time is preferably 1 hour or higher and 6 hours or lower, more preferably 2 hours or higher and 5 hours or lower. Calcination is preferably carried out in an air atmosphere.

[0072] In another embodiment, proton-type zeolite can be prepared by ion-exchanging an alkali metal-type zeolite using an aqueous solution containing protons (e.g., hydrochloric acid, sulfuric acid, nitric acid, etc.) to exchange the alkali metal ions with protons. When preparing a proton-type zeolite by ion-exchanging an alkali metal-type zeolite to exchange the alkali metal ions with protons, the ion-exchange rate of the alkali metal ions is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more. The upper limit is 100 mol%. The ion-exchange rate of the alkali metal ions can be determined in the same manner as above.

[0073] At least a portion of the counter cations may be contained in the zeolite in a metallic state and / or an oxide state. For example, when the zeolite is calcined, at least a portion of the counter cations may become metallic and / or an oxide state. Zeolites in which at least a portion of the counter cations are metallic and / or an oxide state are also included.

[0074] Step (2) will be described below.

[0075] Step (2) includes a step of supporting Zr on the surface of zeolite particles (hereinafter referred to as the "Zr supporting step"), a step of supporting P on the surface of zeolite particles (hereinafter referred to as the "P supporting step"), and a step of supporting Pt on the surface of zeolite particles (hereinafter referred to as the "Pt supporting step").

[0076] The order of carrying out the Zr loading step, the P loading step, and the Pt loading step is not particularly limited. However, from the viewpoint of effectively obtaining a catalyst component that satisfies the condition that Zr and P exist in a state close to each other and close to Pt, the Pt loading step is preferably carried out after the Zr loading step and the P loading step. Two or more of the Zr loading step, the P loading step, and the Pt loading step may be carried out simultaneously. For example, the Zr loading step and the P loading step may be carried out simultaneously.

[0077] <Zr loading step> Hereinafter, the Zr loading step will be described.

[0078] The Zr loading step can be carried out by an impregnation method. Specifically, the Zr loading step can be carried out by mixing a Zr loading solution and zeolite particles. The zeolite particles subjected to the Zr loading step may be zeolite particles that have not been subjected to any of the Zr loading step, the P loading step, or the Pt loading step, or may be zeolite particles after being subjected to one or more of the P loading step and the Pt loading step.

[0079] The Zr loading solution contains a solvent and a Zr-containing compound. The Zr loading solution may be in any state of a solution, a suspension, or a dispersion. The pH of the Zr loading solution is, for example, 0.5 or more and 10 or less, preferably 1 or more and 9 or less. The Zr-containing compound may exist in the Zr loading solution in its original state and / or in an ionized state.

[0080] The temperature at the time of mixing the Zr loading solution and the zeolite particles is, for example, 5°C or more and 200°C or less, preferably 10°C or more and 100°C or less. The time for mixing the Zr loading solution and the zeolite particles is, for example, from 0.1 hour or more to 6 hours or less, preferably from 0.5 hour or more to 4 hours or less.

[0081] The solvent contained in the Zr loading solution is preferably water. The water is preferably pure water such as deionized water.

[0082] The solvent contained in the Zr supporting solution may be a mixed solvent of water and one or more organic solvents. Examples of the organic solvent include alcohol, acetone, dimethyl sulfoxide, and dimethylformamide. The total amount of the one or more organic solvents is, for example, 40% by volume or less, preferably 5% by volume or less, based on the volume of the mixed solvent.

[0083] Examples of Zr-containing compounds include Zr salts, zirconium oxide (ZrO2), and zirconium hydroxide (Zr(OH)4). As the Zr-containing compound, one type of compound may be used alone, or two or more types of compounds may be used in combination. Because of its relatively high solubility in water, the Zr-containing compound is preferably a Zr salt.

[0084] From the viewpoint of more uniformly supporting Zr and P on the surface of the zeolite particles and more effectively realizing a state in which Zr and P are present in close proximity to each other, the Zr salt is preferably water-soluble. Examples of water-soluble Zr salts include zirconium chloride, zirconium oxychloride, zirconium sulfate, zirconium oxysulfate, zirconium nitrate, zirconium oxynitrate, zirconium diacetate, zirconium tetraacetate, zirconium oxyacetate, ammonium zirconium carbonate, and zirconium alkoxide. In consideration of the availability of raw materials, the water-soluble Zr salt compound is preferably selected from zirconium oxynitrate and zirconium oxyacetate. When the water-soluble Zr salt compound is selected from zirconium oxynitrate and zirconium oxyacetate, at least a portion of the Zr is likely to be present in the catalyst component in the form of a Zr-containing oxide.

[0085] This effectively achieves sufficient Zr loading on the surface of zeolite particles and prevents H from the zeolite. +From the viewpoint of effectively suppressing excessive loading of Zr that would prevent the supply of Zr, the concentration of the Zr-containing compound in the Zr loading solution is preferably 0.005 mol / L or more and 1.5 mol / L or less, more preferably 0.01 mol / L or more and 1.0 mol / L or less, and even more preferably 0.03 mol / L or more and 0.5 mol / L or less, in terms of the Zr concentration.

[0086] The Zr supporting step may include a step of mixing the Zr supporting liquid with the zeolite particles and then separating solid matter from the resulting mixture (hereinafter referred to as a "solid matter separation step").

[0087] The solid may be a cake or a dried product. A cake is a solid that has not been dried, which differs from a dried product.

[0088] The cake can be obtained by subjecting the mixture to solid-liquid separation. Examples of solid-liquid separation methods include filtration, centrifugation, and decantation. Filtration is preferred because it is easy to operate and has excellent solid-liquid separation efficiency. Since the solvent is not completely removed, some solvent remains in the cake.

[0089] The dried product can be obtained by drying the cake. The drying temperature is, for example, from 80° C. to 200° C., preferably from 100° C. to 150° C. The drying time is, for example, from 0.5 hours to 24 hours, preferably from 1 hour to 16 hours.

[0090] The Zr supporting step may include a step of calcining the solid obtained after the solid separation step (hereinafter referred to as a "solid calcination step"). When the zeolite constituting the zeolite particles prepared in step (1) is an ammonium type, the ammonium type zeolite is converted to a proton type zeolite by the solid calcination step.

[0091] The firing temperature is, for example, 400°C or higher and 1100°C or lower, preferably 700°C or higher and 1000°C or lower. The firing time is, for example, 1 hour or longer and 6 hours or shorter, preferably 2 hours or longer and 5 hours or shorter. The firing can be carried out, for example, in an air atmosphere.

[0092] The P loading step will be described below. <​​​​​​​​​​​​​​​​​Examples of P-containing compounds include orthophosphoric acid, orthophosphates, condensed phosphoric acid, condensed phosphates, phosphorus oxide (PO), triethyl phosphate, trimethyl phosphate, triethyl phosphite, and trimethyl phosphite. As the P-containing compound, one type of compound may be used alone, or two or more types of compounds may be used in combination. In consideration of solubility in water and ease of handling, the P-containing compound is preferably selected from orthophosphoric acid and orthophosphates.

[0098] Examples of condensed phosphoric acids include pyrophosphoric acid, polyphosphoric acid, ultraphosphoric acid, metaphosphoric acid, and triphosphoric acid.

[0099] The orthophosphate and condensed phosphate are preferably water-soluble from the viewpoint of more uniformly supporting Zr and P on the surface of the zeolite particles and more effectively realizing a state in which Zr and P are present in close proximity to each other. Examples of water-soluble orthophosphates and condensed phosphates include alkali metal salts of orthophosphoric acid and condensed phosphoric acid (e.g., sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, etc.), and ammonium salts of orthophosphoric acid and condensed phosphoric acid (e.g., ammonium dihydrogen phosphate, diammonium hydrogen phosphate, etc.).

[0100] It effectively achieves sufficient P loading on the surface of zeolite particles and prevents H from the zeolite. + From the viewpoint of effectively suppressing excessive loading of P that would hinder the supply of P, the concentration of the P-containing compound in the P loading solution is preferably 0.005 mol / L or more and 3 mol / L or less, more preferably 0.01 mol / L or more and 2 mol / L or less, and even more preferably 0.03 mol / L or more and 1 mol / L or less, in terms of P concentration.

[0101] The P loading step may include a step of mixing the P loading liquid with the zeolite particles and then separating solids from the resulting mixture (hereinafter referred to as the "solid separation step"). The above description of the solid separation step included in the Zr loading step also applies to the solid separation step included in the P loading step.

[0102] The P-supporting step may include a step of firing the obtained solid matter after the solid matter separation step (hereinafter referred to as "solid matter firing step"). The above description regarding the solid matter firing step included in the Zr-supporting step is also applicable to the solid matter firing step included in the P-supporting step.

[0103] <Pt-supporting step> The Pt-supporting step will be described below.

[0104] The Pt-supporting step can be carried out by an impregnation method. Specifically, the Pt-supporting step can be carried out by mixing a Pt-supporting liquid and zeolite particles. The zeolite particles subjected to the Pt-supporting step may be zeolite particles that have not been subjected to any of the Zr-supporting step, the P-supporting step or the Pt-supporting step, or may be zeolite particles after being subjected to one or more of the Zr-supporting step and the P-supporting step.

[0105] The Pt-supporting liquid contains a solvent and a Pt-containing compound. The Pt-supporting liquid may be in any state of a solution, a suspension or a dispersion. The pH of the Pt-supporting liquid is, for example, 1 or more and 13 or less, preferably 2 or more and 12 or less. The Pt-containing compound may be present in the Pt-supporting liquid in its original state and / or in an ionized state.

[0106] The temperature at the time of mixing the Pt-supporting liquid and the zeolite particles is, for example, 5°C or more and 200°C or less, preferably 10°C or more and 100°C or less. The time for mixing the Pt-supporting liquid and the zeolite particles is, for example, 0.1 hour or more and 6 hours or less, preferably 0.5 hour or more and 4 hours or less.

[0107] The above description regarding the solvent contained in the Zr-supporting liquid is also applicable to the solvent contained in the Pt-supporting liquid.

[0108] Examples of Pt-containing compounds include Pt salts, platinum oxide (PtO, PtO2, or Pt3O4), and platinum hydroxide (Pt(OH)2 or Pt(OH)4). As the Pt-containing compound, one type of compound may be used alone, or two or more types of compounds may be used in combination. From the viewpoint of relatively high solubility in water, the Pt-containing compound is preferably a Pt salt.

[0109] From the viewpoint of more uniformly supporting Pt on the surface of zeolite particles and more effectively realizing a state in which Zr, P, and Pt are present in close proximity to one another, the Pt salt is preferably water-soluble. Examples of water-soluble Pt salts include platinum(IV) chloride, platinum(IV) bromide, platinum(IV) iodide, tetradichloroammineplatinum(IV), platinum(II) acetylacetonate, tetraammineplatinum(II) nitrate, tetraammineplatinum(II) hydroxide, and tetraammineplatinum(II) chloride. In consideration of the ability to be supported on zeolite, which is an acidic carrier, the water-soluble Pt salt is preferably selected from tetraammineplatinum(II) hydroxide, tetraammineplatinum(II) hydroxide hydrate, and tetraammineplatinum(II) chloride.

[0110] It effectively achieves sufficient Pt loading on the surface of zeolite particles and prevents H from zeolite. + From the viewpoint of effectively suppressing excessive Pt loading that would prevent the supply of Pt, the concentration of the Pt-containing compound in the Pt loading solution is preferably 0.0001 mol / L or more and 1 mol / L or less, more preferably 0.0002 mol / L or more and 0.5 mol / L or less, and even more preferably 0.0005 mol / L or more and 0.1 mol / L or less, in terms of Pt concentration.

[0111] The Pt loading step may include a step of mixing the Pt loading liquid with the zeolite particles and then separating solid matter from the resulting mixture (hereinafter referred to as the "solid matter separation step"). The above description of the solid matter separation step included in the Zr loading step also applies to the solid matter separation step included in the Pt loading step.

[0112] The Pt supporting step may include a step of calcining the solid obtained after the solid separation step (hereinafter referred to as a "solid calcination step"). The above description of the solid calcination step included in the Zr supporting step also applies to the solid calcination step included in the Pt supporting step.

[0113] When the Zr loading step and the P loading step are carried out simultaneously (hereinafter, the steps carried out are referred to as the "Zr / P loading step"), the Zr / P loading step can be carried out by mixing a Zr / P loading liquid with zeolite particles. The zeolite particles used in the Zr / P loading step may be zeolite particles that have not been subjected to any of the Zr loading step, the P loading step, or the Pt loading step, or may be zeolite particles that have been subjected to the Pt loading step.

[0114] The Zr / P supporting liquid contains a solvent, a Zr-containing compound, and a P-containing compound. The Zr / P supporting liquid may be in the form of a solution, suspension, or dispersion. The pH of the Zr / P supporting liquid is, for example, 0.5 to 11, preferably 1 to 9. The Zr-containing compound and the P-containing compound may exist in the Zr / P supporting liquid in one or more states selected from the group consisting of an intact state, an ionized state, and a complex or reaction product of the Zr-containing compound and the P-containing compound.

[0115] The temperature when mixing the Zr / P supporting liquid and the zeolite particles is, for example, 5° C. or more and 200° C. or less, preferably 10° C. or more and 100° C. or less. The time for mixing the Zr / P supporting liquid and the zeolite particles is, for example, 0.1 hours or more and 6 hours or less, preferably 0.5 hours or more and 4 hours or less.

[0116] The above explanations regarding the solvent and Zr-containing compound contained in the Zr-supporting liquid also apply to the solvent and Zr-containing compound contained in the Zr / P-supporting liquid, and the above explanations regarding the P-containing compound contained in the P-supporting liquid also apply to the P-containing compound contained in the Zr / P-supporting liquid.

[0117] Instead of the Zr-containing compound and the P-containing compound, a Zr- and P-containing compound may be used. Examples of the Zr- and P-containing compound include zirconium phosphate compounds. Examples of the zirconium phosphate compound include zirconium hydrogen phosphates such as Zr(HPO4)2 and Zr(HPO4)2·nH2O, zirconium phosphates such as Zr3(PO4)4, zirconium hydrogen phosphates such as Zr(PO4)(H2PO4) and Zr(PO4)(H2PO4)2·nH2O, HZr2(PO4)3, ZrP2O7, (ZrO)2P2O7, etc. Note that n is typically 0≦n≦2 (e.g., n=1, 1.5, or 2).

[0118] The Zr / P loading step may include a step of mixing the Zr / P loading liquid with the zeolite particles and then separating solids from the resulting mixture (hereinafter referred to as the "solid separation step"). The above description of the solid separation step included in the Zr loading step also applies to the solid separation step included in the Zr / P loading step.

[0119] The Zr / P loading step may include a step of calcining the solid matter obtained after the solid matter separation step (hereinafter referred to as a "solid matter calcination step"). The above description of the solid matter calcination step included in the Zr loading step also applies to the solid matter calcination step included in the Zr / P loading step.

[0120] Step (2) comprises the following steps: (2a) a step of supporting Zr and P on the surface of zeolite particles to obtain a first intermediate; (2b) calcining the first intermediate to obtain a second intermediate; and (2c) Step of supporting Pt on the second intermediate This makes it possible to effectively obtain a catalyst component that satisfies the condition that Zr and P are present in close proximity to each other and in close proximity to Pt, and ensures that electrons are effectively donated from Zr and P to Pt.

[0121] The zeolite particles subjected to step (2a) are zeolite particles that have not been subjected to any of the Zr-loading step, P-loading step, or Pt-loading step. Step (2a) includes a Zr-loading step and a P-loading step. The order in which the Zr-loading step and the P-loading step are performed is not particularly limited. The above explanations regarding the Zr-loading step and the P-loading step also apply to the Zr-loading step and the P-loading step included in step (2a), unless otherwise specified. The Zr-loading step and the P-loading step may be performed simultaneously (hereinafter, the performed steps are referred to as the "Zr / P-loading step"). The above explanations regarding the Zr / P-loading step also apply to the Zr / P-loading step included in step (2a), unless otherwise specified. The Zr / P-loading step included in step (2a) may include a solid separation step, but does not include a solid calcination step. This is because step (2b) includes a solid calcination step.

[0122] When the step (2a) includes a solid separation step, the solid obtained in the solid separation step corresponds to the first intermediate.

[0123] The above description regarding the solid calcination step included in the Zr supporting step also applies to step (2b).

[0124] The fired product obtained in the solid firing step corresponds to the second intermediate.

[0125] In step (2b), it is preferable to subject the first intermediate to hydrothermal treatment before calcining the first intermediate, which allows Zr and P to be more finely dispersed on the surface of the zeolite particles and ensures that electrons are effectively donated from Zr and P to Pt.

[0126] The hydrothermal treatment can be carried out by placing the first intermediate together with water in a pressure-resistant sealed container and heating it at a predetermined temperature for a predetermined time. The hydrothermal treatment temperature is preferably 80°C to 200°C, more preferably 90°C to 190°C, and even more preferably 100°C to 180°C. The hydrothermal treatment time is preferably 1 hour to 84 hours, more preferably 12 hours to 72 hours, and even more preferably 24 hours to 60 hours. The pressure inside the container during the hydrothermal treatment is not particularly limited as long as the water in the container can exist in a liquid state, and can be set appropriately depending on the hydrothermal treatment temperature. The pressure inside the container during the hydrothermal treatment is usually the saturated vapor pressure corresponding to the hydrothermal treatment temperature or a pressure exceeding it. For example, when the hydrothermal treatment temperature is 180°C, the hydrothermal treatment pressure is preferably 0.01 MPa to 3 MPa, more preferably 0.03 MPa to 2.5 MPa, and even more preferably 0.05 MPa to 2 MPa.

[0127] In step (2b), when the first intermediate is subjected to hydrothermal treatment before being calcined, step (2b) includes a step of separating a solid (first intermediate after hydrothermal treatment) from the mixture obtained by the hydrothermal treatment (hereinafter referred to as a "solid separation step"). The above description of the solid separation step included in the Zr loading step also applies to the solid separation step included in step (2b). The solid obtained in the solid separation step (first intermediate after hydrothermal treatment) corresponds to the first intermediate to be calcined in step (2b).

[0128] In step (2b), the first intermediate is preferably calcined at a temperature of 800° C. or higher and 1000° C. or lower, and more preferably at a temperature of 850° C. or higher and 950° C. or lower. This allows Zr and P to be regularly arranged on the surface of the zeolite particles, and ensures that electrons are effectively donated from Zr and P to Pt.

[0129] The above explanation regarding the Pt loading step also applies to step (2c).

[0130] The catalyst component is obtained in step (2c).

[0131] Step (2c) may include a step of mixing the Pt supporting liquid with the second intermediate and then separating solid matter from the resulting mixture (hereinafter referred to as the "solid matter separation step"). The above description of the solid matter separation step included in the Zr supporting step also applies to the solid matter separation step included in step (2c). The solid matter obtained in the solid matter separation step corresponds to the catalyst component.

[0132] Step (2c) may include a step of calcining the solid obtained after the solid separation step (hereinafter referred to as the "solid calcination step"). The above description of the solid calcination step included in the Zr support step also applies to the solid calcination step included in step (2c). The calcined product obtained in the solid calcination step corresponds to the catalyst component.

[0133] The catalyst component obtained by the method of the present invention will now be described.

[0134] Zr is contained in the catalyst component in the form of one type of Zr-containing component or in the form of two or more types of Zr-containing components. The Zr-containing component is contained outside the framework structure of the zeolite constituting the zeolite particles. Examples of the Zr-containing component include a Zr-containing compound, a complex or reaction product of a Zr-containing compound and a P-containing compound, etc. The explanations regarding the Zr-containing compound and the P-containing compound are the same as those above.

[0135] The Zr-containing component may be in the form of particles, for example. The particles may be primary particles or secondary particles. Specific examples of the shape of primary particles and the meaning of secondary particles are the same as those described above.

[0136] When the method of the present invention includes one or more of the above solid calcination steps, at least a portion of the Zr may be present in the catalyst component in the form of a Zr-containing oxide. Examples of Zr-containing oxides include ZrO2 and composites containing ZrO2 and one or more oxides other than ZrO2. Examples of oxides other than ZrO2 include P2O5, PtO, PtO2, and Pt3O4. In the composite, ZrO2 and one or more oxides other than ZrO2 are chemically bonded. The composite also includes a solid solution of ZrO2 and one or more oxides other than ZrO2.

[0137] P is contained in the catalyst component in the form of one type of P-containing component or two or more types of P-containing components. The P-containing component is contained outside the framework structure of the zeolite constituting the zeolite particles. Examples of the P-containing component include a P-containing compound, a complex or reaction product of a Zr-containing compound and a P-containing compound, etc. The explanations regarding the P-containing compound and the Zr-containing compound are the same as those above.

[0138] The form of the P-containing component is, for example, particles. The particles may be primary particles or secondary particles. Specific examples of the shape of primary particles and the meaning of secondary particles are the same as those described above.

[0139] When the method of the present invention includes one or more of the above solid calcination steps, at least a portion of the P may be present in the catalyst component in the form of a P-containing oxide. Examples of P-containing oxides include P2O5 and composites containing P2O5 and one or more oxides other than P2O5. Examples of oxides other than P2O5 include ZrO2, PtO, PtO2, and Pt3O4. In the composite, P2O5 and one or more oxides other than P2O5 are chemically bonded. The composite also includes a solid solution of P2O5 and one or more oxides other than P2O5.

[0140] Pt is contained in the catalyst component in the form of one type of Pt-containing component or two or more types of Pt-containing components. The Pt-containing component is contained outside the framework structure of the zeolite constituting the zeolite particles. Examples of the Pt-containing component include a Pt-containing compound, a complex or reaction product of a Pt-containing compound with a Zr-containing compound and / or a P-containing compound, an elemental metal, an alloy, etc. The explanations for the Pt-containing compound, Zr-containing compound, and P-containing compound are the same as those above.

[0141] The Pt-containing component may be in the form of particles, for example. The particles may be primary particles or secondary particles. Specific examples of the shape of primary particles and the meaning of secondary particles are the same as those described above.

[0142] When the method of the present invention includes any one or more of the above solids calcination steps, at least a portion of the Pt may be present in the catalyst component in the form of elemental metal.

[0143] The catalyst composition obtained by the method of the present invention may contain other components in addition to the catalyst components obtained by the method of the present invention. Examples of other components include binders and stabilizers. Examples of binders include inorganic oxide binders such as alumina sol, ceria sol, zirconia sol, titania sol, and silica sol. Examples of stabilizers include nitrates, carbonates, oxides, and sulfates of alkaline earth metal elements (e.g., Sr, Ba, etc.). [Example]

[0144] The present invention will be described below based on examples.

[0145] Example 1 (1) Production of MRT-type zeolite particles Deionized water (pure water), potassium hydroxide, aluminum hydroxide, cesium hydroxide, choline bromide ((2-hydroxyethyl)trimethylammonium bromide), and colloidal silica (LUDOX® AS-40, manufactured by Sigma-Aldrich Japan K.K.) were prepared and mixed to obtain a raw material composition having the following component ratios: SiO2 / Al2O3 molar ratio = 13 K / Si=0.28 Cs / Si=0.14 Choline bromide / Si molar ratio = 0.42 H2O / Si molar ratio = 20

[0146] The obtained raw material composition was filled into a sealed container and heated at 150°C for 20 days while standing to crystallize. The raw material composition after crystallization was subjected to solid-liquid separation. The obtained solid was washed with deionized water, and the crystals were recovered. The obtained crystals were dried at 100°C for 8 hours and then heat-treated at 600°C for 1 hour in an air atmosphere to obtain MRT-type zeolite particles. The fact that the obtained zeolite particles were MRT-type was confirmed based on the X-ray diffraction (XRD) pattern obtained by measurement using a powder X-ray diffractometer.

[0147] The obtained MRT-type zeolite particles had the following component ratio and specific surface area. The specific surface area of ​​the zeolite particles was determined by the BET method based on the nitrogen adsorption isotherm measured in accordance with ISO 9277 (JIS Z8330:2013). The static volumetric method was used to measure the amount of adsorbed gas, and the multipoint method was used to analyze the adsorption data. SiO2 / Al2O3 molar ratio = 15 K / Al=0.13 Cs / Al=0.15 Specific surface area: 385m 2 / g

[0148] 1 g of the obtained MRT-type zeolite particles was immersed in 10 g of a 0.1 mol / L aqueous ammonium chloride solution at 60°C, followed by solid-liquid separation. The obtained solid was washed with deionized water to obtain NH4-type MRT-type zeolite particles. The ion exchange rate of alkali metal ions was 46 mol%.

[0149] (2) Production of MRT-type zeolite particles modified with P and Zr (hereinafter referred to as "P / Zr-modified MRT-type zeolite particles"). 0.6 g of orthophosphoric acid (H3PO4) and 1.2 g of zirconium oxynitrate (ZrO(NO3)2·2H2O) were suspended in 50 g of pure water. 10 g of the NH4-type MRT-type zeolite particles obtained in (1) above was added to the resulting suspension and stirred at room temperature (20°C) for 4 hours. The resulting slurry was filtered. The filter cake was dried at 120°C for 12 hours and then calcined at 600°C under atmospheric pressure for 3 hours to obtain P / Zr-modified MRT-type zeolite particles. The resulting P / Zr-modified MRT-type zeolite particles were proton-type.

[0150] (3) Preparation of Pt-loaded P / Zr-modified MRT-type zeolite particles 1 g of the P / Zr-modified MRT zeolite particles obtained in (2) above was immersed in a 0.001 mol / L tetraammineplatinum(II) hydroxide solution at 60°C, followed by solid-liquid separation. The obtained solid was washed with deionized water, and a wet powder was recovered. The obtained wet powder was dried at 100°C for 8 hours and then calcined at 600°C for 3 hours in an air atmosphere to obtain Pt-supported P / Zr-modified MRT zeolite particles. The Pt content in the Pt-supported P / Zr-modified MRT zeolite particles was adjusted to 0.4 mass% based on the mass of the Pt-supported P / Zr-modified MRT zeolite particles. The obtained Pt-supported P / Zr-modified MRT zeolite particles were proton-type.

[0151] <Example 2> In Example 1 (2), instead of the NH type MRT type zeolite particles, commercially available proton type BEA type zeolite particles (SiO / AlO molar ratio = 38, specific surface area: 660 m) were used. 2 Pt-supported P / Zr-modified BEA-type zeolite particles were obtained in the same manner as in Example 1, except that a 0.69 g orthophosphoric acid solution containing 0.69 g of orthophosphate and zirconium oxynitrate was used, and that the amounts of orthophosphoric acid and zirconium oxynitrate used in (2) of Example 1 were changed to 0.69 g and 1.56 g, respectively. The obtained Pt-supported P / Zr-modified BEA-type zeolite particles were of the proton type.

[0152] Example 3 Pt-supported P / Zr-modified BEA-type zeolite particles were obtained in the same manner as in Example 2, except that when producing the P / Zr-modified BEA-type zeolite particles, the BEA-type zeolite particles were added to a suspension and stirred, and the resulting mixture was then placed in a sealed container and subjected to hydrothermal treatment at 180°C for 24 hours and then further hydrothermal treatment at 100°C for 24 hours. The pressure inside the container during the hydrothermal treatment was set to a pressure at which water inside the container could exist in a liquid state. The obtained Pt-supported P / Zr-modified BEA-type zeolite particles are proton-type.

[0153] Example 4 Pt-supported P / Zr-modified BEA-type zeolite particles were obtained in the same manner as in Example 2, except that the calcination temperature was changed to 900° C. The obtained Pt-supported P / Zr-modified BEA-type zeolite particles were of the proton type.

[0154] <Comparative Example 1> 1 g of the P / Zr-modified MRT zeolite particles obtained in Example 1(2) was immersed in a 0.01 mol / L tetraamminepalladium(II) hydroxide solution at 60°C, followed by solid-liquid separation. The obtained solid was washed with deionized water, and a wet powder was recovered. The obtained wet powder was dried at 100°C for 8 hours and then calcined at 600°C for 3 hours in an air atmosphere to obtain Pd-supported P / Zr-modified MRT zeolite particles. The Pd content in the Pd-supported P / Zr-modified MRT zeolite particles was adjusted to 0.4 mass% based on the mass of the Pd-supported P / Zr-modified MRT zeolite particles.

[0155] <Comparative Example 2> 1 g of the P / Zr-modified MRT zeolite particles obtained in Example 1(2) was immersed in a 0.003 mol / L hexaamminerhodium(II) hydroxide solution at 60°C, followed by solid-liquid separation. The obtained solid was washed with deionized water, and a wet powder was recovered. The obtained wet powder was dried at 100°C for 8 hours and then calcined at 600°C for 3 hours in an air atmosphere to obtain Rh-loaded P / Zr-modified MRT zeolite particles. The Rh content in the Rh-loaded P / Zr-modified MRT zeolite particles was adjusted to 0.4 mass% based on the mass of the Rh-loaded P / Zr-modified MRT zeolite particles.

[0156] <Comparative Example 3> 1 g of the MRT zeolite particles obtained in Example 1 (1) was immersed in a 0.001 mol / L tetraammineplatinum(II) hydroxide solution at 60°C, followed by solid-liquid separation. The obtained solid was washed with deionized water, and a wet powder was recovered. The obtained wet powder was dried at 100°C for 8 hours and then calcined at 600°C for 3 hours in an air atmosphere to obtain Pt-supported MRT zeolite particles. The Pt content in the Pt-supported MRT zeolite particles was adjusted to 0.4 mass% based on the mass of the Pt-supported MRT zeolite particles.

[0157] <Comparative Example 4> 1 g of the commercially available proton-type BEA-type zeolite particles used in Example 2 was immersed in a 0.001 mol / L tetraammineplatinum(II) hydroxide solution at 60°C, followed by solid-liquid separation. The obtained solid was washed with deionized water, and a wet powder was recovered. The obtained wet powder was dried at 100°C for 8 hours and then calcined at 600°C for 3 hours in an air atmosphere to obtain Pt-supported BEA-type zeolite particles. The Pt content in the Pt-supported BEA-type zeolite particles was adjusted to 0.4 mass% based on the mass of the Pt-supported BEA-type zeolite particles.

[0158] <Comparative Example 5> (1) Preparation of ZrP2O7 Under an argon stream, 8.33 g of Zr(C4H9O)4 was stirred in 200 mL of C2H5OH at 60°C. Then, 4.38 g of orthophosphoric acid and 0.7 g of ultrapure water were added dropwise, and the mixture was stirred at 60°C for 5 hours (Zr / P = 0.5). After drying at 110°C for 12 hours, the mixture was calcined in an air atmosphere at 600°C for 3 hours and then at 900°C for 5 hours to obtain ZrP2O7 (specific surface area: 32.3 m). 2 / g) was obtained.

[0159] (2) Preparation of Pt-loaded ZrP2O7 One gram of ZrP2O7 obtained in (1) above was immersed in a 0.001 mol / L tetraammineplatinum(II) hydroxide solution at 60°C, followed by solid-liquid separation. The resulting solid was washed with deionized water, and a wet powder was recovered. The wet powder obtained was dried at 100°C for 8 hours and then calcined at 600°C for 3 hours in an air atmosphere to obtain Pt-supported ZrP2O7. The Pt content in the Pt-supported ZrP2O7 was adjusted to 0.4% by mass based on the mass of the Pt-supported ZrP2O7.

[0160] <Test example> Each catalyst composition obtained in Examples 1 to 4 and Comparative Examples 1 to 5 was separately loaded into an evaluation apparatus, and its exhaust gas purification performance was evaluated using a fixed-bed flow reactor. Specifically, 0.1 g of the heat-treated catalyst composition was loaded into a reaction tube, and an evaluation gas containing 200 vol ppm NO, 0.5 vol% H, 10 vol% O, and the remainder N was introduced into the reaction tube at a total flow rate of 1 L / min. The temperature was increased from room temperature to 400 °C at a rate of 10 °C / min to induce the H-SCR reaction. The post-reaction gas was diluted 3 times with N and passed through a gas analyzer (MATRIX-MG5, manufactured by Bruker Japan Co., Ltd.). It was detected by Fourier transform infrared spectroscopy (FT-IR). The NO reduction rate (%) was calculated using the following formula: Note that the "NO concentration in the gas flow after passing through the reaction tube" in the formula below refers to the NO concentration obtained by multiplying the NO concentration measured after diluting the post-reaction gas 3 times with N.

[0161] NO reduction rate (%) = (NO concentration (vol ppm) in the gas flow before being introduced into the reaction tube - NO concentration (vol ppm) in the gas flow after passing through the reaction tube) / NO concentration (vol ppm) in the gas flow before being introduced into the reaction tube × 100

[0162] The NO and NO produced by the reaction were also detected, and the NO production rate (%) and NO production rate (%) were calculated using the following formula: Note that "x2" in the formula for the NO production rate means that one molecule of NO is produced from two molecules of NO.

[0163] NO production rate (%) = NO concentration (vol ppm) in the gas flow after passing through the reaction tube × 2 / NO concentration (vol ppm) in the gas flow before being introduced into the reaction tube × 100

[0164] NO2 production rate (%) = NO2 concentration (vol ppm) in the gas flow after passing through the reaction tube / NO concentration (vol ppm) in the gas flow before being introduced into the reaction tube × 100

[0165] As NO is converted into N2O, NO2, and N2 through the reaction, the difference between the amount of NO consumed and the amounts of N2O and NO2 produced is taken as the amount of N2 produced, and the N2 production rate (%) was calculated using the following formula.

[0166] N2 production rate (%) = NO reduction rate (%) - N2O production rate (%) - NO2 production rate (%)

[0167] In this reaction system, the reaction activity itself is generally low in the low-temperature region, resulting in a low N2 production rate. On the other hand, in the high-temperature region, in addition to the reduction of NO to N2, the oxidation of NO to NO2 also occurs, resulting in a decrease in the N2 production rate. Therefore, as the temperature of this reaction system is increased from near room temperature, the N2 production rate initially increases, reaches a maximum at a certain temperature, and then tends to decrease. The temperature at which the N2 production rate first exceeds 50% (T50 (°C)) is defined as the minimum temperature at which an N2 production rate of 50% or more can be achieved. The temperature at which the N2 production rate first decreases and then falls below 50% is defined as the upper limit temperature at which an N2 production rate of 50% or more can be achieved (Tmax (°C)). The difference between Tmax and T50 (Tmax - T50) is defined as the temperature range at which an N2 production rate of 50% or more can be achieved. The maximum N2 production rate is defined as the Max N2 Production Rate (%), and the temperature at which the Max N2 production rate is achieved is defined as the Max N2 Production Temperature (°C). The measurement results for T50 (°C), Tmax (°C), Tmax-T50, Max N2 production rate (%), and Max N2 production temperature (°C) are shown in Table 1. When there was no temperature range where an N2 production rate of 50% or more could be obtained, "Tmax-T50" in Table 1 is shown as "-". The same applies to T50.

[0168] [Table 1]

Claims

1. 1. A method for producing a catalyst composition for the selective catalytic reduction of NOx in exhaust gases using hydrogen as a reducing agent, comprising: the catalyst composition comprises a catalyst component comprising zeolite particles, Zr, P, and Pt; The method comprises the steps of: (1) providing zeolite particles; and (2) A step of supporting Zr, P, and Pt on the surface of the zeolite particles to obtain the catalyst component. The method comprising:

2. Step (2) is the following step: (2a) a step of supporting Zr and P on the surface of the zeolite particles to obtain a first intermediate; (2b) calcining the first intermediate to obtain a second intermediate; and (2c) A step of supporting Pt on the second intermediate The method of claim 1 , comprising:

3. The method according to claim 2, wherein in step (2b), the first intermediate is subjected to a hydrothermal treatment before calcining the first intermediate.

4. The method according to claim 2, wherein in step (2b), the first intermediate is fired at a temperature of 800°C or higher and 1000°C or lower.

5. The method according to any one of claims 1 to 4, wherein the maximum ring of the zeolite constituting the zeolite particles is an eight-membered ring.

6. The method according to claim 5, wherein the zeolite constituting the zeolite particles is selected from the group consisting of AEI type, AFX type, ANA type, CHA type, DDR type, ERI type, GIS type, KFI type, LTA type, MRT type, PAU type and YUG type.

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