Molded catalyst and method for synthesizing ammonia using the same

Abstract

The molded catalyst of the present invention comprises a composite material component (A), a zirconium (Zr) component (B), and a catalytically active metal M component (C). The composite material component (A) is a metal composite oxide containing barium (Ba) and magnesium (Mg), or a mixed oxide containing barium oxide (BaO) and magnesium oxide (MgO). The zirconium component (B) is selected from the group consisting of Zr and a precursor of Zr, Zr, ZrH2-x (0 ≤ x < 2), ZrO2 and a precursor of ZrO2, ZrN, MgH2, and Mg. The catalytically active metal M component (C) is a transition metal.

Description

[DESCRIPTION][Title of Invention]MOLDED CATALYST AND METHOD FOR SYNTHESIZING AMMONIA USING THE SAME[Technical Field]

[0001] The present invention relates to a molded catalyst and a method for synthesizing ammonia using the molded catalyst.This application claims priority under Japanese Patent Application No. 2025-009803, filed in Japan on January 23, 2025, and is hereby incorporated by reference.[Background Art]

[0002] The Haber-Bosch process, a typical method for synthesizing ammonia, uses a doubly promoted iron catalyst containing Fe3O4with several wt.% Al2O3and K2O. A mixed gas of nitrogen and hydrogen is directly reacted with this catalyst under high-temperature and high-pressure conditions to synthesize ammonia. This technology is still used industrially today, with some improvements, in a producing process that remains largely unchanged since its inception.

[0003] Meanwhile, methods for synthesizing ammonia at temperatures lower than the reaction temperature of the Haber-Bosch process are being investigated. Catalysts capable of synthesizing ammonia by bringing nitrogen and hydrogen into contact have been investigated, and transition metals have been considered as catalytically active components. Among these, a method using ruthenium (Ru) as a catalytically active component supported on various supports as an ammonia synthesis catalyst has been proposed as an efficient method (see, for example, PTL 1).

[0004] Catalysts using transition metals such as Ru are known to be highly active, allowing ammonia synthesis under milder conditions than those used in the Haber-Bosch process. For example, the reaction proceeds at low temperatures and low pressures, such as a reaction temperature of 200-400°C and a reaction pressure of atmospheric pressure to approximately 1.1 MPa.

[0005] In addition, considering the high cost of Ru, ammonia synthesis catalysts have also been proposed in which a transition metal compound other than Ru, such as Co, is supported on a support. Co-supported catalysts, in which Co metal particles are immobilized on a support such as an oxide, are commonly used for ammonia synthesis catalysts. For example, PTL 2 discloses Co / BanMgi-nOx, in which cobalt is supported on a composite oxide, BanMgi-nOx. The composite oxide BanMgi-nOxis a composite oxide in a mixed state of Ba oxide and Mg oxide. The Ba oxide and Mg oxide do not form a solid solution, and the Ba oxide particles are deposited on the surfaces of the Mg oxideparticles. PTL 3 also discloses a catalyst in which a solid solution of metal oxides, Mg-Ba-Al-O, is used as a catalyst support, and the catalyst support supports Co as a catalytically active metal. Both of these prior documents involve activation treatment to convert the active species, Co compounds, into Co metal particles. However, these require hydrogen reduction treatment at high temperatures of 500°C or higher, and the catalytic performance is lower than that of Ru catalysts, preventing industrial production of Co catalysts.

[0006] Meanwhile, catalysts in which active metal species are supported on various supports have been reported for the purpose of improving the performance of ammonia synthesis catalysts. For example, PTL 4 (WO 2023 / 217782) describes a catalyst called Fe / ZrO2·LiH, which uses ZrO2as the catalyst support, LiH as the additive, and Fe as the catalytically active metal. PTL 5 (WO 2019 / 207303) describes catalyst supports such as oxynitrides including ZrTiO2-xNyand yttria-stabilized zirconia (YSZ)-doped ZrO2. PTL 6 (WO 2022 / 030603) describes a catalyst called Ru / ZrH2, which uses ZrH2as the catalyst support and Ru as the catalytically active metal. The catalysts in PTLs 4 to 6 focus on Zr compounds and use them as the main component to improve the performance of catalytically active metal species. However, none of these molded catalysts has sufficient ammonia synthesis activity and crushing strength.Furthermore, the catalysts described in PTLs 4 to 6 do not disclose or suggest the effect of adding a Zr compound to the support.[Citation List][Patent Literature]

[0007] [PTL 1] JP 2006-231229 A[PTL 2] WO 2021 / 153738[PTL 3] WO 2023 / 168285[PTL 4] WO 2023 / 217782[PTL 5] WO 2019 / 207303[PTL 6] WO 2022 / 030603[Summary of the Invention][Technical Problem]

[0008] Ammonia synthesis, primarily via the Haber-Bosch process using a doubly promoted iron catalyst, has been put to practical use. However, due to the high temperature and high pressure conditions required, there are problems with the equipment and costs involved, particularly when commercializing the process.On the other hand, the Co-supported catalyst described in PTL 3 has insufficient reaction activity. Even if the reaction activity is sufficient, there are practical issues such as insufficient catalyst durability for industrialization.

[0009] The present invention provides a molded catalyst that is durable enough for industrialization, specifically, that combines high crushing strength and high reaction activity.In one embodiment, the present invention provides a molded catalyst that has a certain degree of resistance to oxygen-containing compounds (CO, CO2, H2O, O2) that deactivate ammonia synthesis activity. Another embodiment of the present invention provides a molded catalyst that shortens the time required to activate an ammonia synthesis catalyst.[Solution to Problem]

[0010] The present inventors discovered that the molded catalyst of the present invention can combine sufficient crushing strength and high ammonia synthesis activity by using a Zr compound, and optionally cobalt, and have thereby completed the present invention.

[0011] The present invention is summarized as follows.[1] A molded catalyst comprising a composite material component (A), a zirconium (Zr) component (B), and a catalytically active metal M component (C), wherein the composite material component (A) is a metal composite oxide containing barium (Ba) and magnesium (Mg) or a mixed oxide containing barium oxide (BaO) and magnesium oxide (MgO);the zirconium component (B) is one or more selected from the group consisting of Zr and a precursor of Zr, ZrFfc-x (0 < x < 2), ZrCh and a precursor of ZrCh, ZrN, MgFh, and Mg; andthe catalytically active metal M component (C) is a transition metal.[2] The molded catalyst according to [1], wherein the catalytically active metal M component (C) is at least one selected from the group consisting of Ru, Co, Fe, and Ni.[3] The molded catalyst according to [1] or [2], wherein the catalytically active metal M component (C) is a cobalt component (Cl),wherein the cobalt component (Cl) is at least one selected from the group consisting of Co, CoO, Co3O4, and CoCO3.[4] The molded catalyst according to any of [1] to [3], wherein the content of the catalytically active metal M component (C) in the molded catalyst is 1 wt.% to 50 wt.%.[5] The molded catalyst according to any of [1] to [4], wherein the composite material component (A) is a material represented by the following general formula (1):BanMg[i-n]Ox (1)(where 0 < n < 0.3 and 0.5 < x < 1.3)[6] The molded catalyst according to any one of [1] to [5], wherein the particle size of the zirconium component (B) contained in the molded catalyst is 100 pm or less.[7] The molded catalyst according to any one of [1] to [6], wherein the content of the zirconium component (B) in the molded catalyst is 5 wt.% or more and less than 50 wt.%.[8] The molded catalyst according to any one of [1] to [4], wherein the size of the molded catalyst is 0.3 mm to 30 mm.[9] The molded catalyst according to any one of [1] to [8], wherein the bulk density of the molded catalyst is 0.5 g cm-3to 2.5 g cm-3.

[0010] The molded catalyst according to any one of [1] to [9], wherein the crushing strength of the molded catalyst is 0.4 kgf or more.

[0011] The molded catalyst according to any one of [1] to

[0010] , wherein the catalytically active metal M component (C) has an average particle size of 20 nm or less.

[0012] A method for producing the molded catalyst according to any one of [1] to

[0011] , comprising:a first step of mixing the composite material component (A) or a precursor thereof with the catalytically active metal M component (C) or a precursor thereof to obtain a mixture;a second step of calcining the mixture obtained in the first step to obtain a calcined product; anda third step of mixing the zirconium component (B) with the calcined product obtained in the second step.

[0013] A method for producing the molded catalyst according to any one of [1] to

[0011] , wherein the zirconium component (B) comprises a first zirconium component (B1) and a second zirconium component (B2), the method comprising:a first step of mixing the composite material component (A) or a precursor thereof, the first zirconium component (B1) or a precursor thereof, and the catalytically active metal M component (C) or a precursor thereof to obtain a mixture;a second step of calcining the mixture obtained in the first step to obtain a calcined product; anda third step of mixing the second zirconium component (B2) with the calcined product obtained in the second step.

[0014] A method for producing ammonia by bringing hydrogen and nitrogen into contact on an ammonia synthesis catalyst, wherein the ammonia synthesis catalyst is the molded catalyst according to any one of [1] to

[0011] ,[Advantageous Effects of Invention]

[0012] The present invention provides a molded catalyst that exhibits sufficient durability for industrial application, specifically, high crushing strength and high reaction activity. Furthermore, in one embodiment of the present invention, a molded catalyst is provided that has a certain degree of resistance to oxygen-containing compounds (e.g., CO, CO2, H2O, O ) that deactivate activity for ammonia synthesis.Furthermore, in another embodiment of the present invention, a molded catalyst is provided that shortens the activation time of the ammonia synthesis catalyst.[Brief Description of Drawings]

[0013] [Fig. 1] A graph showing the Co particle size distribution in the molded catalyst obtained in Example 3 after an ammonia synthesis reaction test. The photograph in the figure is a TEM image of the catalyst.[Fig. 2] A graph showing the ammonia synthesis rate (reaction temperatures 350°C and 400°C) for the molded catalyst obtained in Examples 3, 18-22.[Fig. 3] A graph showing the time dependence of the ammonia synthesis rate (reaction temperature 400°C) for the molded catalyst obtained in Examples 3, 18-22.[Fig. 4] A graph showing the activation time (reaction temperature 400°C) required for the performance of the molded catalysts obtained in Examples 3 and 18 to 22 to reach 80%.[Fig. 5] A graph showing the ammonia synthesis reaction results of the molded catalysts for Example 25 and Comparative Examples 3 and 4, respectively, when using a high-purity feed gas (H2, N2> 6N) and a feed gas containing trace amounts of CO, CO2, and O2 (Reaction Conditions: 4.9 MPaG, 375°C, H2 / N2 = 1.5, 13,000 h-1).[Mode for Carrying Out the Invention]

[0014] The present invention is described in detail below.(Molded Catalyst)The molded catalyst of one embodiment of the present invention (present embodiment) comprises a composite material component (A), a zirconium (Zr) component (B), and a catalytically active metal M component (C). The composite material component (A) is a metal composite oxide containing two or more Group 2 elements. Preferably, the composite material component (A) is a metal composite oxide containing barium (Ba) and magnesium (Mg), or a mixed oxide containing barium oxide (BaO) and magnesium oxide (MgO). The zirconium component (B) is one or more selected from the group consisting of Zr and a precursor of Zr, ZrEb-x (0 < x < 2), ZrO2 and a precursor of ZrCh, ZrN, MgFh-x (x is 0 < x < 2), and Mg. The catalytically active metal M component (C) is a transition metal. Preferably, the catalytically active metal M component (C) is at least one selected from the group consisting of Ru, Co, Fe, and Ni. More preferably, the catalytically active metal M component (C) is a cobalt component (Cl), and the cobalt component (Cl) is at least one selected from the group consisting of Co, CoO, Co3O4, and CoCO3. Furthermore, the composite material component (A) is preferably a material represented by the following general formula (1):BanMg[i-n]Ox (1)(where 0 < n < 0.3 and 0.5 < x < 1.3)

[0015] [Characteristics of the Molded Catalyst]The molded catalyst of the present embodiment (sometimes simply referred to as the "molded catalyst of the present embodiment") is not particularly limited as long as it is suitable for the ammonia synthesis reaction described below. It is preferable that the molded catalyst be suitable for the gas-phase reaction of synthesizing ammonia from amixed gas containing nitrogen and hydrogen. More preferably, the molded catalyst is suitable for use in a reactor for industrial production of ammonia from a mixed gas containing nitrogen and hydrogen under pressures above atmospheric pressure.

[0016] In this context, "suitable for gas-phase reactions" means that the molded catalyst can be used as a solid catalyst (heterogeneous catalyst) for gas-phase reactions.In this context, "suitable for use in a reactor for industrial production of ammonia" means that ammonia can be synthesized through an exothermic reaction by passing a preheated feed gas through the catalyst bed. Reactors suitable for industrially producing ammonia include, for example, adiabatic and isothermal reactors, and can include a reactor with a function capable of quenching the reaction gas that has passed through the catalyst bed.

[0017] < Shape of the Molded Catalyst>The shape of the molded catalyst in the present embodiment is not particularly limited and may be any shape formed using conventional molding techniques. Specific shapes include granular, spherical, tablet, ring, macaroni, four-leaf, cube, and honeycomb shapes. Among these, cylindrical and tablet shapes are preferred from the viewpoint of catalyst producing productivity.

[0018] < Size of Molded Catalyst>To prevent pressure loss within the reactor, the size of the molded catalyst of the present embodiment is preferably 0.3 mm to 30 mm, more preferably 0.4 mm to 20 mm, most preferably 0.5 mm to 15 mm, and still more preferably 1 mm to 5 mm. A molded catalyst of the present embodiment with a size of 0.3 mm or greater is suitable for gas¬ phase reactions to synthesize ammonia gas, and is particularly suitable for reactors producing ammonia gas at an industrial level. A molded catalyst of the present embodiment with a size of 30 mm or less allows for easy handling of the catalyst and achieves a consistent packing density.The molded catalyst of the present embodiment may be of a substantially uniform size, a mixture of two or more sizes, or have a consistent size distribution.Here, "size of the molded catalyst" refers to, for example, in the case of a cylindrical extrusion, the diameter (D) of the circle and the length (L) of the cylinder are parameters that define the size of the extrusion, with L typically referring to the size of the extrusion. In the case of spherical molded catalysts, the catalyst size refers to the diameter of the sphere, which can be evaluated using dimensional measurement methods. For example, when the molded catalyst is in the shape of a tablet, this refers to its diameter.

[0019] < Bulk Density of Molded Catalyst>The bulk density of the molded catalyst of the present embodiment is preferably 0.5 to 2.5 g cm-3, more preferably 0.75 g cm-3or greater, and most preferably 1.0 g cm-3or greater. A bulk density of 0.5 g cm-3or greater of the molded catalyst of the present embodiment can achieve a certain packing density, making it suitable for gas-phase reactions to synthesize ammonia gas, and particularly suitable for reactors that produce ammonia gas on an industrial scale. In the present embodiment, when the bulk density of the molded catalyst is 2.5 g cm-3or less, the catalyst can be handled easily, and a constant gas-phase reaction rate can be maintained.Here, "the bulk density of the molded catalyst" refers to the weight of the molded catalyst per 1 cm3. This can be evaluated using a constant volume measurement method, in which the molded catalyst is filled into a container of known volume, the combined weight of the container and molded catalyst is measured, and the container weight is then subtracted.

[0020] < Crushing Strength of Molded Catalyst>The crushing strength of the molded catalyst of the present embodiment is preferably 0.4 kgf or more, more preferably 0.8 kgf or more, and most preferably 1.0 kgf or more. The crushing strength of the molded catalyst of the present embodiment may be 10 kgf or less. When the crushing strength of the molded catalyst of the present embodiment is 0.4 kgf or more, it is suitable for gas-phase reactions to synthesize ammonia gas, and is particularly suitable for reactors used to produce ammonia gas on an industrial scale. Here, "crushing strength of molded catalyst" refers to the strength that represents the resistance of the molded catalyst to destruction due to compression, and can be evaluated using the compression test method described in JIS Z8841: 1993 and ASTM D6175.For catalysts of the same composition, the crushing strength of the molded catalyst depends on the molding method and molding conditions (temperature, pressure, time, etc.). However, even if the molding method and molding conditions are the same, the crushing strength of the molded catalyst will differ if the material composition of the catalyst to be molded is different. One method of increasing the crushing strength is to add a binder, for example. However, this can affect the catalytic activity contained in the molded catalyst, so it is important for the molded catalyst to achieve both crushing strength and catalytic activity.By selecting the catalyst composition described below, the molded catalyst of the present embodiment becomes suitable for gas-phase ammonia synthesis, and in particular, can achieves both crushing strength and catalytic activity required for industrial-scale ammonia synthesis reactors.

[0021] < Specific Surface Area of Molded Catalyst>The specific surface area of the molded catalyst of the present embodiment is preferably 10 m2g-1or more, more preferably 20 m2g-1or more, and preferably 30 m2g-1or more. Inthe ammonia synthesis reaction, the greater the number of contacts between the nitrogen and hydrogen in the feed gas and the molded catalyst surface, the greater the number of reaction activity points contributing to the ammonia synthesis reaction. Therefore, it is preferable that molded catalysts produced on an industrial scale have a larger specific surface area. The specific surface area can be measured by an N2-BET method.Details of the measurement method are described in the Examples.

[0022] < A verage Particle Diameter of the Catalytically Active Metal M Component (C) in the Molded Catalyst>The average particle diameter of the catalytically active metal M component (C) in the molded catalyst of the present embodiment is preferably 20 nm or less, more preferably 10 nm or less. In ammonia synthesis reactions, the smaller the particle size of the catalytically active metal M component (C) on the surface of the molded catalyst, the greater the number of reaction activity points contributing to the ammonia synthesis reaction, even with the same loading. Therefore, a smaller average particle size of the catalytically active metal M component (C) is preferable for industrially produced molded catalysts. The average particle size can be determined using TEM images. Details of the measurement method are described in the Examples. For example, in Example 3, when the catalytically active metal M component (C) was Co, the average particle size was 3.6 nm, as shown in Fig. 1.

[0023] < Resistance to Poisoning by CO and Other Impurities in Molded Catalysts>The molded catalyst of the present embodiment exhibited almost no decrease in ammonia synthesis rate even when using feed gas from a standard gas cylinder containing trace impurities instead of the N2 (>6N) and H2(>6N) gases used in ammonia synthesis tests. This demonstrates that the molded catalyst of the present embodiment exhibits high resistance to poisoning by CO and other impurities.

[0024] [Composite Material Component (A)]The composite material component (A) contained in the molded catalyst of the present embodiment (sometimes referred to as "composite material component (A) of the present embodiment" or "component (A) of the present embodiment") is a composite oxide of metals containing two or more Group 2 elements. Examples of composite oxides of metals containing two or more Group 2 elements include composite oxides of metals containing barium (Ba) and magnesium (Mg), composite oxides of metals containing barium (Ba) and calcium (Ca), and composite oxides of metals containing calcium (Ca) and magnesium (Mg).Preferably, the composite material component (A) is a composite oxide of metals containing barium (Ba) and magnesium (Mg).More preferably, the composite material component (A) is a material represented by the following general formula (1):

[0025] BanMg[i-n]Ox(1)(where 0 < n < 0.3 and 0.5 < x < 1.3)

[0026] In the composite material component (A), 0 < n < 0.3. Preferably, n is 0.005 or greater, more preferably 0.01 or greater, and most preferably 0.015 or greater. Preferably, n is 0.1 or less, more preferably 0.05 or less, and most preferably 0.025 or less. The preferred range for n may be any combination of the preferred lower limit and upper limit. When n is 0.005 or greater, catalytic activity is improved. When n is significantly below the above range, the reaction-promoting effect of Ba is significantly reduced, making it unsuitable for use as a molded catalyst. Furthermore, when n significantly exceeds the above range, the crushing strength is reduced, making it unsuitable for use as a molded catalyst.

[0027] In the composite material component (A), x is in the range of 0.5 < x < 1.3.Preferably, x is 0.7 or greater, more preferably 0.8 or greater, and most preferably 1.0 or greater. Preferably, x is 1.25 or less, more preferably 1.2 or less, and most preferably 1.1 or less. The preferred range for x may be any combination of the preferred lower limit and upper limit described above.

[0028] Examples of the composite material component (A) include BanMg[i-n]Ox(in the above formula (1), n = 0.005, x = 1.0), BanMg[i-n]Ox(in the above formula (1), n = 0.0075, x = 1.0), BanMg[i-n]Ox(in the above formula (1), n = 0.01, x = 1.0), etc.

[0029] In the above general formula (1), n and (1-n) represent the molar ratios of Ba and Mg, respectively, relative to 1 mole of the total of the metal elements Ba and Mg in the material represented by formula (1). Typically, these can be calculated from the amounts of each metal compound (oxide, inorganic acid compound, organic compound, etc.) in the raw materials. Alternatively, they can be evaluated using structural analysis. In the present invention, unless specifically stated as being evaluated by structural analysis, these are calculated from the amounts of each metal compound (oxide, inorganic acid compound, organic compound, etc.) in the raw materials.In addition, in the above general formula (1), x represents the number of moles of oxygen atoms required, since the overall charge is 0 when the total of each metal element is 1 mole. Since the valence of each metal is not necessarily the same as the valence of each metal compound in the raw materials, for example, x may be greater than 1 ([n x 2+(l-n) x 2] / 2=l) or less than 1.

[0030] " Method for Producing Composite Material Component (A)"The composite material component (A) can be produced by known methods. For example, the following method can be used. Magnesium hydroxide (calcined in air) orpre-calcined magnesium oxide is immersed in a suitable solvent containing a barium compound dissolved or dispersed therein. The solvent is then removed and the resulting mixture is calcined to obtain the composite material component (A). A composite of the composite material component (A) and the catalytically active metal M component (C) can be produced, for example, by mixing and calcining a precursor of the composite material component (A) and a precursor of the catalytically active metal M component (C), as described in (Method for Producing a Molded Catalyst).

[0031] < Content of Composite Material Component (A)>The content of the composite material component (A) in the molded catalyst of the present embodiment is preferably 50.0 wt.% or more, more preferably 60.0 wt.% or more, and most preferably 75.0 wt.% or more. It is preferably 99.0 wt.% or less, more preferably 80.0 wt.% or less. The preferred range of the content of component (A) may be any combination of the preferred lower limit and the preferred upper limit.

[0032] [Zirconium Component (B)]The zirconium component (B) contained in the molded catalyst of the present embodiment (sometimes referred to as "zirconium component (B) of the present embodiment" or "component (B)") is one or more selected from the group consisting of Zr and a precursor of Zr, ZrFB-x (x where 0 < x < 2), ZrCh and a precursor of ZrCh, ZrN, MgHs, and Mg. Preferably, it is one or more selected from the group consisting of Zr and precursors of Zr, ZrHb-x (0 < x < 2), ZrOz and precursors of ZrCh, ZrN, MgHi, and Mg; more preferably, it is one or more selected from the group consisting of ZrH2-x(0 < x < 2), ZrC and precursors of ZrCh, ZrN, and MgFF; most preferably, it is one or more selected from the group consisting of ZrHi-x (0 < x < 2), ZrCh and precursors of ZrCh, and ZrN; and most preferably, it is one or more selected from the group consisting of ZrHj-x (0 < x < 2), ZrCh, and ZrN. Of these, ZrH2is preferred from the standpoint of catalytic performance. Furthermore, from the viewpoint of improving the activation rate of the resulting catalyst, two or more species may be selected from the group consisting of Zr and a precursor of Zr, ZrHz-x (0 < x < 2), ZrO2 and a precursor of ZrO2, ZrN, MgH2, and Mg. For example, it is preferable to contain ZrH -x (0 < x < 2) and ZrO2. In this case, it is more preferable that the content of ZrH -x(0 < x < 2) in the entire catalyst is 20 to 25 wt.%. Furthermore, the content of ZrO2may be 5 mol or more, 8 mol or more, or 15 mol or more relative to 100 mol of catalytically active metal such as Co. When the zirconium component (B) contains two or more selected from the group consisting of Zr and a precursor of Zr, ZrIN-x (where 0 < x < 2), ZrCh and a precursor of ZrCh, ZrN, MgFh, and Mg (for example, when it contains ZrFb-x (where 0 < x < 2) and ZrCh), it is preferably obtained by the production method described in the second embodiment of the catalyst production method described below. That is, a preferred molded catalyst is obtained by mixing a precursor of the first zirconium component (B1) (for example, ZrO2) with a precursor ofa catalytically active metal M component (C), such as Co, calcining the mixture, and then adding a second zirconium component (B2) (for example, ZrEb-x (where 0 < x < 2))-

[0033] An example of a Zr precursor includes ZrCl₄.The above term " Zrtb-x (where 0 < x < 2)" refers to zirconium hydride. Preferably, 0 < x < 1.0, and more preferably 0 < x < 0.5. Examples include ZrH₂, ZrH₁.₅, and ZrH₁.₀. Of these, ZrH₂ is preferred.Precursors of ZrO₂ include, for example, zirconium salts, zirconium hydroxide (Zr(OH)4), and zirconyl hydroxide (ZrO(OH)2). Examples of water-soluble zirconium salts include zirconium chloride, zirconium nitrate, zirconium sulfate, zirconyl chloride (zirconium oxychloride, ZrOCl₂), zirconyl nitrate (ZrO(NO₃)₂), and zirconyl sulfate (ZrOSO4).

[0034] " Particle Size of Zirconium Component (B)"The particle size of the zirconium component (B) in the present embodiment is preferably 180 pm or less, and more preferably 20 to 180 pm. The particle size is preferably 30 pm or more, more preferably 40 pm or more, and most preferably 45 pm or more. It is preferably 160 pm or less, more preferably 150 pm or less, and most preferably 75 pm or less. The preferred range of the particle size of component (B) may be any combination of the above-mentioned preferred lower limit and preferred upper limit.A particle size of component (B) of 180 pm or less has the effect of improving catalytic activity. This is because the contact probability of zirconium particles with catalytic active sites present on the catalyst surface increases relatively.

[0035] In the molded catalyst of the present embodiment, the particle size of the zirconium component (B) contained in the final molded catalyst may be different from or the same as the particle size of the above-mentioned component (B), depending on the producing method and producing conditions described below.

[0036] Furthermore, when the zirconium component (B) contains ZrH2-x(0 < x < 2) and ZrCh and is obtained by the producing method described in the second embodiment of the catalyst producing method described below, the particle size of the zirconium component (B1) composed of ZrO₂ may be within the above range. Furthermore, the particle size of the zirconium component (B2) composed of ZrFE-x (0 < x < 2) is preferably smaller than that of the zirconium component (Bl). For example, a particle size of 20 pm or less is preferable in terms of catalytic performance.

[0037] " Zirconium Component (B) Content"The content of the zirconium component (B) in the molded catalyst of the present embodiment is preferably 5 wt.% to 50 wt.%. Furthermore, the content of the zirconium component (B) in the total mass of the molded catalyst of the present embodiment, excluding the catalytically active metal M component (C), is preferably 5 wt.% to 50 wt.%, and preferably 5 wt.% to 45 wt.%. Furthermore, the content of the zirconium component (B) is preferably less than the content of the composite material component (A), and may be 90 parts by mass or 80 parts by mass relative to 100 parts by mass of the composite material component (A). That is, in the molded catalyst of the present invention, the main component of the support supporting the catalytically active metal M component (C) is the composite material component (A), and the auxiliary component is the zirconium component (B). The main component is a component whose content in the total amount is 50 wt.% or more, 55 wt.% or more, or 60 wt.% or more. The auxiliary component is a component whose content in the total amount is less than 50 wt.%, 45 wt.% or less, or 40 wt.% or less.The zirconium component (B) content is 10 wt.% or more; preferably 20 wt.% or more; and more preferably 25 wt.% or more. It is preferably 40 wt.% or less; more preferably 35 wt.% or less; and most preferably 30 wt.% or less. The preferred range of the zirconium component (B) content may be any combination of the preferred lower limit and the preferred upper limit. A zirconium component (B) content of 5 wt.% or more can improve catalytic performance. A component (B) content of 50 wt.% or less can improve catalytic performance.

[0038] Note that the "zirconium component (B) content" in the present invention is a value calculated from the amount of zirconium component (B) in the raw materials used. The "zirconium component (B) content" in the present invention is a value converted into the Zr element content calculated from the amount of zirconium component (B) in the raw materials used. That is, the content of the zirconium component (B) in the molded catalyst is the content calculated as the Zr element content of the zirconium component (B) relative to 100 wt.% of the molded catalyst.

[0039] " Effect of Zirconium Component (B)"The zirconium component (B) has the effect of increasing the crushing strength of the molded catalyst of the present embodiment. As shown in the examples below, for example, when the zirconium component (B) is contained at 25 wt.%, it is possible to achieve a practical level of crushing strength compared to a molded catalyst without a zirconium component. The reason for the increase in crushing strength due to the zirconium component (B) is still under investigation, but it is believed to be due to interactions between the zirconium component and other metal components.When the zirconium component (B) is blended, resistance to poisoning substances contained in the feed gas is high.

[0040] When the zirconium component (B) contains two or more selected from the group consisting of Zr, ZrFE-x (where 0 < x < 2), ZrCh, ZrN, MgHs, and Mg, and particularly when it contains ZrEb-x (where 0 < x < 2) and ZrC, the activation time of the ammonia synthesis catalyst can be shortened.

[0041] [Catalytically Active Metal M Component (C)]The catalytically active metal molded catalyst of the present embodiment contains a catalytically active metal M component (C). The catalytically active metal M component (C) is a transition metal. The catalytically active metal M component (C) is preferably at least one selected from the group consisting of Ru, Co, Fe, and Ni, and more preferably the cobalt component (Cl).

[0042] " Transition Metal"The term "transition metal" as used herein is not particularly limited, but typically refers to a transition metal in Groups 6, 7, 8, 9, or 10 of the periodic table, preferably a transition metal in Groups 6, 8, or 9, and more preferably a metal in Groups 8 or 9. Specific metal elements are not particularly limited, but are typically Cr, Mo, Mn, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, and Pt. Preferably, Mo, Re, Fe, Ru, Os, and Co are used because they have high bond energy with nitrogen. More preferably, Ru, Co, Fe, and Ni are used because they exhibit catalytic activity for ammonia synthesis when employed as catalysts. Ru is also preferred because it exhibits high catalytic activity. When cost efficiency is a priority, Co or Fe is preferred. The above elements may be used alone or in combination of two or more. Intermetallic compounds of these elements, such as Co₃Mo₃N, Fe₃Mo₃N, Ni₃Mo₃N, Mo₂N, can also be used. Preferably, each element is used alone or in combination of two or more, and more preferably, each element is used alone for cost reasons.

[0043] < Cobalt Component (Cl)>In the present embodiment, the cobalt component (Cl) is preferably at least one selected from the group consisting of Co, CoO, CO3O4, and CoCOs, and the cobalt component (Cl) is more preferably Co.

[0044] The above " Co" refers to metallic Co. An example of metallic Co is commercially available cobalt powder (180 pm, 99.5%).

[0045] The above " CoO" refers to the oxide of cobalt with a valence of +2, i.e., cobalt monoxide. Examples include commercially available products.

[0046] " CO3O4" refers to the oxide of cobalt with a mixed valence, containing both cobalt with a valence of +2 and cobalt with a valence of +3. Examples include commerciallyavailable tricobalt tetroxide (manufactured by Kojundo Chemical Research Institute, purity 3Nup powder).

[0047] " CoCOs" refers to cobalt carbonate. Examples include commercially available cobalt carbonate. Examples of cobalt carbonates include hydrates of cobalt (II) hydroxide and water. These are commonly known as basic cobalt carbonates. While there are no particular restrictions on whether or not the carbonate is basic, basic compounds are preferred as supports suitable for ammonia synthesis reactions, and raw materials that remain basic even after catalyst preparation are preferred.

[0048] The "particle size of component (Cl)" in this specification is the average value evaluated for the raw material cobalt component (Cl) used by direct observation using a transmission electron microscope. For example, when a particle size distribution is created, particle sizes in the range of 10 to 40 nm are observed, and this average value is evaluated to yield a particle size in the range of 20-25 nm.In the molded catalyst of the present embodiment, the particle size of the cobalt component (Cl) contained in the final molded catalyst may be different from or the same as the particle size of the component (Cl), depending on the producing method and producing conditions described below.

[0049] " Content of catalytically active metal M component (C)"In the molded catalyst of the present embodiment, the content of the catalytically active metal M component (C) is preferably 1 wt.% to 50 wt.%.The content of the catalytically active metal M component (C) is preferably 5 wt.% or more, and more preferably 10 wt.% or more. It is preferable that the content be 20 wt.% or more. It is preferable that the content be 40 wt.% or less, more preferably 30 wt.% or less, and most preferably 25 wt.% or less. The preferable range of the content of the catalytically active metal M component (C) may be defined by any combination of the preferable lower limit and the preferable upper limit described above.When the content of catalytically active metal M component (C) is 1 wt.% or more, the catalytic performance can be effectively expressed. When the content of component (C) is 50 wt.% or less, sufficient catalytic performance can be obtained.

[0050] In addition, the "the content of catalytically active metal M component (C)" of the present invention is a value calculated from the amount of catalytically active metal M component (C) in the raw material used.When the catalytically active metal M component (C) is a cobalt component (Cl), the " Co content in the oxide" is the mass ratio, in terms of zero-valent Co atoms, of the total of the mass of composite material A and the mass of the cobalt component (Cl) in terms of zero- valent Co atoms.

[0051] " Effect of catalytically active metal M component (C)"The catalytically active metal M component (C) is the active component of the catalyst and serves as a component for dissociating nitrogen molecules adsorbed on the metal M surface. For example, in the case of a cobalt component (Cl), nitrogen adsorbed on the cobalt surface is dissociated. Even when cobalt monoxide (CoO) or tricobalt tetroxide (CO3O4), which are oxides of the cobalt component (Cl), are used as raw materials, sufficient nitrogen dissociation performance is achieved by activating the catalyst through hydrogen reduction.

[0052] The specific surface area of the molded catalyst of the present embodiment is not particularly limited, but is typically 0.1 m2g-1or greater, preferably 10 m2g-1or greater, and more preferably 30 m2g-1or greater.

[0053] (Method for Producing Molded Catalyst)[First Embodiment]The method for producing the molded catalyst of the present embodiment includes a step of mixing a precursor of the composite material component (A), a precursor of the zirconium component (B), and a precursor of the catalytically active metal M component (C), followed by molding the mixture.The molded catalyst producing method of the present embodiment preferably includes the following steps 1 to 3:Step 1: Mixing a precursor of the composite material component (A) with a precursor of the catalytically active metal M component (C).Step 2: Calcining the raw material mixture obtained in step 1.Step 3: Mixing the calcined product obtained in step 2 with the zirconium component (B) and molding the mixture.Hereinafter, the steps 1, 2, and 3 of the producing method for the molded catalyst of the present embodiment will be described in detail using an example where the catalytically active metal M component (C) is a cobalt component (Cl). This is not intended to limit the producing method for the molded catalyst of the present embodiment.

[0054] < Step 1>In step 1, the precursor of the composite material component (A) (the raw material for producing the composite material component (A)) is a mixture of a Ba compound, which is a raw material serving as a Ba source, and a Mg compound, which is a raw material serving as a Mg source.Examples of the Ba compounds include BaCCE, Ba(OC2Hs)2, Ba(NO3)2, Ba(OH)2, and BaO.Examples of Mg compounds include MgCh, Mg(NCh)2, MgO, Mg(OH)2, and MgCCh.When the catalytically active metal M component (C) is cobalt component (Cl), the precursor of the cobalt component (Cl) is a Co compound that is a raw material serving as Co source for the cobalt component (Cl)Examples of the Co compound include cobalt nitrate (Co(NO3)2), cobalt chloride (CoCl₂), cobalt carbonate, cobalt acetate (Co(C₂H₃O₂)₂), cobalt formate (Co(CHO2)2), cobalt acetylacetonate, cobalt sulfate (CoSO₄), cobalt hydroxide (Co(OH)2, or CO(OH)3), cobalt oxide (Co₃O₄), and hydrates thereof (for example, cobalt nitrate hydrate: Co(NOs)2 ’ 6H2O). Cobalt nitrates, cobalt carbonates, and hydrates thereof are preferred. Examples of cobalt chloride hydrates include CoCl₂·6H₂O.The Ba compound, the Mg compound, and the Co compound may be mixed in a dry state, or may be mixed in a wet state with additional water added as needed. Known methods can be used as the mixing method. An example of the mixing method includes a kneading method. Examples of the kneading method include a twin-screw kneader and a single-shaft kneader. There are no limitations on the type of kneaders, as long as the raw materials can be uniformly mixed. When wet mixing is used, the resulting mixture may be dried.The amounts of Ba compound, Mg compound, and Co compound in the final mixture can be adjusted to match the composition of the final synthesized molded catalyst.

[0055] < Step 2>The calcination temperature for calcining the raw material mixture obtained in Step 1 is preferably between 400°C and 800°C, and is preferably between 500°C and 800°C. A temperature range of 750°C is more preferable, and a temperature range of 500°C to 650°C is most preferable. The calcining atmosphere may be air or nitrogen. The calcining time varies greatly depending on the amount of raw material mixture charged and the type of calcining furnace (for example, a batch-type calcining furnace or a continuous calcining furnace). For example, when the amount of raw material mixture charged is about 10 g and calcining is performed in a batch-type electric furnace, the calcining time may be 3 to 48 hours, or 5 to 20 hours. The heating rate may be 50 to 200°C / hour, or may be 100°C / hour.For example, the temperature may be increased to 60 to 90°C at a heating rate of 100°C / hour, the temperature may be maintained at 60 to 90°C for 3 to 8 hours, and then the temperature may be increased to 500 to 800°C at a heating rate of 100°C / hour and calcined for 10 to 25 hours.

[0056] " Calcined Product of Second Step"When the catalytically active metal M component (C) in the first step is cobalt component (Cl), the calcined product of the second step is a composite material (AC1) of the cobalt component (Cl) and a composite oxide of a metal containing barium (Ba) and magnesium (Mg), preferably represented by the following formula (3 -Co):

[0057] BanCOmMg[l-(n+m)]Ox (3-Co )(In the above general formula (3-Co), 0 < n < 0.3, 0.001 < m < 0.5 and 0.002 < n+m < 0.6, and 0.5 <x< 1.3)

[0058] In the above composite material (ACl), m is preferably 0.005 or more; more preferably 0.0075 or more; and most preferably 0.01 or more. It is preferable that m is 0.4 or less; more preferably 0.3 or less; and most preferably 0.2 or less. The preferred range for m may be any combination of the preferred lower limit and the preferred upper limit described above. When m is significantly below this range, the number of catalytic reaction active sites decreases, resulting in a significant drop in performance per weight of the molded catalyst. Furthermore, when m significantly exceeds the above range, the number of active sites per unit surface area of the catalytically active metal M component (C) decreases, resulting in a drop in performance per weight of the molded catalyst.

[0059] In the above composite material (ACl), 0 < n < 0.3. n is preferably 0.005 or greater; more preferably 0.0075 or greater; and most preferably 0.01 or greater. It is preferable that n is 0.1 or less; more preferably 0.08 or less; and most preferably 0.05 or less.The preferred range of n may be any combination of the above-mentioned preferred lower limit and upper limit. When n is significantly below the above range, the promoting effect of Ba on the reaction rate will be significantly reduced, and when n is significantly above the above range, the strength of the molded catalyst will be significantly reduced, making it undesirable as a molded catalyst.

[0060] In the above composite material (ACl), x is in the range of 0.5 < x < 1.3. Preferably, x is 0.6 or greater; more preferably 0.8 or greater; and most preferably 1.0 or greater. Preferably, x is 1.2 or less; more preferably 1.15 or less; and most preferably 1.1 or less. The preferred range for x may be any combination of the preferred lower limit and upper limit described above.Examples of the above composite material (ACl) includeBa₀.₀₉₉Co₀.₀₁Mg[1-(0.099+0.01)]O₁.₀₀ (in the above formula (3-Co), m = 0.01, n = 0.099, x = 1.00).In the examples described below, Ba₀.₀₁₅Co₀.₁₈MgOₓ and the like were prepared as composite material (AC1).

[0061] < Step 3>The composite material (ACl), which is the calcined product obtained in Step 2, and the zirconium component (B) may be dry mixed, or, if necessary, may be wet mixed with additional water. When water is included, the mixture may be dried. The drying temperature may be, for example, 50-90°C, 60-80°C, or 70°C. The calcined product may be pulverized and then mixed with the zirconium component (B), or the mixturemay be pulverized while being mixed. Known methods can be used as the mixing method. An example of the mixing method includes a kneading method. Examples of the kneading method include a twin-screw kneader and a single-shaft kneader. There are no limitations on the type of kneaders, as long as the raw materials can be uniformly mixed. When wet mixing is used, the resulting molded catalyst may be dried.

[0062] After mixing the composite material (AC1) and the zirconium component (B), any known molding method can be used to mold the mixture. For example, extrusion molding using a molding machine or the like can be used.

[0063] In the third step, the zirconium component (B) is the same as the zirconium component (B) described for the molded catalyst of the present embodiment.As a specific example of the third step, in the examples described below, Ba₀.₀₁₅Co₀.₁₈MgOₓ and ZrH₂ as the zirconium component were mixed and extruded to produce a pellet-shaped molded catalyst (Ba₀.₀₁₅Co₀.₁₈MgOₓ·ZrH₂). The molding method is not limited to extrusion molding, and may also be, for example, tablet molding.

[0064] [Modification of First Embodiment]The producing method of the modification of the first embodiment includes the step of blending the zirconium component (B) and the catalytically active metal M component (C) using the composite material component (A) (e.g., ”BanMg[i-n]O") that has been previously manufactured and then molding it.The composite material component (A) is the same as the composite material component (A) described in the catalyst form of the present embodiment. The producing method of the composite material component (A) is the same as the method described in the " Method for Producing Composite Material Component (A)" above.

[0065] When blending the composite material component (A) (e.g., " BanMg[i-n]Ox"), the catalytically active metal M component (C) or its precursor, and the zirconium component (B) or its precursor, the order in which they are added is not particularly limited. For example, the order may be (1) the composite material component (A), (2) the catalytically active metal M component (C) or its precursor, and (3) the zirconium component (B) or its precursor; or (1) the composite material component (A), (2) the zirconium component (B) or its precursor, and (3) the catalytically active metal M component (C) or its precursor. The resulting mixture is extrusion-molded to obtain a molded catalyst.The catalytically active metal M component (C) is the same as that described above in [Catalytically Active Metal M Component (C)] and is preferably a transition metal. The precursor of the catalytically active metal M component (C) is preferably a transition metal compound.

[0066] " Transition Metals and Transition Metal Compounds"The "transition metal" in the present embodiment is the same as the "transition metal" described in [Catalytically Active Metal M Component (C)].

[0067] The transition metal compound is not particularly limited, but examples include inorganic transition metal compounds or organic transition metal complexes that are easily thermally decomposed. Specifically, examples include transition metal complexes, transition metal oxides, and transition metal salts such as nitrates and hydrochlorides.Examples of Ru compounds include triruthenium dodecacarbonyl [Ru₃(CO)₁₂], dichlorotetrakis(triphenylphosphine)ruthenium(II) [RuCl₂(PPh₃)₄], dichlorotris(triphenylphosphine)ruthenium(II) [RuCl₂(PPh₃)₃], tris(acetylacetonato)ruthenium(III) [Ru(acac)₃], ruthenocene [Ru(C₅H₅)], nitrosyl nitrate ruthenium [Ru(NO)(NO₃)₃], potassium ruthenate, ruthenium oxide, ruthenium nitrate, and ruthenium chloride. Tris(acetylacetonato)ruthenium(III) [Ru(acac)3] is preferable.

[0068] Examples of Fe compounds include iron pentacarbonyl [Fe(CO)₅], triiron dodecacarbonyl [Fe₃(CO)₁₂], diiron nonacarbonyl [Fe₂(CO)₉], iron tetracarbonyl iodide [Fe(CO)₄I₂], tris(acetylacetonato)iron(III) [Fe(acac)₃], ferrocene [Fe(C₅H₅)₂], iron oxide, iron nitrate, and iron chloride (FeCl₃).

[0069] Examples of Co compounds include dicobalt octacarbonyl [Co₂(CO)₈], tris(acetylacetonato)cobalt(III) [Co(acac)₃], cobaltocene [Co(C₅H₅)₂], cobalt oxide, cobalt nitrate, cobalt carbonate and cobalt chloride.Among these transition metal compounds, when transition metal carbonyl complexes such as [Ru3(CO)12], [Fe(CO)5], [Fe3(CO)12], [Fe2(CO)9], [Co2(CO)8], and are used, a transition metal is supported by heating after loading the complex on the support.Therefore, in producing the molded catalyst of the present embodiment, the reduction treatment described later can be omitted, and thus these transition metal carbonyl complexes are preferable.

[0070] The amount of the transition metal compound used is not particularly limited, and an appropriate amount can be used to achieve the desired loading. However, it is typically about 2 wt.% or more, preferably 10 wt.% or more, more preferably 20 wt.% or more, and typically 50 wt.% or less, preferably 40 wt.% or less, more preferably 30 wt.% or less, based on the mass of the support (composite material component (A) + zirconium component (B)) used.

[0071] Specific methods for loading the transition metal compound on the support include, for example, physical mixing method, chemical impregnation method, CVD (chemical vapor deposition) method, and sputtering method.

[0072] The physical mixing method involves solid-state mixing of the support (composite material component (A) or composite material component (A) + zirconium component (Bl)) and the transition metal compound, followed by heating in a stream of inert gas such as air, nitrogen, argon, or helium, or under vacuum. The heating temperature is not particularly limited, but is typically 200°C or more and 600°C or less. The heating time is not particularly limited, but typically 2 hours or more is desirable.

[0073] The chemical impregnation treatment method is a method in which a liquid is caused to penetrate into interstices between particles of a solid material (e.g., metal, wood, ceramics, etc.). This method is applied by immersing a ceramic support, such as a metal oxide with an appropriate specific surface area and acidic or basic properties, in a metal salt solution and then drying it to evaporate the solvent, thereby dispersing and immobilizing the catalytically active component on the support surface.

[0074] The method for reducing the transition metal compound (hereinafter referred to as reduction treatment) is not particularly limited as long as it does not interfere with the objectives of the present invention. Examples include a method in which the reduction treatment is carried out in an atmosphere containing a reducing gas, or a method in which a reducing agent such as NaBH4, NH2NH2, or formalin is added to a solution containing the transition metal compound to precipitate it on the surface of the support. However, the reduction treatment is preferably carried out in an atmosphere containing a reducing gas. Examples of reducing gases include hydrogen, ammonia, methanol (vapor), ethanol (vapor), methane, and ethane.Furthermore, during the reduction treatment, components other than the reducing gas may coexist in the reaction system as long as they do not inhibit the objectives of the present invention, particularly the ammonia synthesis reaction. Specifically, during the reduction treatment, in addition to reducing gases such as hydrogen, gases such as argon or nitrogen, which do not inhibit the reaction, may also be present, with the coexistence of nitrogen being preferred.When the reduction treatment is carried out in a hydrogen-containing gas, the coexistence of nitrogen with hydrogen allows the reduction treatment to be carried out in parallel with the ammonia production described below. That is, when the ammonia synthesis catalyst of the present invention is used as the ammonia synthesis catalyst described below, the transition metal compound supported on the support may be subjected to the reaction conditions for the ammonia synthesis reaction, thereby reducing the transition metal compound and converting it to a transition metal.

[0075] The temperature during the reduction treatment is not particularly limited, but is typically 200°C or higher, preferably 300°C or higher, and typically below the decomposition temperature of the transition metal compound, preferably 600°C or lower. This is because carrying out the reduction treatment within the above temperature range allows the transition metal to grow sufficiently and within a preferred range.The pressure during the reduction treatment is not particularly limited, but is usually 0.01 MPa or more, preferably 5 MPa or more, and more preferably 8 MPa or more. When the pressure during the reduction treatment is the same as the ammonia synthesis conditions described below, complicated operations are not required, which is advantageous in terms of production efficiency.The duration of the reduction treatment is not particularly limited, but when carried out at atmospheric pressure, it is usually 1 hour or more, and 2 hours or more is preferred. Furthermore, when carried out under high reaction pressure conditions, for example 1 MPa or more, 1 hour or more is preferred.

[0076] [Second Embodiment]The present embodiment of the molded catalyst producing method differs from the first embodiment. The zirconium component (B) contained in the molded catalyst manufactured by this producing method includes a first zirconium component (Bl) blended in the first stage and a second zirconium component (B2) blended in the second stage. Since the first zirconium component (Bl) and the second zirconium component (B2) are blended in different stages, their forms in the resulting molded catalyst may differ. For example, in the molded catalyst, the first zirconium component (Bl) may have a particle size different from that of the second zirconium component (B2).Furthermore, while a portion of the first zirconium component (Bl) or a component derived therefrom is contained within the particles of the composite material component (A) contained in the molded catalyst, the second zirconium component (B2) or a component derived therefrom is present outside the particles of the composite material component (A).

[0077] The method for producing a molded catalyst of the present embodiment includes the following Step 1 to Step 3.Step 1: Mixing a precursor of the composite material component (A), a precursor of the catalytically active metal M component (C), and a precursor of the first zirconium component (Bl).Step 2: Calcining the raw material mixture obtained in Step 1.Step 3: Mixing the calcined product obtained in Step 2 with the second zirconium component (B2).

[0078] The first zirconium component (Bl) and the second zirconium component (B2) may be the same or different. It is preferable that the first zirconium component (B 1) is ZrO2and the second zirconium component (B2) is ZrH2−x(0 < x < 2). It is more preferable that the first zirconium component (Bl) is ZrO2and the second zirconium component (B2) is ZrH2.Below, the method for producing a molded catalyst of the present embodiment will be described in detail using an example in which the first zirconium component (Bl) is ZrO2and the second zirconium component (B2) is ZrH2-x(0 < x < 2). The method for producing a molded catalyst of the present embodiment is not limited to the present example.

[0079] < Step 1>The first step of the second embodiment is the same as the first step of the first embodiment, except for the addition of a ZrO2precursor.The ZrO2precursor can be any material that generates ZrO2in the second step of the second embodiment, such as zirconium salts, zirconium hydroxide (Zr(OH)4), or zirconyl hydroxide (ZrO(OH)2). The ZrO2precursor is preferably water-soluble. Examples of the water-soluble zirconium salt include zirconium chloride, zirconium nitrate, zirconium sulfate, zirconyl chloride (zirconium oxychloride, ZrOCl2), zirconyl nitrate (ZrO(NO3)2), and zirconyl sulfate (ZrOSO4). Among these, zirconyl nitrate (ZrO(NO3)2) may be used. In the first step, the precursor of the composite material component (A) and the precursor of the catalytically active metal M component (C) may be wet mixed using the aqueous solution of the water-soluble zirconium salt.

[0080] The molded catalyst produced in the second embodiment is obtained by simultaneously mixing the precursor of ZrO2, the precursor of the composite material component (A), and the precursor of the catalytically active metal M component (C), and calcining the resulting mixture. Therefore, it is believed that ZrO2is present within the resulting calcined product.On the other hand, in the third step of the second embodiment, the ZrH2-x(where 0 < x < 2) particles added to the calcined product obtained in the second step are considered to be adjacent to the particles of the calcined product obtained in the second step.The amounts of Ba compound, Mg compound, and Co compound, and zirconium salt in the final mixture can be adjusted to match the composition of the final synthesized molded catalyst.

[0081] < Second Step>In the second step of the second embodiment, the conditions are the same as those in the second step of the first embodiment.

[0082] " Calcined Product of the Second Step of the Second Embodiment"When the catalytically active metal M component (C) in the first step is cobalt component (Cl), the calcined product in the second step is a composite material (ABC1) of a metal composite oxide containing barium (Ba) and magnesium (Mg), the cobalt component (Cl), and ZrO2as the zirconium component (B1), preferably a material represented by the following formula (3-CoZr):

[0083] BanComMg[i- (n+m)]Ox ' ZrCh (w mol%) (3-CoZr)(In the above general formula (3-CoZr), 0 ≤ n < 0.3, 0.001 ≤ m ≤ 0.5 and 0.002 ≤ n+m ≤ 0.6, 0.5 ≤ x ≤ 1.3, and 1≤w≤30. Note that w mol% is the ratio of Zr atoms to the total number of moles of Co atoms in cobalt component (C1) and Zr atoms in the ZrO2.

[0084] In the above composite material (ABC1), m is preferably 0.005 or more; more preferably 0.0075 or more; and most preferably 0.01 or more. It is preferable that m is 0.4 or less; more preferably 0.3 or less; and most preferably 0.2 or less. The preferred range of m may be any combination of the above preferred lower limit and the above preferred upper limit. When m is significantly below this range, the number of reactive sites for catalytic reaction decreases, resulting in a significant decrease in performance per weight of the molded catalyst. Furthermore, when m significantly exceeds the above range, the number of reactive sites per unit surface area of the catalytically active metal M component (C) decreases, resulting in a decrease in performance per weight of the molded catalyst.

[0085] In the above composite material (ABC1), 0 < n < 0.3. n is preferably 0.005 or greater; more preferably 0.0075 or greater; and most preferably 0.01 or greater. It is preferable that n is 0.1 or less; more preferably 0.08 or less; and most preferably 0.05 or less. The preferred range for n may be any combination of the preferred lower limit and preferred upper limit described above. When n is significantly below the above range, the reaction-accelerating effect of Ba is significantly reduced, while when n is significantly above this range, the strength of the molded catalyst is significantly reduced, making it undesirable as a molded catalyst.

[0086] In the above composite material (ABC1), 0.5 < x < 1.3. Preferably, x is 0.6 or greater; more preferably 0.8 or greater; and most preferably 1.0 or greater. Preferably, x is 1.2 or less; more preferably 1.15 or less; and most preferably 1.1 or less. The preferred range for x may be any combination of the preferred lower limit and the preferred upper limit described above.

[0087] In the above composite material (ABC1), w is preferably 1 or greater, more preferably 3 or greater, and most preferably 5 or greater. Preferably, w is 40 or less; more preferably 20 or less; and most preferably 10 or less. The preferred range for w may be any combination of the preferred lower limit and the preferred upper limit describedabove. When w is significantly below the above range, the effect of shortening the activation time is reduced. Furthermore, when w significantly exceeds the above range, catalytic performance tends to decline, making it undesirable as a molded catalyst for industrial use.

[0088] The above composite material (ABC1) can be, for example,Ba₀.₀₉₉Co₀.₀₁Mg[1-(0.099+0.01)]O₁.₀₀’Zr02 (9 mol%) (in the above formula (3-CoZr), m = 0.01, n = 0.099, x = 1.00, w = 9. ), etc.In the examples described below, Bao.oisCoo.isMgOx’ZrCh (9 mol%) was prepared as the composite material (ABC1).

[0089] < Step 3>In Step 3, the molded catalyst of the second embodiment can be obtained in the same manner as Step 3 of the first embodiment, except that the composite material (ABC1) obtained in Step 2 of the second embodiment is used instead of the composite material (AC1) obtained in Step 2 of the first embodiment, and a second zirconium component (B2) is used instead of the zirconium component (B) in Step 3 of the first embodiment. In Step 3, the second zirconium component (B2) is the same as the zirconium component (B) described for the molded catalyst of the present embodiment above. The second zirconium component (B2) is preferably ZrH2−x(0 ≤ x < 2), and more preferably ZrH2.Specific example of Step 3 includes a step of mixing Bao.oisCoo.isMgOx’ZrC (29 mol%) and ZrJfc as the zirconium component and extruding the mixture to produce a pellet-shaped molded catalyst (Bao.oisCoo.isMgOx’ZrCh (29 mol%). Zrkb (wt.%)).

[0090] (Ammonia Synthesis Catalyst)The ammonia synthesis catalyst of the present embodiment can use the molded catalyst of the present embodiment described above.The producing method of the ammonia synthesis catalyst of the present embodiment is the same as the producing method of the molded catalyst of the present embodiment described above.

[0091] < Ammonia Synthesis Method>The ammonia synthesis method of the present embodiment (hereinafter sometimes referred to as the synthesis method of the present embodiment) uses the ammonia synthesis catalyst of the present embodiment as a catalyst to synthesize ammonia by reacting hydrogen and nitrogen on the catalyst.The specific synthesis method is not particularly limited as long as it is a method of synthesizing ammonia by bringing hydrogen and nitrogen into contact on the catalyst, and ammonia can be produced according to any known synthesis method.

[0092] In the ammonia synthesis method of the present embodiment, while hydrogen and nitrogen are brought into contact on the catalyst, the catalyst is typically heated to synthesize ammonia.The reaction temperature in the synthesis method of the present embodiment is not particularly limited, but is typically 50°C or higher, preferably 200°or higher, and more preferably 300°C or higher, and usually 600°C or lower, preferably 500°C or lower, and more preferably 450°C or lower. Since ammonia synthesis is an exothermic reaction, lower temperatures are advantageous for ammonia synthesis in terms of chemical equilibrium. However, in order to obtain a sufficient ammonia synthesis rate, it is preferable to carry out the reaction within the above temperature range.In the synthesis method of the present invention, the molar ratio of nitrogen and hydrogen brought into contact with the catalyst is not particularly limited, but is usually carried out at a ratio of hydrogen to nitrogen (H2 / N2 (volume / volume)) of usually 0.4 or higher, preferably 0.5 or higher, more preferably 1 or higher, and usually 10 or lower, and preferably 3 or lower.

[0093] The reaction pressure in the synthesis method of the present invention is not particularly limited, but is usually 0.01 MPa or higher, preferably 0.1 MPa or higher, and usually 20 MPa or lower, and preferably 15 MPa or lower, in terms of the pressure of the mixed gas containing nitrogen and hydrogen. Furthermore, considering practical use, it is preferable to carry out the reaction under pressurized conditions of atmospheric pressure or higher.

[0094] In the synthesis method of the present invention, before bringing hydrogen and nitrogen into contact on the catalyst, it is preferable to remove moisture or oxides adhering to the catalyst using a method such as a method using a dehydrating agent, a cryogenic separation method, or a method using hydrogen gas, or the like. An example of the method of removing moisture or oxides includes reduction treatment.In the synthesis method of the present invention, to obtain a better ammonia yield, it is preferable that the moisture content of the nitrogen and hydrogen used in the synthesis method of the present invention is low. Although not particularly limited, it is generally preferable that the total moisture content in the mixed gas of nitrogen and hydrogen be 100 ppm or less, preferably 50 ppm or less. It is even more preferable that it be 1 ppm or less.

[0095] In the synthesis method of the present invention, the type of reaction vessel is not particularly limited, and any reaction vessel commonly used in ammonia synthesis reactions can be used. Specific reaction types that can be used include, for example, batch reaction types, closed-loop reaction types, and flow reaction types. Of these, flow reaction types are preferred from a practical perspective. Furthermore, any of the - following methods can be used: a method in which a single type of reactor packed witha catalyst or multiple reactors packed with a catalyst are connected together, or a method in which a reactor with multiple reaction layers within the same reactor.The reaction of synthesizing ammonia from hydrogen and nitrogen is an exothermic reaction accompanied by volume contraction. Therefore, industrially, it is preferable to remove the heat of reaction to increase the ammonia yield. Known reaction equipment with commonly used heat removal means can be used. For example, a method can be used in which multiple reactors packed with catalyst are connected in series and an intercooler is installed at the outlet of each reactor to remove heat.

[0096] In the ammonia synthesis method of the present invention, the ammonia synthesis catalyst obtained by the synthesis method of the present invention can be used alone or in combination with other known catalysts commonly used in ammonia synthesis.

[0097] The ammonia synthesis catalyst of the present invention will be described in detail below using the first and second embodiments of the present invention, but the technical scope of the present invention is not limited thereto.[Examples]

[0098] The present invention is described in more detail below based on examples. Ammonia synthesis activity was evaluated by measuring the amount of NH3produced by gas chromatography, or by dissolving the produced NH3in a sulfuric acid aqueous solution and quantifying the solution by ion chromatography to determine the ammonia synthesis rate.

[0099] (Method for Evaluating Crushing Strength)Measuring Device: Digital Force Gauge (Nidec, Model: FGP50)Measurement Method: A cylindrical sample approximately 2 mm in diameter and 4 mm in length was placed on a dedicated sample stage. The pressure attachment was gradually lowered at a rate of 10 mm min-1. Even after the side of the sample contacted the pressure attachment, pressure was gradually applied until the sample was crushed. The maximum pressure applied to the pressure attachment until the sample was crushed was defined as the crushing strength, and the average value of 10 pressure applications was used.Evaluation CriteriaThe crushing strength of each molded catalyst was evaluated according to the following criteria.

[0100] A: Crushing strength of 1.0 kgf or greater, providing excellent strength for industrial production solid catalysts. B: Crushing strength of 0.4 kgf or greater, allowing use as a solid catalyst for industrial production. C: Crushing strength of less than 0.4 kgf, making it difficult to use as a solid catalyst for industrial production.

[0101] (BET Specific Surface Area Measurement Method)BET specific surface area was measured by adsorbing nitrogen gas onto the surface of the sample at liquid nitrogen temperature and determining the adsorption isotherm based on the adsorption and desorption of nitrogen gas at -196°C. The analytical conditions were as follows.

[0102] [Measurement Conditions]Measuring Instrument: High-Speed Specific Surface / Pore Distribution Analyzer BELSORP-mini 2 (manufactured by Microtrac BEL)Adsorbed Gas: Nitrogen 99.99995% by volume.Adsorption Temperature: Liquid nitrogen temperature -196°C.

[0103] (Gas Chromatography Analysis)Ammonia gas discharged from the reaction vessel was analyzed using a gas chromatograph (GC) or ion chromatograph. The analytical conditions were as follows:

[0104] [Gas Chromatography Measurement Conditions]Apparatus: Shimadzu Corporation, GC-8A or GL Sciences, Inc., GC3210 Detector: Thermal Conductivity Detector (TCD Detector)Column: Gaskropack-54, MS-5A (GL Sciences, Inc.)Carrier Gas: HeCarrier Gas Supply Pressure: 300 kPaColumn Temperature / Detector Temperature: 100-110°C[Ion Chromatography Measurement Conditions]Apparatus: Shimadzu Corporation, HPLC ProminenceDetector: Electrical Conductivity Detector CDD10A VP (Shimadzu Corporation) Column: Shim-pack IC-C4LC-2000plus ion chromatography column (Shimadzu Corporation)

[0105] (Example 1)(Preparation of Molded Catalyst)[Preparation of Bao.oi5Coo.24MgOx]26.4 g of Co(NO3)2·6H2O powder (purity ≥ 98 wt.%),1.50 g of Ba(NO3)2powder (purity ≥ 99.8%, particle size ≥ 100 μm),water,and 22.5 g of Mg(OH)2(MgO content 67.4 wt.%, purity 97.5%)were physically mixed under air to prepare a mixture. The resulting mixture was heated to 80°C at a heating rate of 2°C min-1and held at that temperature for 5 hours, then heated to 600°C at a heating rate of 2°C min-1and calcined for 18 hours.As a result, a composite metal oxide, Bao.oisCoo.24MgOx(Co content in the oxide: 25 wt.%) was obtained. The BET surface area was 32 m2g'1. The Co content in the oxide refers to the mass fraction of Co in terms of zero-valent Co atoms, based on the total mass of the composite material component (A) and the catalytically active metal M component (C) in terms of zero-valent Co atoms.In the present example, "physical mixing" refers to mixing using an agate mortar or the like.

[0106] [Preparation of Bao.oi5Coo.24MgOx*ZrH2(25wt.%) Molded Catalyst]9.0 g of the Bao.oi5Coo.24MgOxobtained above,3.0 g of ZrH2 powder (purity 99 wt.%, average particle size D50 = 12 pm),and water were physically mixed (kneaded) under air to prepare a mixture. The resulting mixture was dried at 70°C and then a pellet-shaped molded catalyst was prepared by an extrusion method. As a result, a molded catalyst of the present example (Bao.oi5Coo.24MgOx-ZrH2(25 wt.%)) (Co content in the oxide: 25 wt.%) was obtained. The ZrH2content is the percentage of ZrH2in the total mass of the molded catalyst.Using the above evaluation method, the BET surface area was evaluated as 26 m2g'1. The crushing strength was evaluated as 0.9 kgf.Subsequently, ammonia synthesis was carried out using the molded catalyst obtained in the present example as an ammonia synthesis catalyst.

[0107] (Ammonia Synthesis Reaction)The molded catalyst was pretreated in a nitrogen and hydrogen gas atmosphere at 450°C for 20 hours.A reaction (hereinafter referred to as the ammonia synthesis reaction) was carried out by reacting nitrogen gas (N2) and hydrogen gas (H2) on the catalyst to produce ammonia (NH3). 0.14 g of the ammonia synthesis catalyst was packed into a stainless steel tube, and the ammonia synthesis reaction was carried out in a fixed-bed flow reactor. The moisture concentration of each feed gas was below 1 ppm. The feed gas flow rate was set at 15 mL min−1of N2and 45 mL min−1of H2, for a total of 60 mL min−1. The pressure was 0.8 MPaG, and the reaction temperature was 400°C or 350°C. The • ammonia synthesis rate was calculated by dividing the ammonia produced per unit time (mmol h'1) by the amount of catalyst used.

[0108] (Ammonia Synthesis Rate)The gas exiting the fixed-bed flow reactor was bubbled through a 5 mM aqueous sulfuric acid solution to dissolve the ammonia in the gas. The resulting ammonium ions were quantified using ion chromatography as described above. The ammonia synthesis rate at 400°C was 18.2 mmol g'1h'1.

[0109] (Examples 2-5)" Dependence of Co Content in Oxide"(Preparation of Molded Catalyst)In Examples 2-5, pellet-shaped molded catalysts were prepared using the same method as in Example 1, except that the Co contents used were the same as those in Table 1. As a result, the molded catalysts of the present examples (Bao.oi5ComMgOx-ZrH2(25 wt.%)) shown in Table 1 were obtained. The evaluation results for crushing strength are shown in Table 1.

[0110] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as ammonia synthesis reaction) was carried out in the same manner as in Example 1, except that (Bao.oi5ComMgOx,ZrH2(25 wt.%)) (Co content in the oxide: 5 wt.% to 50 wt.%) obtained in Examples 2 to 5 was used instead of (Bao.oi5Coo.24MgOx-ZrH2(25 wt.%)) in Example 1.

[0111] (Ammonia Synthesis Rate)The ammonia synthesis rates were measured using the same method as in Example 1. The results are shown in Table 1.

[0112] (Co Particle Size Distribution)TEM observation (image shown in Fig. 1) was performed on the molded catalyst obtained in Example 3 after the ammonia synthesis reaction test to obtain the Co particle size distribution. The results are shown in Fig. 1. The number of particles measured was 372, with an average particle size of 3.6 + / - 2.8 nm and a dispersion of 7.97.TEM Measurement ConditionsObservation Device: JEM-200F NEOARM (Dual-SDD) (JEOL Ltd.) Accelerating Voltage: 200 kVAnalysis Device: EDS (JEOL JED-2300T DrySDD 100 mm2)

[0113] [Table 1]NH3 synthesis rate Co content CrushingCatalyst @400°C (wt.%) Strength(mmol gHhH) Example 1 Bao,oi5ComMgOx-ZrH2(25 wt.%) 25 B(0.9) 18.2 Example 2 Bao.oi5ComMgOx,ZrH2(25 wt.%) 10 B(0.6) 12.5 Example 3 Bao.oi5ComMgOx-ZrH2(25 wt.%) 20 B(0.9) 18.4 Example 4 Bao,oi5ComMgOx-ZrH2(25 wt.%) 30 B(0.5) 19.1 Example 5 Bao.oi5ComMgOx-ZrH2(25 wt.%) 50 C(0.2) 18.3

[0114] (Examples 6-9)" Dependence of Zirconium Content"(Preparation of Molded Catalyst)Pellet-shaped molded catalysts were prepared using the same method as in Example 3, except that the ZrH2contents in Examples 6-9 were changed from 25 wt.% in Example 3 to the ZrH2contents shown in Table 2. As a result, the molded catalysts of the present examples (Bao.oisCoo.isMgOx'ZrH^x wt%)) shown in Table 2 were obtained. The evaluation results for crushing strength are shown in Table 2.

[0115] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) was carried out using the same method and conditions as in Example 3, except that (Bao.oi5Coo.i8MgOx’ZrH2(x wt.%)) obtained from the ZrEb content shown in Table 2 was used instead of (Bao.oi5Coo.i8 gOx,ZrH2(25 wt.%)) obtained from the ZrlTz content in Example 3.

[0116] (Ammonia Synthesis Rate)The ammonia synthesis rate was measured using the same method as in Example 1. The results are shown in Table 2.

[0117] [Table 2]NH3 synthesis ZrH2rate CrushingCatalyst content @400°C Strength(wt.%) (mmol g-1h-1) ExampleBao.oi5Coo.i8MgOx,ZrH2(5 wt.%) 5 B(0.5) 8.9 6ExampleBao.oi5Coo.i8MgOx-ZrH2(15 wt.%) 15 B(0.5) 15.0 7ExampleBao.oi5Coo.i8MgOx’ZrH2(25 wt.%) 25 B(0.9) 18.4 8ExampleBao.oi5Coo.isMgOx,ZrH2(50 wt.%) 50 B(0.7) 15.99

[0118] (Examples 10-15)" Dependence of Types of Zirconium Component (B)"(Preparation of Molded Catalysts)For Examples 10-15, pellet-shaped molded catalysts were prepared using the same method as in Example 8, except that each zirconium component (B) (hereinafter sometimes referred to as " Component B") shown in Table 3 was used instead of ZrH2in Example 8. As a result, a molded catalyst of the present examples (Bao.oisCoo.isMgOx-Component B (25 wt.%)) shown in Table 3 was obtained. The evaluation results for crushing strength are shown in Table 3.Each zirconium component (B) content in Examples 10-15 was calculated by converting each feed amount of zirconium component (B) in the raw materials used into a Zr element or Mg element content (in the case of MgH2).Zr: Sigma-Aldrich, gray powderZrCh: Daiichi Kigenso Kagaku Kogyo Co., Ltd., white powder, median diameter (D50) <20 pmZrN: Kojundo Chemical Laboratory Co., Ltd., brown powder, purity 98%MgHz: Fujifilm Wako Pure Chemical Corporation, white to off-white powder, MgFL content 70.0% or higher

[0119] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) was carried out using the same method and conditions as in Example 3, except that (Bao.oisCoo.isMgOx’ Component B (25 wt.%)) obtained from each B component shown in Table 3 was used instead of (Bao.oi5Coo.i8MgOx-ZrH2(25 wt.%)) obtained from ZrH2 in Example 3.

[0120] (Ammonia Synthesis Rate)The ammonia synthesis rate was measured using the same method as in Example 1. The results are shown in Table 3.

[0121] [Table 3]NH3synthesis Component Crushing rate CatalystB Strength @400°C (mmol g-1h-1) Example Bao.oisCoo.isMgOx Component BZr B(0.4) 19.3 10 (25 wt.%)Example Bao.oisCoo.isMgOx Component BZrH2B(0.9) 18.4 11 (25 wt.%)Example Bao.oisCoo.isMgOx Component BZrO2B(0.7) 5.612 (25 wt.%)Example Bao.oisCoo.isMgOx Component BZrN B(0.5) 6.013 (25 wt.%)Example Bao.oisCoo.isMgOx Component BMgH2A(3.1) 15.0 14 (25 wt.%)Example Bao.oisCoo.isMgOx Component BZrH2+MgH2A(2.8) 17.715 (25 wt.%)

[0122] (Examples 16-17)" Dependence on Type of Co Compound"(Preparation of Molded Catalyst)In Examples 16-17, pellet-shaped molded catalysts were prepared using the same method as in Example 3, except that the Co compounds shown in Table 4 were used instead of the Co nitrate salt used in Example 3. As a result, molded catalysts of the present examples (Bao.oisCoo.isMgOx. ZrH2(25 wt.%)) shown in Table 4 were obtained. The evaluation results for crushing strength are shown in Table 4.

[0123] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NEb) (hereinafter referred to as the ammonia synthesis reaction) was carried out using the same method and conditions as in Example 3, except that molded catalysts (Bao.oisCoo.isMgOx. ZrH2(25 wt.%)) obtained from the Co compounds shown in Table 4 were used instead of the molded catalyst (Bao.oisCoo.isMgOx. ZrH2(25 wt.%)) obtained in Example 3 using Co nitrate.

[0124] (Ammonia Synthesis Rate)The ammonia synthesis rate was measured using the same method as in Example 1. The results are shown in Table 4.

[0125] [Table 4]NH3Raw material synthesis rate CrushingCatalyst for @400°C Strength component C (mmol g-1h-1) Example CO(NO3)2’Bao.oisCoo.isMgOx ZrH2(25 wt.%) B(0.9) 18.43 6H2OExample CobaltBao.oisCoo.isMgOx ZrH2(25 wt.%) A(1.2) 13.516 CarbonateExampleBao.oisCoo.isMgOx ZrH2(25 wt.%) COC12- 6H2O B(0.4) 15.517

[0126] (Example 18)(Molded Catalyst Containing ZrO2as First Zirconium Component (Bl) and ZrH2as Second Zirconium Component (B2))[Preparation of Bao.oisCoo.isMgOx'ZrCh (9 mol%)]19.8 g of CO(NO3)2'6H2O powder (purity 98 wt.% or higher) and1.50 g of Ba(NO3)2powder (purity 99.8%, particle size 100 pm or more),water,22.5 g of Mg(OH)2 (MgO content 67.4 wt.%), and3.3 g of ZrO(NO3)2 (zirconyl nitrate solution, Zircosol ZN, ZrO2content 25 wt.%, manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.)were physically mixed under air to prepare a mixture. The resulting mixture was heated to 80°C at a heating rate of 2°C min-1and held there for 5 hours, then heated to 600°C at a heating rate of 2°C min-1and calcined for 18 hours.As a result, a composite metal oxide Bao.oisCoo.isMgOx ZrCh (9 mol%) (Co content in BaCoMgO oxide: 20 wt.%; Zr ratio to the total molar number of Co and Zr: 9 mol%). The BET surface area was 31.6 m2g-1.

[0127] [Preparation of Ba0.015Co0.18MgOx·ZrO2(9 mol%) ZrH2(22.5 wt.%) Molded Catalyst] 7.5 g of the Bao.oisCoo.isMgOx’ZrC (9 mol%) obtained above,2.2 g of ZrH2powder (purity 99 wt.%, average particle size Dso = 12 pm), andwater were physically mixed (kneaded) under air to prepare a mixture. The resulting mixture was dried at 70°C and then extruded into pellets. As a result, a molded catalyst of the present example (Bao.oisCoo.isMgOx-ZrCh (9 mol%) ZrH2(22.5 wt.%)) (Co content in the oxide: 20 wt.%) was obtained. The ZrH2content is the percentage of ZrH2in the total mass of the molded catalyst.Using the above evaluation method, a BET surface area was evaluated as 26.5 m2g”1. A crushing strength was evaluated as 0.9 kgf.Ammonia synthesis was carried out using the molded catalyst obtained in the present example as an ammonia synthesis catalyst.

[0128] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as ammonia synthesis reaction) was carried out in the same manner as in Example 1, except that the molded catalysts (Bao.oisCoo.isMgOx'ZrCh (9 mol%) and ZrEb (22.5 wt%)) obtained from the Bl and B2 component contents in Example 18 was used instead of (Bao.oisCoo^MgOx’ ZrH2(25 wt.%)) in Example 1.

[0129] (Ammonia Synthesis Rate)The ammonia synthesis rates were measured using the same method as in Example 1. The ammonia synthesis rate at 400°C was 19.9 mmol g-1h-1. The results are shown in Table 5 and Fig. 2.

[0130] (Activation Time of Molded Catalyst)The time required for the ammonia synthesis reaction to reach a stable ammonia production rate from the start (activation time of the molded catalyst) was measured. The results are shown in Fig. 3.

[0131] (Examples 19-22)" Dependence of the Content of First Zirconium Component (Bl) and Second Zirconium Component (B2)"(Preparation of the Molded Catalyst)In Examples 19-22, pellet-shaped molded catalysts were prepared using the same method as in Example 18, except that ZrO2contents of the first zirconium component (Bl) (" Component Bl") were increased from 9 mol% in Example 19 to the Bl component content shown in Table 5; and ZrH2contents of the second zirconium component (B2) (" Component B2") were increased from 22.5 wt.% in Example 18 to the B2 component content shown in Table 5. As a result, the molded catalysts of the present examples (Ba0.015Co0.18MgOx-B1: ZrO2, B2: ZrH2) shown in Table 5 were obtained. The results of the crushing strength evaluation are shown in Table 5.

[0132] (Ammonia Synthesis Reaction)Reactions to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) were carried out using the same method and conditions as in Example 18, except that instead of the molded catalysts (Bao.oisCoo.isMgOx'ZrCh (9 mol%) and ZrH2(22.5 wt%)) obtained from the B1 and B2 component contents in Example 18, the molded catalysts (Ba0.015Co0.18MgOx· B1: ZrO2, B2: ZrH2) obtained from the Bl and B2 components contents shown in Table 5 were used.

[0133] (Ammonia Synthesis Rate)The ammonia synthesis rate was measured using the same method as in Example 18. The results are shown in Table 5 (400°C) and Fig. 2 (350°C and 400°C).(Activation Time of Molded Catalyst)The activation times of the molded catalyst were measured using the same method as in Example 18. The results are shown in Fig. 3.

[0135] [Table 5]Bl B2 (B1+B2) NH3synthesis component component component Crushing rate Catalyst content content content Strength @.400°C mol% wt.% wt.% (mmol g"‘ h-1) Example Bao.oisCoo.isMgOx ' 9 22.5 25.8 B(0.9) 19.918 Bl: ZrO2, B2: ZrH2Example Ba0.015Co0.1sMgOx • 9 20 23.1 B(0.5) 19.319 Bl: ZrO2, B2: ZrH2Example Ba0.015Co0.18MgOx· 17 20 26.3 B(0.9) 17.820 B 1: ZrO2, B2: ZrH2Example Bao.oisCoo.isMgOx ' 29 25 37.5 B(0.8) 15.221 Bl: ZrO2, B2: ZrH2Example Bao.oisCoo.isMgOx • 29 12.5 25.0 B(0.9) 15.122Bl: ZrO2, B2: ZrH2

[0136] (Example 23)(Preparation of Molded Catalyst)A pellet-shaped molded catalyst was prepared using the same method as in Example 3. As a result, a molded catalyst for Example 23 (Ba0.015Co0.18MgOx·ZrH2(25 wt.%)) shown in Table 6 was obtained. The crushing strength evaluation results are shown in Table 6.

[0137] (Ammonia Synthesis Rate)Ammonia synthesis rate was measured using the same method as in Example 1. A reaction to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) by reacting nitrogen gas (N2) and hydrogen gas (H2) on a catalyst. A 0.14 g of the pretreated ammonia synthesis catalyst was packed into a stainless steel tube, and the ammonia synthesis reaction was carried out in a fixed-bed flow reactor. The moisture concentration of the feed gas was 1 ppm or less. The feed gas flow rate was set to N2: 15 mL min-1and H2: 45 mL min-1, for a total of 60 mL min-1. The pressure was 0.8 MPaG, and the reaction temperatures were 400°C and 350°C. The ammonia synthesis rate under each reaction condition was measured. The test results at 400°C are shown in Table 6.

[0138] (Comparative Example 1)(Preparation of a Zr-Free Molded Catalyst)[Preparation of Bao.oisCoo.isMgOx-ZrEb (0 wt.%)]Bao.oisCoo.isMgOx was prepared using the same method as in Example 3.

[0139] [Preparation, of Bao.oisCoo.isMgO Molded Catalyst]7.5 g of the Bao.oisCoo.isMgOx obtained above was physically mixed (kneaded) with water under air to prepare a mixture. The resulting mixture was dried at 70°C and then extruded into pellet-shaped molded catalysts. As a result, a molded catalyst of the present comparative example (Bao.oisCoo.isMgOx-ZrH2(0 wt.%)) was obtained (Co content in the oxide: 20 wt.%).Using the above evaluation method, the BET surface area was evaluated as 20.6 m2g-1. The crushing strength was evaluated as 0.5 kgf.

[0140] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) was carried out using the same method and conditions as in Example 23, except that the molded catalyst (Bao.oisCoo.isMgOx-ZrH2(0 wt.%)) obtained in Comparative Example 1 was used instead of the (Bao.oisCoo.isMgOx’ZrH2(25 wt.%) ) used in Example 23.

[0141] (Ammonia Synthesis Rate)Ammonia synthesis rate was measured using the same method as in Example 1. The results are shown in Table 6.

[0142] (Comparative Example 2)(Preparation of Ti-Added Molded Catalyst)[Preparation of Bao.oisCoo.isMgOx]Bao.oisCoo.igMgOx was prepared using the same method as in Example 3.

[0143] [Preparation of Bao.oisCoo.isMgOx’Ti (25 wt.%) Molded Catalyst ]7.5 g of the Bao.oisCoo.igMgOx obtained above,2.5 g of metallic Ti powder (purity 99 wt.%, average particle size 45 pm),and water were physically mixed (kneaded) under air to prepare a mixture. The resulting mixture was dried at 70°C and then extruded into a pellet-shaped molded catalyst. As a result, a molded catalyst of the present comparative example (Ba0.015Co0.18MgOx·Ti (25 wt.%)). (Co content in the oxide: 20 wt.%)Using the above evaluation method, the BET surface area was evaluated as 19 m2g-1. The crushing strength was evaluated as A.

[0144] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) was carried out using the same method and conditions as in Example 23, except that the molded catalyst (Ba0.015Co0.18MgOx· Ti (25 wt.%)) obtained inComparative Example 2 was used instead of the molded catalyst (Ba0.015Co0.18MgOx· ZrH2(25 wt.%)) in Example 23.

[0145] (Ammonia Synthesis Rate)Ammonia synthesis rate was measured using the same method as in Example 1. The results are shown in Table 6.

[0146] [Table 6]NH3 synthesis Crushing rate CatalystStrength @400°C (mmol g-1h-1) Example 23 Bao.oisCoo.isMgOx -ZrH2(25 wt.%) B(0.9) 18.4 ComparativeB(0.5) 16 example 1 Bao.oisCoo.isMgOx -ZrH2(0 wt.%)ComparativeBao.oisCoo.isMgOx -Ti(25 wt.%) A (3.9) 15.7example 2

[0147] (Example 24)(Preparation of Molded Catalyst)[Preparation of Bao.oisMgOx]0.67 g of Ba(NO3)2 powder (purity 99.8%, particle size 100 pm or greater), water, and14.61 g of Mg(OH)2(MgO content 67.4 wt.%) were physically mixed under air to prepare a mixture. The resulting mixture was then dried at 70°C. The mixture was heated to 700°C at a heating rate of 5°C min-1and then calcined for 24 hours. As a result, a composite metal oxide of Bao.oisMgOx was obtained. The BET surface area was 26 m2g-1.In the present example, "physical mixing" refers to mixing using an agate mortar or similar.

[0148] [Preparation of Ru / Bao.oisMgOx'ZrHb (25 wt.%) Molded Catalyst]1.080 g of the Bao.oisMgOx obtained above,0.239 g of an Ru(NO)(NO3)3 aqueous solution (Ru concentration 18.81 wt.%), 0.375 g of ZrH2 (average particle size D50 = 12 pm), andwater were mixed to prepare a mixture. The resulting mixture was extruded to prepare pellet-shaped molded catalysts. The resulting molded catalysts were dried and then heated to 300°C in a nitrogen atmosphere. As a result, a molded catalyst of the present example (Ru / Bao.oisMgOx,ZrH2(25 wt.%)) was obtained. (Ru loading: 3 wt.%).As evaluated using the above evaluation method, the BET surface area was evaluated as 24.8 m2g-1. The crushing strength was evaluated as 1.2 kgf.Ammonia synthesis was carried out below using the molded catalyst obtained in the present example as a catalyst for ammonia synthesis.

[0149] (Ammonia Synthesis Reaction)A reaction to produce ammonia (NH3) (hereinafter referred to as ammonia synthesis reaction) was carried out in the same manner as in Example 1, except that the molded catalyst (Ru / Bao.oi5MgOx,ZrH2(25 wt.%)) (Ru loading: 3 wt.%) obtained in Example 24 was used instead of (Bao.oi5Coo.24MgOx-ZrH2(25 wt.%)) in Example 1.

[0150] (Ammonia Synthesis Rate)Ammonia synthesis rate was measured using the same method as in Example 1. The ammonia synthesis rate at 400°C was 25.6 mmol g-1h-1.

[0151] (Example 25, Comparative Examples 3-4)" Evaluation of Resistance to CO, CO2, and O2"(Preparation of Molded Catalyst)The molded catalysts used in Example 25 and Comparative Examples 3-4 were the same as those in Example 23, Comparative Example 1, and Comparative Example 2, respectively.

[0152] (Ammonia Synthesis Reaction)The molded catalyst of Example 25 was pretreated for 25 hours at 400°C under a nitrogen and hydrogen gas atmosphere at a reaction pressure of 4.9 MPaG. The molded catalysts of Comparative Examples 3 and 4 were pretreated for 25 hours at 500°C under a nitrogen and hydrogen gas atmosphere at a reaction pressure of 4.9 MPaG.Reactions to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) were carried out, using the molded catalysts after pretreatment in Example 25 and Comparative Examples 3-4, respectively and using the same method as in Example 23, except that instead of the N2 (>6N) and H2 (>6N) feed gases used in Example 23, a feed gas from a standard gas cylinder containing trace impurities (N2 and H2 gases containing 0.83 ppm CO, 0.61 ppm CO2, and 0.74 ppm O2) were used, and under condition of a reaction pressure of 4.9 MPaG, a reaction temperature of 375°C, a flow rate of 13,000 hr1, and a H2 / N2 ratio of 1.5. For comparison, reactions to produce ammonia (NH3) (hereinafter referred to as the ammonia synthesis reaction) were also carried out using N2 (>6N) and H2 (>6N) feed gases at a reaction pressure of 4.9 MPaG and a reaction temperature of 375 °C.

[0153] (Ammonia Concentration)The gas from the reactor outlet was analyzed while passing a constant amount of gas through a gas chromatograph, and the ammonia concentration under each reactioncondition was measured. The measurement results were obtained 12 hours after the feed gas (N2 gas and H2 gas containing CO: 0.83 ppm, CO2: 0.61 ppm, O2: 0.74 ppm) was passed through the gas chromatograph and the measurement pressure was reached. The results are shown in Table 7 and Fig. 5.[Table 7]Outlet NH3 concentration _ (%) _ Crushing N2+H2CatalystStrength Trace N2+H2 amount CO, (>6N) CO2, O2Bao.oisCoo.isMgOx ■ ZrH2(25Example 25 B(0.9) 5.6 6 wt.%)Comparative Bao.oisCoo.isMgOx • ZrH2(0B(0.5) 0 2.6 example 3 wt.%)Comparative Bao.oisCoo.isMgOx • Ti(25A(3.9) 0 2.7 example 4wt.%)

[0154] (Discussion)The molded catalyst exhibited excellent ammonia synthesis activity by using appropriate transition metal components as the raw material. The molded catalyst fully met the crushing strength requirements, one of the requirements for industrial catalytic applications. It was found that zirconium compounds not only increased the crushing strength of catalysts containing supports, but also improved their catalytic performance. Zirconium hydride accelerated the reduction reaction of catalytically active metal components and is believed to have the effect of promoting the ammonia synthesis activity of the support composite material (A) containing barium and magnesium. It is believed that the combined effect of these two effects allowed the molded catalyst of the present invention to exhibit a certain level of durability against trace amounts of CO, CO2, and O2 contained in the feed gas.Furthermore, the molded catalyst obtained in the second embodiment of the method for producing a molded catalyst is obtained through a process of mixing and calcining a precursor of the composite material component (A), a precursor of the catalytically active metal M component (C), and a precursor of the first zirconium component (Bl), as shown in Example 18, which uses ZrC>2 as the first zirconium component (Bl), for example, and therefore it is expected that the first zirconium component (Bl) will be highly dispersed on the support. Therefore, it is presumed that by highly dispersing the first zirconium component (Bl) on the support, the activation of each component is promoted more efficiently, thereby shortening the time until the ammonia synthesis activity performance becomes stable.

Claims

[CLAIMS]

1. A molded catalyst comprising a composite material component (A), a zirconium (Zr) component (B), and a catalytically active metal M component (C),wherein the composite material component (A) is a metal composite oxide containing barium (Ba) and magnesium (Mg) or a mixed oxide containing barium oxide (BaO) and magnesium oxide (MgO);the zirconium component (B) is one or more selected from the group consisting of Zr and a precursor of Zr, ZrH2-x (0 < x < 2), ZrCh and a precursor of ZrCh, ZrN, MgH2, and Mg; andthe catalytically active metal M component (C) is a transition metal.

2. The molded catalyst according to claim 1, wherein the catalytically active metal M component (C) is at least one selected from the group consisting of Ru, Co, Fe, and Ni.

3. The molded catalyst according to claim 1, wherein the catalytically active metal M component (C) is a cobalt component (Cl),wherein the cobalt component (Cl) is at least one selected from the group consisting of Co, CoO, Co3O4, and CoCO3.

4. The molded catalyst according to claim 1, wherein the content of the catalytically active metal M component (C) in the molded catalyst is 1 wt.% to 50 wt.%.

5. The molded catalyst according to any one of claims 1 to 4, wherein the composite material component (A) is a material represented by the following general formula (1): BanMg[i-n]Ox(1)(where 0 < n < 0.3 and 0.5≤ x ≤ 1.3)

6. The molded catalyst according to any one of claims 1 to 4, wherein the particle size of the zirconium component (B) contained in the molded catalyst is 100 pm or less.

7. The molded catalyst according to any one of claims 1 to 4, wherein the content of the zirconium component (B) in the molded catalyst is 5 wt.% or more and less than 50 wt.%.

8. The molded catalyst according to any one of claims 1 to 4, wherein the size of the molded catalyst is 0.3 mm to 30 mm.

9. The molded catalyst according to any one of claims 1 to 4, wherein the bulk density of the molded catalyst is 0.5 g cm-3to 2.5 g cm-3.

10. The molded catalyst according to any one of claims 1 to 4, wherein the crushing strength of the molded catalyst is 0.4 kgf or more.

11. The molded catalyst according to any one of claims 1 to 4, wherein the average particle size of the catalytically active metal M component (C) is 20 nm or less.

12. A method for producing the molded catalyst according to any one of claims 1 to 4, comprising:a first step of mixing the composite material component (A) or a precursor thereof with the catalytically active metal M component (C) or a precursor thereof to obtain a mixture;a second step of calcining the mixture obtained in the first step to obtain a calcined product;a third step of mixing the zirconium component (B) with the calcined product obtained in the second step.

13. A method for producing the molded catalyst according to any one of claims 1 to 4, wherein the zirconium component (B) comprises a first zirconium component (B1) and a second zirconium component (B2),the method comprising:a first step of mixing the composite material component (A) or a precursor thereof, the first zirconium component (B1) or a precursor thereof, and the catalytically active metal M component (C) or a precursor thereof to obtain a mixture;a second step of calcining the mixture obtained in the first step to obtain a calcined product;and a third step of mixing the second zirconium component (B2) with the calcined product obtained in the second step.

14. A method for producing ammonia by bringing hydrogen and nitrogen into contact on an ammonia synthesis catalyst,wherein the ammonia synthesis catalyst is the molded catalyst according to any one of claims 1 to 4.

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