Oxynitrogen hydride, metal support containing oxynitrogen hydride, and catalyst for ammonia synthesis

Abstract

Provided is an oxynitrogen hydride which, when used as a catalyst carrier, can simultaneously achieve improved catalyst performance and stabilization, thereby facilitating synthesis. An oxynitrogen hydride represented by the following general formula (1): A n B m O l‑x N y H z (1) (In the above general formula (1), x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.0).

Description

Technical Field

[0001] The present invention relates to an oxynitrogen hydride, a metal support containing the oxynitrogen hydride, and a catalyst for ammonia synthesis.

[0002] This application claims priority based on Japanese Patent Application No. 2020-030730 filed in Japan on February 26, 2020, the contents of which are incorporated herein by reference. Background Art

[0003] The Haber-Bosch process, a representative ammonia synthesis method, is a method of producing ammonia by directly reacting a mixed gas of nitrogen and hydrogen on a doubly promoted iron catalyst containing several mass % of Al2O3 and K2O in Fe3O4 under high temperature and high pressure conditions. This technology is still used in industry almost exclusively to complete the production process at that time.

[0004] On the other hand, a method for synthesizing ammonia at a temperature lower than the reaction temperature of the Haber-Bosch process has been studied. A catalyst capable of synthesizing ammonia by bringing nitrogen and hydrogen into contact has been studied, and a method using a transition metal as a catalytically active component has been studied. Among them, as a highly efficient method, a method of using ruthenium (Ru) as a catalytically active component supported on various supports as a catalyst for ammonia synthesis has been proposed (for example, Patent Document 1).

[0005] In addition, the oxynitride BaTi(O) with a perovskite crystal structure was reported. 3-z H x N y ), a metal supported catalyst formed by using BaCeO3, a metal oxide having a perovskite crystal structure, as a carrier and supporting Ru (e.g., Patent Document 2, Non-Patent Document 1). In addition, a metal supported catalyst formed by using BaCeO3 doped with Zr as a carrier and supporting Ru (Ru / BaCe 1-x Y x O 3-y ) (for example, non-patent document 2).

[0006] On the other hand, although the synthesis method of nitrogen-doped BaCeO3 (perovskite-type oxynitride, BaCe2(O,N)4) has been reported, its use as a catalyst for ammonia synthesis has not been disclosed (for example, Non-Patent Document 3).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2006-231229

[0010] Patent Document 2: International Publication No. 2015 / 136953

[0011] Non-patent literature

[0012] Non-patent document 1: Yang, Xiao-Long et al., "Catalysis Communications" 11, p.867-870 (2010)

[0013] Non-patent document 2: Shimoda, Naohiro et al., "International Journal of Hydrogen Energy" 42, p. 29745-29755 (2017)

[0014] Non-patent document 3: Liu, Guo et al. "Journal of Solid State Chemistry" 89, p. 366-371 (1990) Summary of the invention

[0015] Problems to be solved by the invention

[0016] Although ammonia synthesis based on the Haber-Bosch process using mainly a doubly promoted iron catalyst has been put into practical use, it requires high temperature and high pressure conditions, and thus has a problem of heavy burdens in terms of equipment and cost.

[0017] The supported metal catalysts described in Patent Document 1 usually use carbonaceous carriers such as activated carbon and inorganic oxide carriers. However, the reaction activity of these supported metal catalysts is low, and they only have insufficient performance in practical applications. The catalytic activity of the supported metal catalysts described in Patent Document 2 and Non-Patent Document 1 is insufficient.

[0018] That is, there is a need for an ammonia synthesis catalyst having sufficient reaction activity even under conditions of lower temperature and lower pressure than the reaction conditions of the Haber-Bosch process.

[0019] [Methods for solving the problem]

[0020] The inventors of the present application have found that the catalyst for ammonia synthesis of the present invention can achieve both improvement in catalyst performance and stabilization by supporting a transition metal on a composition containing oxynitrogen hydride, thereby completing the present invention.

[0021] That is, the gist of the present invention is:

[0022] [1] An oxynitrogen hydride represented by the following general formula (1).

[0023] A n B mO l-x N y H z (1)

[0024] (In the above general formula (1), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Al, Ga, In, Si, Ge and Sn, n is an integer of 1 to 3, m is 1 or 2, l is 4 or 5, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; z represents a number represented by 0.1≤z≤2.0.)

[0025] [2] The oxynitride according to [1], wherein in the general formula (1), B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4.

[0026] [3] The oxynitride as described in [1], wherein in the general formula (1), B is at least one selected from the group consisting of Si, Ge and Sn, n=3, m=1, and l=5.

[0027] [4] A metal support comprising a transition metal (M) supported on a support, wherein the support is a composition comprising the oxynitrogen hydride according to any one of [1] to [3].

[0028] [5] The metal support according to [4], wherein the amount of the transition metal (M) supported is 0.01 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the support.

[0029] [6] The metal support according to [4] or [5], wherein the transition metal (M) is at least one selected from the group consisting of Ru, Co and Fe.

[0030] [7] A supported metal catalyst comprising the metal supported material according to any one of [4] to [6].

[0031] [8] An ammonia synthesis catalyst comprising the metal support according to any one of [4] to [6]. [9] An ammonia synthesis catalyst characterized in that the ammonia synthesis catalyst is a composition comprising the oxynitrogen hydride according to any one of [1] to [3].

[0032]

[10] A method for producing ammonia, comprising reacting nitrogen and hydrogen in the presence of the supported metal catalyst according to [7].

[0033]

[11] A method for producing an oxynitrogen hydride, which is a method for producing an oxynitrogen hydride represented by the following general formula (1), characterized in that it includes a step of heating a compound represented by the following general formula (2) and a compound represented by the following general formula (3) under an ammonia atmosphere.

[0034] A n B m O l-x N y H z (1)

[0035] A(NH2)2 (2)

[0036] B k O j (3)

[0037] (In the above general formulae (1) to (3), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Al, Ga, In, Si, Ge and Sn, n is an integer of 1 to 3, m is 1 or 2, l is 4 or 5, k is 1 or 2, j is 1 to 3, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.0.)

[0038]

[12] The method for producing oxynitrogen hydride as described in

[11] , wherein in the general formula (1), B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4.

[0039]

[13] The method for producing oxynitrogen hydrides as described in

[11] , wherein in the general formula (1), B is at least one selected from the group consisting of Si, Ge and Sn, n=3, m=1, and l=5.

[0040] Effects of the Invention

[0041] When the oxynitrogen hydride of the present invention is used as an ammonia synthesis catalyst, it has high ammonia synthesis activity even at low reaction temperature and low reaction pressure, and no decrease in catalyst activity is observed even when the synthesis reaction is repeated. Therefore, it is suitable as an ammonia synthesis catalyst.

[0042] Furthermore, compared with conventional methods for synthesizing oxynitrides or oxyhydrides, the composition containing the oxynitride hydride of the present invention can be synthesized in a low-temperature heat treatment step, and is also excellent in terms of productivity and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] [ Figure 1] is the oxynitride BaAl2O synthesized by using various heating treatment temperatures and treatment times as the powder treatment conditions in Example 1. 4-x N y H z XRD patterns of powders.

[0044] [ Figure 2 ] is the BaAl2O obtained in Example 1 4-x N y H z Temperature desorption spectrum.

[0045] [ Figure 3 ] is a graph showing the reaction temperature dependence of the ammonia synthesis rate in Examples 1 and 2 and Comparative Example 1.

[0046] [ Figure 4 ] is the oxynitride Ba3SiO4 synthesized by using various heating treatment temperatures and treatment times as the powder treatment conditions in Examples 2, 3 to 5. 5-x N y H z XRD patterns of powders. DETAILED DESCRIPTION

[0047] (oxygen, nitrogen and hydride)

[0048] The oxynitrogen hydride of the present invention is an oxynitrogen hydride in which nitrogen and hydrogen are doped at the oxygen sites of the composite oxide represented by the following general formula (5). The oxynitrogen hydride of the present invention is a compound represented by the following general formula (1). It is preferred to have the same type of crystal structure as the composite oxide represented by the following general formula (5) without being doped with nitrogen and hydrogen. That is, preferably, the oxynitrogen hydride of the present embodiment is a substance that maintains the crystal structure of the composite oxide while doping nitrogen and hydrogen at the oxygen sites of the composite oxide represented by the following general formula (5).

[0049] A n B m O l (5)

[0050] In the above general formula (5), A is at least one selected from the group consisting of Ba and Sr, and B is at least one selected from the group consisting of Al, Ga, In, Si, Ge, and Sn.

[0051] A n B m O l-x N y H z (1)

[0052] In the above general formula (1), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Al, Ga, In, Si, Ge and Sn, n is an integer of 1 to 3, m is 1 or 2, l is 4 or 5, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; z represents a number represented by 0.1≤z≤2.0.

[0053] The amount of nitrogen and the amount of hydrogen doped in the oxynitride of the present invention are not particularly limited. It is preferable to maintain the crystal structure of the composite oxide represented by the general formula (5).

[0054] Regarding the relationship among x, y, and z, for example, 2x-(3y+z)=0 is preferable so that the oxynitride is charge neutral.

[0055] In the above general formula (1), x represents a number represented by 0.5≤x≤3.5; y represents a number represented by 0.25≤y≤1.8; and z preferably represents a number represented by 0.25≤z≤1.8.

[0056] In the above general formula (1), x represents a number represented by 1.0≤x≤3.4; y represents a number represented by 1.0≤y≤1.7; and z represents a number represented by 1.0≤z≤1.8, which is more preferable.

[0057] The nitrogen and hydrogen to be doped may be partially substituted with atoms other than nitrogen and hydrogen, and specifically, may include electrons, carbon, halogen atoms, etc., as long as the effects of the present invention are not impaired.

[0058] Specific examples of the oxynitrogen hydride of the present invention include, for example, the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Al; the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Ga; the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is In; the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Si; the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Ge; the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Sn; the oxynitrogen hydride represented by the general formula (1) in which A is Sr and B is at least one selected from the group consisting of Al, Ga, Si and Ge, etc. Among them, the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Al, and the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Si are preferred, and the oxynitrogen hydride represented by the general formula (1) in which A is Ba and B is Al is more preferred.

[0059] Examples of the oxynitride represented by the general formula (1) in which A is Ba and B is Al include BaAl2O 4-x N y H z 、Ba3Al2O6- x N y H z 、Ba3Al 17 O 20-x N y H z 、Ba4Al2O 7-x N y H z , Ba 17 Al3O 7-x N y H z 、BaAl4O 7-x N y H z , BaAl 12 O 19-x N y H z Among them, BaAl2O 4-x N y H z is more preferred.

[0060] Examples of the oxynitride represented by the general formula (1) in which A is Ba and B is Ga include BaGa2O 4-x N y H z 、BaGa4O 7- x N y H z 、Ba4Ga2O 7-x N y H z 、Ba3Ga2O 6-x N y H z wait.

[0061] Examples of the oxynitride represented by the general formula (1) in which A is Ba and B is In include BaInO 2.5-x N y H z 、Ba3In2O 6- x N y H z 、Ba8In6O 17-x N y H z 、Ba2In2O 5-x N y H z 、Ba4In2O 7-x N y H z 、Ba4In6O 13-x N y Hz wait.

[0062] Examples of the oxynitride represented by the general formula (1) in which A is Ba and B is Si include Ba3SiO 5-x N y H z 、Ba2SiO 4- x N y H z 、Ba2Si4O 10-x N y H z 、Ba4Si6O 16-x N y H z 、BaSi4O 9-x N y H z 、Ba5Si8O 21-x N y H z 、Ba6Si 10 O 26-x N y H z 、BaSiO 3-x N y H z 、BaSi2O 5-x N y H z Among them, Ba3SiO 5-x N y H z is more preferred.

[0063] Examples of the oxynitride represented by the general formula (1) in which A is Ba and B is Ge include Ba3GeO 1-x N y H z 、BaGe4O 9- x N y H z 、BaGe2O 5-x N y H z , Ba 10 7O 3-x N y H z 、BaGeO 3-x N y H z 、Ba3Ge3O 9-x N y H z wait.

[0064] Examples of the oxynitride represented by the general formula (1) in which A is Ba and B is Sn include Ba2SnO 4-x N y H z 、BaSnO 3- x N y H z 、Ba3SnO 1-x N y H z wait.

[0065] Examples of the oxynitride represented by the general formula (1) in which A is Sr and B is at least one selected from the group consisting of Al, Ga, Si and Ge include SrAl2O 4-x N y H z 、SrGa2O 4-x N y H z 、Sr3SiO 5-x N y H z 、Sr3GeO 5-x N y H z wait.

[0066] (Method for producing oxynitrogen hydride)

[0067] The method for producing the oxynitrogen hydride represented by the following general formula (1) of the present invention comprises the step of heating a compound represented by the following general formula (2) and a compound represented by the following general formula (3) in an ammonia atmosphere.

[0068] A n B m O l-x N y H z (1)

[0069] A(NH2)2 (2)

[0070] B k O j (3)

[0071] (In the above general formulae (1) to (3), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Al, Ga, In, Si, Ge and Sn, n is an integer of 1 to 3, m is 1 or 2, l is 4 or 5, k is 1 or 2, j is 1 to 3, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.0.)

[0072] Preferred embodiments and specific examples of the oxynitrogen hydride represented by the above general formula (1) as a product of the production method of the present invention are the same as those of the above-mentioned oxynitrogen hydride of the present invention.

[0073] Examples of the compound represented by the general formula (2) as a raw material in the production method of the present invention include Ba(NH 2 ) 2 and Sr(NH 2 ) 2 .

[0074] Examples of the compound represented by the general formula (3) as a raw material for the production method of the present invention include Al2O3, SiO2, SnO, In2O3, GeO2 and the like.

[0075] The method for producing the oxynitrogen hydride represented by the general formula (1) of one embodiment of the present invention includes the step of heating the metal amide compound of Ba(NH2)2 or Sr(NH2)2 and the oxide of the element represented by B in the general formula (1) (for example, Al2O3, SiO2) under an ammonia atmosphere. The detailed production method is described in each embodiment described later. For example, it includes a mixing step of mixing the metal amide compound with the oxide, and a heating step of heating the mixture obtained by the mixing step in an ammonia atmosphere. In addition, it is preferred that a pretreatment step of further dehydrating the metal amide compound is included before the mixing step. In this case, preferably, the mixing step is a step of mixing the dehydrated oxide in a rare gas atmosphere such as an Ar glove box.

[0076] Examples of the dehydration treatment step include a method of performing vacuum heat treatment at 300°C to less than 900°C, preferably 400°C to less than 800°C, and more preferably 500°C to less than 700°C.

[0077] As the above-mentioned heat treatment, for example, a method of heating at 300°C to less than 900°C in an ammonia gas flow for 1 to 50 hours, preferably at 300°C to less than 900°C for 2 to 30 hours, and more preferably at 400°C to less than 900°C for 5 to 20 hours.

[0078] When producing the compound represented by the general formula (1), it is preferred that the oxide and the metal amide compound be mixed so that the molar ratio of element A to element B (A:B) is 0.5×n:m to 1.5×n:m (mol / mol), more preferably 0.8×n:m to 1.2×n:m, and even more preferably 0.9×n:m to 1.1×n:m. A, B, n, and m herein have the same meanings as those of the general formula (1).

[0079] It is preferred that the raw material of the metal amide and the raw material of the oxide used are in the form of powder. For example, the metal amide may be a commercially available substance. The metal amide may be synthesized by the following steps. A metal A (A is selected from at least one of the group consisting of Ba and Sr) with a purity of 99.99% is placed in a pressure-resistant container, and ammonia gas is introduced into the container while cooling to -50°C to dissolve the metal A. After stirring at -50°C for 1 hour, the temperature is restored to room temperature.

[0080] Thereafter, the container was immersed in an oil bath, maintained at 100° C. for 1 hour while stirring, and then cooled to room temperature. Ammonia gas remaining in the container after cooling was exhausted to obtain the above-mentioned metal amide.

[0081] Hereinafter, the oxynitrogen hydride of the present invention, the metal support on which a transition metal is supported as a support, the supported metal catalyst, the catalyst for ammonia synthesis, and the catalyst for ammonia synthesis are described in detail, taking the first embodiment and the second embodiment of the present invention as examples. In addition, the method for producing ammonia using the catalyst for ammonia synthesis and the method for producing the oxynitrogen hydride of the present invention are described in detail, taking the first embodiment and the second embodiment of the present invention as examples. However, the present invention is not limited to the above-mentioned embodiments, and various forms can be adopted.

[0082] "First Implementation Method"

[0083] (oxynitrogen hydride containing a typical element of Group 13)

[0084] The oxynitrogen hydride of the present embodiment is an oxynitrogen hydride in which nitrogen and hydrogen are doped at the oxygen sites of the composite oxide represented by the following general formula (6). The oxynitrogen hydride of the present invention is a compound represented by the following general formula (7). It is preferred to have a crystal structure of the same type as the composite oxide represented by the following general formula (6) without being doped with nitrogen and hydrogen. That is, preferably, the oxynitrogen hydride of the present embodiment dopes nitrogen and hydrogen at the oxygen sites of the composite oxide represented by the following general formula (6) while maintaining the crystal structure of the composite oxide.

[0085] AB2O4 (6)

[0086] AB2O 4-x N y H z (7)

[0087] (In the above general formula (7), B is at least one selected from the group consisting of Al, Ga and In, and A, x, y and z have the same meanings as A, x, y and z in the general formula (1).)

[0088] The compound represented by the general formula (7) is a compound represented by the general formula (1) wherein n is 1, m is 2, l is 4, and B is at least one selected from the group consisting of Al, Ga, and In.

[0089] The amount of nitrogen and the amount of hydrogen doped in the oxynitrogen hydride of this embodiment are not particularly limited as long as the crystal structure of AB 2 O 4 can be maintained.

[0090] As for the relationship among x, y, and z, for example, 2x-(3y+z)=0 is preferable so that the oxynitride is charge neutral.

[0091] In the above general formula (7), x represents a number represented by 0.5≤x≤1.6; y represents a number represented by 0.25≤y≤0.8; and z represents a number represented by 0.25≤z≤0.8. It is preferred that.

[0092] In the above general formula (7), x is a number represented by 1.0≤x≤1.4; y is a number represented by 0.4≤y≤0.6; and z is a number represented by 0.3≤z≤0.5, which is more preferable.

[0093] For example, BaAl2O was synthesized by the following examples. 4-x N y H z Represents oxygen, nitrogen and hydride.

[0094] The nitrogen and hydrogen to be doped may be partially substituted with atoms other than nitrogen and hydrogen, and specifically may include electrons, carbon, halogen atoms, etc., as long as the effects of the present invention are not impaired.

[0095] (Method for producing oxynitrogen hydride)

[0096] The method for producing the oxynitrogen hydride represented by the general formula (7) of the present embodiment includes the step of heating the metal amide represented by the general formula (8) and the oxide of the Group 13 element represented by the general formula (9) in an ammonia atmosphere. The detailed production method is described in the examples described below. 4-x N y H z The manufacturing method includes, for example, a mixing step of mixing A(NH2)2 and B2O3, and a heating step of heating the mixture obtained by the mixing step in an ammonia atmosphere. In addition, it is preferred that a pretreatment step of further dehydrating A(NH2)2 is included before the mixing step. In this case, preferably, the mixing step is a step of mixing the dehydrated A(NH2)2 and B2O3 in a rare gas atmosphere such as an Ar glove box.

[0097] A(NH2)2 (8)

[0098] B2O3 (9)

[0099] In the above general formulae (8) and (9), A and B have the same meanings as A and B in the above general formula (7).

[0100] Examples of the dehydration treatment step include a method of performing vacuum heat treatment at 300°C to less than 900°C, preferably 400°C to less than 800°C, and more preferably 500°C to less than 700°C.

[0101] As the above-mentioned heat treatment, for example, a method of heating treatment at 300°C to less than 900°C in an ammonia gas flow for 1 to 50 hours, preferably at 400°C to less than 900°C for 2 to 50 hours, and more preferably at 500°C to less than 900°C for 5 to 25 hours.

[0102] It is preferred that A and B be mixed so that the molar ratio (A:B) is 0.8:2.0 to 1.2:2.0 (mol / mol), more preferably 0.9:2.0 to 1.1:2.0, and even more preferably 0.95:2.0 to 1.05:2.0.

[0103] It is preferred that the raw material A(NH2)2 used and the raw material B2O3 be in the form of powder. For example, commercially available Al2O3 powder (average particle size: 2-3 μm) manufactured by a high purity chemical company can be cited. Ba(NH2)2 can be synthesized by the following steps. Metal Ba (manufactured by Aldrich, purity 99.99%) is placed in a pressure-resistant container, and ammonia gas is introduced into the above container while cooling to about -50°C, thereby dissolving the metal Ba. The obtained dissolve is stirred at -50°C for 1 hour and then returned to room temperature. Thereafter, the above container containing the obtained dissolve is immersed in an oil bath, kept at 100°C for 1 hour while stirring, and then cooled to room temperature. Next, after cooling, the ammonia gas remaining in the container is exhausted, thereby obtaining Ba(NH2)2.

[0104] The oxynitrogen hydride of the present embodiment is preferably an oxynitrogen hydride obtained by heating A(NH2)2 and B2O3 in an ammonia atmosphere. The oxynitrogen hydride obtained by a manufacturing method including a mixing step of mixing A(NH2)2 and B2O3 and a heating treatment step of heating the mixture obtained by the mixing step in an ammonia atmosphere is more preferred. It is preferred that a pretreatment step further dehydrates B2O3 before the above-mentioned mixing step. In this case, preferably, in the above-mentioned mixing step, the dehydrated B2O3 and A(NH2)2 are mixed in a rare gas atmosphere such as an Ar glove box. In addition, the preferred heating treatment temperature, the preferred heating time, the preferred ratio of the amount of raw materials added, etc. are the same as those of the above-mentioned manufacturing method.

[0105] <Quantitative determination of nitrogen and hydrogen contained in oxynitrogen hydride>

[0106] The synthesized oxynitrogen hydride AB2O can be analyzed by temperature rising desorption analysis device (BELCATA). 4-x N y H z The amount of desorbed nitrogen and hydrogen can be analyzed to determine the amount of desorbed nitrogen and hydrogen. Based on the results of the amount of desorbed nitrogen and hydrogen, the ratio of nitrogen and hydrogen contained in the oxynitrogen hydride can be obtained. For example, in the following examples, based on the results obtained by temperature desorption analysis (BELCATA), BaAl2O synthesized at 800°C 4-x N y H z The composition is BaAl2O 3.7 N 0.17 H 0.09 .

[0107] (Metal support)

[0108] The metal support of the present embodiment is a substance obtained by supporting a transition metal (M) on a carrier. The above-mentioned carrier is a composition comprising an oxy-nitrogen hydride obtained by doping nitrogen and hydrogen at the oxygen site of AB2O4. The metal support of the present embodiment is a substance obtained by supporting a transition metal (M) on a carrier. The above-mentioned carrier is a composition comprising an oxy-nitrogen hydride represented by the above-mentioned general formula (7). It is preferred that the above-mentioned carrier is a composition comprising the oxy-nitrogen hydride of the present embodiment described above. It is preferred that the above-mentioned transition metal (M) is at least one selected from the group consisting of Ru, Co and Fe.

[0109] The amount of the transition metal loaded is not particularly limited, and is usually 0.01 mass parts (0.01 mass%) or more relative to 100 mass parts of the carrier, preferably 0.5 mass parts (0.5 mass%) or more, more preferably 1 mass part (1 mass%) or more, further preferably 2 mass parts (2 mass%) or more, usually 50 mass parts (50 mass%) or less, preferably 30 mass parts (30 mass%) or less, more preferably 20 mass parts (20 mass%) or less, and further preferably 10 mass parts (10 mass%) or less. As long as it is above the above lower limit, the effect of the present invention can be achieved, and as long as it is below the above upper limit, the effect of the present invention that the loading amount is commensurate with the cost can be achieved.

[0110] The metal support of this embodiment is a substance in which a transition metal (M) is supported on a carrier. The above-mentioned carrier is preferably a composition comprising an oxynitrogen hydride obtained by heating B2O3 and A(NH2)2 under an ammonia atmosphere. More preferably, it is the following composition, which comprises an oxynitrogen hydride obtained by a manufacturing method including a mixing process of mixing B2O3 and A(NH2)2, and a heating treatment process of heating the mixture obtained by the mixing process in an ammonia atmosphere. It is preferred that a pretreatment process of further dehydrating B2O3 is included before the above-mentioned mixing process. In this case, preferably, the above-mentioned mixing process is a process of mixing the dehydrated B2O3 and A(NH2)2 under a rare gas atmosphere such as an Ar glove box. In addition, the preferred heating treatment temperature, the preferred heating time, the preferred ratio of the amount of raw materials added, etc. are the same as those of the above-mentioned manufacturing method.

[0111] <Transition Metals>

[0112] The transition metal used in this embodiment is not particularly limited, but is generally a transition metal of Group 6, 7, 8, 9 or 10 of the periodic table, preferably a transition metal of Group 6, 8 or 9, and more preferably a metal of Group 8 or 9.

[0113] In addition, although there are no particular limitations on specific metal elements, they are generally Cr, Mo, Mn, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, and Pt. In view of high bond energy with nitrogen, Mo, Re, Fe, Ru, Os, and Co are preferred. When the ammonia synthesis catalyst is used as an ammonia synthesis catalyst, Ru, Co, or Fe is more preferred in view of having ammonia synthesis activity. In view of having the highest catalytic activity, Ru is further preferred.

[0114] Each of the above elements can be used alone or in combination of two or more. In addition, intermetallic compounds of these elements can be used, for example, Co3Mo3N, Fe3Mo3N, Ni2Mo3N, Mo2N, etc. Preferably, each element is used alone or in combination of two or more, and more preferably, it is advantageous to use it alone from the perspective of cost.

[0115] <Method of supporting transition metal (M) on oxynitride>

[0116] The method for supporting the transition metal (M) on the oxynitride is not particularly limited. For example, the powdered oxynitride (AB2O 4-x N y H z ), the metal compound to be supported is placed in a quartz glass tube, heated at 50°C to 90°C for 0.5 to 4 hours in a vacuum, and then continued to be heated at 100°C to 150°C for 0.5 to 4 hours, thereby attaching the metal compound to be supported to the powdered AB2O 4-x N y H z Finally, heat at 150°C to 300°C for 0.5 to 5 hours to thermally decompose the metal compound, thereby obtaining AB2O 4-x N y H z A support having a transition metal (M) fixed thereon (hereinafter, M / AB2O 4-x N y H z ).

[0117] For example, a transition metal compound Ru3(CO) in which the transition metal (M) is Ru, Co, or Fe is used. 12 、Co2(CO)8、Fe2(CO)9,can synthesize metal support Ru-supported AB2O 4-x N y H z (Abbreviated as Ru / AB2O 4-x N y H z ), Co supported AB2O 4-x N y H z (abbreviated as Co / AB2O 4-x N y H z ), Fe-supported AB2O 4-x N y H z (abbreviated as Fe / AB2O 4-x N y H z ).

[0118] <Shape of Metal Support>

[0119] The shape of the metal support of this embodiment is not particularly limited, and specifically can be any shape such as bulk, powder, film, etc., but is usually in powder form. The particle size of the powdered metal support is not particularly limited, but is usually 1 nm or more and 10 μm or less.

[0120] The transition metal particle size in the metal support of the present embodiment is not particularly limited, but is generally 1 nm or more and 100 nm or less. Preferably, when used as an ammonia synthesis catalyst, it is advantageous to have a particle size of 20 nm or less, and more preferably 10 nm or less, from the perspective of increasing the number of step sites that are active sites for nitrogen dissociation.

[0121] (Supported Metal Catalyst)

[0122] The supported metal catalyst of the present embodiment includes the metal support described above. The supported metal catalyst of the present embodiment includes a transition metal and a support for supporting the transition metal, and the support is a composition including an oxynitrogen hydride represented by the following general formula (7).

[0123] AB2O 4-x N y H z (7)

[0124] (In the above general formula (7), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Al, Ga and In, x represents a number represented by 0.2≤x≤2.0; y represents a number represented by 0.1≤y≤1.0; and z represents a number represented by 0.1≤z≤1.0.)

[0125] (Ammonia synthesis catalyst)

[0126] The catalyst for ammonia synthesis of the present invention is a substance obtained by supporting a transition metal (M) on a carrier. The above-mentioned carrier is a composition containing an oxy-nitrogen hydride in which nitrogen and hydrogen are doped at the oxygen site of AB2O4. The catalyst for ammonia synthesis of the present embodiment comprises a transition metal and a carrier for supporting the above-mentioned transition metal, and the above-mentioned carrier is a composition containing an oxy-nitrogen hydride represented by the following general formula (7). It is preferred that the above-mentioned carrier is a composition containing the oxy-nitrogen hydride of the present embodiment described above.

[0127] AB2O 4-x N y H z (7)

[0128] (In the above general formula (7), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Al, Ga and In, x represents a number represented by 0.2≤x≤2.0; y represents a number represented by 0.1≤y≤1.0; and z represents a number represented by 0.1≤z≤1.0.)

[0129] The nitrogen and hydrogen mentioned above may further contain atoms other than nitrogen and hydrogen, specifically, electrons, carbon, halogen atoms, etc., as long as the effects of the present invention are not impaired.

[0130] <Transition Metals>

[0131] The transition metal used in this embodiment is not particularly limited, but is generally a transition metal of Group 6, 7, 8, 9 or 10 of the periodic table, preferably a transition metal of Group 6, 8 or 9, and more preferably a metal of Group 8 or 9.

[0132] In addition, although there are no particular limitations on specific metal elements, they are generally Cr, Mo, Mn, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, and Pt. In view of high bond energy with nitrogen, Mo, Re, Fe, Ru, Os, and Co are preferred. When the ammonia synthesis catalyst is used as an ammonia synthesis catalyst, Ru, Co, or Fe is more preferred in view of having ammonia synthesis activity. In view of having the highest catalytic activity, Ru is further preferred.

[0133] Each of the above elements can be used alone or in combination of two or more. In addition, intermetallic compounds of these elements can be used, for example, Co3Mo3N, Fe3Mo3N, Ni2Mo3N, Mo2N, etc. Preferably, each element is used alone or in combination of two or more, and more preferably, it is advantageous to use it alone from the perspective of cost.

[0134] (Method for producing ammonia synthesis catalyst)

[0135] The catalyst for ammonia synthesis of the present invention is a substance in which a transition metal (M) is supported on a carrier. The above-mentioned carrier is a composition containing an oxynitrogen hydride in which nitrogen and hydrogen are doped at the oxygen site of AB2O4. In the case of the catalyst for ammonia synthesis of the present embodiment, the above-mentioned transition metal is supported on the above-mentioned carrier containing the composition containing the above-mentioned oxynitrogen hydride for production. The production method is not particularly limited, and generally, the transition metal or a compound that becomes a precursor of the transition metal (hereinafter referred to as a transition metal compound) is supported on the above-mentioned carrier for production.

[0136] The above-mentioned composition of oxynitrogen hydrides serving as a raw material of the ammonia synthesis catalyst of the present embodiment may be a commercially available reagent or an industrial raw material, or may be obtained by a known method from a corresponding metal.

[0137] The oxynitride hydride composition used in this embodiment may be pre-treated by heating at about 200 to 500° C. for several hours (eg, 340° C. for 2 hours) in a hydrogen atmosphere, and then the transition metal may be supported in the transition metal supporting step described below.

[0138] In the case of a catalyst produced using a sample in which the above-mentioned carrier is heated in advance in a hydrogen atmosphere, for example, when used in an ammonia synthesis reaction, high activity can be obtained immediately after the start of the reaction.

[0139] The method for supporting the transition metal (M) on the above-mentioned carrier used in the present embodiment is not particularly limited, and a known method can be used. A method of converting a transition metal compound that is a compound of the supported transition metal and can be converted into a transition metal by reduction, thermal decomposition, etc., to a transition metal after being supported on the above-mentioned carrier is generally used.

[0140] The transition metal compound is not particularly limited, and an inorganic compound of a transition metal that is easily thermally decomposed or an organic transition metal complex can be used. Specifically, a transition metal complex, a transition metal oxide, a transition metal salt such as a nitrate or hydrochloride can be used.

[0141] For example, as Ru compounds, there can be mentioned triruthenium dodecacarbonyl [Ru3(CO) 12 ], tetrakis(triphenylphosphine) ruthenium(II) dichloride[RuCl2(PPh3)4], tris(triphenylphosphine) ruthenium(II) dichloride[RuCl2(PPh3)3], tris(acetylacetonate) ruthenium(III)[Ru(acac)3], bis(cyclopentadienyl) ruthenium[Ru(C5H5)], nitrosyl nitrate ruthenium[Ru(NO)(NO3)3], potassium ruthenate, ruthenium oxide, ruthenium nitrate, ruthenium chloride, etc. Tris(acetylacetonate) ruthenium(III)[Ru(acac)3] is preferred.

[0142] Examples of Fe compounds include iron pentacarbonyl [Fe(CO)5], iron tridodecyl [Fe3(CO) 12 ], nonacarbonyl iron [Fe2(CO)9], tetracarbonyl iron iodide [Fe(CO)4I2], tris(acetylacetonate)iron (III) [Fe(acac)3], ferrocene [Fe(C5H5)2], iron oxide, iron nitrate, iron chloride (FeCl3), etc.

[0143] Examples of Co compounds include cobalt octacarbonyl [Co2(CO)8], cobalt(III) tris(acetylacetonate) [Co(acac)3], cobalt(II) acetylacetonate [Co(acac)2], cobaltocene [Co(C5H5)2], cobalt oxide, cobalt nitrate, cobalt chloride, and the like.

[0144] Among these transition metal compounds, [Ru3(CO) 12 ]、[Fe(CO)5]、[Fe3(CO) 12 ], [Fe2(CO)9], [Co2(CO)8] and other transition metal carbonyl complexes are used to load transition metals by heating after loading, and therefore, it is preferred from the perspective of omitting the reduction treatment described later when manufacturing the ammonia synthesis catalyst of the present embodiment.

[0145] The amount of the transition metal compound used is not particularly limited, and an amount for achieving a desired loading amount may be appropriately used, but is generally 0.01 parts by mass (0.01 mass%) or more, preferably 2 parts by mass (2 mass%) or more, preferably 10 parts by mass (10 mass%) or more, more preferably 20 parts by mass (20 mass%) or more, and generally 50 parts by mass (50 mass%) or less, preferably 40 parts by mass (40 mass%) or less, and more preferably 30 parts by mass (30 mass%) or less, relative to 100 parts by mass of the carrier used.

[0146] As a method for supporting the above transition metal compound on a carrier, specifically, for example, a physical mixing method, a CVD method (chemical vapor deposition method), a sputtering method or the like can be used.

[0147] The physical mixing method is a method in which the carrier and the transition metal compound are mixed in a solid state and then heated in a stream of an inert gas such as nitrogen, argon, helium, or under vacuum. The heating temperature at this time is not particularly limited, and is usually 200° C. or more and 600° C. or less. The heating time is not particularly limited, and is usually expected to be 2 hours or more.

[0148] Here, as long as the transition metal compound can be converted into a transition metal by thermal decomposition, the transition metal is usually supported at the above-mentioned stage to become the ammonia synthesis catalyst of the present embodiment.

[0149] When a substance other than the transition metal compound that is converted into a transition metal by thermal decomposition is used, the transition metal compound is usually reduced to become the ammonia synthesis catalyst of the present embodiment.

[0150] As for the method for reducing the above-mentioned transition metal compound (hereinafter referred to as reduction treatment), there is no particular limitation as long as it does not hinder the purpose of the present invention, but for example, a method carried out under an atmosphere containing a reducing gas, a method in which a reducing agent such as NaBH4, NH2NH2 or formalin is added to a solution containing the above-mentioned transition metal compound to precipitate it on the surface of the above-mentioned metal hydride, preferably carried out under an atmosphere containing a reducing gas. As the above-mentioned reducing gas, hydrogen, ammonia, methanol (steam), ethanol (steam), methane, ethane, etc. can be mentioned.

[0151] Furthermore, during the reduction treatment, other components other than the reducing gas which do not hinder the purpose of the present invention, in particular, the ammonia synthesis reaction, may coexist in the reaction system. Specifically, during the reduction treatment, in addition to reducing gases such as hydrogen, gases such as argon and nitrogen which do not hinder the reaction may coexist, and it is preferred to coexist nitrogen.

[0152] When the reduction treatment is performed in a gas containing hydrogen, hydrogen and nitrogen are allowed to coexist, so that the reduction treatment can be performed simultaneously with the production of ammonia described later. That is, when the catalyst for ammonia synthesis of the present embodiment is used as the catalyst for ammonia synthesis described later, the transition metal compound supported on the metal hydride can be subjected to the reaction conditions of the ammonia synthesis reaction, thereby reducing the transition metal compound and converting it into a transition metal.

[0153] The temperature during the reduction treatment is not particularly limited, and can be generally performed at 200° C. or higher, preferably 300° C. or higher, and preferably lower than 700° C. More preferably, it can be performed at 400° C. or higher and lower than 700° C. By performing the reduction treatment in the above-mentioned temperature range, the growth of the transition metal occurs sufficiently or in a preferred range.

[0154] The pressure during the reduction treatment is not particularly limited, but is usually 0.01 MPa to 10 MPa. If the pressure during the reduction treatment is the same as the ammonia synthesis conditions described below, complicated operations are no longer necessary, which is advantageous in terms of production efficiency.

[0155] The time for the reduction treatment is not particularly limited, but is usually 1 hour or longer, preferably 2 hours or longer when carried out under normal pressure.

[0156] When the reaction is carried out under high reaction pressure, for example, 1 MPa or more, 1 hour or more is preferred.

[0157] When a substance other than the transition metal compound converted into a transition metal by thermal decomposition is used, the transition metal compound contained in the solid mixture is reduced by a common method in the same manner as the above-mentioned reduction treatment method to obtain the ammonia synthesis catalyst of the present embodiment.

[0158] As components other than the above-mentioned oxynitrogen hydride and the above-mentioned transition metal, SiO2, Al2O3, ZrO2, MgO, activated carbon, graphite, SiC, etc. may be further included as a carrier of the above-mentioned oxynitrogen hydride.

[0159] The ammonia synthesis catalyst of the present embodiment can be used as a molded body using a common molding technique. Specifically, the shapes include granular, spherical, sheet, ring, macaroni, four-leaf, dice, honeycomb, etc. In addition, it can be used after being coated on a suitable support.

[0160] When the catalyst for ammonia synthesis of the present embodiment is used, its reaction activity is not particularly limited. Taking the ammonia generation rate at a reaction temperature of 300°C and a reaction pressure of 0.9 MPa as an example, 1.0 mmol / g·h or more is preferred. From the perspective of suitability for practical production conditions, 2.0 mmol / g·h or more is more preferred. From the perspective of suitability for highly efficient production conditions, 3.0 mmol / g·h or more is further preferred. From the perspective of suitability for even more efficient production conditions, 5.0 mmol / g·h or more is further preferred.

[0161] The following describes a method for producing ammonia using the ammonia synthesis catalyst of the present embodiment.

[0162] (Method for producing ammonia)

[0163] The method for producing ammonia according to the present embodiment (hereinafter sometimes referred to as the production method of the present embodiment) is a method for synthesizing ammonia by using the supported metal catalyst of the present embodiment or the catalyst for ammonia synthesis of the present embodiment as a catalyst and reacting hydrogen and nitrogen on the catalyst.

[0164] The specific production method is not particularly limited as long as it is a method of synthesizing ammonia by bringing hydrogen and nitrogen into contact over the above-mentioned catalyst, and the ammonia can be produced according to an appropriate known production method.

[0165] In the method for producing ammonia according to the present embodiment, generally, when hydrogen and nitrogen are brought into contact on the above-mentioned catalyst, the catalyst is heated to produce ammonia.

[0166] The reaction temperature in the production method of the present embodiment is not particularly limited, but is usually 200° C. or higher, preferably 250° C. or higher, more preferably 300° C. or higher, and is usually 600° C. or lower, preferably 500° C. or lower, more preferably 450° C. or lower. Ammonia synthesis is an exothermic reaction, so ammonia production is more favorable in a low temperature region from the perspective of chemical equilibrium theory, but in order to achieve a sufficient ammonia production rate, it is preferred to conduct the reaction in the above temperature range.

[0167] In the manufacturing method of this embodiment, the molar ratio of nitrogen and hydrogen in contact with the above-mentioned catalyst is not particularly limited. Usually, the ratio of hydrogen to nitrogen (H2 / N2 (volume / volume)) is usually above 0.4, preferably above 0.5, more preferably above 1, and usually below 10, preferably below 5.

[0168] The reaction pressure in the manufacturing method of the present embodiment is not particularly limited, and is usually 0.01 MPa or more, preferably 0.1 MPa or more, usually 20 MPa or less, preferably 15 MPa or less, and more preferably 10 MPa or less, based on the pressure gauge of the mixed gas containing nitrogen and hydrogen. In addition, if practical applications are considered, it is preferred to react under pressurized conditions above atmospheric pressure.

[0169] In the production method of this embodiment, before bringing nitrogen and hydrogen into contact with the catalyst, it is preferred to remove water and oxides attached to the catalyst by using a dehydrating material, a cryogenic separation, hydrogen gas, etc. Examples of the removal method include reduction treatment.

[0170] In the manufacturing method of the present embodiment, in order to achieve a better ammonia yield, it is preferred that the moisture content in the nitrogen and hydrogen used in the manufacturing method of the present embodiment is low. There is no particular limitation. Usually, the total moisture content in the mixed gas of nitrogen and hydrogen is less than 100 ppm, preferably less than 50 ppm.

[0171] In the production method of this embodiment, the form of the reaction container is not particularly limited, and a reaction container that can be generally used in an ammonia synthesis reaction can be used. As a specific reaction form, for example, a batch reaction form, a closed cycle reaction form, a flow reaction form, etc. can be used. Among them, from a practical point of view, the flow reaction form is preferred. In addition, any method of connecting a reactor filled with a catalyst or a plurality of reactors, or a reactor having a plurality of reaction layers in the same reactor can also be used.

[0172] The reaction of synthesizing ammonia from hydrogen and nitrogen is an exothermic reaction accompanied by volume contraction, so in order to improve the ammonia yield, it is preferable to remove the reaction heat industrially, and a known reaction apparatus with a commonly used heat removal means can be used. For example, specifically, a method of connecting a plurality of reactors filled with catalysts in series and installing an intercooler at the outlet of each reactor to remove heat can be used.

[0173] In the ammonia production method of the present embodiment, the ammonia synthesis catalyst obtained by the production method of the present embodiment may be used alone or in combination with other known catalysts that can be generally used in ammonia synthesis.

[0174] "Second Implementation Method"

[0175] (oxynitrogen hydride containing a typical element of Group 14)

[0176] The oxynitrogen hydride of the present embodiment is an oxynitrogen hydride in which nitrogen and hydrogen are doped at the oxygen sites of the composite oxide represented by the following general formula (10). The oxynitrogen hydride of the present invention is a compound represented by the following general formula (11). It is preferred to have a crystal structure of the same type as the composite oxide represented by the following general formula (10) which is not doped with nitrogen and hydrogen. That is, preferably, the oxynitrogen hydride of the present embodiment is a compound in which the crystal structure of the composite oxide is maintained while nitrogen and hydrogen are doped at the oxygen sites of the composite oxide represented by the following general formula (10).

[0177] A3BO5 (10)

[0178] A3BO 5-x N y H z (11)

[0179] (In the above general formula (7), B is at least one selected from the group consisting of Si, Ge and Sn, and A, x, y and z have the same meanings as A, x, y and z in the general formula (1).)

[0180] The compound represented by the general formula (11) is a compound represented by the general formula (1) wherein n is 3, m is 1, l is 5, and B is at least one selected from the group consisting of Si, Ge and Sn.

[0181] The amount of nitrogen and the amount of hydrogen doped in the oxynitride of the present embodiment are not particularly limited as long as the crystal structure of A3BO5 can be maintained.

[0182] Regarding the relationship among x, y, and z, for example, 2x-(3y+z)=0 is preferable so that the oxynitride is charge neutral.

[0183] In the above general formula (1), x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z preferably represents a number represented by 0.1≤z≤2.0.

[0184] In the above general formula (1), x represents a number represented by 2.0≤x≤3.5; y represents a number represented by 1.0≤y≤2.0; and z represents a number represented by 1.0≤z≤2.0, which is more preferable.

[0185] For example, Ba3SiO 5-x N y H z Represents oxygen, nitrogen and hydride.

[0186] The nitrogen and hydrogen to be doped may be partially substituted with atoms other than nitrogen and hydrogen, and specifically may include electrons, carbon, halogen atoms, etc., as long as the effects of the present invention are not impaired.

[0187] (Method for producing oxynitrogen hydride)

[0188] The method for producing the oxynitrogen hydride represented by the general formula (11) of the present embodiment includes the step of heating the metal amide represented by the general formula (8) and the oxide of the Group 14 element represented by the general formula (12) in an ammonia atmosphere. The detailed production method is described in the examples described below. 5-x N y H z The manufacturing method includes, for example, a mixing step of mixing A(NH2)2 and BO2, and a heating step of heating the mixture obtained by the mixing step in an ammonia atmosphere. In addition, it is preferred that a pretreatment step of further dehydrating A(NH2)2 is included before the mixing step. In this case, preferably, in the above-mentioned mixing step, the dehydrated A(NH2)2 and BO2 are mixed in a rare gas atmosphere such as an Ar glove box.

[0189] A(NH2)2 (8)

[0190] BO2 (12)

[0191] In the above general formulae (8) and (13), A and B have the same meanings as A and B in the above general formula (11).

[0192] Examples of the dehydration treatment step include a method of performing vacuum heat treatment at 300°C to less than 900°C, preferably 400°C to less than 800°C, and more preferably 500°C to less than 700°C.

[0193] Examples of the above-mentioned heat treatment include a method of heating in an ammonia gas flow at a temperature of 300°C to less than 900°C for 1 to 24 hours, preferably at a temperature of 300°C to less than 700°C for 2 to 12 hours, and more preferably at a temperature of 400°C to less than 700°C for 2 to 6 hours.

[0194] It is preferred that A and B be mixed so that the molar ratio (A:B) is 2.4:1 to 3.6:1 (mol / mol), more preferably 2.7:1 to 3.3:1, and even more preferably 2.85:1 to 3.15:1.

[0195] The form of the raw material A(NH2)2 and the raw material BO2 used is preferably a powder. For example, commercially available SiO2 powder (average particle size: less than 10 nm) manufactured by Aldrich can be cited. Ba(NH2)2 can be manufactured by the same method as the first embodiment.

[0196] The oxynitrogen hydride of the present embodiment is preferably an oxynitrogen hydride obtained by heating A(NH2)2 and BO2 in an ammonia atmosphere. The oxynitrogen hydride obtained by a manufacturing method including a mixing step of mixing A(NH2)2 and BO2 and a heating treatment step of heating the mixture obtained by the mixing step in an ammonia atmosphere is more preferred. It is preferred that a pretreatment step further dehydrates BO2 before the mixing step. In this case, preferably, in the mixing step, the dehydrated A(NH2)2 and BO2 are mixed in a rare gas atmosphere such as an Ar glove box. In addition, the preferred heating treatment temperature, the preferred heating time, the preferred ratio of the amount of raw materials added, etc. are the same as those of the above-mentioned manufacturing method.

[0197] <Quantitative determination of nitrogen and hydrogen contained in oxynitrogen hydride>

[0198] The synthesized oxynitrogen hydride A3BO can be analyzed by temperature rising desorption analysis device (BELCATA) 5-x N y H z The amount of desorbed nitrogen and hydrogen can be analyzed to determine the amount of desorbed nitrogen and hydrogen. Based on the results of the amount of desorbed nitrogen and hydrogen, the ratio of nitrogen and hydrogen contained in the oxynitrogen hydride can be obtained. For example, in the following examples, based on the results of the temperature rise desorption analysis device (BELCATA), A3BO synthesized at 600°C 5-x N y H z The composition is A3BO 1.62 N 1.66 H 1.77 .

[0199] (Metal support)

[0200] The metal support of the present embodiment is a substance in which a transition metal (M) is supported on a support. The support is a composition comprising an oxynitrogen hydride in which nitrogen and hydrogen are doped at the oxygen site of A3BO5. The support is a composition comprising an oxynitrogen hydride represented by the general formula (11). It is preferred that the support is a composition comprising the oxynitrogen hydride of the present embodiment described above. It is preferred that the transition metal (M) is at least one selected from the group consisting of Ru, Co and Fe.

[0201] The type of the transition metal, the method of supporting the transition metal (M) on the oxynitride, the supported amount thereof, the method of producing the metal-supported material, and the shape of the metal-supported material are the same as those of the first embodiment.

[0202] (Supported Metal Catalyst)

[0203] The supported metal catalyst of the present embodiment includes the above-mentioned metal support. The supported metal catalyst of the present embodiment includes a transition metal and a support that supports the above-mentioned transition metal, and the above-mentioned support includes a composition of an oxynitrogen hydride represented by the following general formula (11).

[0204] A3BO 5-x N y H z (11)

[0205] (In the above general formula (11), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Si, Ge and Sn, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.0.)

[0206] (Ammonia synthesis catalyst)

[0207] The catalyst for ammonia synthesis of the present invention is a substance in which a transition metal (M) is supported on a carrier. The above-mentioned carrier is a composition containing an oxy-nitrogen hydride formed by doping nitrogen and hydrogen at the oxygen site of A3BO5. The catalyst for ammonia synthesis of the present embodiment comprises a transition metal and a carrier supporting the above-mentioned transition metal, and the above-mentioned carrier is a composition containing an oxy-nitrogen hydride represented by the following general formula (11). It is preferred that the above-mentioned carrier is a composition containing the oxy-nitrogen hydride of the present embodiment described above.

[0208] A3BO 5-x N y H z (11)

[0209] (In the above general formula (11), A is at least one selected from the group consisting of Ba and Sr, B is at least one selected from the group consisting of Si, Ge and Sn, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.0.)

[0210] The nitrogen and hydrogen mentioned above may further contain atoms other than nitrogen and hydrogen, specifically, electrons, carbon, halogen atoms, etc., as long as the effects of the present invention are not impaired.

[0211] The transition metal used in this embodiment is the same as the transition metal in the first embodiment.

[0212] (Method for producing ammonia synthesis catalyst)

[0213] The catalyst for ammonia synthesis of the present embodiment is a substance in which a transition metal (M) is supported on a carrier. The above-mentioned carrier is a composition containing an oxy-nitrogen hydride in which nitrogen and hydrogen are doped at the oxygen site of A3BO5. The catalyst for ammonia synthesis of the present embodiment is manufactured by supporting the above-mentioned transition metal on the above-mentioned carrier containing the composition containing the above-mentioned oxy-nitrogen hydride. The manufacturing method is not particularly limited, and generally, the transition metal or a compound that becomes a precursor of the transition metal (hereinafter referred to as a transition metal compound) is supported on the above-mentioned carrier for manufacturing.

[0214] The ammonia synthesis catalyst of the present embodiment can be produced by the same method as that of the first embodiment.

[0215] As components other than the above-mentioned oxynitrogen hydride and the above-mentioned transition metal, SiO2, Al2O3, ZrO2, MgO, activated carbon, graphite, SiC, etc. may be further included as a carrier of the above-mentioned oxynitrogen hydride.

[0216] The catalyst for ammonia synthesis of the present embodiment can be used as a molded body using a common molding technique. Specifically, the shapes include granular, spherical, sheet, ring, macaroni, four-leaf, dice, honeycomb, etc. In addition, the catalyst can be used after being coated on a suitable support.

[0217] When the catalyst for ammonia synthesis of the present embodiment is used, its reaction activity is not particularly limited. Taking the ammonia generation rate at a reaction temperature of 300°C and a reaction pressure of 0.9 MPa as an example, 1.0 mmol / g·h or more is preferred. From the perspective of suitability for practical production conditions, 2.0 mmol / g·h or more is more preferred. From the perspective of suitability for highly efficient production conditions, 3.0 mmol / g·h or more is further preferred. From the perspective of suitability for even more efficient production conditions, 5.0 mmol / g·h or more is further preferred.

[0218] (Method for producing ammonia)

[0219] The method for producing ammonia according to the present embodiment is the same as the method for producing ammonia according to the first embodiment, except that the catalyst for synthesizing ammonia according to the present embodiment is used.

[0220] In the method for producing ammonia according to the present embodiment, the catalyst for ammonia synthesis obtained by the method for producing ammonia according to the present embodiment may be used alone or in combination with other known catalysts that can be generally used for ammonia synthesis.

[0221] Example

[0222] The present invention is described in more detail below based on examples. The ammonia synthesis activity is evaluated by determining the amount of NH3 generated using a gas chromatograph or by dissolving the generated NH3 in a sulfuric acid aqueous solution and quantifying the solution using an ion chromatograph to determine the ammonia generation rate.

[0223] (Ion Chromatography Analysis)

[0224] The ammonia gas discharged from the reaction vessel was dissolved in a 5 mM sulfuric acid aqueous solution, and the captured ammonium ions (NH4 + The analysis conditions are as follows.

[0225] [Measurement conditions]

[0226] Device: Prominence manufactured by Shimadzu Corporation

[0227] Detector: Conductivity detector CDD-10Avp (manufactured by Shimadzu Corporation)

[0228] Column: Ion chromatography column IC-C4 (manufactured by Shimadzu Corporation)

[0229] Eluent: 3.0 mM oxalic acid + 2.0 mM 18-crown-6-ether aqueous solution Flow rate: 1.0 mL / min

[0230] Column temperature: 40°C

[0231] (Example 1)

[0232] (Preparation of Catalyst for Ammonia Synthesis)

[0233] [BaAl2O 4-x N y H z Synthesis of powder]

[0234] Al2O3 was vacuum heated at 600°C to remove the water adsorbed on the surface, and the dehydrated Al2O3 and Ba(NH2)2 were mixed using an agate mortar in an Ar glove box. At this time, the molar ratio of Ba to Al was 1:2. The obtained powder was heated to 800°C in 2 hours in an NH3 gas flow at a flow rate of 100 mL / min, and heated at 800°C for 20 hours to obtain BaAl2O3 of this embodiment. 4-x N y H z powder.

[0235] like Figure 1 As shown in the figure, when the synthesis was performed at 600°C for 6 hours, the target BaAl2O4 phase was not obtained. On the other hand, when the synthesis was performed at 800°C for 6 hours, the presence of the target BaAl2O4 phase was confirmed. Furthermore, in the present embodiment in which the synthesis was performed at 800°C for 20 hours, a substantially single-phase BaAl2O4 phase was obtained.

[0236] <BaAl2O 4-x N y H z Quantification of nitrogen and hydrogen contained in >

[0237] The BaAl2O synthesized in this example was analyzed by temperature rise desorption analysis (BELCATA). 4-x N y H z The results of the analysis are shown in Figure 2 middle.

[0238] like Figure 2 As shown in the figure, nitrogen and hydrogen begin to desorb from around 550°C, confirming that BaAl2O 4-x N y H z Nitrogen and hydrogen are contained in BaAl2O. Nitrogen is not completely desorbed even at 900°C, so it is difficult to 4-x N y H z When all nitrogen in the mixture is quantified and the approximate content is estimated, the composition is BaAl2O 3.7 N 0.17 H 0.09 .

[0239] [Ru to BaAl2O 4-x N y H z Load]

[0240] The powdered BaAl2O 4-x N y H z0.50g, Ru3(CO) 12 (Aldrich, 99%) 0.056 g (relative to Ba3SiO 5-x N y H z , as the supported metal Ru equivalent to 5 mass %) was placed in a quartz glass tube, which was heated at 70°C for 1 hour in a vacuum, and then continued to be heated at 120°C for 1 hour, thereby making Ru3(CO) 12 Adhesion to powdered BaAl2O 4-x N y H z The powdery substance thus obtained was finally heated at 250°C for 2 hours to 12 Thermal decomposition, thus obtaining BaAl2O 4-x N y H z A support on which Ru is fixed (hereinafter referred to as Ru / BaAl2O 4-x N y H z ).

[0241] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0242] [Using Ru to support BaAl2O 4-x N y H z Ammonia synthesis]

[0243] <Ammonia synthesis reaction>

[0244] The above Ru / BaAl2O 4-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 4-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used for the reaction. The water concentrations of the nitrogen gas and hydrogen gas of the raw materials were respectively below the detection limit. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 300°C, and the reaction time was 30 hours.

[0245] <Ammonia generation rate>

[0246] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified by the above method using an ion chromatograph. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph, and the result was that Ru / BaAl2O 4-x N y H z Compared with the existing Cs-Ru / MgO as Ru catalyst, it shows much higher catalyst activity under all reaction temperature conditions (such as Figure 3 The ammonia generation rate at 300°C was 8.4 mmol / g·hr. This value is much higher than that of Cs-Ru / MgO (0.55 mmol / g·hr). The results are shown in Table 1.

[0247] (Example 2)

[0248] (Preparation of Catalyst for Ammonia Synthesis)

[0249] [Ba3SiO 5-x N y H z Synthesis of powder]

[0250] The water adsorbed on the surface of SiO2 was removed by vacuum heating at 600°C, and the dehydrated SiO2 and Ba(NH2)2 were mixed using an agate mortar in an Ar glove box. At this time, the molar ratio of Ba to Si was 3:1. The obtained powder was heated to 600°C in 2 hours in an NH3 gas flow at a flow rate of 100 mL / min, and heated at 600°C for 6 hours to obtain Ba3SiO 5-x N y H z powder.

[0251] [Ru to Ba3SiO 5-x N y H z Load]

[0252] The powdered Ba3SiO 5-x N y H z 0.50g, Ru3(CO) 12 (Aldrich, 99%) 0.056 g (relative to Ba3SiO 5-x N y H z , as the supported metal Ru equivalent to 5 mass %) was placed in a quartz glass tube, which was heated at 70°C for 1 hour in a vacuum, and then continued to be heated at 120°C for 1 hour, thereby Ru3(CO)12 Adhesion to powdered Ba3SiO 5-x N y H z The powdery substance thus obtained was finally heated at 250°C for 2 hours to form Ru3(CO) 12 Thermal decomposition, thus obtaining Ba3SiO 5-x N y H z A support having Ru fixed thereon (hereinafter, Ru / Ba3SiO 5-x N y H z ) Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0253] [Using Ru to support Ba3SiO 5-x N y H z Ammonia synthesis]

[0254] <Ammonia synthesis reaction>

[0255] The above Ru / Ba3SiO 5-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 5-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used for the reaction. The water concentration of the nitrogen gas and the water concentration of the hydrogen gas of the raw material were respectively below the detection limit. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 300°C, and the reaction time was 30 hours.

[0256] <Ammonia generation rate>

[0257] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified by the above method using an ion chromatograph. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The synthesis rate of ammonia at 300°C and 0.9MPa was 6.34mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0258] In addition, the reaction temperature of the above ammonia synthesis reaction was changed to evaluate the reaction temperature dependence of the ammonia production rate. The results are shown in Figure 3 middle.

[0259] (Comparative Example 1)

[0260] [Synthesis of Cs-Ru / MgO powder]

[0261] In addition to using MgO with Cs added (denoted as Cs / MgO) instead of BaAl2O 4-x N y H z In addition, the same method as in Example 1 was used to prepare a 5 mass % Ru-Cs / MgO catalyst (Cs / Ru element ratio = 1).

[0262] [Ammonia synthesis using Cs-Ru / MgO]

[0263] <Ammonia synthesis reaction>

[0264] The ammonia synthesis reaction was carried out under the same conditions as in Example 1. The synthesis rate of ammonia at 300°C and 0.9 MPa was 0.55 mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0265] (Comparative Example 2)

[0266] [Synthesis of Ru / CeO2 powder]

[0267] In addition to using CeO2 instead of BaAl2O 4-x N y H z In addition, the same method as in Example 1 was used to prepare a 5 mass % Ru / CeO2 catalyst.

[0268] [Ammonia synthesis using Ru / CeO2]

[0269] <Ammonia synthesis reaction>

[0270] The ammonia synthesis reaction was carried out under the same conditions as in Example 1. The synthesis rate of ammonia at 300°C and 0.9 MPa was 0.72 mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0271] (Comparative Example 3)

[0272] [Synthesis of Ru / C12A7:e-powder]

[0273] Instead of BaAl2O in Example 1 4-x N y H z A 2 mass % Ru / C12A7:e- catalyst was prepared by the same method as described in International Publication No. 2012 / 0077658.

[0274] [Ammonia synthesis using Ru / C12A7:e-]

[0275] <Ammonia synthesis reaction>

[0276] The ammonia synthesis reaction was carried out under the same conditions as in Example 1. The synthesis rate of ammonia at 300°C and 0.9 MPa was 0.76 mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0277] (Comparative Example 4)

[0278] [Synthesis of Ca2NH powder]

[0279] Instead of BaAl2O in Example 1 4-x N y H z A 5 mass % Ru / Ca2NH3 catalyst was prepared by the same method as described in International Publication No. 2015 / 129471.

[0280] [Synthesis of ammonia using Ru / Ca2NH]

[0281] <Ammonia synthesis reaction>

[0282] The ammonia synthesis reaction was carried out under the same conditions as in Example 1. The synthesis rate of ammonia at 300°C and 0.9 MPa was 1.74 mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0283] <BaAl2O 4-x N y H z Powder XRD>

[0284] The XRD pattern of the sample synthesized in Example 1 by the above method is shown in Figure 1 In addition, for comparison, the XRD patterns of Al2O3, BaO, and BaAl2O4 are also shown in Figure 1 middle.

[0285] (Examples 3 to 5)

[0286] [Ba3SiO synthesized at various heat treatment temperatures 5-x N y H z Powder Evaluation]

[0287] Ba3SiO2 was prepared in the same manner as in Example 1 except that the heating temperatures shown in Table 2 were used instead of the heating temperature of 600°C in the NH3 gas flow in Example 1. 5-x N y H z powder.

[0288] <Ba3SiO5-x N y H z Powder XRD>

[0289] The XRD patterns of the samples synthesized by the above method at various heat treatment temperatures are shown in Figure 4 In addition, for comparison, the XRD pattern of Ba3SiO5 is also shown in Figure 4 middle.

[0290] like Figure 4 As shown in the figure, when the heat treatment temperature is 400°C or above for synthesis, the presence of Ba3SiO5 crystalline phase can be confirmed, and a material roughly of a single phase can be obtained. In addition, even if the heat treatment temperature is as high as 800°C, the presence of Ba3SiO5 crystalline phase can also be confirmed. Furthermore, it is confirmed that compared with the standard oxide Ba3SiO5, the peak is shifted to the low angle side as a whole. It is believed that this is because nitrogen, which has a larger ion radius than oxygen, is doped at a high concentration.

[0291] [Table 1]

[0292]

[0293] The following are the reaction conditions of the Examples and Comparative Examples in Table 1.

[0294] Catalyst amount: 0.1 g, reaction temperature: 300 °C, reaction gas flow rate: 60 mL / min,

[0295] Reaction gas composition: N2 / H2=1 / 3 (v / v), reaction pressure: 0.9 MPa. [Table 2]

[0296]

[0297] (Example 6)

[0298] [Co to BaAl2O 4-x N y H z Load]

[0299] The powdered BaAl2O synthesized in Example 1 4-x N y H z 0.855 g, Co2(CO)8 (manufactured by Kanto Chemical Co., Ltd., 95%) 0.145 g (relative to Ba3SiO 5-x N y H z , as the metal Co supported, equivalent to 5 mass %) was placed in a quartz glass reaction tube, nitrogen 15 mL / min and hydrogen 45 mL / min were circulated therein, the temperature was raised to 400°C in 2 hours and maintained for 5 hours, thereby obtaining BaAl2O4-x N y H z A support having Co fixed thereon (hereinafter referred to as Co / BaAl2O 4-x N y H z ).

[0300] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0301] [Using Co to support BaAl2O 4-x N y H z Ammonia synthesis]

[0302] <Ammonia synthesis reaction>

[0303] The above Co / BaAl2O 4-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 4-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used for the reaction. The water concentrations of the nitrogen gas and hydrogen gas of the raw materials were respectively below the detection limit. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min, and the hydrogen gas was 45mL / min (60mL / min in total). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 300°C, and the reaction time was 30 hours.

[0304] <Ammonia generation rate>

[0305] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified by the above method using an ion chromatograph. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The synthesis rate of ammonia at 300°C and 0.9MPa was 1.11mmol / g·hr as shown in Table 3. The results are shown in Table 3.

[0306] (Example 7)

[0307] (Preparation of Catalyst for Ammonia Synthesis)

[0308] [Co to Ba3SiO 5-x N y H z Load]

[0309] The powdered Ba3SiO5-x N y H z 、Co2(CO)8(Kanto Chemical Co., Ltd., 95%) (relative to Ba3SiO 5-x N y H z , as the supported metal Co equivalent to 5 mass %) was placed in a quartz glass reaction tube, nitrogen 15 mL / min and hydrogen 45 mL / min were circulated therein, the temperature was raised to 400°C in 2 hours and maintained for 5 hours, thereby obtaining Ba3SiO 5-x N y H z A support having Co fixed thereon (hereinafter referred to as Co / Ba3SiO 5-x N y H z ).

[0310] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0311] [Using Co to support Ba3SiO 5-x N y H z Ammonia synthesis]

[0312] <Ammonia synthesis reaction>

[0313] The above Co / Ba3SiO 5-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 5-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used to react. Confirm that the water concentration of the nitrogen gas and the water concentration of the hydrogen gas of the raw material were below the detection limit. Regarding the flow rate of the raw material gas during the reaction, the nitrogen gas was 15mL / min and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 300°C, and the reaction time was 30 hours.

[0314] <Ammonia generation rate>

[0315] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified using an ion chromatograph by the above method. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The ammonia synthesis rate (mmol / g·hr) at 300°C and 0.9MPa was calculated.

[0316] (Example 8)

[0317] [Fe to BaAl2O 4-x N y H z Load]

[0318] The powdered BaAl2O synthesized in Example 1 4-x N y H z 、Fe2(CO)2(made by STREM CHEMICALS, 99%) (relative to Ba3SiO 5-x N y H z , as the supported metal Fe equivalent to 5 mass %) was placed in a quartz glass tube, nitrogen 15 mL / min and hydrogen 45 mL / min were circulated thereto, the temperature was raised to 400°C in 2 hours and maintained for 5 hours, thereby obtaining BaAl2O 4-x N y H z A support on which Fe is fixed (hereinafter, Fe / BaAl2O 4-x N y H z ).

[0319] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0320] [Using Fe to support BaAl2O 4-x N y H z Ammonia synthesis]

[0321] <Ammonia synthesis reaction>

[0322] The above Fe / BaAl2O 4-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 4-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used to react. Confirm that the water concentrations of the nitrogen gas and hydrogen gas of the raw materials were below the detection limit, respectively. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min, and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 300°C, and the reaction time was 30 hours.

[0323] <Ammonia generation rate>

[0324] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified using an ion chromatograph by the above method. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The ammonia synthesis rate (mmol / g·hr) at 300°C and 0.9MPa was calculated.

[0325] (Example 9)

[0326] (Preparation of Catalyst for Ammonia Synthesis)

[0327] [Fe to Ba3SiO 5-x N y H z Load]

[0328] The powdered Ba3SiO 5-x N y H z 0.837 g, Fe2(CO)9 (manufactured by STREM CHEMICALS, 99%) 0.163 g (relative to Ba3SiO 5-x N y H z , as the supported metal Fe equivalent to 5 mass %) was placed in a quartz glass reaction tube, nitrogen 15 mL / min and hydrogen 45 mL / min were circulated thereto, the temperature was raised to 400°C in 2 hours and maintained for 5 hours, thereby obtaining Ba3SiO 5-x N y H z A support having Fe fixed thereon (hereinafter, Fe / Ba3SiO 5-x N y H z ).

[0329] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0330] [Using Fe to support Ba3SiO 5-x N y H z Ammonia synthesis]

[0331] <Ammonia synthesis reaction>

[0332] The above Fe / Ba3SiO 5-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 5-x N y Hz 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used for the reaction. The water concentration of the nitrogen gas and the water concentration of the hydrogen gas of the raw material were respectively below the detection limit. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 300°C, and the reaction time was 30 hours.

[0333] <Ammonia generation rate>

[0334] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified by the above method using an ion chromatograph. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The synthesis rate of ammonia at 300°C and 0.9MPa was 0.916mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0335] (Example 10)

[0336] [Ni to BaAl2O 4-x N y H z Load]

[0337] The powdered BaAl2O synthesized in Example 1 4-x N y H z 0.839 g, Ni(C5H5)2 (Tokyo Chemical Industry Co., Ltd., 98%) 0.161 g (relative to Ba3SiO 5-x N y H z , as the supported metal Ni equivalent to 5 mass %) was placed in a quartz glass reaction tube, nitrogen 15 mL / min and hydrogen 45 mL / min were circulated thereto, the temperature was raised to 400°C in 2 hours and maintained for 5 hours, thereby obtaining BaAl2O 4-x N y H z A support having Ni fixed thereon (hereinafter, Ni / BaAl2O 4-x N y H z ).

[0338] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0339] [Using Ni to support BaAl2O 4-x N y H z Ammonia synthesis]

[0340] <Ammonia synthesis reaction>

[0341] The above Ni / BaAl2O 4-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 4-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used for the reaction. The water concentrations of the nitrogen gas and hydrogen gas of the raw materials were respectively below the detection limit. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 400°C, and the reaction time was 30 hours.

[0342] <Ammonia generation rate>

[0343] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified by the above method using an ion chromatograph. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The synthesis rate of ammonia at 400°C and 0.9MPa was 1.20mmol / g·hr as shown in Table 3. The results are shown in Table 3.

[0344] (Example 11)

[0345] (Preparation of Catalyst for Ammonia Synthesis)

[0346] [Ni to Ba3SiO 5-x N y H z Load]

[0347] The powdered Ba3SiO 5-x N y H z 0.839 g, Ni(C5H5)2 (Tokyo Chemical Industry Co., Ltd., 98%) 0.161 g (relative to Ba3SiO 5-x N y H z , as the supported metal Ni equivalent to 5 mass %) was placed in a quartz glass reaction tube, nitrogen 15 mL / min and hydrogen 45 mL / min were circulated thereto, the temperature was raised to 400°C in 2 hours and maintained for 5 hours, thereby obtaining Ba3SiO 5-x N y H zA support having Ni fixed thereon (hereinafter, Ni / Ba3SiO 5-x N y H z ).

[0348] Next, ammonia synthesis was carried out using the above-mentioned ammonia synthesis catalyst.

[0349] [Using Ni to support Ba3SiO 5-x N y H z Ammonia synthesis]

[0350] <Ammonia synthesis reaction>

[0351] The above Ni / Ba3SiO 5-x N y H z The catalyst is brought into contact with a mixed gas of nitrogen and hydrogen to carry out an ammonia synthesis reaction. 5-x N y H z 0.1g was loaded into a SUS reaction tube, and a fixed bed flow-through reactor equipped therewith was used for the reaction. The water concentration of the nitrogen gas and the water concentration of the hydrogen gas of the raw material were respectively below the detection limit. Regarding the flow rate of the raw gas during the reaction, the nitrogen gas was 15mL / min and the hydrogen gas was 45mL / min (a total of 60mL / min). In addition, the reaction pressure during the reaction was 0.9MPa, the reaction temperature was 400°C, and the reaction time was 30 hours.

[0352] <Ammonia generation rate>

[0353] The gas from the fixed bed flow reactor was bubbled in a 0.005M sulfuric acid aqueous solution to dissolve the ammonia in the gas, and the generated ammonium ions were quantified by the above method using an ion chromatograph. The generation rate of ammonia generated by the ammonia synthesis reaction was measured over time using an ion chromatograph. The synthesis rate of ammonia at 400°C and 0.9MPa was 0.282mmol / g·hr as shown in Table 1. The results are shown in Table 1.

[0354] [Table 3]

[0355]

[0356] The following are the reaction conditions of Examples 6 and 9 in Table 3.

[0357] Catalyst amount: 0.1 g, reaction temperature: 300 °C, reaction gas flow rate: 60 mL / min,

[0358] Reaction gas composition: N2 / H2=1 / 3 (v / v), reaction pressure: 0.9 MPa.

[0359] The following are the reaction conditions of Examples 10 and 11 in Table 3.

[0360] Catalyst amount: 0.1 g, reaction temperature: 400 °C, reaction gas flow rate: 60 mL / min,

[0361] Reaction gas composition: N2 / H2=1 / 3 (v / v), reaction pressure: 0.9 MPa.

[0362] The effect of the ammonia synthesis catalyst of the present invention is as follows: unlike the conventional method of replacing the oxygen sites of the composite oxide with nitrogen or hydrogen after the composite oxide is synthesized, n B m O l By using a metal amide material of the A-site element of a type composite oxide and a transition metal oxide containing a B-site element as raw materials, oxynitrogen hydride can be synthesized in one step and at a low temperature.

[0363] In addition, in a catalyst in which transition metal nanoparticles such as Ru are fixed on a conventional oxide, dissociation of nitrogen molecules and hydrogen molecules occurs on the transition metal nanoparticles, and the reaction proceeds through the Langmuir-Hinshelwood reaction mechanism to generate ammonia, similarly to a conventional ammonia synthesis catalyst. However, in the catalyst of the present invention, ammonia synthesis proceeds through the Mars van krevelen mechanism in which nitrogen and hydrogen doped in the skeleton of the support material directly participate in the reaction, and high catalytic activity is shown even in a low temperature region. As a result, the activation energy of the catalyst of the present invention for ammonia synthesis is about half of that of conventional catalysts.

Claims

1. A catalyst for ammonia synthesis, comprising a metal support having a transition metal (M) supported on a support, characterized in that: The carrier is a composition comprising an oxynitrogen hydride represented by the following general formula (1): The transition metal (M) is at least one selected from the group consisting of Ru, Co and Fe, The oxynitrogen hydride is an oxynitrogen hydride having the same type of crystal structure as that of the composite oxide not doped with nitrogen and hydrogen while nitrogen and hydrogen are doped into oxygen sites of the composite oxide represented by the following general formula (5), A n B m O l-x N y H z (1) In the general formula (1), A is at least one selected from the group consisting of Ba and Sr, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; z represents a number represented by 0.1≤z≤2.0, (1) B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4; or (2) B is at least one selected from the group consisting of Si, Ge and Sn, n=3, m=1, and l=5, A n B m O l (5) In the general formula (5), n, m, and l have the same meanings as n, m, and l in the general formula (1).

2. The ammonia synthesis catalyst according to claim 1, wherein the oxynitrogen hydride is obtained by the following production method: in, The production method comprises the step of heating a compound represented by the following general formula (2) and a compound represented by the following general formula (3) under the following treatment conditions in an ammonia atmosphere, The treatment conditions are as follows: (i) the heating treatment condition is 400° C. or higher and lower than 900° C., (ii) the molar ratio of A to B (A:B) as the raw material addition ratio is 0.5×n:m to 1.5×n:m (mol / mol), A n B m O l-x N y H z (1) A(NH2)2(2) B k O j (3) In the general formulae (1) to (3), A is at least one selected from the group consisting of Ba and Sr, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.

0. (1) when B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4, k is 2, and j is 3; or (2) When B is at least one selected from the group consisting of Si, Ge, and Sn, n=3, m=1, and l=5, k is 1, and j is 2.

3. The catalyst for ammonia synthesis according to claim 1, wherein The amount of the transition metal (M) supported is 0.01 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the support.

4. A method for producing ammonia, characterized in that: Nitrogen and hydrogen are reacted in the presence of the catalyst for ammonia synthesis according to any one of claims 1 to 3.

5. A method for producing an oxynitrogen hydride, which is a method for producing an oxynitrogen hydride represented by the following general formula (1) contained in a composition as an ammonia synthesis catalyst, characterized in that: The method comprises the steps of heating a compound represented by the following general formula (2) and a compound represented by the following general formula (3) under the following treatment conditions in an ammonia atmosphere, The oxynitrogen hydride is an oxynitrogen hydride having the same type of crystal structure as that of the composite oxide not doped with nitrogen and hydrogen while nitrogen and hydrogen are doped into oxygen sites of the composite oxide represented by the following general formula (5), The treatment conditions are as follows: (i) the heating treatment condition is 400° C. or higher and lower than 900° C., (ii) the molar ratio of A to B (A:B) as the raw material addition ratio is 0.5×n:m to 1.5×n:m (mol / mol), A n B m O l-x N y H z (1) A(NH2)2(2) B k O j (3) In the general formulae (1) to (3), A is at least one selected from the group consisting of Ba and Sr, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.

0. (1) when B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4, k is 2, and j is 3; or (2) When B is at least one selected from the group consisting of Si, Ge and Sn, n=3, m=1, and l=5, k is 1, j is 2, A n B m O l (5) In the general formula (5), n, m, and l have the same meanings as n, m, and l in the general formula (1).

6. The method for producing oxynitrogen hydride according to claim 5, wherein: The heat treatment is performed at a temperature of 400° C. or higher and lower than 900° C. for 5 to 20 hours.

7. The method for producing oxynitrogen hydride according to claim 5, wherein: In the general formula (1), B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4, The treatment conditions are as follows: (i) the heating treatment condition is above 400° C. and below 900° C. for 5 to 20 hours, and (ii) the molar ratio of A to B (A:B) as the raw material addition ratio is 0.8:2.0 to 1.2:2.0 (mol / mol).

8. The method for producing oxynitrogen hydride according to claim 5, wherein: In the general formula (1), B is at least one selected from the group consisting of Si, Ge and Sn, n=3, m=1, and l=5, The treatment conditions are as follows: (i) the heating treatment condition is above 400° C. and below 700° C. for 2 to 6 hours, and (ii) the molar ratio of A to B (A:B) as the raw material addition ratio is 2.4:1 to 3.6:1 (mol / mol).

9. A method for producing an ammonia synthesis catalyst, which is a method for producing the ammonia synthesis catalyst according to claim 1, characterized in that: The method comprises the step of supporting at least one transition metal selected from the group consisting of Ru, Co and Fe on a carrier, wherein the carrier comprises a composition containing an oxynitrogen hydride obtained by the following method for producing an oxynitrogen hydride, The method for producing oxynitrogen hydride comprises the step of heating a compound represented by the following general formula (2) and a compound represented by the following general formula (3) under the following treatment conditions in an ammonia atmosphere. The treatment conditions are as follows: (i) the heating treatment condition is 400° C. or higher and lower than 900° C., (ii) the molar ratio of A to B (A:B) as the raw material addition ratio is 0.5×n:m to 1.5×n:m (mol / mol), A n B m O l-x N y H z (1) A(NH2)2(2) B k O j (3) In the general formulae (1) to (3), A is at least one selected from the group consisting of Ba and Sr, x represents a number represented by 0.1≤x≤3.5; y represents a number represented by 0.1≤y≤2.0; and z represents a number represented by 0.1≤z≤2.

0. (1) when B is at least one selected from the group consisting of Al, Ga and In, n=1, m=2, and l=4, k is 2, and j is 3; or (2) When B is at least one selected from the group consisting of Si, Ge, and Sn, n=3, m=1, and l=5, k is 1, and j is 2.

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