Catalyst for ammonia production, and method for producing ammonia using same

Abstract

A catalyst for ammonia production, which comprises a carrier and a nitrogen activation catalyst, the carrier comprising a metal organic structure, and the nitrogen activation catalyst being supported on the carrier. According to the present invention, a catalyst for ammonia production, which can be separated and recovered from a reaction raw material and a product and can be repeatedly reused, and a method for producing ammonia using the catalyst can be provided.

Description

Technical Field

[0001] The technology of the present application relates to a catalyst for producing ammonia and a method for producing ammonia using the catalyst. Background Art

[0002] Ammonia is an important chemical raw material used as a base material for fertilizers and chemical products. In recent years, its use as a co-firing agent in coal-fired power generation and as an energy carrier has also attracted much attention.

[0003] Conventionally, ammonia has been produced by the Haber-Bosch process, which involves reacting nitrogen and hydrogen in the presence of an iron-based catalyst.

[0004] Nishibayashi Hitoshi et al. at the University of Tokyo developed a complex catalyst with Mo as the central metal and discovered a method for producing ammonia at room temperature and pressure by using SmI2 as a reducing agent and H2O as a proton source (see the following route (1)). This is the first example of catalytic nitrogen fixation that exhibits extremely high activity compared to conventional catalytic nitrogen fixation reactions and uses readily and inexpensively available H2O as a direct proton source (see, for example, Patent Document 1, Patent Document 2, and Non-Patent Document 1).

[0005] [Chemistry 1] .

[0006] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Laid-Open No. 2013-159568 Patent Document 2: Japanese Patent Application Laid-Open No. 2010-195703 Non-patent literature Non-patent literature 1: Y. Ashida, K. Arashiba, K. Nakajima, and Y. Nishibayashi; Molybdenum-Catalysed Ammonia Production with Samarium Diiodide and Alcoholsor Water Nature, 2019, 568, 536-540, DOI: https: / / doi.org / 10.1038 / s41586-019-1134-2. Summary of the Invention

[0007] Problems to be solved by the invention The electrons used in ammonia production (e - ) is supplied by SmI2, protons (H +) is supplied by H2O. Generally, the OH bonds within H2O are very strong, making H2O unusable as a proton source for ammonia production. Conventional production methods coordinate H2O to SmI2, weakening the OH bonds within H2O and allowing ammonia production to proceed. The reaction equations are shown in (2) and (3) below.

[0008] (PCET reaction (proton conjugated electron transfer reaction)) SmI2+H2O→SmI2(H2O)→SmI2(OH)+H + +e - (2) (NH3 generation reaction) N2+6SmI2+6H2O→(PCET+Mocat)→2NH3+6SmI2(OH) (3) Mocat refers to molybdenum catalyst.

[0009] In the reaction shown in route (1), the catalyst is a homogeneous system dissolved in the solution. Therefore, a large amount of ammonia is generated per unit of catalyst, and the catalytic activity is high. In addition, there is a possibility that the SmI2(OH) generated in the reaction shown in route (2) can be reduced to the raw material SmI2 using an electrolysis device. On the other hand, it is difficult to separate and recover the catalyst from the reaction system for any reaction.

[0010] The technology of the present application is developed in view of the above situation. The technical problem of the present application is to provide a catalyst for ammonia production that can be separated and recovered from reaction raw materials and products and repeatedly reused, and a method for producing ammonia using the catalyst. The purpose of the present application is to solve the above-mentioned problems.

[0011] Solutions for solving problems <1> A catalyst for producing ammonia comprises a support and a nitrogen-activated catalyst, wherein the support comprises a metal-organic structure, and the nitrogen-activated catalyst is supported on the support.

[0012] <2> according to <1> The catalyst for ammonia production, wherein the average diameter of the window of the metal organic structure is 3×10 -10 m~50×10 -10 m.

[0013] <3> according to <1> or <2> The catalyst for ammonia production, wherein the average diameter of the cage of the metal organic structure is 8×10 -10 m~60×10 -10 m.

[0014] <4> according to <1> ~ <3> The catalyst for producing ammonia according to any one of the preceding claims, wherein the metal-organic structure contains zirconium, aluminum, or chromium as the metal.

[0015] <5> according to <4> The catalyst for producing ammonia, wherein the metal organic structure contains one or more atoms selected from the group consisting of zirconium, oxygen atoms, and hydrogen atoms.

[0016] <6> according to <4> or <5> The catalyst for ammonia production, wherein the metal organic structure is one or more selected from the group consisting of MOF-808, UiO-66, UiO-67, UiO-68, PCN-222, PCN-224, and UN-1000.

[0017] <7> according to <1> ~ <6> The catalyst for ammonia production according to any one of the preceding claims, wherein the content of the nitrogen activation catalyst is 0.1 to 60 parts by mass relative to 100 parts by mass of the support.

[0018] <8> according to <1> ~ <7> The catalyst for ammonia production according to any one of the preceding claims, wherein the nitrogen activation catalyst is a molybdenum complex.

[0019] <9> according to <8> The catalyst for ammonia production, wherein the nitrogen activation catalyst is a molybdenum complex having a PCP, PPP or PNP pincer ligand.

[0020] <10> A method for producing ammonia, wherein <1> ~ <9> Ammonia is synthesized in the presence of any one of the catalysts for ammonia production.

[0021] <11> according to <10> In the method for producing ammonia, after synthesizing ammonia, the support including the metal organic structure and the nitrogen activation catalyst are recovered together.

[0022] Effects of the Invention According to the technology of the present application, it is possible to provide a catalyst for producing ammonia that can be separated and recovered from reaction raw materials and products and repeatedly reused, and a method for producing ammonia using the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the UV-Vis absorption spectrum of the sample prepared in the example.

[0024] Figure 2 is the UV-Vis absorption spectrum of the sample prepared in the example. DETAILED DESCRIPTION

[0025] The upper and lower limits of the numerical ranges described in this specification may be arbitrarily combined. For example, when "A to B" and "C to D" are described as numerical ranges, the numerical ranges of "A to D" and "C to B" are also included in the scope of this application.

[0026] In addition, the numerical range "lower limit value to upper limit value" described in this specification means more than the lower limit value and less than the upper limit value unless otherwise specified.

[0027] <Catalysts for Ammonia Production> The catalyst for producing ammonia according to the present embodiment includes a support and a nitrogen-activated catalyst. The support includes a metal-organic structure, and the nitrogen-activated catalyst is supported on the support.

[0028] Since the nitrogen activation catalyst is adsorbed and supported on the carrier, the ammonia production catalyst according to this embodiment can be separated from the reaction raw materials and reaction products in the ammonia synthesis reaction and recovered from the reaction system, and can therefore be repeatedly reused.

[0029] Metal-organic structures have a higher surface area than conventional activated carbon and zeolites, resulting in higher immobilization capabilities through physical adsorption. Furthermore, the metal clusters and organic ligands that comprise the metal-organic structure can also interact with complexes to achieve chemical adsorption and immobilization. It is believed that metal-organic structures themselves do not have the ability to activate nitrogen and therefore do not contribute to the ammonia synthesis reaction, a fact that has been confirmed experimentally.

[0030] In the catalyst for ammonia production described in this embodiment, the substance having catalytic activity for ammonia production is a nitrogen-activated catalyst supported on a carrier. However, in this specification, "a form in which the nitrogen-activated catalyst is supported on a carrier" is referred to as "catalyst for ammonia production."

[0031] In the ammonia production catalyst described in this embodiment, "a catalyst that can be separated from the reaction raw materials and reaction products in the ammonia synthesis reaction and can be recovered from the reaction system" refers to the ammonia production catalyst described in this embodiment, not the nitrogen activation catalyst described in this embodiment.

[0032] [Carrier] The carrier described in this embodiment comprises a metal-organic framework (MOF). A MOF is a highly regular crystalline porous material formed from metal ions and organic ligands. Depending on the type of metal and ligand used, the pore size and properties of the porous surface can be designed at the molecular level. The MOF described in this embodiment has a portion called a window and spaces (also called cages or pores) within the MOF. The window is an opening through which substances such as complexes can enter and exit, and can be determined using the measurement method described below.

[0033] Specifically, examples of the metal organic structure include UiO-66, UiO-67, UiO-68, BUT-12, BUT-13, BUT-14, BUT-15, CAU-1, Cu-BTC, DUT-4(Al), DUT-5(Al), HKUST-1, MIL-53(Al), MIL-68(Ga), MIL-101(Cr), MIL-125, MOF-5, MOF-74(M), MOF-76(M), MOF-808, PCN-222, PCN-223, PCN-224, NU-1000, and ZIF-8.

[0034] Only one type of the metal organic structure may be used, or two or more types may be used.

[0035] The abbreviations shown in the above specific examples have the following meanings, respectively.

[0036] UiO-66: Zr6O4(OH)4(bdc)6 BDC: benzene-1,4-dicarboxylate UiO-67: Zr6O4(OH)4(bpdc)6 bpdc: biphenyl-4,4´-dicarboxylate UiO-68: Zr6O4(OH)4(tpdc)6 TPDC: [1,1':4',1''-terphenyl]-4,4''-dicarboxylate BUT-12: Zr6O4(OH)4(ctta) 8 / 3 (H2O)4(OH)4 ctta: 5'-(4-carboxyphenyl)-2',4',6'-trimethyl-[1,1':3',1''-quaterphenyl]-4,4''-dicarboxylate BUT-13: Zr6O4(OH)4(ttna) 8 / 3 (H2O)4(OH)4 ttna: 6,6',6''-(2,4,6-trimethylbenzene-1,3,5-triyl) tris(2-naphthalenecarboxylate) BUT-14: Zr6O4(OH)4(5',5'''-bis(4-carboxyphenyl)-[1,1':3',1'':4'',1''':3''',1''''-pentaphenyl]-4,4''''-dicarboxylate)2(H2O)4(OH)4 BUT-15: Zr6O4(OH)4(4,4',4'',4'''-(4,4'-(1,4-phenylene)bis(pyridin-6,4,2-triyl))triphenylate)2(H2O)4(OH)4 CAU-1:Al4(OH)2(OCH3)4(H2N-bdc)3 Cu-BTC: Cu3 (BTC)2 BTC: benzene-1,3,5-tricarboxylate DUT-4(Al):Al(OH)(ndc) NDC: 2,6-naphthalene dicarboxylate DUT-5(Al):Al(OH)(bpdc) HKUST-1:Cu3(btc)2(H2O) MIL-53(Al):Al(OH)(bdc) MIL-68(Ga):Ga(OH)(bdc) MIL-101(Cr):Cr3F(H2O)2O(bdc)3 MIL-125: Ti8O8(OH)4(bdc)6 MOF-5:Zn4(bdc)3 MOF-74(M)=M2(dobdc) M: Co, Zn or Mg dobdc: 2,5-diepoxy-benzene-1,4-dicarboxylate MOF-76(M):M(BTC) M: Yb, Y, Tb or Co MOF-808: Zr6O4(OH)4(btc)2(H2O)6(OH)6 PCN-222: Zr6O4(OH)4(tcpp)2(H2O)4(OH)4 tcpp: meso-tetrakis(4-carboxylatephenyl)porphyrin PCN-223: Zr6O4(OH)4(tcpp)3 PCN-224: Zr6O4(OH)4(tcpp) 3 / 2 (H2O)6(OH)6 NU-1000: Zr6O4(OH)4(tbapy)2(H2O)6(OH)6 tbapy: 1,3,6,8-tetrakis(p-phenylenediato)pyrene ZIF-8: Zn(min)2 min: 2-methylimidazolium ester.

[0037] The metal organic structure preferably contains zirconium, aluminum, or chromium as the metal, and more preferably contains one or more selected from zirconium, an oxygen atom, and a hydrogen atom.

[0038] From this viewpoint, the metal organic structure is preferably one or more selected from the group consisting of MOF-808, UiO-66, UiO-67, UiO-68, PCN-222, PCN-224, and UN-1000.

[0039] Furthermore, from the viewpoint of window size, the metal organic structure is preferably UiO-66, UiO-67, UiO-68, MOF-808, and PCN-222, and more preferably MOF-808.

[0040] The sizes of the windows and cages of the metal-organic structure according to this embodiment vary depending on the structure, but the metal-organic structure preferably has the following structure.

[0041] The average diameter of the windows of the metal organic structure is preferably 3×10 -10 m~50×10 -10 m, more preferably 5×10 -10 m~45×10 -10 m, more preferably 6×10 -10 m~40×10 -10 m, more preferably 6×10 -10 m~15×10 -10 m.

[0042] In addition, the average diameter of the cage of the metal organic structure is preferably 8×10 -10 m~60×10 -10 m, more preferably 8×10 -10 m~50×10 -10 m, more preferably 8×10 -10 m~40×10 -10 m.

[0043] The average diameter of the windows and cages of the metal-organic structure described in this embodiment is based on known literature values ​​and can be estimated or measured by cage diameter distribution calculation using NLDFT (Non-Local Density Functional Theory) or single crystal X-ray structure analysis.

[0044] For example, respectively, For UiO:66, UiO:67, and UiO:68, see Cavka, JH; Jakobsen, S.; Olsbye, U.; Guillou, N.; Lamberti, C.; Bordiga, S.; Lillerud, KPJ Am. Chem. Soc. 2008, 130, 13850-13851. For MOF-808, please refer to Furukawa, H.; Gandara, F.; Zhang, Y.-B.; Jiang, J.; Queen, WL; Hudson, MR; Yaghi, OMJ Am. Chem. Soc. 2014, 136, 4369-4381. For PCN-222, please refer to Feng, D.; Gu, Z.-Y.; Li, J.-R.; Jiang, H.-L.; Wei, Z.; Zhou, H.-C. Angew. Chem. Int. Ed. 2012, 51, 10307-10310.

[0045] [Nitrogen activation catalyst] The nitrogen activation catalyst according to the present embodiment is not particularly limited, and a conventional homogeneous catalyst that cannot be separated from the reaction raw materials and reaction products and cannot be recovered from the reaction system can be used.

[0046] For example, a complex represented by the following formula (Q) can be used.

[0047] [Chemistry 2] In the above formula (Q), Y represents a neutral or anionic donor atom. M represents a metal element, which means that n ligands L are present corresponding to the valence of the metal. Y represents one or more atomic groups selected from carbon atoms, nitrogen atoms, and phosphorus atoms. Ligand L represents a halogen atom (e.g., an iodine atom, a bromine atom, a chlorine atom), a nitrogen atom, or an oxygen atom. R 1 ~R 4 Each independently represents an alkyl group.

[0048] Examples of the atomic group represented by Y include groups obtained by removing three hydrogen atoms from a heterocyclic compound such as benzimidazolidine.

[0049] R 1 ~R 4 They can be different or the same.

[0050] The nitrogen activation catalyst according to this embodiment is preferably a molybdenum complex, and the metal element M in formula (Q) is preferably molybdenum (Mo).

[0051] Specifically, examples of the complex represented by formula (Q) include the following compounds.

[0052] [Chemistry 3] [Chemistry 4] The atomic group represented by Y is not particularly limited as long as it is a group obtained by removing three hydrogen atoms from a heterocyclic compound. In the above specific examples, the benzene ring has no substituent, but a substituent may be introduced into the benzene ring, or a heterocyclic ring containing a heteroatom may be present instead of the benzene ring.

[0053] The nitrogen activation catalyst is preferably a molybdenum complex having a PCP, PPP, or PNP pincer ligand, and specific examples thereof include the following compounds.

[0054] (A) a molybdenum complex having 2,6-bis(dialkylphosphinomethyl)pyridine as a PNP ligand (wherein the two alkyl groups may be the same or different, and at least one hydrogen atom in the pyridine ring may be optionally substituted with an alkyl group, an alkoxy group, or a halogen atom); (B) a molybdenum complex having an N,N-bis(dialkylphosphinomethyl)dihydrobenzimidazolidine as a PCP ligand (wherein the two alkyl groups may be the same or different, and at least one hydrogen atom in the benzene ring may be optionally substituted with an alkyl group, an alkoxy group, or a halogen atom); (C) A molybdenum complex having a bis(dialkylphosphinoethyl)arylphosphine as a PPP ligand (wherein the two alkyl groups may be the same or different) Examples of the molybdenum complex (A) include molybdenum complexes represented by formula (A1), (A2), or (A3).

[0055] [Chemistry 5] In formulas (A1), (A2) and (A3), R 1 and R 2 are alkyl groups which may be the same or different. X is an iodine atom, a bromine atom or a chlorine atom. At least one hydrogen atom on the pyridine ring may be substituted with an alkyl group, an alkoxy group or a halogen atom.

[0056] In the molybdenum complex (A), examples of the alkyl group include C1 to C 10The alkyl group preferably has 1 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, and even more preferably isopropyl, tert-butyl, or cyclohexyl. In the platinum complex (A), examples of the alkoxy group include C1-C8 alkoxy and benzyloxy groups, preferably having 1 to 8 carbon atoms. When the alkoxy group is a benzyloxy group, at least one hydrogen atom on the benzyl ring of the benzyloxy group may be substituted with a resin. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms.

[0057] As R 1 and R 2 , preferably a bulky alkyl group such as tert-butyl, isopropyl or cyclohexyl. The hydrogen atoms on the pyridine ring are preferably unsubstituted, or the hydrogen atom at position 4 is replaced by a C1~C 10 Alkyl, C1-C8 alkoxy, or benzyloxy substitution. More preferred alkoxy groups include benzyloxy groups in which at least one hydrogen atom on the benzene ring is substituted with a resin. Examples of such resins include chloromethyl resins (e.g., polymer-bound 5-[4-(chloromethyl)phenyl]pentyl]styrene, polymer-bound 4-(benzyloxy)benzyl chloride, and polymer-bound 4-methoxydiphenylmethane chloride), (chloromethyl)polystyrene, Merrifield resin, and JandaJel-Cl (trademark). Among these, (chloromethyl)polystyrene, Merrifield resin, and JandaJel-Cl (trademark) are preferred.

[0058] Examples of the molybdenum complex (B) include molybdenum complexes represented by the following formula (B1) or (B2).

[0059] [Chemistry 6] In formulas (B1) and (B2), R 1 and R 2 are alkyl groups which may be the same or different. X is an iodine atom, a bromine atom or a chlorine atom. At least one hydrogen atom on the benzene ring may be substituted with an alkyl group, an alkoxy group or a halogen atom. 3 and R 4 At least one of them is substituted with a trifluoromethyl group.

[0060] As C1~C 10 The alkyl group, C1 to C8 alkoxy group and halogen atom may be the same as those already exemplified. 1 and R 2 , preferably tert-butyl, isopropyl or cyclohexyl as a bulky alkyl group.

[0061] (B2) Molybdenum complex R 3 and R 4 Each independently represents an electron-withdrawing group, R 3 and R4 It can be an electron-withdrawing group. 3 When R is an electron-withdrawing group, 4 It may be a hydrogen atom. Electron-withdrawing groups, also known as electron-attracting groups or electron-accepting groups, refer to substituents that attract electrons from the bound electron side compared to hydrogen atoms, based on theories that attempt to unify the changes in the electron density and binding state of a substance, namely, the mediating effect and the induced effect in electronic theory.

[0062] Examples of electron-withdrawing groups include: substituents whose mesotropic effect is electron-donating but whose inductive effect contributes significantly to the electron-withdrawing property; and substituents whose mesotropic effect and inductive effect are electron-withdrawing. Examples of substituents whose mesotropic effect is electron-donating but whose inductive effect contributes significantly to the electron-withdrawing property include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, -CH2Cl, or -CH=CHNO2. Examples of substituents whose mesotropic effect and inductive effect are electron-withdrawing properties include quaternary ammonium groups with anions as counterions, trifluoromethyl groups, perfluoroalkyl groups, trichloromethyl groups, cyano groups, nitro groups, formyl groups, carboxylic acid groups, sulfonic acid groups, and sulfonylamino groups. Examples of quaternary ammonium groups include trialkylammonium groups, such as trimethylammonium groups, triethylammonium groups, and tributylammonium groups. Examples of the counter ion for the nitrogen atom constituting the quaternary ammonium group include hexafluorophosphate ion, hexachloroantimonate ion, trifluoromethanesulfonate ion, tetrafluoroborate ion, phosphate ion, sulfate ion, chloride, bromide, iodide, and hydroxide.

[0063] R 3 and R 4 Preferred are a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and a trifluoromethyl group, and more preferred are a chlorine atom and a trifluoromethyl group.

[0064] Examples of the molybdenum complex (C) include a molybdenum complex represented by formula (C1).

[0065] [Chemistry 7] In formula (C1), R 1 and R 2 C1~C 10 Alkyl. R 5 is an Ar6 aryl group. X is an iodine atom, a bromine atom or a chlorine atom.

[0066] As C1~C 10 The alkyl group includes the same groups as those already exemplified. 10 The alkyl group and Ar6 aryl group may be the same groups as those already exemplified. 1 and R 2, preferably tert-butyl, isopropyl or cyclohexyl as a bulky alkyl group. 5 , preferably phenyl.

[0067] In formulas (A1), (A2) and (A3), formulas (B1) and (B2), and formula (C1), C a ~C b The expression of alkyl means a monovalent group formed by losing one hydrogen from a linear, branched or cyclic aliphatic hydrocarbon having a to b carbon atoms. Specific examples include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethylpropyl, cyclopentyl, n-hexyl, isohexyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, cyclohexyl, n-heptyl, 2-methylhexyl, 3-ethylpentyl, n-octyl, 2,2,4-trimethylpentyl, 2,5-dimethylhexyl, n-nonyl, 2,7-dimethyloctyl, and n-decyl. The number of carbon atoms is set within the range specified in each. In the "C" indicating the number of carbon atoms, a ~C b ”, a is an integer greater than 1, and b is an integer greater than a.

[0068] In formulae (A1), (A2), and (A3), formulae (B1), (B2), and (C1), C a ~C b The term "alkoxy" refers to a monovalent group in which an alkyl group having the above-mentioned meaning and having a carbon number of a to b is bonded to oxygen. Specific examples include methoxy, ethoxy, n-propoxy, isopropoxy, cyclopropyloxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclobutyloxy, n-pentyloxy, isopentyloxy, neopentyloxy, tert-pentyloxy, 1,1-dimethylpropoxy, cyclopentyloxy, n-hexyloxy, isohexyloxy, 3-methylpentyloxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, cyclohexyloxy, n-heptyloxy, 2-methylhexyloxy, 3-ethylpentyloxy, n-octyloxy, 2,2,4-trimethylpentyloxy, and 2,5-dimethylhexyloxy. The number of carbon atoms in each group is set within the range specified.

[0069] In formulae (A1), (A2), (A3), (B1), (B2), and (C1), specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0070] In formula (C1), the term "Ar6 aryl" refers to a monovalent group formed by the loss of one hydrogen atom from the aromatic ring of an aromatic hydrocarbon having 6 carbon atoms, and examples thereof include a phenyl group and a phenyl group having a substituent at at least one of the 2nd to 6th positions. Examples of substituents on the aromatic ring of the Ar6 aryl group include halogen atoms such as fluoro, chloro, bromo, and iodo; as well as methyl, trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl. Specific examples of the Ar6 aryl group include phenyl, o-fluorophenyl, m-fluorophenyl, p-fluorophenyl, o-trifluoromethylphenyl, m-trifluoromethylphenyl, p-trifluoromethylphenyl, o-chlorophenyl, m-chlorophenyl, p-chlorophenyl, o-bromophenyl, m-bromophenyl, p-bromophenyl, o-tolyl, m-tolyl, p-tolyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, o-(tert-butyl)phenyl, m-(tert-butyl)phenyl, p-(tert-butyl)phenyl, 3,5-dimethylphenyl, 3,5-bistrifluoromethylphenyl, 3,4,5-trifluorophenyl, o-methoxyphenyl, m-methoxyphenyl, p-methoxyphenyl, and the like.

[0071] The nitrogen activation catalyst according to this embodiment can use an organic metal complex that can cleave a nitrogen triple bond.

[0072] The organometallic complex capable of cleaving a nitrogen triple bond is preferably an organometallic complex capable of cleaving a nitrogen triple bond and soluble in an organic solvent.

[0073] Here, the term "soluble in an organic solvent" means, for example, that the nitrogen-activated catalyst is mixed in an organic solvent in an amount to give a concentration of 0.1 mmol / L and dissolution thereof can be visually confirmed.

[0074] Examples of the central metal of the metal complex that activates nitrogen include Ti, V, Mo, Fe, Mn, Co, Pt, Ir, and W, with Mo being preferred.

[0075] Ligands of the metal complex that activate nitrogen include, for example, halide ions and tertiary phosphines. Preferably, it is a combination of a clamp ligand (i.e., a ligand having three coordinating atoms bonded from three directions on the same plane containing the central metal) and a halide ion. More preferably, it is a combination of a PCP (phosphorus-carbon-phosphorus) type clamp ligand or a PNP (phosphorus-nitrogen-phosphorus) type clamp ligand and a halide ion. Still more preferably, it is a combination of a PCP type clamp ligand and a halide ion.

[0076] As the metal complex that activates nitrogen, a complex that corresponds to the solubility in an organic solvent and the reactivity with a reducing agent can be suitably used.

[0077] As metal complexes that activate nitrogen, among these, molybdenum complexes whose central metal is Mo are preferred, more preferred are molybdenum complexes having a clamp ligand and a halide ion as ligands, further preferred are molybdenum complexes having a PCP-type clamp ligand or a PNP-type clamp ligand and a halide ion as ligands, and further preferred are molybdenum complexes having a PCP-type clamp ligand and a halide ion as ligands.

[0078] Examples of platinum complexes having a PNP-type clamp ligand and a halide ion as a ligand include those represented by the following formulas (D1), (D5), or (D6). Examples of platinum complexes having a PCP-type clamp ligand and a halide ion as a ligand include those represented by the following formulas (D2) or (D3). Other examples of platinum complexes include those represented by the following formula (D4).

[0079] [Chemistry 8] In the above formula (D1), R 1 ~R 4 Each independently represents hydrogen, or a chain, cyclic or branched hydrocarbon group having 1 to 14 carbon atoms, R 5 is hydrogen or a group in which a hydrogen on a ring is substituted, and represents a chain, cyclic or branched hydrocarbon group having 1 to 14 carbon atoms; and X each independently represents a halide ion selected from fluorine, chlorine, bromine and iodine.

[0080] Here, R 1 With R 2 , and / or R 3 With R 4 Optionally bonded to each other to form a ring, PR 1 R 2 With PR 3 R 4 Can be the same or different, R 1 ~R 4 They may all be the same, or at least partly be different.

[0081] R 1 ~R 5 The "chain, cyclic or branched hydrocarbon group having 1 to 14 carbon atoms" in the formula (a) can be selected from, for example, alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, alkynyl groups having 2 to 6 carbon atoms, cycloalkyl groups having 3 to 6 carbon atoms, cycloalkenyl groups having 3 to 6 carbon atoms, cycloalkynyl groups having 3 to 6 carbon atoms, and aryl groups having 6 to 14 carbon atoms. 1 ~R 4 , preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. 1 ~R4 , preferably butyl, more preferably tert-butyl.

[0082] In addition, R 5 When there are 2 or 3 of these R 5 They are optionally bonded to each other to form a ring. 5 When there are two or three, they may all be the same or at least some may be different.

[0083] X is preferably bromine, chlorine or iodine, more preferably chlorine or iodine.

[0084] Here, X3 in the formula means that three Xs are bonded to Mo.

[0085] [Chemistry 9] In the above formula (D2), R 1 ~R 5 and X are the same as those in the above formula (D1).

[0086] [Chemistry 10] In the above formula (D3), R 1 ~R 5 and X are the same as those in the above formula (D1).

[0087] [Chemistry 11] In the above formula (D4), R 1 ~R 3 Same as the above formula (D1).

[0088] [Chemistry 12] In the above formula (D5), R 1 ~R 5 and X are the same as those in the above formula (D1).

[0089] [Chemistry 13] In the above formula (D6), R 1 ~R 5 and X are the same as those in the above formula (D1).

[0090] The nitrogen activation catalyst according to this embodiment can use a nitrogen activation catalyst having a structure represented by any one of the following formulas (I-1) to (I-4).

[0091] [Chemistry 14] In formula (I-1) ~ (I-4), R 1 ~R 4 Each independently represents an alkyl group having 1 to 10 carbon atoms.

[0092] R 5 It represents a phenyl group or a naphthyl group which may have one or more substituents selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a halogen atom, and a perfluoromethyl group (-CF3).

[0093] n1 and n2 each independently represent an integer of 1 to 3.

[0094] m1 means 1 or 2.

[0095] m2 represents an integer from 1 to 4.

[0096] m3 and m4 represent integers from 1 to 6.

[0097] Z represents a structure represented by the following formula (i) or (ii).

[0098] [Chemistry 15] In formulas (i) and (ii), X represents a halogen atom. The wavy line represents a bond to an adjacent atom.

[0099] The nitrogen activation catalyst having the structure shown in formula (I-1) to (I-4) is an organic metal complex having molybdenum (Mo) as the central metal and a PCP-type pincer ligand.

[0100] The nitrogen activation catalyst has an activity capable of cleaving the triple bond of the nitrogen molecule.

[0101] In the PCP-type clamp ligand, three elements, namely, two phosphorus atoms located in the same plane and a carbon atom forming a carbene, are coordinated to molybdenum.

[0102] When Z represents the structure represented by the above formula (i), three halogen atoms form Sigma bonds with Mo. In this case, a trivalent Mo complex is obtained.

[0103] When Z represents the structure represented by the above formula (ii), one halogen atom forms a sigma bond with Mo, and one nitrogen atom forms a triple bond with Mo. In this case, a tetravalent Mo complex is obtained.

[0104] In formula (I-1) ~ (I-4), R 1 ~R 4Each independently represents an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group may be linear or branched. Specific examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-hexyl, hexyl (tert-hexyl, 2,3-dimethylbutan-2-yl), and the like. 1 ~R 4 It is preferably a branched alkyl group with large steric hindrance, more preferably a tert-butyl group or a hexyl group. 1 ~R 4 are tert-butyl or R 1 ~R 4 All are hexyl.

[0105] The imidazole skeleton in formula (I-1) is bonded with m1 R 5 . m1 is 1 or 2.

[0106] The benzene skeleton in formula (I-2) is bonded with m2 R 5 . m2 is an integer from 1 to 4.

[0107] The naphthalene skeletons in formula (I-3) and formula (I-4) are bonded with m3 and m4 R 5 . m3 and m4 are integers ranging from 1 to 6 respectively.

[0108] R 5 The position of bonding to the benzene skeleton in (I-2) and the naphthalene skeleton in the above-mentioned formula (I-3) and formula (I-4) is not limited.

[0109] In formula (I-1) ~ (I-4), R 5 It is a phenyl group or a naphthyl group which may have one or more substituents selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a halogen atom, and a perfluoromethyl group (-CF3).

[0110] The alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. The alkoxy group having 1 to 6 carbon atoms is an alkyl group having 1 to 6 carbon atoms, preferably an alkoxy group having 1 to 3 carbon atoms, more preferably a methoxy group or an ethoxy group.

[0111] The halogen atom is a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br) or an iodine atom (I).

[0112] R 5 In the case of a phenyl group having a substituent, the number of substituents is 1 to 5, preferably 1 to 3, and more preferably 1 or 2. The position of the substituent is not limited.

[0113] R 5When it is a naphthyl group which may have one or more substituents, the naphthyl group may be either 1-naphthyl or 2-naphthyl. 5 In the case of a naphthyl group having a substituent, the number of substituents is 1 to 7, preferably 1 to 4, and more preferably 1 or 2. The position of the substituent is not limited.

[0114] There are multiple R 5 When each R 5 Can be the same or different.

[0115] As R 5 Specific examples of include those represented by the following chemical formulas.

[0116] [Chemistry 16] In the formula, Y represents a substituent selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a halogen atom, and a perfluoromethyl group (-CF3). Multiple Y groups may be the same or different.

[0117] p1 represents an integer from 1 to 5.

[0118] p2 represents an integer from 1 to 7.

[0119] Wavy lines represent bonds to adjacent atoms.

[0120] R 5 When it is a phenyl group having a substituent, R 5 It preferably has the following structure.

[0121] [Chemistry 17] Wherein, Y is the same as above. The wavy lines represent bonds to adjacent atoms.

[0122] The content of the nitrogen activation catalyst in the ammonia production catalyst according to this embodiment is preferably 0.1 to 60 parts by mass, more preferably 0.5 to 40 parts by mass, and even more preferably 1 to 20 parts by mass per 100 parts by mass of the support including the metal organic structure.

[0123] <Method for producing ammonia production catalyst> The method for producing the catalyst for ammonia production according to the present embodiment is not particularly limited as long as it is a method capable of supporting the nitrogen activation catalyst on a support composed of a metal organic structure.

[0124] For example, there is a method of mixing a nitrogen-activated catalyst and a support composed of a metal organic structure in the presence of an organic solvent.

[0125] According to this method, the nitrogen activation catalyst is adsorbed on the support composed of the metal organic structure, thereby producing a catalyst for ammonia production in which the nitrogen activation catalyst is supported on the support.

[0126] The amounts of the nitrogen activation catalyst and the support composed of the metal organic structure blended are the same as the amounts within the ranges described as the content of the nitrogen activation catalyst in the catalyst for ammonia production according to the present embodiment.

[0127] The organic solvent may be a solvent inactive to both the nitrogen-activated catalyst and the support containing the metal organic structure, and examples thereof include tetrahydrofuran (THF), dimethoxyethane, 1,4-dioxane, acetonitrile, and toluene. Among them, the organic solvent preferably contains tetrahydrofuran.

[0128] The method for producing the ammonia production catalyst according to this embodiment preferably includes the steps of dissolving the nitrogen-activated catalyst in an organic solvent to obtain a solution, and then further mixing the carrier with the solution to obtain a suspension. The suspension is filtered, the residue is recovered, and the residue is vacuum-dried to generally obtain the ammonia production catalyst according to this embodiment in powder form.

[0129] Support of the nitrogen-activating catalyst on the support can be confirmed by UV-Vis (ultraviolet-visible) absorption measurement. For example, when the UV-Vis absorption spectrum of the nitrogen-activating catalyst is compared with the UV-Vis absorption spectrum of the solution obtained by the method for producing the ammonia production catalyst described in this embodiment, the peak intensity is weakened, indicating that the nitrogen-activating catalyst is supported on the support.

[0130] In UV-Vis (ultraviolet-visible) absorption measurement, light is transmitted through a solution to measure the wavelengths absorbed by the substance (transmission method). For solid samples that cannot transmit light, light is reflected and the absorption band is identified from the reflected light (reflection method). The nitrogen-activated catalyst described in this embodiment does not decompose in solution. Therefore, a decrease in absorption by the nitrogen-activated catalyst in solution indicates that the nitrogen-activated catalyst is supported on a carrier.

[0131] <Method for producing ammonia> The method for producing ammonia according to the present embodiment is a method for producing ammonia in which ammonia is synthesized in the presence of the catalyst for producing ammonia according to the present embodiment.

[0132] When ammonia (NH3) is synthesized using a molybdenum complex (Mocat) as a nitrogen activation catalyst, samarium iodide (SmI2) as a reducing agent, and water (H2O) as a proton source, ammonia is obtained through the following reactions (2) and (3).

[0133] (PCET reaction (proton conjugated electron transfer reaction)) SmI2+H2O→SmI2(H2O)→SmI2(OH)+H + +e - (2) (NH3 generation reaction) N2+6SmI2+6H2O→(PCET+Mocat)→2NH3+6SmI2(OH) (3) In the ammonia production method according to this embodiment, a molybdenum complex (Mocat) serving as a nitrogen activation catalyst is supported on a support comprising a metal-organic structure. Therefore, after the ammonia synthesis reaction is completed, the ammonia production catalyst according to this embodiment can be recovered by filtering the reaction liquid. In other words, after ammonia synthesis, the support comprising a metal-organic structure and the nitrogen activation catalyst can be recovered together.

[0134] Furthermore, the recovered ammonia production catalyst according to the present embodiment can be reused in the ammonia synthesis reaction. Therefore, the ammonia production catalyst according to the present embodiment can be repeatedly reused until the nitrogen activation catalyst or the ammonia production catalyst deteriorates. Example

[0135] Next, the technology of the present application will be specifically described using examples, but the technology of the present application is not limited to these examples at all.

[0136] <Raw Materials for Ammonia Production Catalysts> (Nitrogen-activated catalyst) As the nitrogen activation catalyst 1, MoI 3 (PCP) (structure shown below) was used.

[0137] [Chemistry 18] .

[0138] [Synthesis of Nitrogen-Activated Catalyst 1] To 1,3-bis((di-tert-butylphosphino)methyl)-1H-benzo[d]imidazolium-3-yl hexafluorophosphate (117 mg, 0.200 mmol) and potassium hexamethyldisilazane (55.0 mg, 0.276 mmol) was added 15 mL of toluene. After stirring at room temperature for 2 hours, the mixture was filtered through Celite, and the resulting filtrate was distilled off under reduced pressure. To the residue, [MoI3(thf)3] (107 mg, 0.154 mmol) and 20 mL of THF were added, and the mixture was stirred at 50°C for 19 hours. The reaction solution was then filtered through Celite. The filtrate was washed with THF. The filtrate from the Celite filtration and the washing solution were combined, and the solvent was distilled off under reduced pressure. The residue was washed with diethyl ether to obtain the target compound.

[0139] As the nitrogen activation catalyst 2, Mo(N)I(PCP) (structure shown below) was used.

[0140] [Chemistry 19] .

[0141] [Synthesis of Nitrogen-Activated Catalyst 2] Under a nitrogen atmosphere, 20 mL of toluene cooled to -78°C was added to a mixture of [MoI3(PCP)] (347 mg, 0.398 mmol) and KC8 (120 mg, 0.888 mmol). The mixture was stirred at -78°C for 5 minutes, then warmed to room temperature and stirred at room temperature for 18 hours. Volatile components were removed under vacuum, and the residue was washed three times with 5 mL of diethyl ether. 15 mL of THF was added to the residue, and the mixture was filtered through Celite, and the filtrate was washed three times with 5 mL of THF. The filtrate from the Celite filtration and the washing solution were combined and concentrated to approximately 20 mL. When 50 mL of hexane was slowly added to the concentrated solution, brown crystals precipitated. The precipitate was collected by filtration, washed three times with 4 mL of diethyl ether, and dried under reduced pressure to obtain the desired product (96.8 mg, 0.153 mmol).

[0142] (Carrier containing metal organic structure) The following supports 1 to 5 were used as supports containing a metal organic structure.

[0143] [Carrier 1: MOF-808] ZrCl4 (233 mg, 1.0 mmol), 1,3,5-benzenetricarboxylic acid (H3BTC, 70.6 mg, 0.236 mmol), formic acid (5.6 mL, 98 mmol), and N,N'-dimethylformamide (DMF, 10 mL) were placed in a screw-capped vial, dissolved using ultrasound, and heated at 135°C for 24 hours. After cooling to 30°C, the white precipitate was filtered and then extracted with methanol using a Soxhlet extractor overnight. The resulting precipitate was dried at 80°C overnight to obtain MOF-808FA. MOF-808 (500 mg) was placed in a screw-capped vial, 110 mL of DMF (N,N-dimethylformamide) and 10 mL of concentrated hydrochloric acid were added, and the suspension was incubated at 80°C for 24 hours. After naturally cooling to 30°C, a white precipitate was collected by suction filtration and extracted with methanol overnight using a Soxhlet extractor. The obtained precipitate was dried at 80°C overnight to obtain MOF-808.

[0144] [Carrier 2: UiO-66] ZrCl₄ (0.053 g, 0.227 mmol) and 1,4-benzenedicarboxylic acid (H₂BDC) (0.034 g, 0.227 mmol) were dissolved in N,N'-dimethylformamide (DMF) (24.9 g, 340 mmol) and stirred at room temperature. The reaction solution was sealed and placed in an oven preheated to 120°C for 24 hours. After cooling to room temperature in air, the resulting solid was filtered, repeatedly washed with DMF, and dried at room temperature to yield UiO-66.

[0145] [Carrier 3: UiO-67] ZrCl₄ (0.053 g, 0.227 mmol) and 1,4-benzenedicarboxylic acid (H₂BDC) (0.034 g, 0.227 mmol) were dissolved in N,N'-dimethylformamide (DMF) (24.9 g, 340 mmol) and stirred at room temperature. The reaction solution was sealed and placed in an oven preheated to 120°C, where it was allowed to stand for 24 hours. After cooling to room temperature in air, the resulting solid was filtered, repeatedly washed with DMF, and dried at room temperature to yield UiO-67.

[0146] [Carrier 4: UiO-68] UiO-68 was obtained according to the following reference.

[0147] References: Schaate, A.; Roy, P.; Godt, A.; Lippke, J.; Waltz, F.; Wiebcke, M.; Behrens, P. Chem. Eur. J. 2011, 17, 6643-6651. [Carrier 5: PCN-222] First, ZrOCl2·8H2O (200 mg), benzoic acid (3.0 g), and DMF (20 mL) were placed in a 30 mL vial and ultrasonically treated for 30 minutes. Separately, tetrakis(4-carboxyphenyl)porphyrin (TCPP) (100 mg) was dissolved in DMF (20 mL). The two solutions were then incubated at 100°C for 60 minutes. Then, 1 mL of the ultrasonically treated solution, 1 mL of TCPP in DMF, and 0.05 mL of trifluoroacetic acid (6 mL) were added, and the mixture was divided among several vials. Each vial was sealed and heated in an oil bath at 120°C for 48 hours. The supernatant of the reaction mixture was removed, and the MOF sample was washed with DMF. Next, it was immersed in 40 mL of DMF and 1.5 mL of 8M HCl. The sample was then heated at 120°C. After cooling to room temperature, the solid was washed with DMF and acetone. Next, the sample was immersed in acetone for 12 hours and dried under reduced pressure at 90° C. for 3 hours. The sample was heated at 120° C. to obtain activated PCN-222.

[0148] <Manufacturing of Catalyst for Ammonia Production> [Production Example 1] To a 100 mL eggplant-shaped flask, 8 μmol of nitrogen-activated catalyst 1 (MoI3(PCP)) and 40 mL of an organic solvent (tetrahydrofuran, THF) were added to obtain a MoI3(PCP) solution. 69.9 mg of support 1 (MOF-808) was further added to the MoI3(PCP) solution and stirred for 5 hours to obtain a suspension. The resulting suspension was filtered, and the residue was recovered and vacuum-dried to yield catalyst 1 for ammonia production as a light green solid (82.0 mg).

[0149] [Production Example 2] In the production of the ammonia production catalyst 1, the same operation was carried out except that 26.6 mg of the carrier 2 (UiO-66) was used instead of 69.9 mg of the carrier 1 (MOF-808), to obtain the ammonia production catalyst 2.

[0150] [Production Example 3] In the production of the ammonia production catalyst 1, the same operation was carried out except that 33.9 mg of the carrier 3 (UiO-67) was used instead of 69.9 mg of the carrier 1 (MOF-808), to obtain the ammonia production catalyst 3.

[0151] [Production Example 4] In the production of the ammonia production catalyst 1, the same operation was carried out except that 41.2 mg of the carrier 4 (UiO-68) was used instead of 69.9 mg of the carrier 1 (MOF-808), to obtain the ammonia production catalyst 4.

[0152] [Production Example 5] In the production of the ammonia production catalyst 1, the same operation was carried out except that 108 mg of the carrier 5 (PCN-222) was used instead of 69.9 mg of the carrier 1 (MOF-808), to obtain the ammonia production catalyst 5.

[0153] [Production Example 6] To a 100 mL eggplant-shaped flask, 4 μmol of nitrogen-activated catalyst 2 (Mo(N)I(PCP)) and 20 mL of an organic solvent (tetrahydrofuran, THF) were added to obtain a Mo(N)I(PCP) solution. 35.0 mg of support 1 (MOF-808) was further added to the Mo(N)I(PCP) solution, and the mixture was stirred for 5 hours to obtain a suspension. The resulting suspension was filtered, and the residue was recovered and vacuum-dried to obtain ammonia production catalyst 6 as a yellow solid (30.2 mg).

[0154] <Confirmation of load> UV-Vis absorption spectra of the following samples 1 to 4 were measured under the following conditions.

[0155] Device: Made by Shimadzu Co., Ltd., trade name "UV-1850" Optical path length: 10mm 1) Sample 1: MoI3(PCP) solution (initial concentration: 0.2 mmol / L) prepared in the production of ammonia production catalyst 1. This solution was obtained immediately after MoI3(PCP) was dissolved in THF (0 h). 2) Sample 2: MoI3(PCP) solution (initial concentration 0.2 mmol / L) prepared in the production of ammonia production catalyst 1. This solution was obtained after dissolving MoI3(PCP) in THF for 5 hours (5 h). 3) Sample 3: THF-diluted filtrate obtained by filtering the suspension prepared in the production of the ammonia production catalyst 1 4) Sample 4: THF-diluted filtrate obtained by filtering the suspension prepared in the production of ammonia production catalyst 4 In addition, in samples 3 and 4, a dilution solution prepared by adjusting the volume of 40 mL of the filtrate to 50 mL with THF was used.

[0156] The results are shown in Figure 1 and Figure 2 .

[0157] Figure 1 The UV-Vis absorption spectra of samples 1 to 3 are shown in FIG. Figure 2 The UV-Vis absorption spectra of samples 1, 3 and 4 are shown in FIG. Figure 1 and Figure 2The vertical axis represents relative intensity, and the horizontal axis represents wavelength.

[0158] In addition, Figure 1 and Figure 2 In FIG. 1 , for comparison with Sample 1, the UV-Vis absorption spectra of Samples 3 and 4 are shown with the absorption intensity increased by 1.25.

[0159] Figure 1 In the wavelength ranges of 350-380 nm and 400-500 nm, the absorption of Sample 1 (MoI3(PCP), 0h) is slightly stronger than that of Sample 2 (MoI3(PCP), 5h), but the spectra of Sample 1 and Sample 2 generally overlap. The spectrum of Sample 3 (filtrate, MOF-808) shows a relative intensity of less than 0.4 near the wavelength range of 300-600 nm.

[0160] Figure 2 The absorption spectrum of Sample 4 (UiO-68) has three peaks. Near a wavelength of 310 nm, Sample 4's absorption is greater than that of Sample 1 (MoI3(PCP)), but overall, its absorption spectrum lies between those of Sample 1 and Sample 3 (MOF-808). The absorption spectrum of Sample 1 has roughly two peaks. Near a wavelength of 310 nm, Sample 1's absorption is smaller than that of Sample 4, but overall, Sample 1 has the highest absorption of the three absorption spectra. Sample 3's absorption is significantly lower than that of Samples 1 and 4.

[0161] Figure 1 and Figure 2 The spectrum of sample 1 is the spectrum of the nitrogen-activated catalyst (MoI3(PCP)).

[0162] Figure 1 In the spectrum of Sample 2, since there is no change in the nitrogen-activated catalyst (MoI 3 (PCP)), it can be considered that the spectrum shows a waveform substantially the same as that of Sample 1. Figure 1 The spectrum of Sample 3 is different from the spectrum of Sample 1, and therefore it can be considered that the nitrogen-activated catalyst is supported on the carrier.

[0163] in addition, Figure 2 Since the spectrum of Sample 4 shown is different from the spectrum of Sample 1, it can be considered that the nitrogen-activated catalyst is supported on the carrier.

[0164] <Manufacturing of Ammonia> [Example 1] According to the following reaction scheme (A), an ammonia synthesis reaction was carried out for 1 hour while stirring the reaction liquid in the presence of the ammonia production catalyst 1.

[0165] In reaction route (A), rt refers to room temperature (25 °C). Cat. refers to catalyst. Additionally, 1 atm (one atmosphere) is 1,013 hPa.

[0166] X is the amount shown in Table 1. The unit [equiv / Mo] refers to the number of equivalents of each compound relative to the amount of substance of the Mo catalyst used.

[0167] [Chemical formula 20] .

[0168] [Comparative Example 1] In the ammonia synthesis reaction of Example 1, MOF-808 itself without the supported nitrogen activation catalyst 1 was used instead of the ammonia production catalyst 1, and otherwise, the same operation was carried out. While stirring the reaction solution, the ammonia synthesis reaction was carried out for 1 hour.

[0169] [Examples 2 to 6] In the ammonia synthesis reaction of Example 1, the ammonia production catalysts 2 to 6 shown in the "Catalyst" column of Table 1 were used instead of the ammonia production catalyst 1, and otherwise, the same operation was carried out. While stirring the reaction solution, the ammonia synthesis reaction was carried out for 1 hour.

[0170] [Yield of NH3 and H2] The yield of NH3 obtained in Examples 1 to 6 and Comparative Example 1 was determined by the colorimetric quantification method based on the indophenol method using UV-1850 manufactured by Shimadzu Corporation. The yield of H2 was calculated by quantitative analysis using gas chromatography with a Shimadzu GC-8A equipped with a thermal conductivity detector and a ShinCarbon ST column. The results are shown in Table 1.

[0171] It should be noted that in Table 1, the amounts shown in (a), that is, the mol yield (%) of NH3 and the mol yield (%) of H2, are based on the amount of substance of SmI2.

[0172] The amount shown in (b) represents the TON assuming that the catalyst is completely supported on the carrier.

[0173] (TON: Represents the number of moles of substance that can be converted from the substrate to the product per 1 mol of catalyst before the catalyst is activated) [Table 1] .

[0174] [Relationship between the structure of the carrier and the amount of ammonia generated] The relationship between the ammonia yield (%) in Examples 1 to 5 and the structure of the carriers of the ammonia production catalysts 1 to 5 used in these examples is shown in Table 2.

[0175] [Table 2] .

[0176] The average diameter of the windows and the average diameter of the cages of each carrier refer to the values ​​of the following references.

[0177] UiO: 66, UiO: 67 and UiO: 68 Cavka, JH; Jakobsen, S.; Olsbye, U.; Guillou, N.; Lamberti, C.;Bordiga, S.; Lillerud, KPJ Am. Chem. Soc. 2008, 130, 13850-13851. MOF-808 Furukawa, H.; Gandara, F.; Zhang, Y.-B.; Jiang, J.; Queen, WL;Hudson, MR; Yaghi, OMJ Am. Chem. Soc. 2014, 136, 4369-4381. PCN-222 Feng, D.; Gu, Z.-Y.; Li, J.-R.; Jiang, H.-L.; Wei, Z.; Zhou, H.-C. Angew. Chem. Int. Ed. 2012, 51, 10307-10310.

[0178] A comparison of Preparation Examples 2 to 4 in Table 2 shows that when MOFs with similar structures are used as supports, the larger the window size and the larger the cage size, the higher the ammonia yield.

[0179] <Evaluation of Recycling of Ammonia Production Catalysts> [Example 7] According to reaction scheme (A), ammonia production catalyst 1 (19.3 mg, supported amount of nitrogen-activated catalyst 1: 2.0 μmol), SmI2 (360 μmol), and ethylene glycol (360 μmol) were stirred in THF (6 mL) for 1 hour to perform an ammonia synthesis reaction.

[0180] [Example 8] After the ammonia synthesis reaction of Example 7 was completed, the reaction liquid was filtered to recover the filtrate. Next, the ammonia synthesis reaction of Example 7 was carried out in the same manner except that the recovered filtrate was used instead of the ammonia production catalyst 1.

[0181] 〔Example 9〕 After the ammonia synthesis reaction of Example 8 was completed, the reaction solution was filtered to recover the filtrate. Then, in the ammonia synthesis reaction of Example 7, the recovered filtrate was used instead of ammonia production catalyst 1, and the same operations were carried out to conduct the ammonia synthesis reaction.

[0182] 〔Example 10〕 After the ammonia synthesis reaction of Example 9 was completed, the reaction solution was filtered to recover the filtrate. Then, in the ammonia synthesis reaction of Example 7, the recovered filtrate was used instead of ammonia production catalyst 1, and the same operations were carried out to conduct the ammonia synthesis reaction.

[0183] <Yield of NH3 and H2> The yield of NH3 obtained in Examples 7 to 10 was determined by the colorimetric method based on the indophenol method using a UV-1850 manufactured by Shimadzu Corporation. The yield of H2 was calculated by quantitative analysis using gas chromatography with a Shimadzu GC-8A equipped with a thermal conductivity detector and a ShinCarbon ST column. The results are shown in Table 3.

[0184] It should be noted that in Table 3, the amount shown in (a) is based on the amount of SmI2.

[0185] The amount shown in (b) is the value assuming that the catalyst is completely supported on the carrier.

[0186] [Table 3] . [[ID=​​

Claims

1. A catalyst for ammonia production, comprising a support and a nitrogen-activated catalyst, wherein the support comprises a metal organic structure, The nitrogen-activated catalyst is supported on the carrier.

2. The catalyst for ammonia production according to claim 1, wherein The average diameter of the window of the metal organic structure is 3×10 -10 m~50×10 -10 m.

3. The catalyst for ammonia production according to claim 1 or 2, wherein The average diameter of the cage of the metal organic structure is 8×10 -10 m~60×10 -10 m.

4. The catalyst for ammonia production according to any one of claims 1 to 3, wherein The metal-organic structure comprises zirconium, aluminum or chromium as metal.

5. The catalyst for ammonia production according to claim 4, wherein The metal organic structure includes one or more atoms selected from zirconium, oxygen atoms, and hydrogen atoms.

6. The metal-organic structure according to claim 4 or 5, wherein The metal organic structure is one or more selected from the group consisting of MOF-808, UiO-66, UiO-67, UiO-68, PCN-222, PCN-224, and UN-1000.

7. The catalyst for ammonia production according to any one of claims 1 to 6, wherein The content of the nitrogen activation catalyst is 0.1 to 60 parts by mass relative to 100 parts by mass of the support.

8. The catalyst for ammonia production according to any one of claims 1 to 7, wherein The nitrogen activation catalyst is a molybdenum complex.

9. The catalyst for ammonia production according to claim 8, wherein The nitrogen activation catalyst is a molybdenum complex having PCP, PPP or PNP pincer ligands.

10. A method for producing ammonia, wherein: Ammonia is synthesized in the presence of the catalyst for ammonia production according to any one of claims 1 to 9.

11. The method for producing ammonia according to claim 10, wherein: After ammonia synthesis, the support including the metal organic structure and the nitrogen activated catalyst are recovered together.

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