Catalyst for gas-phase ammonia decomposition, catalyst body, process, and device for gas-phase ammonia decomposition

Abstract

According to the present invention, a catalyst for gas-phase ammonia decomposition includes a mixture of a primary catalyst powder and a secondary catalyst powder as an active catalyst component. The primary catalyst powder includes: a carrier that contains at least one substance selected from the group that consists of ceria, silica, alumina, titania, zirconia, titanosilicates, and aluminosilicates; and ruthenium and platinum that are carried on the carrier. The second catalyst powder includes at least one substance selected from the group that consists of iron ion–exchanged BEA aluminosilicates, cobalt ion–exchanged BEA aluminosilicates, and copper ion–exchanged BEA aluminosilicates. The platinum content of the first catalyst powder is at least 0.001 but less than 1 part by mass per 1 part by mass of ruthenium.

Description

Catalyst for vapor-phase ammonia decomposition, catalytic body, process, and apparatus for vapor-phase ammonia decomposition

[0001] The present invention relates to an ammonia decomposition catalyst and an exhaust gas treatment method. Ｘ and / or N ２ While suppressing the by-production of O, ammonia (NH ３ ) and can promote the gas phase decomposition reaction of NO Ｘ and / or N ２ Catalysts capable of promoting the gas-phase decomposition reaction of O (catalysts for gas-phase ammonia decomposition), and NO Ｘ and / or N ２ While suppressing the by-production of O, NH ３ Decomposes and NO Ｘ and / or N ２ This application claims priority to Japanese Patent Application No. 2024-030683, filed on February 29, 2024, with the Japan Patent Office, the contents of which are incorporated herein by reference.

[0002] To achieve carbon neutrality, ammonia fuel, which does not emit carbon dioxide when burned, is expected. ３ , NO Ｘ and N ２ Gas containing O is discharged. Ｘ and N ２ O can have a negative impact on the environment. ２ Since O has a high global warming potential (GWP) of approximately 300, there is a strong demand to reduce emissions. In addition, in fields where ammonia is stored and used, such as ammonia fuel ships, ammonia transport ships, ammonia fuel storage bases, ammonia tanks for denitration systems in power plants, and ammonia cooling and refrigeration systems, for example, when tanks and pipes are purged with nitrogen or the like, NH ３ In the treatment of wastewater containing ammonia, such as wastewater from food and drinking water production, chemical factories, plating plants, semiconductor parts manufacturing, and domestic wastewater, a large amount of gas containing NH is released. ３ A large amount of gas containing NH is released. ３is a malodorous substance that causes mucous membrane irritation, respiratory irritation, conjunctival edema, and corrosion.

[0003] NO Ｘ (Nitric oxide (NO) and nitrogen dioxide (NO ２ )) or N ２ Catalyst and method for promoting the decomposition reaction of nitrous oxide (NH) ３ Various catalysts and methods have been proposed for promoting the decomposition reaction of .

[0004] For example, Patent Document 1 discloses an exhaust gas purification catalyst having a function of reducing nitrogen oxides to ammonia and a function of oxidatively decomposing ammonia, characterized in that it comprises a first component which is a composition comprising titanium oxide and oxides of one or more elements selected from molybdenum, tungsten, and vanadium, or a composition comprising zeolite supported with copper or iron, and a second component which is pre-supported on a porous body and which comprises at least one metal selected from the group consisting of iridium, palladium, rhodium, and ruthenium and platinum, the weight ratio of the metal to the platinum being greater than 0 but not greater than 5. However, Patent Document 1 only specifically discloses in examples an exhaust gas purification catalyst which combines a first component comprising Ti oxide, W oxide, and V oxide with a second component comprising ruthenium and platinum, and an exhaust gas purification catalyst which combines a first component obtained by ion-exchanging Cu ions into mordenite with a second component comprising iridium and platinum.

[0005] Patent Document 2 discloses an exhaust gas aftertreatment device for a diesel engine, comprising a diesel particulate matter filter disposed at the most upstream position on an exhaust pipe connected to an exhaust manifold of the engine, a diesel oxidation catalyst (DOC catalyst) disposed downstream of the diesel particulate matter filter, and an ammonia SCR catalyst containing zeolite disposed downstream of the diesel oxidation catalyst, wherein the diesel oxidation catalyst is comprised of a carrier supporting a single active material made of ruthenium or a carrier supporting a composite active material made of platinum and ruthenium, with the platinum to ruthenium weight ratio being equal to or less than 2. However, Patent Document 2 only discloses the placement of the ammonia SCR catalyst downstream of the diesel oxidation catalyst.

[0006] Patent Document 3 discloses an ammonia slip catalyst including a first SCR catalyst and an oxidation catalyst including ruthenium or a ruthenium mixture (e.g., a mixture of Pt and Ru) supported on a support including a rutile phase and a substrate. Patent Document 3 discloses that the ammonia slip catalyst contains 0.1 to 10 wt. % ruthenium, and that the term "mixture of Pt and Ru" includes an alloy of platinum and ruthenium, a mixed metal oxide of Pt and Ru, a mixture of discrete Pt and Ru oxide particles on a support, or a combination thereof, in each case with more than 50 mol. ruthenium present. Patent Document 3 also discloses that examples of the first SCR catalyst include a Cu-SCR catalyst including copper and a molecular sieve, or an Fe-SCR catalyst including iron and a molecular sieve. However, Patent Document 3 only specifically discloses an oxidation catalyst in which only ruthenium is supported on a support in the examples.

[0007] Patent Document 4 discloses an ammonia decomposition catalyst for treating exhaust gases containing ammonia and moisture, comprising: a first layer containing a precious metal, an inorganic oxide, and a first proton-type zeolite or a first ion-exchanged zeolite ion-exchanged with Cu, Co, or Fe ions; and a second layer provided on the surface of the first layer and containing a second proton-type zeolite or a second ion-exchanged zeolite ion-exchanged with Cu, Co, or Fe ions, wherein the first and second proton-type zeolites and the first and second ion-exchanged zeolites have CHA structures. Patent Document 4 states that the precious metal is at least one selected from the group consisting of Pt, Pd, Ir, and Rh.

[0008] Patent Document 5 discloses a catalytic device for removing nitrogen oxides and ammonia from the exhaust gas of a lean-burn combustion engine, the catalytic device including an upstream SCR catalyst including a support substrate and a first washcoat containing a first SCR catalytically active composition applied to the support substrate, and a downstream ASC catalyst including a support substrate and a lower layer including a third washcoat containing an oxidation catalyst applied to the support substrate, and an upper layer including a second washcoat containing a second SCR catalytically active composition applied to the lower layer. Patent Document 5 teaches that the oxidation catalyst includes a platinum group metal selected from the group consisting of ruthenium, rhodium, palladium, iridium, and platinum.

[0009] Furthermore, as a catalyst for treating wastewater containing nitrogen compounds such as ammonia, for example, Patent Document 6 discloses a catalyst for use in wet oxidation treatment of wastewater, which is characterized in that it is composed of ruthenium, a compound containing at least one element selected from the group consisting of iron, titanium, silicon, aluminum, zirconium, and cerium as component A, and at least one noble metal selected from the group consisting of silver, gold, platinum, palladium, and iridium as component B or a compound containing said noble metal, and the mass ratio of ruthenium to component B (Ru / B ratio) is 2 / 1 or more and 50 / 1 or less.

[0010] Japanese Patent Laid-Open No. 8-290062 Japanese Patent Laid-Open No. 2011-52679 WO2018 / 057844A1 Japanese Patent Laid-Open No. 2022-105849 Special Publication No. 2024-500370 Japanese Patent Laid-Open No. 2014-140800

[0011] The object of the present invention is to Ｘ and / or N ２ While suppressing the by-production of O, ammonia (NH ３ ) and can promote the gas phase decomposition reaction of NO Ｘ and / or N ２ Catalysts capable of promoting the gas-phase decomposition reaction of O (catalysts for gas-phase ammonia decomposition), and NO Ｘ and / or N ２ While suppressing the by-production of O, NH ３ Decomposes and NO Ｘ and / or N ２The present invention aims to provide a gas phase reaction process capable of decomposing O.

[0012] [1] A catalyst for gas-phase ammonia decomposition, comprising, as active catalyst components, a mixture of: a first catalyst powder comprising a carrier containing at least one selected from the group consisting of ceria, silica, alumina, titania, zirconia, titanosilicate, and aluminosilicate, and ruthenium and platinum supported on the carrier; and a second catalyst powder comprising at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate, wherein the amount of platinum in the first catalyst powder is 0.001 parts by mass or more but less than 1 part by mass per part by mass of ruthenium.

[0013] [2] The catalyst according to [1], wherein the amount of platinum in the first catalyst powder is 0.01 parts by mass or more and less than 0.5 parts by mass per part by mass of ruthenium, the amount of platinum contained in 100 parts by mass of the first catalyst powder is 0.01 to 2 parts by mass, and the amount of ruthenium contained in 100 parts by mass of the first catalyst powder is 2 to 10 parts by mass.

[0014] [3] The catalyst according to [1], wherein the first catalyst powder contains platinum in an amount of 0.01 parts by mass or more but less than 0.5 parts by mass per part by mass of ruthenium, the amount of platinum contained in a total of 100 parts by mass of the first catalyst powder and the second catalyst powder is 0.001 to 0.1 parts by mass, and the amount of ruthenium contained in a total of 100 parts by mass of the first catalyst powder and the second catalyst powder is 0.01 to 1 part by mass.

[0015] [4] The catalyst according to any one of [1] to [3], wherein the first catalyst powder has a support containing at least one selected from the group consisting of silica, titanosilicate, MEL-type aluminosilicate, and MFI-type aluminosilicate.

[0016] [5] The catalyst according to any one of [1] to [4], wherein the second catalyst powder comprises an iron ion-exchanged BEA-type aluminosilicate.

[0017] [6] The catalyst according to any one of [1] to [5], wherein the second catalyst powder comprises an iron ion-exchanged, OSDA-free, BEA-type aluminosilicate.

[0018] [7] A catalyst body for gas-phase ammonia decomposition, comprising a support and the catalyst according to any one of [1] to [6] supported on the support. [8] A catalyst body for gas-phase ammonia decomposition, comprising a molded body containing the catalyst according to any one of [1] to [6].

[0019] [9] In the presence of the catalyst according to any one of [1] to [6], in a gas to be treated, ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ and a chemical reaction of O to nitrogen and water.

[0020]

[10] A method for treating a gas to be treated, comprising: continuously passing the gas to be treated through a first catalyst layer containing, as an active catalyst component, only a second catalyst powder containing at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate; and then continuously passing the gas to be treated through a second catalyst layer containing the catalyst according to any one of [1] to [6]. ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ and a process for carrying out a chemical reaction of O to nitrogen and water.

[0021]

[11] A method for producing a gas to be treated, comprising: continuously passing the gas to be treated through a first catalyst layer containing the catalyst according to any one of [1] to [6]; and subsequently continuously passing the gas to be treated through a second catalyst layer containing the catalyst according to any one of [1] to [6]; wherein the proportion of platinum contained in the catalyst placed in the first catalyst layer is lower than the proportion of platinum contained in the catalyst placed in the second catalyst layer. ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ and a process for carrying out a chemical reaction of O to nitrogen and water.

[0022]

[12] The process according to [9],

[10] or

[11] , further comprising adding at least one reaction aid selected from the group consisting of ammonia and urea to the gas to be treated.

[0023]

[13] An apparatus for vapor-phase ammonia decomposition, comprising: a first catalyst layer containing, as an active catalyst component, only a second catalyst powder containing at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate; and a second catalyst layer disposed downstream of the first catalyst layer and containing the catalyst according to any one of [1] to [6].

[0024]

[14] An apparatus for vapor-phase ammonia decomposition, comprising: a first catalyst layer comprising the catalyst according to any one of [1] to [6]; and a second catalyst layer disposed downstream of the first catalyst layer, comprising the catalyst according to any one of [1] to [6]; wherein the proportion of platinum contained in the catalyst disposed in the first catalyst layer is lower than the proportion of platinum contained in the catalyst disposed in the second catalyst layer.

[0025] The catalyst of the present invention is a catalyst for reducing nitrogen oxides (NO Ｘ ) and nitrous oxide (N ２ O) and ammonia (NH ３ The catalyst of the present invention has the function of oxidizing and decomposing NO Ｘ and / or N ２ While suppressing the by-production of O, ammonia (NH ３ ) and can promote the gas phase decomposition reaction of NO Ｘ and / or N ２ The catalyst of the present invention can promote the gas phase decomposition reaction of NH ３ A gas containing low NH ３ Low NO concentration Ｘ Concentration and / or low N ２ The process of the present invention is suitable for chemical reactions to convert NO into a gas with a high concentration of O. Ｘ and / or N ２ While suppressing the by-production of O, ammonia (NH ３ ) and NOＸ and / or N ２ The process of the present invention can decompose NH ３ A gas containing low NH ３ Low NO concentration Ｘ Concentration and / or low N ２ It is preferable to convert it into a gas with an O concentration.

[0026] NH ３ The chemical reaction that can directly convert ammonia into nitrogen and water (direct decomposition reaction of ammonia) is expressed by formula (4). ３ +30 ２ →2N ２ +6H ２ O (4)

[0027] NO Ｘ into nitrogen and water (NO Ｘ The gas phase decomposition reaction of 4NO+4NH is represented by the following equations (6), (7) and (8): ３ +O ２ →4N ２ +6H ２ O (6) 6NO ２ +8NH ３ →7N ２ +12H ２ O (7) NO+NO ２ +2NH ３ →2N ２ +3H ２ O (8) N ２ A chemical reaction that can change O into nitrogen and water (N ２ The gas-phase decomposition reaction of 3N ２ O + 2NH ３ →4N ２ +3H ２ O (9)

[0028] In parallel with the chemical reaction represented by formula (4), the chemical reactions (side reactions) represented by formulas (1), (2), and (3) may proceed. ３ +5O ２ → 4NO + 6H２ O (1) 4NH ３ +7O ２ →4NO ２ +6H ２ O (2) 2NH ３ +20 ２ →N ２ O+3H ２ O (3) NO Ｘ and N ２ O is a harmful substance that affects the environment, etc. As described above, the catalyst of the present invention is ３ This promotes a chemical reaction (direct decomposition of ammonia) that can directly convert NO into nitrogen and water. Ｘ and N ２ The catalyst of the present invention reduces the rate of progress of the reaction (side reaction) that produces NO Ｘ Decomposition reaction of and N ２ As a result, the catalyst of the present invention also promotes the decomposition reaction of NH ３ to the intermediate (NO Ｘ and N ２ This promotes a chemical reaction (indirect decomposition of ammonia) that can convert ammonia into nitrogen and water via oxygen.

[0029] The result of evaluation (1) is NO Ｘ By-product rate @ 500℃ and NH ３ 1 is a graph showing the relationship between the decomposition reaction rate at 350°C and the results of evaluation (1). ２ O by-production rate @ 350℃ and NH ３ 1 is a graph showing the relationship between the decomposition reaction rate at 350°C and the NO Ｘ By-production rate @ 500°C and the results of evaluation (1) and evaluation (2) are NH ３ 1 is a graph showing the relationship between the decomposition reaction rate and the aging rate at 350°C. ２ O by-production rate @ 350 °C and NH ３ 1 is a graph showing the relationship between the decomposition reaction rate and the aging rate at 350°C. Ｘ By-product rate @ 500℃ and NH ３1 is a graph showing the relationship between the decomposition reaction rate at 350°C and the results of evaluation (2). ２ O by-production rate @ 350℃ and NH ３ 1 is a graph showing the relationship between the decomposition reaction rate at 350°C and the NO Ｘ By-production rate @ 500°C and the results of evaluation (1) and evaluation (2) are NH ３ 1 is a graph showing the relationship between the decomposition reaction rate and the aging rate at 350°C. ２ O by-production rate @ 350 °C and NH ３ FIG. 1 is a graph showing the relationship between decomposition reaction rate and aging rate at 350° C.

[0030] The catalyst for vapor phase ammonia decomposition of the present invention comprises a mixture of a first catalyst powder and a second catalyst powder as an active catalyst component.

[0031] The first catalyst powder comprises a support and ruthenium and platinum supported on the support.

[0032] The support used in the first catalyst powder is a support containing at least one selected from the group consisting of ceria, silica, alumina, titania, zirconia, titanosilicate, and aluminosilicate. The support used in the first catalyst powder is preferably a support containing silica, alumina, and / or titania, and more preferably a support containing silica, titanosilicate, or aluminosilicate. The support used in the first catalyst powder is preferably porous. The specific surface area of ​​the support used in the first catalyst powder is not particularly limited, and may be, for example, 10 to 1000 m. ２ / g is preferred, and 50 to 500m ２Specific examples of the carrier used in the first catalyst powder include ceria powder, silica powder, alumina powder, titania powder, zirconia powder, titanosilicate powder, or aluminosilicate powder; a mixture of two or more powders selected from the group consisting of ceria powder, silica powder, alumina powder, titania powder, zirconia powder, titanosilicate powder, and aluminosilicate powder; a composite of two or more oxides selected from the group consisting of ceria, silica, alumina, titania, zirconia, titanosilicate, and aluminosilicate (for example, silica-titania, alumina-titania, ceria-titanium, Examples of suitable powders include powders of silica-alumina, silica-zirconia, alumina-zirconia, etc.; and powders in which at least one powder selected from the group consisting of ceria powder, silica powder, alumina powder, titania powder, zirconia powder, titanosilicate powder, and aluminosilicate powder is doped, supported, or composited with at least one element selected from the group consisting of cerium, silicon, aluminum, titanium, and zirconium and different from the elements constituting the powder, and / or other rare metal elements such as molybdenum, tungsten, and vanadium. Doped, supported, or composited powders tend to have high resistance to hydrothermal aging.

[0033] Titanosilicate is a composite of titania and silica, and aluminosilicate is a composite of alumina and silica. Silica, titanosilicate, or aluminosilicate may be a hydrous oxide, a hydrated oxide, or an anhydrous oxide. The support used in the first catalyst powder is preferably crystalline porous. Silica and aluminosilicate are preferably SiO ４ A structure consisting of stacked tetrahedron sheets (SiO ４ The structure may be a layer structure (a structure in which tetrahedrons are two-dimensionally linked via oxygen atoms), but it may also be a zeolite structure or SiO ４Preferably, the titanosilicate has a structure in which tetrahedra are three-dimensionally linked via oxygen atoms. The titanosilicate may be a composite having a structure in which titania is coated with silica, or a composite having a structure in which silica is coated with titania. The titanosilicate preferably used in the present invention has a titania / silica ratio of preferably 0.1 / 99.9 to 99.9 / 0.1, more preferably 50 / 50 to 99.5 / 0.5, and even more preferably 70 / 30 to 99 / 1.

[0034] Examples of the structure of the aluminosilicate used in the first catalyst powder include A-type (LTA-type), X-type (FAU-type), LSX-type (FAU-type), beta-type (BEA-type), ZSM-5-type (MFI-type), ZSM-11-type (MEL-type), ferrierite-type (FER-type), mordenite-type (MOR-type), L-type (LTL-type), Y-type (FAU-type), MCM-22-type (MWW-type), offretite / erionite-type (O / E-type), AEI-type, AEL-type, AFT-type, AFX-type, CHA-type, EAB-type, ERI-type, KFI-type, LEV-type, LTN-type, MSO-type, RHO-type, SAS-type, SAT-type, SAV-type, SFW-type, TON-type, and TSC-type. Of these, the MFI type or MEL type is preferred, and the MFI type is more preferred.

[0035] The first catalyst powder has ruthenium and platinum supported on a carrier, and the amount of platinum (Pt) per part by mass of ruthenium (Ru) in the first catalyst powder is 0.001 parts by mass or more and less than 1 part by mass, more preferably 0.005 parts by mass or more and less than 0.8 parts by mass, even more preferably 0.01 parts by mass or more and less than 0.5 parts by mass, still more preferably 0.03 parts by mass or more and 0.3 parts by mass or less, and even more preferably 0.015 parts by mass or more and 0.25 parts by mass or less.

[0036] In the first catalyst powder, the amount of platinum (Pt) contained in 100 parts by mass of the first catalyst powder is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1.5 parts by mass, and even more preferably 0.01 to 1.2 parts by mass.

[0037] In the first catalyst powder, the amount of ruthenium (Ru) contained in 100 parts by mass of the first catalyst powder is preferably 2 to 10 parts by mass, more preferably 3 to 8 parts by mass, and even more preferably 4 to 6 parts by mass.

[0038] The first catalyst powder may have a metal element other than ruthenium and platinum supported on a carrier. Examples of such other metal elements include gold, silver, rhodium, palladium, osmium, iridium, and rhenium; rare earth elements such as cerium (Ce); and rare metal elements such as molybdenum, tungsten, and vanadium. The ratio of the rare earth element to the carrier in the first catalyst powder is not particularly limited as long as it does not impair the effects of the present invention. For example, the amount of the rare earth element per 1 part by mass of the total amount of ruthenium and platinum in the first catalyst powder is preferably 1 part by mass or more but less than 10 parts by mass, more preferably 3 parts by mass or more but 7 parts by mass or less, and even more preferably 4 parts by mass or more but 6 parts by mass or less. A first catalyst powder having a metal element other than ruthenium and platinum supported on a carrier tends to have high resistance to hydrothermal aging (a high aging ratio).

[0039] Preparation of the first catalyst powder involves, for example, supporting ruthenium and platinum on a support, followed by pulverization or crushing as necessary. Supporting can be performed, for example, by immersing the support in a solution, suspension, or emulsion containing ruthenium and platinum. Supporting of metal elements other than ruthenium and platinum can also be performed in a similar manner. After immersion, kneading, evaporation to dryness, drying, calcination, etc. can be performed. The drying temperature may be any temperature at which the liquid can be removed, for example, 100 to 150°C. The calcination temperature may be any temperature lower than the heat resistance temperature of the support, for example, 350 to 550°C. The calcination time is, for example, 1 to 5 hours.

[0040] The first catalyst powder is preferably porous. The pore size distribution of the first catalyst powder is not particularly limited. The first catalyst powder is not particularly limited by its particle size distribution as long as it is in the form of a fine powder. The particle size distribution can be adjusted by pulverization / crushing, classification, etc.

[0041] The second catalyst powder comprises at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate.

[0042] The iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, or copper ion-exchanged BEA-type aluminosilicate is obtained by exchanging a part or all of the cations in the BEA-type aluminosilicate with iron ions, cobalt ions, or copper ions.

[0043] The BEA-type aluminosilicate that can be subjected to ion exchange has a Si / Al ratio in skeletal analysis. 骨格 Preferably, the ratio is 9 or more. The higher the proportion of Si, the higher the durability of the catalyst tends to be. ２９ The spectrum measured by Si MAS NMR is (SiO ４ ) ４－ The four TOs adjacent to ４ Depending on the number n of T's where T is Al, resonance absorptions of Si(0Al), Si(1Al), Si(2Al), Si(3Al) and Si(4Al) are observed. Their peak intensities I Ｓｉ(ｎＡｌ) to Si / Al 骨格 is calculated by a known method. The BEA type aluminosilicate that can be subjected to ion exchange is preferably porous. The pore size of the BEA type aluminosilicate that can be subjected to ion exchange is not particularly limited, and is preferably, for example, 0.01 to 10 nm, and more preferably 0.2 to 2 nm. The specific surface area of ​​the BEA type aluminosilicate that can be subjected to ion exchange is not particularly limited, and is, for example, 100 to 1200 m ２ / g is preferred, and 200 to 800m ２ / g is more preferred.

[0044] BEA-type aluminosilicate can be obtained, for example, by mixing a silica source, an alumina source, an alkali source, a solvent, an organic structure-directing agent (OSDA), a surfactant, etc. to obtain a starting reaction mixture, which is then subjected to a hydrothermal reaction under high temperature and pressure in an autoclave. The BEA-type aluminosilicate obtained by this method contains organic components derived from the OSDA. However, it appears that the organic components can be removed by subsequent calcination.

[0045] BEA-type aluminosilicate can be obtained by hydrothermal reaction without using an OSDA. BEA-type aluminosilicate can be obtained by utilizing mechanochemical treatment and steam synthesis without using an OSDA. BEA-type aluminosilicate obtained without using an OSDA (hereinafter sometimes referred to as OSDA-free BEA-type aluminosilicate) does not contain organic components derived from OSDA. In the present invention, OSDA-free BEA-type aluminosilicate can be preferably subjected to ion exchange.

[0046] Ion exchange can be performed by immersing a BEA-type aluminosilicate or an OSDA-free BEA-type aluminosilicate in a solution containing iron ions, cobalt ions, or copper ions, followed by filtration, drying, and calcination as necessary. The pH of the solution containing iron ions, cobalt ions, or copper ions is preferably adjusted appropriately to promote ion exchange. The pH of the solution containing iron ions, cobalt ions, or copper ions is, for example, 1 to 8, preferably 1.2 to 6, and more preferably 1.5 to 5. To adjust the pH, basic compounds such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, sodium carbonate, and potassium carbonate, or acidic compounds such as hydrochloric acid and nitric acid, can be used. The drying temperature may be any temperature at which the liquid can be removed, such as 100 to 150°C. The calcination temperature need only be lower than the heat resistance temperature of the BEA-type aluminosilicate or OSDA-free BEA-type aluminosilicate, and is, for example, 350 to 800°C. The calcination time can be appropriately set depending on the calcination temperature, and is, for example, 1 to 10 hours. After ion exchange, the product can be powdered by pulverization or crushing, as necessary. The amount of iron ions, cobalt ions, or copper ions exchanged for cations is preferably 0.1 to 10 mass%, and more preferably 0.7 to 7 mass%, relative to the BEA-type aluminosilicate or OSDA-free BEA-type aluminosilicate. The second catalyst powder may contain a BEA-type aluminosilicate or OSDA-free BEA-type aluminosilicate having at least one element selected from the group consisting of Fe, Co, and Cu attached (supported) thereon.

[0047] The second catalyst powder is preferably porous. The pore size distribution of the second catalyst powder is not particularly limited. The second catalyst powder is not particularly limited by the particle size distribution as long as it is in the form of a fine powder. The particle size distribution can be adjusted by pulverization / crushing, classification, etc. In addition, the second catalyst powder is preferably Si / Al 骨格 The second catalyst powder preferably has a Si / Al ratio of 9 or more before and after ion exchange. 骨格 It is preferable that the value has not changed.

[0048] The second catalyst powder has acid sites derived from OH groups and the like. The properties of the acid sites can be observed by a method generally known as the pyridine-TPD method. In the pyridine-TPD method, for example, a flame ionization detector (FID) can be used as a detector. Pyridine adsorbs to the acid sites. Pyridine can adsorb to acid sites on the outer surface of the catalyst pores and on the inner surface of the pores. It is generally understood that the higher the temperature at which the adsorbed pyridine desorbs, the stronger the acid strength of the acid sites. It is also said that pyridine desorbed at high temperatures is from acid sites affected by diffusion, i.e., acid sites on the inner surface of the pores (Nakano et al., "Measurement of the Acidity of Zeolites by Temperature Programmed Desorption Method," Toyo Soda Research Report, Vol. 29, No. 1 (1985), pp. 3-11). The effective molecular diameter of pyridine is said to be 5.8 Å (see Anderson et al. J. Catal., 58, 114 (1979)). The total number of acid sites can be determined from the saturated adsorption amount of pyridine. When pyridine is adsorbed and then the temperature is raised at a constant rate (20°C / min), the acid strength distribution of the acid sites can be determined from the distribution of the amount of pyridine desorbed at each temperature (this distribution is sometimes referred to as a TPD spectrum). In the present invention, pyridine adsorption can be performed at room temperature to 150°C, preferably at 150°C.

[0049] In the TPD spectrum of the second catalyst powder, the ratio of the total amount of pyridines eliminated within a temperature range of 150° C. or higher and lower than 450° C. to the total amount of pyridines eliminated within a temperature range of 450° C. or higher and 800° C. is preferably 0.9 or higher, more preferably 0.98 or higher, even more preferably 1 or higher, and still more preferably 1.1 or higher. There is no particular upper limit to the ratio of the total amount of pyridines eliminated within a temperature range of 150° C. or higher and lower than 450° C. to the total amount of pyridines eliminated within a temperature range of 450° C. or higher and 800° C., as long as the powder can be produced.

[0050] In the second catalyst powder, the total amount of pyridine eliminated within a temperature range of 150° C. or higher and lower than 450° C. in a TPD spectrum is preferably 100 μmol or more, more preferably 200 μmol or more, even more preferably 250 μmol or more, and still more preferably 300 μmol or more per gram of catalyst. There is no particular upper limit to the total amount of pyridine eliminated within a temperature range of 150° C. or higher and lower than 450° C., as long as it can be produced.

[0051] In the second catalyst powder, the total amount of pyridine eliminated within the temperature range of 450° C. to 800° C. in TPD spectrum is preferably 1000 μmol or less, more preferably 800 μmol or less, and even more preferably 500 μmol or less per gram of catalyst. The lower limit of the total amount of pyridine eliminated within the temperature range of 450° C. to 800° C. is not particularly limited, as long as it can be produced.

[0052] In the TPD spectrum of the second catalyst powder, the L peak value (the amount of pyridine desorption at the maximum peak top located in the range of 150°C or higher but lower than 450°C) is greater than the H peak value (the amount of pyridine desorption at the maximum peak top located in the range of 450°C or higher but lower than 800°C). That is, the ratio of the L peak value to the H peak value is preferably greater than 1, more preferably 1.12 or higher, even more preferably 1.2 or higher, still more preferably 1.4 or higher, and most preferably 1.6 or higher. There is no particular upper limit to the ratio of the L peak value to the H peak value, as long as it is producible.

[0053] The second catalyst powder has a lower limit of the temperature at which an H peak appears in a TPD spectrum (the temperature at the maximum peak top within the range of 450°C or higher and 800°C or lower) of preferably 490°C, more preferably 510°C, and even more preferably 530°C, and an upper limit of 650°C, more preferably 620°C, even more preferably 600°C, and still more preferably 580°C.

[0054] The second catalyst powder preferably has a high saturated adsorption amount of pyridine. The saturated adsorption amount of pyridine in the second catalyst powder is preferably 100 μmol or more, more preferably 200 μmol or more, even more preferably 500 μmol or more, and even more preferably 700 μmol or more per gram of catalyst. The upper limit of the saturated adsorption amount of pyridine in the second catalyst powder is not particularly limited as long as it can be produced, and is, for example, preferably 2000 μmol, more preferably 1500 μmol per gram of catalyst. The saturated adsorption amount of pyridine can be measured at 150°C.

[0055] The second catalyst powder preferably has a large crystallite size. The crystallite size of the second catalyst powder is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, and even more preferably 30 nm or more. The upper limit of the crystallite size of the second catalyst powder is not particularly limited as long as it can be produced, and is, for example, preferably 100 nm, more preferably 80 nm. The crystallite size can be measured by X-ray diffraction (see, for example, JIS H 7805 or JIS R 7651).

[0056] The second catalyst powder is H ２ O20% and SO ２ After 70 hours of exposure to gas containing 20 ppm NO at 530°C, ２ The second catalyst powder preferably has a high decomposition rate of H and NO. ２ O20% and SO ２ Even after 70 hours of exposure to gas containing 20 ppm NO at 530°C, ２ It is preferable that the decomposition rate is 60% or more and the NO decomposition rate is 90% or more.

[0057] The catalyst for vapor phase ammonia decomposition of the present invention may contain a third catalyst powder as an active catalyst component in addition to the first catalyst powder and the second catalyst powder.

[0058] The third catalyst powder comprises an oxide of titanium, an oxide of tungsten and / or molybdenum, and an oxide of cerium and / or vanadium, preferably an oxide of titanium, an oxide of tungsten, and an oxide of cerium.

[0059] The ratio of Ce element and / or V element to Ti element is (CeO ２ +V ２ O ５ ) / TiO ２ The ratio of Mo and / or W to Ti, expressed as a weight percentage of (MoO3 + WO3) / TiO2, is preferably 1 to 50% by weight, more preferably 10 to 40% by weight.

[0060] In preparing the third catalyst powder, titanium oxide powder or a titanium oxide precursor can be used as the titanium oxide raw material. Examples of titanium oxide precursors include titanium oxide slurry, titanium oxide sol, titanium sulfate, titanium tetrachloride, titanates, and titanium alkoxides. In the present invention, a material that forms anatase titanium oxide is preferably used as the titanium oxide raw material. Vanadium compounds such as vanadium pentoxide, ammonium metavanadate, and vanadyl sulfate can be used as the vanadium oxide raw material. Ammonium paratungstate, ammonium metatungstate, tungsten trioxide, and tungsten chloride can be used as the tungsten oxide raw material. Ammonium molybdate and molybdenum trioxide can be used as the molybdenum oxide raw material. Cerium oxide raw materials include cerous nitrate, ceric nitrate, cerium carbonate, cerous sulfate, ceric sulfate, and cerous acetate.

[0061] The third catalyst powder may contain, as a promoter or additive, an oxide of P, an oxide of S, an oxide of Al (e.g., alumina), an oxide of Si (e.g., glass fiber), an oxide of Zr (e.g., zirconia), gypsum (e.g., gypsum dihydrate), zeolite, etc. These may be used in the form of powder, sol, slurry, fiber, etc. when preparing the catalyst.

[0062] The preparation of the third catalyst powder includes, for example, adding a solvent (e.g., water) to the raw materials of each oxide and, if necessary, a co-catalyst or additive, kneading the mixture, evaporating to dryness, drying, calcining the resulting mixture, and then, if necessary, pulverizing or crushing it to obtain a powder. The drying temperature may be any temperature at which the liquid can be removed, for example, 100 to 150°C. The calcination temperature may be any temperature lower than the heat resistance temperature of the oxide, for example, 350 to 550°C. The calcination time is, for example, 1 to 5 hours.

[0063] The third catalyst powder is preferably porous. The pore size distribution of the third catalyst powder is not particularly limited. The third catalyst powder is not particularly limited by its particle size distribution as long as it is in the form of a fine powder. The particle size distribution can be adjusted by pulverization / crushing, classification, etc.

[0064] The mixture contained in the catalyst of the present invention can be obtained by mixing a first catalyst powder, a second catalyst powder, and, if necessary, a third catalyst powder. Mixing may be dry or wet. After mixing, drying or calcination, pulverization / crushing, granulation, and classification may be performed as needed. The drying temperature may be any temperature at which the liquid can be removed, for example, 100 to 150°C. The calcination temperature may be any temperature lower than the heat resistance temperature of the oxide, for example, preferably 350 to 650°C, more preferably 450 to 600°C, and even more preferably 480 to 570°C. The calcination time can be appropriately set depending on the calcination temperature, for example, 1 to 5 hours. The catalyst of the present invention is not particularly limited by particle size distribution. The particle size distribution can be adjusted by pulverization / crushing, granulation, classification, etc.

[0065] The mixing ratio of the first catalyst powder to the second catalyst powder or the mixing ratio of the first catalyst powder to the second catalyst powder to the third catalyst powder may be determined based on, for example, the amount of NH ３ Concentration, NO Ｘ concentration and N ２ The O concentration can be set to fall within a predetermined range.

[0066] The amount of the first catalyst powder contained in the catalyst of the present invention is preferably 0.01 to 10 mass%, more preferably 0.1 to 5 mass%, and even more preferably 0.5 to 3 mass%. The amount of the second catalyst powder per part by mass of the first catalyst powder is preferably 1 to 100 mass parts, more preferably 10 to 70 mass parts, and even more preferably 20 to 55 mass parts.

[0067] In the catalyst of the present invention, the amount of platinum contained in 100 parts by mass of the combined total of the first catalyst powder and the second catalyst powder is preferably 0.0005 to 0.2 parts by mass, and more preferably 0.001 to 0.1 parts by mass. In the catalyst of the present invention, the amount of ruthenium contained in 100 parts by mass of the combined total of the first catalyst powder and the second catalyst powder is preferably 0.01 to 1 part by mass, and more preferably 0.05 to 0.5 parts by mass. The total amount of ruthenium and platinum contained in the catalyst of the present invention is preferably 1 to 5000 ppm, more preferably 10 to 3000 ppm, even more preferably 100 to 2000 ppm, and even more preferably 250 to 1800 ppm.

[0068] The third catalyst powder can be mixed when heat resistance is required. The amount of the third catalyst powder relative to 1 part by mass of the first catalyst powder is preferably 0 to 70 parts by mass, more preferably 0 to 50 parts by mass, and even more preferably 0 to 30 parts by mass. As the proportion of the third catalyst powder increases, the NH ３ The outlet concentration can be reduced.

[0069] In the present invention, the catalyst of the present invention may be attached (supported) to a support to form a catalyst body for gas-phase ammonia decomposition, or a molded body obtained by molding the catalyst of the present invention may be used as a catalyst body for gas-phase ammonia decomposition. Examples of the support include honeycomb supports; corrugated supports; and plate-shaped supports (lath plates) such as expanded metal and perforated metal (punched metal). The amount of catalyst attached to the support can be appropriately set, taking into consideration factors such as improving the catalyst loading rate. The molded body can have a shape such as honeycomb, corrugated, cone, truncated cone, ellipsoid, spindle, Raschig ring, Dixon, saddle, or McMahon, taking into consideration factors such as improving the catalyst loading rate and suppressing an increase in head loss.

[0070] When producing the catalyst body, the catalyst of the present invention may contain an amorphous metal oxide such as amorphous silica, amorphous alumina, or amorphous titania as an additive.

[0071] After being supported on the support or formed, drying or calcination can be carried out as necessary. The drying temperature may be any temperature at which the liquid can be removed, for example, 100 to 150°C. The calcination temperature may be any temperature lower than the heat resistance temperature of the mixture, for example, preferably 350 to 650°C, more preferably 450 to 600°C, and even more preferably 480 to 570°C. The calcination time can be set appropriately depending on the calcination temperature, for example, 1 to 5 hours.

[0072] The process of the present invention comprises reacting NH ３ The chemical reaction that turns NO into nitrogen and water, Ｘ and N ２ This involves a chemical reaction that converts O into nitrogen and water. Ｘ and N ２ As will be described later, O may be originally contained in the gas to be treated, or may be generated during the chemical reaction.

[0073] The gas to be treated is NH ３ It contains a contained gas. ３Examples of the contained gas include exhaust gas generated by the combustion of ammonia fuel, exhaust gas released during purging of ammonia-related equipment, and exhaust gas released during the treatment of ammonia-containing wastewater. ３ Examples of the ammonia-containing gas that can be used include gases emitted from fields where ammonia is stored and utilized, such as ammonia-fueled ships, ammonia transport ships, ammonia fuel storage bases, ammonia tanks for denitration devices in power plants, and ammonia cooling and freezing devices, and fields where ammonia-containing wastewater is treated, such as wastewater from food and drinking water production, chemical plant wastewater, plating wastewater, wastewater from semiconductor component manufacturing, and domestic wastewater. ３ When dissolved in a liquid, NH ３ When the compound is adsorbed on a solid, it can be vaporized using a stripping tower, vaporizer, or the like and used.

[0074] The gas to be treated is O ２ It is preferable that the mixture further contains an inclusion gas. ２ The contained gas may be, for example, air. ３ O in the gas ２ When the concentration is at a level sufficient to carry out the chemical reaction, NH ３ The gas containing the NH ３ Gases contained and O ２ The gas obtained by mixing the gas containing the oxygen-containing compound can be used as the gas to be treated.

[0075] NH ３ O against ２ The mass ratio of NH ３ Concentration, NO Ｘ concentration and N ２ The exhaust gas generated by the combustion of ammonia fuel contains NO Ｘ or / and N ２ The gas to be treated contains NO Ｘ or / and N ２ It may further contain O.

[0076] The chemical reaction in the process of the present invention is preferably carried out in a continuous flow reactor. A catalyst layer is installed in the reactor, and a catalyst is placed in the catalyst layer. The catalyst layer can be in the form of a fixed bed, a fluidized bed, a moving bed, a simulated moving bed, or the like, preferably in the form of a fixed bed or a simulated moving bed. In the continuous flow type, gas adjusted to a predetermined temperature is introduced from the reactor inlet, a chemical reaction occurs in the catalyst layer in the reactor, and the gas is discharged from the reactor outlet. The space velocity [1 / hr] of the gas flowing in the reactor (=volumetric flow rate (m3 / hr) / catalyst volume (m3)) is, for example, determined by the amount of NH ３ Concentration, NO Ｘ concentration and N ２ The temperature of the gas at the reactor inlet is, for example, preferably 300 to 600°C, more preferably 350 to 550°C.

[0077] In a preferred embodiment of the process of the present invention, NH ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ In order to carry out the chemical reaction of converting O into nitrogen and water, for example, the process comprises continuously passing the gas to be treated through a first catalyst layer containing, as an active catalyst component, only a second catalyst powder containing at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate, and then continuously passing the gas to be treated through a second catalyst layer containing the catalyst of the present invention. Another preferred embodiment of the process of the present invention is a process in which NH ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ In order to carry out a chemical reaction of converting O into nitrogen and water, the method includes, for example, continuously passing the gas to be treated through a first catalyst layer containing the catalyst of the present invention, and then continuously passing the gas through a second catalyst layer containing the catalyst of the present invention, wherein the proportion of platinum contained in the catalyst placed in the first catalyst layer is lower than the proportion of platinum contained in the catalyst placed in the second catalyst layer.

[0078] In the catalyst layer (second catalyst layer) where the catalyst of the present invention is placed, NO Ｘ (reaction represented by formula (6), formula (7) or formula (8)), N ２ The gas-phase decomposition reaction of O (reaction represented by formula (9)) and NH ３ The direct decomposition reaction of N (reaction represented by formula (4)) is promoted in a balanced manner, ２ The side reaction of producing O (reaction represented by formula (3)) is suppressed. ２ Gas-phase decomposition reaction of O and NH ３ This tends to promote the direct decomposition reaction of

[0079] In the first catalyst layer, NO Ｘ The gas-phase decomposition reaction of (the reaction represented by formula (6), formula (7), or formula (8)) is mainly promoted, and N ２ The gas-phase decomposition reaction of NO (reaction represented by formula (9)) is also promoted. Ｘ and N ２ The gas-phase decomposition reaction of O tends to be promoted.

[0080] NO promoted in the first catalyst layer Ｘ The gas phase decomposition reaction of N generates a large amount of heat. As a result, the gas flowing out from the first catalyst layer tends to be at a higher temperature than the gas flowing into the first catalyst layer. The higher the temperature of the gas flowing into the catalyst layer (second catalyst layer) using the catalyst of the present invention, the higher the temperature of the catalyst layer (second catalyst layer) using the catalyst of the present invention. ２ Gas-phase decomposition reaction of O and NH ３ The direct decomposition reaction of NH promoted in the catalyst layer (second catalyst layer) using the catalyst of the present invention tends to be promoted. ３ As a result, even if the gas to be treated has a high ammonia concentration, in the process of the present invention using the first catalyst layer and the second catalyst layer, heat is generated by the direct decomposition reaction of NH ３ can be efficiently decomposed, and N ２ A treated gas with a low O emission concentration can be obtained.

[0081] NO promoted in the first catalyst layer Ｘand N ２ In the gas-phase decomposition reaction of O, NH ３ is consumed in the first catalyst layer. ３ When the amount of ammonia contained in the gas flowing into the catalyst layer (second catalyst layer) using the catalyst of the present invention is small, N ２ As a result, even if the treated gas has a low ammonia concentration, the process of the present invention using the first catalyst layer and the second catalyst layer can suppress the progression of side reactions (reactions represented by formula (3) and the like) that produce O. ２ The O concentration is significantly reduced.

[0082] As described above, the process of the present invention using the first catalyst layer and the second catalyst layer can handle gases with a wide range of ammonia concentrations, from gases with low ammonia concentrations to gases with high ammonia concentrations. ３ In fuel-powered marine engines, the NOx and N contained in the exhaust gas are ２ O and NH ３ Even in exhaust gases with such concentration fluctuations, the amount of NH ３ can be efficiently decomposed, and N ２ A treated gas with a low O emission concentration can be obtained.

[0083] The temperature during the chemical reaction is, for example, ３ Concentration, NO Ｘ concentration and N ２The temperature can be appropriately set so that the O concentration falls within the desired range. Temperature control can be performed using known methods, such as a heater, jacket, or heat transfer tube, to heat or cool the gas or equipment surrounding the catalyst (hereinafter sometimes referred to as the catalyst layer) or the gas to be treated flowing into the catalyst layer. Gases emitted from combustion devices such as furnaces and internal combustion engines are often at high temperatures. The inflow of high-temperature gas to be treated easily increases the temperature of the catalyst. Continuous exposure of the catalyst to excessively high temperatures can lead to deterioration of catalytic performance. The temperature of the gas to be treated can be controlled by adding a low-temperature gas such as air to the gas to be treated, or by heat exchange via a partition between the gas to be treated and the heat transfer medium. Treated gas may also be used as the heat transfer medium.

[0084] The process of the present invention preferably includes adding at least one reaction aid selected from the group consisting of ammonia and urea to the gas to be treated. Urea decomposes into carbon dioxide and ammonia through an endothermic reaction. The addition of the reaction aid is performed by removing NO contained in the gas to be treated. Ｘ and N ２ This is preferably carried out when the amount of O is large.

[0085] The amount of the reaction aid added to the gas to be treated depends on the temperature of the gas to be treated or the treated gas and the NOx contained in the gas to be treated or the treated gas. Ｘ and N ２ It is preferable to adjust the amount of the reaction aid based on the amount of O. The reaction aid is added to the gas to be treated. ３ Direct decomposition reaction of NO Ｘ and N ２ NH in the gas-phase decomposition reaction of O ３ The amount of NH in the reaction site increases. ３ The increase in the amount of NH 3 in the treated gas increases the temperature of the catalyst layer and the treated gas. ３ , NO Ｘ and N ２ This results in a decrease in the amount of O.

[0086] The higher the temperature of the catalyst layer, the more NH ３Direct decomposition reaction of N ２ The rate of the gas-phase decomposition reaction of NH 3 tends to increase. However, the higher the temperature of the catalyst layer, the greater the risk of catalyst deterioration. ３ Direct decomposition reaction of NO Ｘ and N ２ The gas phase decomposition reaction of O occurs when NH ３ Reduce NH ３ If it decreases too much, NO Ｘ and N ２ The gas phase decomposition reaction of O becomes difficult to proceed, but N ２ The side reaction that generates O also becomes less likely to proceed.

[0087] The temperature of the treated gas at each catalyst layer is, for example, preferably 400 to 600° C., more preferably 450 to 550° C. Ｘ The concentration of N in the final stage treated gas is, for example, preferably 500 ppm or less, more preferably 200 ppm or less. ２ The O concentration is, for example, preferably 100 ppm or less, more preferably 10 ppm or less.

[0088] Next, examples will be described to demonstrate the effects of the present invention. However, the scope of the present invention is not limited by these examples. Table 6 shows the mass ratio of the first catalyst powder to the second catalyst powder and the Ru / Pt ratio in the catalyst bodies produced in Examples 1 to 18.

[0089] [Example 1: Honeycomb catalyst body A] (Preparation of first catalyst powder (1)) A chloroplatinic acid solution and a ruthenium nitrate solution were added to pure water and stirred to obtain a dipping solution of a predetermined concentration. MFI-type aluminosilicate (pentasil type, pore diameter = 5.8 Å, cation (nominal cation form) = hydrogen ion, SiO ２ / Al ２ O ３ Ratio = 24 "mol / mol", specific surface area = 330m ２ / g-BET method, crystal size = 0.1 [μm] x 0.5 [μm], particle size = 5 μm, NH ３-TPD=1.8 mmol / g) was added and stirred to obtain a slurry. This slurry was evaporated to dryness. The obtained dry product was dried at 120°C for 2 hours or more. The obtained dried product was subjected to a calcination treatment in air by raising the temperature from room temperature to 500°C at a rate of 250°C / h, and then maintaining it at 500°C for 2 hours. The obtained calcined product was dry-pulverized to obtain a first catalyst powder (1) comprising an MFI-type aluminosilicate supporting 0.1% by mass of platinum and 5.0% by mass of ruthenium.

[0090] (Preparation of second catalyst powder (1)) Iron nitrate nonahydrate was dissolved in 1 L of ion-exchanged water at 80°C to obtain an aqueous iron nitrate solution (Fe concentration = 6 mass%) at 80°C. The pH of this aqueous iron nitrate solution was 1.7. OSDA-free BEA-type aluminosilicate (SiO ２ / Al ２ O ３ Ratio = 12, specific surface area = 370m ２ 60 g (dry mass) of ZnO (100%) / g was added and stirred for 2 hours while maintaining the temperature at 80°C, resulting in an ion exchange treatment to obtain a slurry. The slurry was dehydrated using a suction funnel equipped with filter paper. Pure water was poured onto the cake on the filter paper and washed. The washed cake was dried at 120°C for 4 hours or more. The obtained dried product was pulverized. The pulverized product was calcined in air by increasing the temperature from room temperature to 600°C at a rate of 100°C / h and then maintaining the temperature at 600°C for 5 hours. The calcined product was dry-pulverized to obtain a second catalyst powder (1) consisting of an OSDA-free BEA-type aluminosilicate ion-exchanged with Fe ions.

[0091] (Production of catalyst body) 2 parts by mass of the first catalyst powder (1), 98 parts by mass of the second catalyst powder (1), silica sol (OS-1 manufactured by Nissan Chemical Industries, Ltd.) and alumina sol (AS-200 manufactured by Nissan Chemical Industries, Ltd.) were added to pure water to obtain a slurry. A cordierite honeycomb substrate (50 cpsi) was immersed in this slurry. The cordierite honeycomb substrate was pulled out of the slurry and subjected to an air blowing treatment to drain the liquid. Next, this was dried at 120°C for 2 hours or more. The obtained dried product was subjected to a firing treatment in air by raising the temperature from room temperature to 500°C at a temperature increase rate of 250°C / h and subsequently maintaining at 500°C for 2 hours, thereby obtaining a honeycomb catalyst body A. The mass of platinum was 20 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (1) and the second catalyst powder (1).

[0092] (Catalyst Evaluation (1)) The honeycomb catalyst body A was fitted and fixed in a tubular reactor. A simulated gas A containing the components shown in Table 1 was fed into the tubular reactor at SV=10,000 hr. －１ The temperature of the tubular reactor was set to 350°C, 400°C, 450°C or 500°C. ３ Concentration, NO Ｘ concentration and N ２ Measure the O concentration and NH ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The by-production rate of NH was calculated using the following formula. The results are shown in Table 3 and Figures 1 and 2. ３ Decomposition rate = {(inlet NH ３ Concentration - Outlet NH ３ Concentration) - (Inlet NO. ｘ Concentration - Outlet No. ｘ Concentration) - 2 / 3 x (Inlet N ２ O concentration - outlet N ２ O concentration)} / {Inlet NH ３ Concentration - (Inlet NO. ｘ Concentration - Outlet No. ｘ Concentration) - 2 / 3 x (Inlet N ２ O concentration - outlet N ２ O concentration)}×100 NH ３ Decomposition reaction rate = AV × -Ln (1-NH ３ Decomposition rate / 100) NO ｘ Replication rate = exit no.ｘ Concentration / {(Inlet NH ３ Concentration - Outlet NH ３ Concentration) - Inlet NO. ｘ Concentration - 2 / 3 x (Inlet N ２ O concentration - outlet N ２ O concentration)}×100 N ２ O replication rate = (exit N ２ O concentration - inlet N ２ O concentration) / {(inlet NH ３ Concentration - Outlet NH ３ Concentration) - (Inlet NO. ｘ Concentration - Outlet No. ｘ concentration) × 100 AV = gas volume / geometric surface area of ​​honeycomb catalyst body

[0093]

[0094] (Catalyst Evaluation (2)) A simulated gas B containing the components shown in Table 2 was introduced into the tubular reactor at SV=10,000 hr. －１ The temperature of the tubular reactor was set to 530°C and the reactor was left standing for 70 hours (hydrothermal aging). After that, simulated gas A containing the components shown in Table 1 was introduced into the tubular reactor at SV = 10,000 hr. －１ The temperature of the tubular reactor was set to 350°C, 400°C, 450°C or 500°C. ３ Concentration, NO Ｘ concentration and N ２ The O concentration was measured, and NH ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The by-production rate of NH in evaluation (1) was calculated. ３ Evaluation of decomposition reaction rate (2) NH ３ The ratio of the decomposition reaction rates (aging ratio) was calculated. The results are shown in Tables 4 and 5 and Figures 3 to 8.

[0095]

[0096]

[0097]

[0098]

[0099]

[0100] [Example 2: Honeycomb catalyst body B] (Preparation of first catalyst powder (2)) A first catalyst powder (2) having 0.2 mass % of platinum and 5.0 mass % of ruthenium supported on an MFI-type aluminosilicate was obtained in the same manner as in the preparation of the first catalyst powder (1), except that the amount of chloroplatinic acid aqueous solution added was changed.

[0101] A honeycomb catalyst body B was obtained in the same manner as in the production of the honeycomb catalyst body A, except that the first catalyst powder (1) was changed to the first catalyst powder (2). The mass of platinum was 40 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (2) and the second catalyst powder (1).

[0102] NH was measured in the same manner as in evaluation (1) and evaluation (2), except that honeycomb catalyst body A was changed to honeycomb catalyst body B. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0103] [Example 3: Honeycomb catalyst body C] (Preparation of first catalyst powder (3)) A first catalyst powder (3) having 0.5 mass % of platinum and 5.0 mass % of ruthenium supported on an MFI-type aluminosilicate was obtained in the same manner as in the preparation of the first catalyst powder (1), except that the amount of chloroplatinic acid aqueous solution added was changed.

[0104] A honeycomb catalyst body C was obtained in the same manner as in the production of the honeycomb catalyst body A, except that the first catalyst powder (1) was changed to the first catalyst powder (3). The mass of platinum was 100 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (3) and the second catalyst powder (1).

[0105] NH was measured in the same manner as in evaluation (1) and evaluation (2), except that the honeycomb catalyst body A was changed to honeycomb catalyst body C. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0106] [Example 4: Honeycomb catalyst body D] (Preparation of first catalyst powder (4)) A first catalyst powder (4) having 1.0 mass % of platinum and 5.0 mass % of ruthenium supported on an MFI-type aluminosilicate was obtained in the same manner as in the preparation of the first catalyst powder (1), except that the amount of chloroplatinic acid aqueous solution added was changed.

[0107] A honeycomb catalyst body D was obtained in the same manner as in the production of the honeycomb catalyst body A, except that the first catalyst powder (1) was changed to the first catalyst powder (4). The mass of platinum was 200 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (4) and the second catalyst powder (1).

[0108] NH was measured in the same manner as in evaluation (1) and evaluation (2), except that the honeycomb catalyst body A was changed to honeycomb catalyst body D. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0109] [Example 5: Honeycomb catalyst body E] (Preparation of first catalyst powder (5)) A first catalyst powder (5) comprising 0.2 mass % of platinum and 5.0 mass % of ruthenium supported on titanosilicate was obtained in the same manner as in the preparation of the first catalyst powder (2), except that the MFI-type aluminosilicate was changed to titanosilicate (a composite of titania and silica).

[0110] A honeycomb catalyst body E was obtained in the same manner as in the production of the honeycomb catalyst body A, except that the first catalyst powder (1) was changed to the first catalyst powder (5). The mass of platinum was 40 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (5) and the second catalyst powder (1).

[0111] NH was measured in the same manner as in evaluation (1) and evaluation (2), except that the honeycomb catalyst body A was changed to honeycomb catalyst body E. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0112] [Example 6: Honeycomb catalyst body F] (Preparation of first catalyst powder (6)) A first catalyst powder (6) comprising 0.2 mass % of platinum and 5.0 mass % of ruthenium supported on silica was obtained in the same manner as in the preparation of the first catalyst powder (2), except that the MFI-type aluminosilicate was changed to silica (Si oxide).

[0113] A honeycomb catalyst body F was obtained in the same manner as in the production of the honeycomb catalyst body A, except that the first catalyst powder (1) was changed to the first catalyst powder (6). The mass of platinum was 40 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (6) and the second catalyst powder (1).

[0114] NH ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0115] [Example 7: Honeycomb catalyst body R] (Preparation of second catalyst powder (2)) OSDA-free BEA-type aluminosilicate (SiO ２ / Al ２ O ３ Ratio = 12, specific surface area = 370m ２ / g) was added to OSDA-free BEA-type aluminosilicate (SiO ２ / Al ２ O ３ Ratio = 10, specific surface area = 370m ２ A second catalyst powder (2) consisting of an OSDA-free BEA-type aluminosilicate ion-exchanged with Fe ions was obtained in the same manner as in the preparation of the second catalyst powder (1), except that the amount of the OSDA-free BEA-type aluminosilicate was changed to 0.1 wt. / g.

[0116] A honeycomb catalyst body R was obtained in the same manner as in the production of the honeycomb catalyst body B, except that the second catalyst powder (1) was changed to the second catalyst powder (2). The mass of platinum was 40 ppm and the mass of ruthenium was 1000 ppm relative to the total mass of the first catalyst powder (2) and the second catalyst powder (2).

[0117] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to the honeycomb catalyst body R.３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0118] [Example 8: Honeycomb catalyst body G] (Preparation of first catalyst powder (a)) A chloroplatinic acid solution and cerium nitrate hexahydrate were added to pure water and stirred to obtain an immersion liquid of a predetermined concentration. Titanosilicate (a composite of titania and silica) was added to this immersion liquid and stirred to obtain a slurry. This slurry was evaporated to dryness. The obtained dried product was dried at 120°C for 2 hours or more. The obtained dried product was subjected to a calcination treatment in air by raising the temperature from room temperature to 500°C at a rate of 250°C / h and then maintaining it at 500°C for 2 hours. The obtained calcined product was dry-pulverized to obtain a first catalyst powder (a) in which 0.5 mass% of platinum and 2.5 mass% of cerium were supported on titanosilicate.

[0119] (Preparation of second catalyst powder (a)) Iron sulfate heptahydrate was dissolved in 1 L of ion-exchanged water at 80°C to obtain an aqueous iron sulfate solution (Fe concentration = 3 mass%) at 80°C. The pH of this aqueous iron sulfate solution was 3.6. BEA-type aluminosilicate (SiO ２ / Al ２ O ３ Ratio = 25 [mol / mol], Cation (Nominal Cation Form) = Ammonium ion, Na ２ O=0.05% by weight, specific surface area=680m ２ 60 g (dry mass) of ZnO (Fe / g) was added and stirred for 2 hours while maintaining the temperature at 80°C, resulting in an ion exchange treatment to obtain a slurry. The slurry was dehydrated using a suction funnel equipped with filter paper. Pure water was poured onto the cake on the filter paper and washed. The washed cake was dried at 120°C for 4 hours or more. The obtained dried product was pulverized. The pulverized product was calcined in air by increasing the temperature from room temperature to 500°C at a rate of 100°C / h and then maintaining it at 500°C for 5 hours. The calcined product was dry-pulverized to obtain a second catalyst powder (a) consisting of a BEA-type aluminosilicate ion-exchanged with Fe ions.

[0120] (Production of Catalyst Body) 2 parts by mass of the first catalyst powder (a), 98 parts by mass of the second catalyst powder (a), silica sol (OS-1, manufactured by Nissan Chemical Industries, Ltd.), and alumina sol (AS-200, manufactured by Nissan Chemical Industries, Ltd.) were added to pure water to obtain a slurry. A cordierite honeycomb substrate (50 cpsi) was immersed in this slurry. The cordierite honeycomb substrate was removed from the slurry and subjected to an air blowing treatment to drain the liquid. It was then dried at 120°C for at least 2 hours. The resulting dried product was subjected to a firing treatment in air by raising the temperature from room temperature to 500°C at a heating rate of 250°C / h, and then maintaining it at 500°C for 2 hours, thereby obtaining a honeycomb catalyst body G. The mass of platinum relative to the total mass of the first catalyst powder (a) and the second catalyst powder (a) was 100 ppm.

[0121] NH was measured in the same manner as in evaluation (1) and evaluation (2), except that the honeycomb catalyst body A was changed to honeycomb catalyst body G. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0122] [Example 9: Honeycomb catalyst body H] (Preparation of first catalyst powder (b)) A first catalyst powder (b) having 1.0 mass % of platinum and 5 mass % of cerium supported on titanosilicate was obtained in the same manner as in the preparation of the first catalyst powder (a), except that the amounts of chloroplatinic acid aqueous solution and cerium nitrate hexahydrate added were changed.

[0123] A honeycomb catalyst body H was obtained in the same manner as in the production of the honeycomb catalyst body A, except that the first catalyst powder (1) was changed to the first catalyst powder (b). The mass of platinum relative to the total mass of the first catalyst powder (b) and the second catalyst powder (1) was 200 ppm.

[0124] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to the honeycomb catalyst body H. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0125] [Example 10: Honeycomb catalyst body I] (Preparation of first catalyst powder (c)) A first catalyst powder (c) having 0.5 mass % of platinum, 0.5 mass % of ruthenium, and 2.5 mass % of cerium supported on titanosilicate was obtained in the same manner as in the preparation of the first catalyst powder (a), except that an aqueous ruthenium nitrate solution was added to pure water in addition to an aqueous chloroplatinic acid solution and cerium nitrate hexahydrate.

[0126] A honeycomb catalyst body I was obtained by the same method as that for producing the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (c). The mass of platinum was 100 ppm and the mass of ruthenium was 100 ppm relative to the total mass of the first catalyst powder (c) and the second catalyst powder (a).

[0127] NH ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0128] [Example 11: Honeycomb catalyst body J] (Preparation of first catalyst powder (d)) A first catalyst powder (d) having 0.05 mass % of platinum and 0.25 mass % of cerium supported on silica was obtained in the same manner as in the preparation of the first catalyst powder (a), except that the amounts of chloroplatinic acid aqueous solution and cerium nitrate hexahydrate added were changed and titanosilicate was changed to silica.

[0129] A honeycomb catalyst body J was obtained by the same method as that for producing the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (d). The mass of platinum relative to the total mass of the first catalyst powder (d) and the second catalyst powder (a) was 10 ppm.

[0130] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to honeycomb catalyst body J. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0131] [Example 12: Honeycomb catalyst body K] (Preparation of first catalyst powder (e)) A first catalyst powder (e) having 0.25 mass % of platinum and 1.25 mass % of cerium supported on silica was obtained in the same manner as in the preparation of the first catalyst powder (a), except that the amounts of chloroplatinic acid aqueous solution and cerium nitrate hexahydrate added were changed and titanosilicate was changed to silica.

[0132] A honeycomb catalyst body K was obtained by the same method as that for producing the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (e). The mass of platinum relative to the total mass of the first catalyst powder (e) and the second catalyst powder (a) was 50 ppm.

[0133] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to the honeycomb catalyst body K. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0134] [Example 13: Honeycomb catalyst body L] (Preparation of first catalyst powder (f)) A first catalyst powder (f) having 0.5 mass % of platinum and 2.5 mass % of cerium supported on silica was obtained in the same manner as in the preparation of the first catalyst powder (a), except that the amounts of chloroplatinic acid aqueous solution and cerium nitrate hexahydrate added were changed and titanosilicate was changed to silica.

[0135] A honeycomb catalyst body L was obtained by the same method as that for producing the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (f). The mass of platinum relative to the total mass of the first catalyst powder (f) and the second catalyst powder (a) was 100 ppm.

[0136] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to the honeycomb catalyst body L. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0137] [Example 14: Honeycomb catalyst body M] A honeycomb catalyst body M was obtained in the same manner as in the production of honeycomb catalyst body J, except that the mass ratio of the first catalyst powder (d) to the second catalyst powder (a) was changed from 2:98 to 20:80. The mass of platinum relative to the total mass of the first catalyst powder (d) and the second catalyst powder (a) was 100 ppm.

[0138] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to the honeycomb catalyst body M. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0139] [Example 15: Honeycomb catalyst body N] (Preparation of first catalyst powder (g)) A first catalyst powder (g) comprising 0.5 mass % of platinum and 2.5 mass % of cerium supported on an MOR-type aluminosilicate was obtained in the same manner as in the preparation of the first catalyst powder (a), except that titanosilicate was changed to an MOR-type aluminosilicate.

[0140] A honeycomb catalyst body N was obtained in the same manner as in the production of the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (g). The mass of platinum relative to the total mass of the first catalyst powder (g) and the second catalyst powder (a) was 100 ppm.

[0141] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to honeycomb catalyst body N. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0142] [Example 16: Honeycomb catalyst body O] (Preparation of first catalyst powder (h)) A first catalyst powder (h) was obtained in the same manner as in the preparation of the first catalyst powder (a), except that titanosilicate was changed to BEA-type aluminosilicate, and in which 0.5 mass% of platinum and 2.5 mass% of cerium were supported on BEA-type aluminosilicate.

[0143] A honeycomb catalyst body O was obtained in the same manner as in the production of the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (h). The mass of platinum relative to the total mass of the first catalyst powder (g) and the second catalyst powder (a) was 100 ppm.

[0144] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to honeycomb catalyst body O. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0145] [Example 17: Honeycomb catalyst body P] (Preparation of first catalyst powder (i)) A first catalyst powder (i) having 0.25 mass % of platinum and 1.25 mass % of cerium supported on titania was obtained in the same manner as in the preparation of the first catalyst powder (e), except that silica was changed to titania.

[0146] A honeycomb catalyst body P was obtained in the same manner as in the production of the honeycomb catalyst body G, except that the first catalyst powder (a) was changed to the first catalyst powder (i). The mass of platinum relative to the total mass of the first catalyst powder (i) and the second catalyst powder (a) was 50 ppm.

[0147] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to the honeycomb catalyst body P. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0148] [Example 18: Honeycomb catalyst body Q] (Preparation of first catalyst powder (j)) A first catalyst powder (j) having 0.5 mass % of platinum and 2.5 mass % of cerium supported on titania was obtained in the same manner as in the preparation of the first catalyst powder (f), except that silica was changed to titania.

[0149] Except for changing the first catalyst powder (a) to the first catalyst powder (j), a honeycomb catalyst body Q was obtained in the same manner as in the production of the honeycomb catalyst body G. The mass of platinum relative to the total mass of the first catalyst powder (j) and the second catalyst powder (a) was 100 ppm.

[0150] The same method as in evaluation (1) and evaluation (2) was used except that the honeycomb catalyst body A was changed to honeycomb catalyst body Q. ３ Decomposition reaction rate, NO Ｘ By-production rate and N ２ The O by-production rate and aging rate were calculated. The results are shown in Tables 3 to 5 and Figures 1 to 8.

[0151] The catalyst bodies produced in Examples 1 to 7 were found to have a higher N value in both evaluation (1) and evaluation (2) than the catalyst bodies produced in Examples 8 to 18. ２ O by-production rate and NO Ｘ Low by-product rate and NH ３ The decomposition reaction rate is high (see Figures 1-2 and 5-6). The catalyst bodies prepared in Examples 1-7 have a higher aging rate than the catalyst bodies prepared in Examples 8-18 (see Figures 3-4 and 7-8).

[0152] As shown by the above results, the catalyst of the present invention Ｘ and / or N ２ While suppressing the by-production of O, ammonia (NH ３ ) and can promote the gas phase decomposition reaction of NO Ｘ and / or N ２ This can promote the gas phase decomposition reaction of O.

Claims

1. A catalyst for gas-phase ammonia decomposition, comprising as active catalyst components a mixture of: a first catalyst powder comprising a carrier containing at least one selected from the group consisting of ceria, silica, alumina, titania, zirconia, titanosilicate, and aluminosilicate, and ruthenium and platinum supported on the carrier; and a second catalyst powder comprising at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate, wherein the amount of platinum in the first catalyst powder is 0.001 parts by mass or more but less than 1 part by mass per part by mass of ruthenium.

2. The catalyst according to claim 1, wherein the first catalyst powder contains 0.01 to less than 0.5 parts by mass of platinum per 1 part by mass of ruthenium, the amount of platinum contained in 100 parts by mass of the first catalyst powder is 0.01 to 2 parts by mass, and the amount of ruthenium contained in 100 parts by mass of the first catalyst powder is 2 to 10 parts by mass.

3. The catalyst according to claim 1, wherein the first catalyst powder contains 0.01 to less than 0.5 parts by mass of platinum per 1 part by mass of ruthenium, the amount of platinum contained in 100 parts by mass of the first catalyst powder and the second catalyst powder is 0.001 to 0.1 parts by mass, and the amount of ruthenium contained in 100 parts by mass of the first catalyst powder and the second catalyst powder is 0.01 to 1 part by mass.

4. The catalyst according to claim 1, 2 or 3, wherein the first catalyst powder has a carrier containing at least one selected from the group consisting of silica, titanosilicate, MEL-type aluminosilicate and MFI-type aluminosilicate.

5. The catalyst according to claim 1, 2 or 3, wherein the second catalyst powder comprises an iron ion-exchanged BEA-type aluminosilicate.

6. The catalyst according to claim 1, 2 or 3, wherein the second catalyst powder comprises an iron ion-exchanged, OSDA-free, BEA-type aluminosilicate.

7. A catalyst body for gas-phase ammonia decomposition, comprising a support and the catalyst according to claim 1, 2 or 3 supported on said support.

8. A catalyst body for gas-phase ammonia decomposition, comprising a molded body containing the catalyst according to claim 1, 2 or 3.

9. In the presence of the catalyst according to claim 1, 2 or 3, in the gas to be treated, NH ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ and a chemical reaction of O to nitrogen and water.

10. A method for treating a gas to be treated, comprising: continuously passing the gas to be treated through a first catalyst layer containing, as an active catalyst component, only a second catalyst powder containing at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate; and then continuously passing the gas to be treated through a second catalyst layer containing the catalyst according to claim 1, 2, or 3. ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ and a process for carrying out a chemical reaction of O to nitrogen and water.

11. A method for producing a gas to be treated, comprising: continuously passing the gas to be treated through a first catalyst layer containing the catalyst according to claim 1, 2 or 3; and then continuously passing the gas to be treated through a second catalyst layer containing the catalyst according to claim 1, 2 or 3; wherein the proportion of platinum contained in the catalyst in the first catalyst layer is lower than the proportion of platinum contained in the catalyst in the second catalyst layer. ３ The chemical reaction that turns NO into nitrogen and water Ｘ and N ２ and a process for carrying out a chemical reaction of O to nitrogen and water.

12. The process according to claim 9, further comprising adding at least one reaction aid selected from the group consisting of ammonia and urea to the gas to be treated.

13. An apparatus for vapor-phase ammonia decomposition, comprising: a first catalyst layer containing, as an active catalyst component, only a second catalyst powder comprising at least one selected from the group consisting of iron ion-exchanged BEA-type aluminosilicate, cobalt ion-exchanged BEA-type aluminosilicate, and copper ion-exchanged BEA-type aluminosilicate; and a second catalyst layer disposed downstream of the first catalyst layer and comprising the catalyst according to claim 1, 2, or 3.

14. An apparatus for vapor-phase ammonia decomposition, comprising: a first catalyst layer comprising the catalyst according to claim 1, 2 or 3; and a second catalyst layer comprising the catalyst according to claim 1, 2 or 3, which is placed downstream of the first catalyst layer; and wherein the proportion of platinum contained in the catalyst placed in the first catalyst layer is lower than the proportion of platinum contained in the catalyst placed in the second catalyst layer.

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