Production method for ammonia and production device

Abstract

[Problem] To produce ammonia electrochemically. [Solution] A production method for ammonia according to the present invention involves producing ammonia from molecular nitrogen in a production device for performing electrolysis by providing electrons from a power source, protons from a proton source, and molecular nitrogen from a means for supplying nitrogen gas in the presence of a metal complex and a solid catalyst in a cathode, and by providing molecular hydrogen in a means for delivering molecular hydrogen to an anode, where said means includes a means for delivering hydrogen gas generated at the cathode to the anode. With regard to the metal complex and the solid catalyst, e.g., rac-​ethylenebis​(4,5,6,7-​tetrahydro-​1-​indenyl)​zirconium dichloride is used as the metal complex and a metal catalyst is used as the solid catalyst.

Description

Ammonia production method and production apparatus

[0001] The present invention relates to a method and an apparatus for producing ammonia.

[0002] In a method for producing ammonia from nitrogen molecules by electrolysis in a low temperature range, there is a report of ammonia production by electrolysis at 90°C using a platinum electrode as the anode and a ruthenium-supported cathode on carbon felt (Non-Patent Document 1). １．５ Sr ０．５ CoO ４ There have been reports of producing ammonia by electrolysis using the above (Non-Patent Document 2).

[0003] Chem. Commun. 2000, pp. 1673-1674 Sci. Rep. 2013, vol. 3, pp. 1145-1151

[0004] Non-Patent Document 1 has an issue that the efficiency of ammonia synthesis decreases at room temperature, around 20 to 30° C., because it operates at around 90 to 100° C. Non-Patent Document 2 has an issue that the membrane to be used as an electrolyte membrane must be treated with ammonia before being incorporated into an electrolysis device.

[0005] The present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to provide a novel method for electrochemically producing ammonia.

[0006] In order to achieve the above-mentioned object, the present inventors have discovered that ammonia can be electrochemically produced in a newly designed ammonia production apparatus using a membrane electrode assembly or a gas diffusion electrode, which is a catalyst layer in which an electrode catalyst is arranged, and which combines the function of a metal complex, typified by a complex catalyst, and the function of a solid catalyst, typified by a metal catalyst, a transition metal catalyst, a noble metal catalyst, an alloy catalyst, or an oxide catalyst, in a catalyst layer in which an electrode catalyst is arranged, and have thereby completed the present invention.

[0007] The present invention based on these findings includes, for example, the following [1] to

[10] . [1] A method for producing ammonia using nitrogen molecules as a raw material by providing electrons from a power source, protons from a proton source, and nitrogen molecules from a nitrogen gas supply means in the presence of a metal complex and a solid catalyst at a cathode in a production apparatus that performs an electrolytic reaction, and providing hydrogen molecules from a hydrogen gas supply means at an anode. [2] The method for producing ammonia according to [1], wherein the hydrogen gas supply means at the anode includes a means for feeding hydrogen gas produced at the cathode to the anode. [3] The method for producing ammonia according to [1] or [2], wherein the metal complex is a compound that can form a nitrogen complex by coordinating a nitrogen molecule to a metal at the center of the catalyst, the solid catalyst is a metal catalyst, a transition metal catalyst, a noble metal catalyst, an alloy catalyst, an oxide catalyst, or a combination thereof, and the proton source is at least one selected from the group consisting of an electrolyte membrane, an electrolytic solution, a catalyst layer, and an electrolyte in the catalyst layer. [4] The method for producing ammonia according to any one of [1] to [3], wherein the metal complex is a metallocene compound or a half-metallocene compound. [5] The method for producing ammonia according to any one of [1] to [4], wherein the metal complex is bis(cyclopentadienyl)titanium dichloride, bis(cyclopentadienyl)zirconium dichloride, rac-dimethylsilylbis(1-indenyl)zirconium dichloride, or rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride. [6] The method for producing ammonia according to any one of [1] to [5], wherein the solid catalyst contains platinum, gold, palladium, or zinc oxide.[7] An apparatus for producing ammonia from nitrogen molecules by an electrolytic reaction, the apparatus comprising: a cathode having a cathode catalyst layer bonded to one side of an electrolyte membrane and a cathode current collector disposed on the outside thereof; and an anode having an anode catalyst layer bonded to the other side of the electrolyte membrane and an anode current collector disposed on the outside thereof; the cathode comprising the cathode catalyst layer and the cathode current collector; the anode comprising an anode catalyst layer and an anode current collector; the cathode comprising a cathode electrolyte tank allowing solid-liquid-gas contact; the anode comprising an anode electrolyte tank allowing solid-liquid-gas contact; a means for feeding hydrogen gas to the anode; a power source for supplying electrons to the cathode; a proton source for supplying protons to the cathode; and a means for supplying nitrogen gas to the cathode electrolyte tank, the cathode electrolyte, or the cathode; [8] The ammonia manufacturing apparatus according to [7], wherein the means for feeding hydrogen gas to the anode includes means for feeding hydrogen gas generated at the cathode to the anode. [9] An apparatus for producing ammonia from nitrogen molecules by an electrolytic reaction, the apparatus comprising: a cathode having a cathode catalyst layer bonded to one side of an electrolyte membrane and a cathode current collector disposed on the outside thereof; and an anode having an anode catalyst layer bonded to the other side of the electrolyte membrane and an anode current collector disposed on the outside thereof; the cathode comprising the cathode catalyst layer and the cathode current collector; the anode comprising the anode catalyst layer and the anode current collector; the cathode comprising a flow path allowing solid-liquid-gas contact; the anode comprising a flow path allowing solid-liquid-gas contact; a means for feeding hydrogen gas to the anode; a power source for supplying electrons to the cathode; a proton source for supplying protons to the cathode; and a means for supplying nitrogen gas to the cathode electrolyte tank, the cathode electrolyte, or the cathode;

[10] The ammonia manufacturing apparatus according to [9], wherein the means for feeding hydrogen gas to the anode includes means for feeding hydrogen gas generated at the cathode to the anode.

[0008] According to the ammonia production method of the present invention, in a production apparatus that performs electrolysis, electrons from a power source, protons from a proton source, and nitrogen molecules from a means for supplying nitrogen gas are supplied in the presence of a metal complex and a solid catalyst at the cathode, hydrogen molecules are supplied from a means for supplying hydrogen gas at the anode, and hydrogen molecules are supplied by a means for feeding hydrogen gas generated at the cathode to the anode, thereby enabling efficient production of ammonia from nitrogen molecules.Furthermore, the hydrogen gas generated at the cathode can be reused, making it possible to provide an apparatus that can produce ammonia with reduced energy consumption.

[0009] FIG. 1 is an explanatory diagram of an ammonia electrolysis device (part 1); FIG. 2 is an explanatory diagram of an ammonia electrolysis device (part 2); FIG. 3 is an explanatory diagram of an ammonia electrolysis device (part 3); FIG. 4 is an explanatory diagram of an ammonia electrolysis device (part 5); FIG. 5 is an explanatory diagram of a gas flow during operation of an ammonia electrolysis device (part 3); and FIG. 6 is an explanatory diagram of a gas flow during operation of an ammonia electrolysis device (part 4).

[0010] Preferred embodiments of the method and apparatus for producing ammonia according to the present invention are described below.

[0011] In this specification, "n" represents normal, "s" represents secondary, "t" represents tertiary, "o" represents ortho, "m" represents meta, "p" represents para, and "rac" represents racemic.

[0012] C in this specification ａ ~C ｂThe notation of alkyl group represents a monovalent group generated by removing one hydrogen atom from a straight or branched chain aliphatic hydrocarbon having a to b carbon atoms, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a t-pentyl group, a 1,1-dimethylpropyl group, an n-hexyl group, an isohexyl group, a 3-methylpentyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, an n-heptyl group, a 2-methylhexyl group, a 3-ethylpentyl group, an n-octyl group, a 2,2,4-trimethylpentyl group, a 2,5-dimethylhexyl group, an n-nonyl group, a 2,7-dimethyloctyl group, an n-decyl group, and the like, and each of these is set within the range of the number of carbon atoms specified. ａ ~C ｂ In the formula, a is an integer of 1 or more, and b is an integer of a or more.

[0013] The ammonia production method of this embodiment can be carried out in a production apparatus that performs electrolysis. In this specification, a production apparatus that performs electrolysis is sometimes referred to as an electrolysis apparatus, and is composed of an electrolysis cell, a nitrogen gas supply means, a hydrogen gas supply means, an ammonia recovery means, and an exhaust gas removal means. The electrolysis apparatus will be described in detail below. The electrolysis cell is composed of electrodes, an electrolyte tank, a nitrogen gas supply port, a hydrogen gas supply port, and an exhaust gas outlet. The electrode where an oxidation reaction occurs is the anode, and the electrode where a reduction reaction occurs is the cathode.

[0014] The ammonia production method of this embodiment is a method for producing ammonia from nitrogen molecules by providing electrons from a power source, protons from a proton source disposed in an electrolysis device, and nitrogen molecules from a nitrogen gas supply means in the presence of a metal complex and a solid catalyst at a cathode, and providing hydrogen molecules from a hydrogen gas supply means at an anode. The hydrogen gas may be provided by a means for delivering hydrogen gas generated at the cathode to the anode. In this method, a catalyst for producing ammonia is used in the cathode in a combined form with a metal complex and a solid catalyst. This catalyst in a combined form with a metal complex and a solid catalyst is sometimes referred to as a catalyst body in this specification. The proton source is preferably capable of supplying at least one of protons and hydroxonium ions when the catalyst body is placed in an acidic environment, and preferably capable of supplying at least one of water and hydroxide ions when the catalyst body is placed in an alkaline environment. These proton sources may be used alone or in combination.

[0015] The metal complex in the ammonia production method of this embodiment may have a role of capturing nitrogen molecules when the nitrogen molecules react near the electrode and then providing protons and electrons for reduction, and is not particularly limited as long as it becomes a compound in which a nitrogen molecule is coordinated at the metal center of the metal complex. The compound is sometimes called a nitrogen complex. Specifically, the metal complex [Ru(NH ３ ) ５ N ２ ] ２＋Since the discovery of the above, nitrogen complexes have been reported in non-patent literature, such as Science, 1968, Vol. 159, pp. 320-322; J. Am. Chem. Soc., 1968, Vol. 90, pp. 3263-3264; J. Am. Chem. Soc., 1968, Vol. 90, pp. 5295-5296; Chem. Lett., 1993, Vol. 22, pp. 1329-1332; Polyhedron, 1996, Vol. 24, pp. 4421-4423; and Chem. Rev., 2004, Vol. 104, pp. 385-401, and these can be cited as examples of the above-mentioned nitrogen complexes. More specifically, examples of such compounds include a molybdenum nitrogen complex having a triamide monoamine tetradentate ligand, as described in the non-patent literature Science, Vol. 301, pp. 76-78, 2003; an iron nitrogen complex having a triphosphine borane tetradentate ligand, as described in the non-patent literature Nature, Vol. 501, pp. 84-87, 2013; and metallocene compounds, such as bis(cyclopentadienyl)titanium dichloride, as described in patent literature Japanese Patent No. 5,729,022, and half-metallocene compounds. Metallocene compounds have two rings of cyclopentadiene, benzene, cyclooctatetraene, or derivatives thereof, with a metal atom sandwiched between the rings, and are sometimes called sandwich compounds. Half-metallocene compounds have a structure with one ring, and are sometimes called open-sandwich compounds.

[0016] Examples of the metallocene compound of this embodiment include bis(cyclopentadienyl)titanium dichloride, μ-chloro-μ-methylene[bis(cyclopentadienyl)titanium]dimethylaluminum, bis(cyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)zirconium chloride hydride, bis(butylcyclopentadienyl)zirconium(IV) dichloride, decamethylzirconocene dichloride bis(pentamethylcyclopentadienyl)zirconium(IV) dichloride, 1,1'-isopropylidene zirconocene dichloride, hafnocene dichloride, 1,1'-dipropylhafnocene dichloride bis(propylcyclopentadienyl)hafnium(IV) dichloride, bis(cyclopentadienyl)zirconium(IV) dichloride, Examples of the half metallocene compound include cyclopentadienyltitanium(IV) trichloride, (pentamethylcyclopentadienyl)titanium(IV) trichloride, (indenyl)titanium(IV) trichloride, trichloro(indenyl)titanium(IV), cyclopentadienylzirconium(IV) trichloride, dimethylsilylbis(1-indenyl)zirconium dichloride, rac-dimethylsilylbis(1-indenyl)zirconium dichloride, ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride, and rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride. Of these, bis(cyclopentadienyl)titanium dichloride, bis(cyclopentadienyl)zirconium dichloride, rac-dimethylsilylbis(1-indenyl)zirconium dichloride, and rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride are preferred.

[0017] The metal complex used in the method for producing ammonia according to the present embodiment may be a metal complex supported on a support. For example, a metal complex represented by formula (S1) having a vinyl group, which is described in the non-patent document Journal of Organometallic Chemistry, Vol. 655, pp. 167-171, 2002, is radically polymerized with styrene to give a metal complex represented by formula (S2): Furthermore, the mode in which a metallocene compound is supported on a polymer is described, for example, in the non-patent literature, Comprehensive Organometallic Chemistry III (2007), pp. 728-738.

[0018] Examples of the solid catalyst in the ammonia production method of this embodiment include metal catalysts and oxide catalysts, and it is also possible to use a combination of multiple solid catalysts. Metal catalysts include metal catalysts that are used in a single composition or in a mixture of multiple metal components such as alloy catalysts, and it is also possible to use metal nanoparticles formed using a surfactant, metal particles having self-organized portions formed by bonding between a metal and a thiol using a thiol compound, metal nanoparticles, metal films, metal foils, etc.

[0019] Examples of the thiol compound include R １ -SH(R １ has the same meaning as below.) １ is R １The organic group is not particularly limited and can be any appropriate group, taking into consideration the boiling point of —SH, ease of isolation by chromatography, etc., but is preferably an organic group having 1 to 20 carbon atoms, and more preferably an organic group having 6 to 16 carbon atoms. Examples of the organic group include hydrocarbon groups, chain saturated hydrocarbon groups, chain unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups, cyclic unsaturated hydrocarbon groups, aromatic hydrocarbon groups, and groups in which a portion of the carbon-carbon bond of these groups is interrupted by a heteroatom or substituted with a substituent containing a heteroatom. Specific examples of the thiol compound include 2-methylbenzenethiol, 3-methylbenzenethiol, 4-methylbenzenethiol, phenylmethanethiol, 1-butanethiol, 1-decanethiol, 1-dodecanethiol, 1-heptanethiol, 1-hexadecanethiol, 1-hexanethiol, 1-nonanethiol, 1-octadecanethiol, 1-octanethiol, 1-pentadecanethiol, 1-pentanethiol, 1-methylbenzene ... -propanethiol, 1-tetradecanethiol, 1-undecanethiol, 11-mercaptoundecyl trifluoroacetate, 1H,1H,2H,2H-perfluorodecanethiol, 2-ethylhexanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propanethiol, 3-methyl-1-butanethiol, methyl 3-mercaptopropionate, tert-dodecyl mercaptan, (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide, (11-mercaptoundecyl)hexa(ethylene glycol), (11-mercaptoundecyl)tetra(ethylene glycol), 1-(11-mercaptoundecyl)imidazole, 1-mercapto-2-propanol, 11-(1H-pyrrol-1-yl)undecane-1-thiol, 11-amino-1-undecanethiol hydrochloride, 11-mercapto-1-undecanol, 11-mercaptoundecanamide, 11-mercaptoundecanoic acid, 11-mercaptoundecyl perhydroquinone, 11-mercaptoundecylphosphonic acid, 12-mercaptododecanoic acid, 16-amino-1-hexadecanethiol hydrochloride, 16-mercaptohexadecanamide, 16-mercaptohexadecanoic acid, 3-amino-1-propanethiol hydrochloride, 3-chloro-1-propanethiol, 3-mercapto-1-propanol, 3-mercaptopropionic acid, 6-amino-1-hexanethiol hydrochloride, 6-mercapto-1-hexanol, 6-mercaptohexanoic acid, 8-amino-1-octanethiol hydrochloride, 8-Mercapto-1-octanol, 8-mercaptooctanoic acid, 9-mercapto-1-nonanol, triethylene glycol mono-11-mercaptoundecyl ether, 1,4-butanediol diacetate, [11-(methylcarbonylthio)undecyl]hexa(ethylene glycol), [11-(methylcarbonylthio)undecyl]tetra(ethylene glycol), [11-(methylcarbonylthio)undecyl]tri(ethylene glycol)acetic acid, hexa(ethylene glycol)mono-11-(acetylthio) e) Undecyl ether, S,S'-[1,4-phenylenebis(2,1-ethynediyl-4,1-phenylene)]bis(thioacetate), S-[4-[2-[4-(2-phenylethynyl)phenyl]ethynylphenyl]thioacetate, S-(10-undecyl)thioacetate, S-(11-bromoundecyl thioacetate), S-(4-azidobutyl)thioacetate, S-(4-bromobutyl)thioacetate, S-(4-cyanobutyl thioacetate), 1,1',4',1''-terphenyl-4-thiol, 1,4-benzenedimethanethiol, 1-adamantanethiol, 1-naphthalenethiol, 2-phenylethanethiol, 4'-bromo-4-mercaptophenyl, 4'-mercaptophenylcarbonitrile, 4,4'-bis(mercaptomethyl)biphenyl, 4,4'-dimercaptostilbene, 4-(6-mercaptohexyloxy)benzyl alcohol, 4-mercaptobenzoic acid, 9-fluorenylmethylthiol, 9-mercaptofluorene, biphenyl-4,4-dithiol, biphenyl-4-thiol, cyclohexanethiol, cyclopentanethiol, p-terphenyl-4,4''-dithiol, thiophenol, aminoethanethiol mercaptomethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriazole, 3-mercaptopropyltriazole, 3-mercaptopropyltrimethoxysilane, 3-mercaptoethylimidazole, 3-mercaptopropyltriazole, 3-mercaptobutyltriazole, 3-mercaptopropyltriazole, 3-mercaptopropyltrimethoxysilane, 3-mercaptoethylimidazole, 3-mercaptopropyltriazole, 3-mercaptopropyltriazole, 3-mercaptoethylimidazole, 3-mercaptopropyltriazole, 3-mercaptoethyltriazole, 3-mercaptopropyl ...ethyltriazole, 3-mercaptopropyltriazole, 3-mercaptoethyltriazole, 3-mercaptoethyltriazole, 3-mercaptopropyltriazole, 3-mercaptoethyltriazole, 3-mercaptoethyltriazole, 3-mercaptopropyltriazole, 3-mercaptoethyltriazole, 3-mercaptoethyltriazole, 3-mercaptoethyltriazole, 3-mercaptopropyltriazole, 3-

[0020] Examples of oxide catalysts include those using metal oxides of main group elements, those using transition metal oxides, and those using a mixture of multiple metal oxides, and the metal oxides may be used as supports for solid catalysts.

[0021] Examples of the solid catalyst in the ammonia production method of the present embodiment include metals such as iridium (IV) oxide powder catalyst, iridium oxide catalyst, platinum catalyst, gold catalyst, silver catalyst, ruthenium catalyst, iridium catalyst, rhodium catalyst, palladium catalyst, osmium catalyst, tungsten catalyst, lead catalyst, iron catalyst, chromium catalyst, cobalt catalyst, nickel catalyst, manganese catalyst, vanadium catalyst, molybdenum catalyst, gallium catalyst, and aluminum catalyst, and alloys thereof; aluminum oxide, zirconium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, niobium pentoxide, molybdenum oxide, cerium oxide, samarium oxide, ruthenium oxide, rhodium oxide, silver oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, indium oxide, platinum oxide, gold oxide, magnesium oxide, silica, silica-alumina, silica-magnesia, and combinations of the above solid catalysts. Examples of platinum catalysts, gold catalysts, and silver catalysts include thiol-protected platinum nanoparticle catalysts, thiol-protected platinum catalysts, thiol-protected gold nanoparticle catalysts, thiol-protected gold catalysts, thiol-protected silver nanoparticle catalysts, and thiol-protected silver catalysts. Among these, the solid catalyst used on the cathode side is defined as a cathode solid catalyst, and preferred cathode solid catalysts include platinum catalysts, thiol-protected platinum nanoparticle catalysts, thiol-protected platinum catalysts, gold catalysts, thiol-protected gold nanoparticle catalysts, thiol-protected gold catalysts, iridium catalysts, palladium catalysts, zinc oxide, molybdenum oxide, cerium oxide, and samarium oxide, and more preferred are platinum catalysts, thiol-protected platinum nanoparticle catalysts, gold catalysts, thiol-protected gold nanoparticle catalysts, thiol-protected gold catalysts, palladium catalysts, and zinc oxide. When a plurality of these solid catalysts are combined, a combination of a platinum catalyst and zinc oxide, a combination of a platinum catalyst and a gold catalyst, a combination of a platinum catalyst and a thiol-protected gold catalyst, a combination of a platinum catalyst and a palladium catalyst, a combination of a thiol-protected platinum nanoparticle catalyst and zinc oxide, a combination of a thiol-protected platinum nanoparticle catalyst and a gold catalyst, a combination of a thiol-protected platinum nanoparticle catalyst and a thiol-protected gold catalyst, or a combination of a thiol-protected platinum nanoparticle catalyst and a palladium catalyst is preferred.

[0022] In the ammonia production method of this embodiment, the cathode-side catalyst body, which is a catalyst combining a metal complex and a solid catalyst, is defined as a cathode catalyst body, and preferred combinations of the cathode catalyst body include a combination of bis(cyclopentadienyl)titanium dichloride and a platinum catalyst, a combination of bis(cyclopentadienyl)titanium dichloride and a thiol-protected platinum nanoparticle catalyst, a combination of bis(cyclopentadienyl)titanium dichloride and a palladium catalyst, a combination of bis(cyclopentadienyl)titanium dichloride and a palladium catalyst, and a combination of bis(cyclopentadienyl)titanium dichloride and a palladium catalyst. Combination with gold catalyst, combination of bis(cyclopentadienyl)titanium dichloride and thiol-protected gold nanoparticle catalyst, combination of bis(cyclopentadienyl)titanium dichloride and thiol-protected gold catalyst, combination of bis(cyclopentadienyl)titanium dichloride and zinc oxide, combination of bis(cyclopentadienyl)titanium dichloride, platinum catalyst and zinc oxide, combination of bis(cyclopentadienyl)zirconium dichloride and platinum catalyst, bis(cyclopentadienyl)zirconium a combination of bis(cyclopentadienyl)zirconium dichloride with a thiol-protected platinum nanoparticle catalyst, a combination of bis(cyclopentadienyl)zirconium dichloride with a palladium catalyst, a combination of bis(cyclopentadienyl)zirconium dichloride with a gold catalyst, a combination of bis(cyclopentadienyl)zirconium dichloride with a thiol-protected gold nanoparticle catalyst, a combination of bis(cyclopentadienyl)zirconium dichloride with a thiol-protected gold catalyst, a combination of bis(cyclopentadienyl)zirconium dichloride with zinc oxide, a combination of bis( rac-dimethylsilylbis(1-indenyl)zirconium dichloride in combination with a platinum catalyst and zinc oxide, rac-dimethylsilylbis(1-indenyl)zirconium dichloride in combination with a platinum catalyst, rac-dimethylsilylbis(1-indenyl)zirconium dichloride in combination with a thiol-protected platinum nanoparticle catalyst, rac-dimethylsilylbis(1-indenyl)zirconium dichloride in combination with a palladium catalyst, rac-dimethylsilylbis(1-indenyl)zirconium dichloride in combination with a gold catalyst,A combination of rac-dimethylsilylbis(1-indenyl)zirconium dichloride with a thiol-protected gold nanoparticle catalyst, a combination of rac-dimethylsilylbis(1-indenyl)zirconium dichloride with zinc oxide, a combination of rac-dimethylsilylbis(1-indenyl)zirconium dichloride with a platinum catalyst and zinc oxide, a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride with a platinum catalyst, a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride with a thiol-protected platinum nanoparticle catalyst, rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride Examples of such a combination include a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride and a palladium catalyst, a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride and a gold catalyst, a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride and a thiol-protected gold nanoparticle catalyst, a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride and zinc oxide, and a combination of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride, a platinum catalyst, and zinc oxide. Examples of metal complexes of these combinations also include combinations in which the above-mentioned metal complexes are supported.

[0023] The cathode catalyst layer 103 for producing ammonia in this embodiment includes a catalyst support, an electron conductor, an electrolyte, and a gas diffusion layer in addition to a cathode catalyst body which is a catalyst combining a metal complex and a solid catalyst. In this specification, the cathode catalyst layer 103 including the cathode catalyst body which combines a metal complex and a cathode solid catalyst, the catalyst support, the electron conductor, the electrolyte, and the gas diffusion layer may be referred to as a gas diffusion electrode 133.

[0024] The catalyst support in the cathode catalyst layer 103 of this embodiment may be responsible for electron conduction and is not particularly limited as long as it can support the catalyst of this embodiment. Examples of catalyst supports include carbon black, carbon materials, metal mesh, metal foam, metal oxides, composite oxides, polymer electrolytes, ionic liquids, activated carbon, graphene oxide, reduced graphene oxide, carbon nitride, and g-carbon nitride. Furthermore, when the catalyst support is used in an electrode, it not only serves to support the catalyst but can also participate as a catalyst or co-catalyst in the reaction occurring at the electrode.

[0025] Examples of carbon black include channel black, furnace black, thermal black, acetylene black, ketjen black, and ketjen black EC. Examples of carbon materials include activated carbon obtained by carbonizing and activating various carbon-containing materials, coke, natural graphite, artificial graphite, and graphitized carbon. Examples of metal meshes include metal meshes of nickel, tungsten, titanium, zirconium, and hafnium. Examples of metal foams include aluminum, magnesium, tungsten, titanium, zirconium, and hafnium. Examples of the metal oxide include aluminum oxide, zirconium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, niobium pentoxide, molybdenum oxide, ruthenium oxide, rhodium oxide, silver oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, indium oxide, platinum oxide, gold oxide, magnesium oxide, and silica. Examples of the composite oxide include silica-alumina and silica-magnesia. Examples of the polymer electrolyte include fluorine-based polymer electrolytes, hydrocarbon-based polymer electrolytes, carboxyl group-containing acrylic copolymers, and carboxyl group-containing methacrylic copolymers. Examples of fluorine-based polymer electrolytes include fluorine-based sulfonic acid polymers, hydrocarbon-based sulfonic acid polymers, partially fluorinated hydrocarbon-based sulfonic acid polymers, anion conduction electrolytes, etc., such as DuPont's Nafion (registered trademark), Solvay's Aquivion (registered trademark), AGC's Flemion (registered trademark), and Asahi Kasei's Aciplex (registered trademark). Examples of hydrocarbon-based polymer electrolytes include sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, and sulfonated polyphenylene. Specific examples of carboxyl group-containing acrylic copolymers include acrylic acid, propiolic acid, crotonic acid, isocrotonic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, etc., which have a carboxyl group and a copolymerizable double bond.Gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, acrylic acid dimer, 2-acryloyloxypropylhexahydrophthalic acid, 2-acryloyloxyethylsuccinic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, atropic acid, cinnamic acid, linoleic acid, eicosadienoic acid, docosadienoic acid, linolenic acid, pinolenic acid, eleostearic acid, mead acid, dihomo-Y-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, Homopolymers or copolymers of eicosatetraenoic acid, adrenic acid, bosseopentaenoic acid, eicosapentaenoic acid, osbondo acid, sardine acid, tetracosapentaenoic acid, docosahexaenoic acid, herring acid, 2,2,2-trisacryloyloxymethyl succinic acid, 2-trisacryloyloxymethylethyl phthalic acid, etc., and further, methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, acrylic acid decyl, dodecyl acrylate, stearyl acrylate and other alkyl acrylate esters; diacetone acrylamide, acrylamide, 2-hydroxyethyl acrylamide, N-methyl acrylamide, N-t-butyl acrylamide, N-isopropyl acrylamide, N-phenyl acrylamide, N-methylolacrylamide, dimethylaminopropyl acrylamide, dimethylaminopropyl acrylamide, diacetone acrylamide, N,N-dimethyl acrylamide, N-vinyl formamide, acryloyl morpholine, acryloyl piperidine and other acrylamides; [3-(acryloyloxy)propyl]phosphonic acid, [3-(methacryloyloxy)propyl]phosphonic acid and other phosphonic acids; acrylonitrile and vinyl alcohol esters such as vinyl-n-butyl ether; acrylic acid tetrahydrofurfuryl ester, acrylic acid dimethylaminoethyl ester, acrylic acid diethylaminoethyl ester, acrylic acid glycidyl ester, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, styrene,Examples of the radical polymerization initiator include azo compounds such as azobisisobutyronitrile, azobis(2-methylbutyronitrile), 2,2'-azobis-2,4-dimethylvaleronitrile, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidinemethyl]tetrahydrate; organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, dicumyl peroxide, and di-t-butyl peroxide; persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; and hydrogen peroxide. These may be used alone or in combination of two or more. Specific examples of carboxyl group-containing methacrylic copolymers include homopolymers or copolymers of methacrylic acid, ω-carboxy-polycaprolactone monomethacrylate, monohydroxyethyl phthalate methacrylate, methacrylic acid dimer, 2-methacryloyloxypropyl hexahydrophthalic acid, 2-methacryloyloxyethyl succinic acid, and the like, which have a carboxyl group and a copolymerizable double bond, as well as methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, methacrylic acid methyl methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, methyl methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl ... Methacrylic acid alkyl esters such as nonyl acrylate, decyl methacrylate, dodecyl methacrylate, and stearyl methacrylate; methacrylamides such as methacrylamide and dimethylaminopropyl methacrylamide; phosphonic acids such as α-phosphono-ω-(methacryloyloxy)poly(n=1 to 15)(oxypropylene); methacrylic acid tetrahydrofurfuryl ester, methacrylic acid dimethylaminoethyl ester, methacrylic acid diethylaminoethyl ester, methacrylic acid glycidyl ester, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, styrene,Examples of the radical polymerization initiator include azo compounds such as azobisisobutyronitrile, azobis(2-methylbutyronitrile), 2,2'-azobis-2,4-dimethylvaleronitrile, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidinemethyl]tetrahydrate; organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, dicumyl peroxide, and di-t-butyl peroxide; persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; and hydrogen peroxide. These may be used alone or in combination of two or more. Examples of anion-conducting electrolytes include Fumion (registered trademark) FAA-3-SOLUT-10 manufactured by FUMATECH BWT GmbH, and A3 ver. 2 and AS-4 manufactured by Tokuyama Corporation (A3 ver. 2 and AS-4 are described, for example, in the magazine "Hydrogen Energy System," Vol. 1.35, No. 2, 2010, page 9). When a cation exchange membrane (hereinafter also referred to as a cation exchange membrane) is used as the electrolyte membrane described below, Nafion (registered trademark) and Aquivion (registered trademark) are preferred, and when an anion exchange membrane (hereinafter also referred to as an anion exchange membrane) is used, FAA-3-SOLUT-10 and AS-4 are preferred. As the polymer electrolyte, it is possible to use a combination of a plurality of the above-mentioned polymer electrolytes, and examples of polymer alloys in which two or more types of polymers are mixed include polymer blends in which two or more types of polymers are physically mixed, and interpenetrated polymer networks (IPNs) in which a network structure is entangled.

[0026] The ionic liquid of this embodiment will be described below. Examples of the ionic liquid include imidazolium salts, pyridinium salts, ammonium salts, phosphonium salts, pyrrolidinium salts, piperidinium salts, and sulfonium salts.

[0027] Specific examples of imidazolium salts include those represented by formula (1): Examples include those represented by the following formula:

[0028] In formula (1), R １ａ ~R ５ａ may be the same or different, and each represents a hydrogen atom, C １ ~C １０ Examples of the alkyl group include an alkyl group, an allyl group, and a vinyl group. － Examples of the fluorine ion include a chloride ion, a bromide ion, an iodide ion, tetrafluoroborate, trifluoro(trifluoromethyl)borate, a dimethylphosphate ion, a diethylphosphate ion, hexafluorophosphate, tris(pentafluoroethyl)trifluorophosphate, trifluoroacetate, methyl sulfate, trifluoromethanesulfonate, and bis(trifluoromethanesulfonyl)imide.

[0029] Specific examples of the compound of formula (1) include a 1-allyl-3-methylimidazolium ion, a 3-ethyl-1-vinylimidazolium ion, a 1-methylimidazolium ion, a 1-ethylimidazolium ion, a 1-n-propylimidazolium ion, a 1,3-dimethylimidazolium ion, a 1,2,3-trimethylimidazolium ion, a 1-ethyl-3-methylimidazolium ion, a 1-ethyl-2,3-dimethylimidazolium ion, a 1,2,3,4-tetramethylimidazolium ion, a 1,3-diethylimidazolium ion, a 1-methyl-3-n-propylimidazolium ion, a 1-ethyl-3-methylimidazolium ion, a 2-ethyl-1,3-dimethylimidazolium ion, a 1-ethyl-2,3-dimethylimidazolium ion, a 1,3-dimethyl-n-propylimidazolium ion, imidazolium ions such as 1,3,4-trimethylimidazolium ion, 2-ethyl-1,3,4-trimethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl-2,3-dimethylimidazolium ion, 1-butyl-3-methylimidazolium ion, 1-hexyl-3-methylimidazolium ion, and 1-methyl-3-n-octylimidazolium ion, and X in the formula (1) － Examples of salt include:

[0030] Specific examples of pyridinium salts include those represented by formula (2): Examples include those represented by the following formula:

[0031] In formula (2), R １ｂ ~R ６ｂ may be the same or different, and each represents a hydrogen atom, a hydroxymethyl group, or C １ ~C ６ In addition, X in formula (2) may be an alkyl group. － Examples of the compound include the same compounds as those of formula (1).

[0032] Specific examples of the formula (2) include pyridinium ions such as 1-butyl-3-methylpyridinium ion, 1-butyl-4-methylpyridinium ion, 1-butyl-pyridinium ion, 1-ethyl-3-methylpyridinium ion, 1-ethylpyridinium ion, and 1-ethyl-3-(hydroxymethyl)pyridinium ion, and the like, and X in the formula (1) － Examples of salt include:

[0033] Specific examples of ammonium salts include those represented by formula (3): Examples include those represented by the following formula:

[0034] In formula (3), R １ｃ ~R ４ｃ may be the same or different, and each represents a hydrogen atom, a methoxyethyl group, a phenylethyl group, a methoxypropyl group, a cyclohexyl group, or C １ ~C ８ In addition, X in formula (3) may be an alkyl group. － Examples of the compound include the same compounds as those of formula (1).

[0035] Specific examples of the formula (3) include ammonium ions such as triethylpentylammonium ion, diethyl(methyl)propylammonium ion, methyltri-n-octylammonium ion, trimethylpropylammonium ion, cyclohexyltrimethylammonium ion, diethyl(2-methoxyethyl)-methylammonium ion, ethyl(2-methoxyethyl)-dimethylammonium ion, ethyl(3-methoxypropyl)dimethyl-ammonium ion, and ethyl(dimethyl)(2-phenylethyl)-ammonium ion, and the like, and X in the formula (1) － Examples of salt include:

[0036] Specific examples of phosphonium salts include those represented by formula (4): Examples include those represented by the following formula:

[0037] In formula (4), R １ｄ ~R ４ｄ may be the same or different, and each represents a hydrogen atom, a methoxyethyl group, or C １ ~C １０In addition, X in formula (3) may be an alkyl group. － Examples of the compound include the same compounds as those of formula (1).

[0038] Specific examples of the formula (4) include phosphonium ions such as tributylmethylphosphonium ion, tetrabutylphosphonium ion, trihexyl(tetradecyl)phosphonium ion, trihexyl(ethyl)phosphonium ion, and tributyl(2-methoxyethyl)phosphonium ion, and the like, and X in the formula (1) － Examples of salt include:

[0039] Specific examples of pyrrolidinium salts include those represented by formula (5): Examples include those represented by the following formula:

[0040] In formula (5), R １ｅ ~R ２ｅ may be the same or different, and each represents a hydrogen atom, an allyl group, a methoxyethyl group, or C １ ~C ８ In addition, X in formula (5) － Examples of the compound include the same compounds as those of formula (1).

[0041] Specific examples of the formula (5) include a pyrrolidinium ion such as 1-allyl-1-methylpyrrolidinium ion, 1-(2-methoxyethyl)-1-methylpyrrolidinium ion, 1-butyl-1-methylpyrrolidinium ion, 1-methyl-1-propylpyrrolidinium ion, 1-octyl-1-methylpyrrolidinium ion, and 1-hexyl-1-methylpyrrolidinium ion, and a compound represented by the formula (1) above. － Examples of salt include:

[0042] Specific examples of piperidinium salts include those represented by formula (6): Examples include those represented by the following formula:

[0043] In formula (6), R １ｆ ~R ２ｆ may be the same or different, and each represents a hydrogen atom or C １ ~C ６ In addition, X in formula (6) －Examples of the compound include the same compounds as those of formula (1).

[0044] Specific examples of the formula (6) include a compound obtained by combining a piperidinium ion such as a 1-butyl-1-methylpiperidinium ion or a 1-methyl-1-propylpiperidinium ion with X in the formula (1). － Examples of salt include:

[0045] Specific examples of sulfonium salts include those represented by formula (7): Examples include those represented by the following formula:

[0046] In formula (7), R １ｇ ~R ３ｇ may be the same or different, and each represents a hydrogen atom or C １ ~C ４ In addition, X in formula (3) may be an alkyl group. － Examples of the compound include the same compounds as those of formula (1).

[0047] Specific examples of the formula (4) include sulfonium ions such as triethylsulfonium ion and trisulfonium ion, and the X in the formula (1) － Examples of salt include:

[0048] More specifically, the ionic liquid may include 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium tris(pentafluoro ... iodide, 1-butyl-3-methylimidazolium tris(pentafluoro)imide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium trifluoromethyl)trifluorophosphate, 1-butyl-3-methylimidazolium trifluoro(trifluoromethyl)borate, 1-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium methylsulfate, 1,3-dimethylimidazolium dimethylphosphate, 2,3-dimethyl-1-propylimidazolium bis(trifluoromethyl) 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methylsulfate, 1-decyl-3-methylimidazolium bromide, 1-decyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium trifluoro(trifluoromethyl)borate, 3-ethyl-1-vinylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium methylsulfate, 1-ethyl-3-methylimidazolium diethylphosphate,1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-hexyl-3-methylimidazolium bromide, 1-(2-hydroxyethyl)-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-(2-hydroxyethyl)-3-methylimidazolium Imidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium iodide, 1-methyl-3-propylimidazolium iodide, 1-methyl-3-n-octylimidazolium bromide, 1-methyl-3-n-octylimidazolium chloride, 1-methyl-3-n-octylimidazolium hexafluorophosphate, 1-methyl-3-n-octylimidazolium trifluoromethanesulfonate, 1-methyl-3-n-octylimidazolium tetrafluoroborate, 1-methyl-3-propylimidazolium bromide, 1-methyl-3-propylimidazolium tetrafluoroborate, 1-methyl-3-pentylimidazolium bromide, 1-methyl-3-n-octylimidazolium bis(trifluoromethanesulfonyl)imide, 1-methyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium tetrafluoroborate, 1-butylpyridinium bis(trifluoromethanesulfonyl)imide, 1-butyl-4-methylpyridinium tetrafluoroborate pyridinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylpyridinium ethyl sulfate, 1-ethyl-3-(hydroxymethyl)pyridinium ethyl sulfate, 1-ethyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, triethylpentylammonium bis(trifluoromethanesulfonyl)imide, diethyl(methyl)propylammonium bis(fluorosulfonyl)imide, diethyl(2-methoxyethyl)methylammonium bis(fluorosulfonyl)imide,Ethyl(2-methoxyethyl)dimethylammonium bis(fluorosulfonyl)imide, ethyl(2-methoxyethyl)dimethylammonium bis(trifluoromethanesulfonyl)imide, ethyl(3-methoxypropyl)dimethylammonium bis(trifluoromethanesulfonyl)imide, ethyl(dimethyl)(2-phenylethyl)ammonium bis(trifluoromethanesulfonyl)imide, methyltri-n-octylammonium bis(trifluoromethanesulfonyl)imide, tributylmethylammonium bis(trifluoromethanesulfonyl)imide, trimethylpropylammonium bis(trifluoromethanesulfonyl)imide, tributylmethylphosphonium bis(trifluoromethanesulfonyl)imide, 1-allyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, triethylsulfonium bis(trifluoromethanesulfonyl)imide, or a combination of the above ionic liquids.

[0049] Of these, carbon black, Ketjen Black, Ketjen Black EC, Nafion (registered trademark), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorotrifluorophosphate are preferred as the catalyst support of this embodiment. These catalyst supports may be used alone or in combination of two or more, and preferred are a combination of carbon black and zinc oxide, a combination of Ketjen Black EC and zinc oxide, a combination of carbon black and molybdenum oxide, a combination of Ketjen Black EC and molybdenum oxide, a combination of carbon black, zinc oxide and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, a combination of Ketjen Black EC, zinc oxide and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, a combination of carbon black, zinc oxide and 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorotrifluorophosphate, and a combination of Ketjen Black EC, zinc oxide and 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorotrifluorophosphate.

[0050] The electron conductor in the cathode catalyst layer 103 of this embodiment is not particularly limited as long as it is capable of conducting electrons. Examples thereof include carbon black such as channel black, furnace black, thermal black, acetylene black, ketjen black, and ketjen black EC, activated carbon obtained by carbonizing and activating various materials containing carbon atoms, carbon materials such as coke, natural graphite, artificial graphite, and graphitized carbon, metal mesh such as nickel or titanium, and metal foam.

[0051] Of these, carbon black, ketjen black, ketjen black EC, nickel metal mesh, titanium metal mesh, and metal foam are preferred as the electron conductor of this embodiment because they have a large specific surface area and excellent electron conductivity, and titanium metal mesh and metal foam are more preferred because they have excellent durability.

[0052] The electrolyte in the cathode catalyst layer 103 of this embodiment is not particularly limited as long as it is capable of ion conduction. Examples of suitable electrolytes include fluorine-based polymer electrolytes, hydrocarbon-based polymer electrolytes, and anion-conducting electrolytes. Examples of suitable fluorine-based polymer electrolytes include fluorine-based sulfonic acid polymers, hydrocarbon-based sulfonic acid polymers, and partially fluorinated hydrocarbon-based sulfonic acid polymers, such as Nafion (registered trademark) from DuPont, Aquivion (registered trademark) from Solvay, Flemion (registered trademark) from AGC, and Aciplex (registered trademark) from Asahi Kasei. Examples of suitable hydrocarbon-based polymer electrolytes include sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, and sulfonated polyphenylene. Examples of suitable anion-conducting electrolytes include Fumion (registered trademark) FAA-3-SOLUT-10 from FUMATECH BWT GmbH and A3ver. from Tokuyama Corporation. 2 and AS-4 (A3ver. 2 and AS-4 are described, for example, in the magazine "Hydrogen Energy System," Vol. 1.35, No. 2, 2010, page 9). When a cation exchange membrane (hereinafter also referred to as a cation exchange membrane) is used as the electrolyte membrane described below, Nafion (registered trademark) and Aquivion (registered trademark) are preferred, and when an anion exchange membrane (hereinafter also referred to as an anion exchange membrane) is used, FAA-3-SOLUT-10 and AS-4 are preferred.

[0053] Among these, the electrolyte in the cathode catalyst layer 103 of this embodiment is preferably one that is responsible for proton conduction, and Nafion, Aquivion, Flemion, and Aciplex are preferred. The above electrolytes may be used in combination, and a perfluoroacid polymer such as Nafion is preferred.

[0054] The gas diffusion layer in the cathode catalyst layer 103 of this embodiment is not particularly limited as long as it is responsible for electron conduction, gas diffusion, and electrolyte diffusion. Examples include carbon paper, carbon felt, and carbon cloth. In this specification, the cathode catalyst layer 103 having a catalyst body that is a metal complex, a cathode solid catalyst, or a metal complex and a cathode solid catalyst, and a gas diffusion layer may be referred to as a gas diffusion electrode 133.

[0055] Examples of carbon paper include TGP-H-060, TGP-H-090, TGP-H-120, TGP-H-060H, TGP-H-090H, and TGP-H-120H from Toray Industries, Inc., EC-TP1-030T, EC-TP1-060T, EC-TP1-090T, and EC-TP1-120T from Electrochem Co., Ltd., and 22BB, 28BC, 36BB, and 39BB from SIGRACET Co., Ltd. Examples of carbon cloth include EC-CC1-060, EC-CC1-060T, and EC-CCC-060 manufactured by Electrochem Corporation, and Torayca (registered trademark) cloth manufactured by Toray Industries, Inc., as well as CO6142, CO6151B, CO6343, CO6343B, CO6347B, CO6644B, CO1302, CO1303, CO5642, CO7354, CO7359B, CK6244C, CK6273C, and CK6261C. Examples of carbon felt include H1410 and H2415 manufactured by Freudenberg.

[0056] Among these, the gas diffusion layer in the cathode catalyst layer 103 of this embodiment is preferably TGP-H-060, TGP-H-090, TGP-H-060H, TGP-H-090H, or EC-TP1-060T.

[0057] In the ammonia production method of this embodiment, examples of the proton source disposed in the electrolysis device include the electrolyte membrane 102 disposed beside the cathode catalyst layer 103, an electrolyte solution derived from the electrolyte membrane, and an electrolyte solution in an electrolyte solution tank disposed beside the cathode catalyst layer 103. The electrolyte solution is not particularly limited as long as it is a solution containing an electrolyte and is responsible for proton conduction. These proton sources may be used alone or in combination of two or more.

[0058] Examples of the solution in the electrolytic solution in the ammonia production method of the present embodiment include water, an aqueous sulfuric acid solution, an ionic liquid, methanol, isopropyl alcohol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, diethylamine, hexamethylphosphonic acid triamide, acetic acid, acetonitrile, methylene chloride, trifluoroethanol, nitromethane, sulfolane, pyridine, tetrahydrofuran, dimethoxyethane, and propylene carbonate, with water, an aqueous sulfuric acid solution, and an ionic liquid being preferred.

[0059] Examples of the ionic liquid include imidazolium salts, pyridinium salts, ammonium salts, phosphonium salts, pyrrolidinium salts, piperidinium salts, sulfonium salts, and the like, as described above.

[0060] An acid such as sulfuric acid or trifluoromethanesulfonic acid can be added to the ionic liquid. Preferred ionic liquids to which an acid is added include 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorotrifluorophosphate.

[0061] Examples of electrolytes contained in the electrolytic solution in the ammonia production method of this embodiment include cations such as protons, lithium ions, sodium ions, potassium ions, imidazolium ions, pyridinium ions, quaternary ammonium ions, phosphonium ions, pyrrolidinium ions, and phosphonium ions, either singly or in combination, and examples of anions include chloride ions, bromide ions, iodide ions, tetrafluoroborate, trifluoro(trifluoromethyl)borate, dimethylphosphate ions, diethylphosphate ions, hexafluorophosphate, tris(pentafluoroethyl)trifluorophosphate, trifluoroacetate, methyl sulfate, trifluoromethanesulfonate, bis(trifluoromethanesulfonyl)imide, perchlorate ions, sulfate ions, and nitrate ions, either singly or in combination. One type of electrolyte may be used alone, or two or more types may be used in combination.

[0062] Examples of the quaternary ammonium ion in the electrolyte include triethylpentylammonium ion, diethyl(methyl)propylammonium ion, methyltri-n-octylammonium ion, trimethylpropylammonium ion, cyclohexyltrimethylammonium ion, diethyl(2-methoxyethyl)methylammonium ion, ethyl(2-methoxyethyl)dimethylammonium ion, ethyl(3-methoxypropyl)dimethylammonium ion, ethyl(dimethyl)(2-phenylethyl)ammonium ion, tetramethylammonium ion, tetraethylammonium ion, triethylpentylammonium ion, tetra-n-butylammonium ion, diethyl(methyl)propylammonium ion, methyltri-n-octylammonium ion, trimethylpropylammonium ion, cyclohexyltrimethylammonium ion, diethyl(2-methoxyethyl)methylammonium ion, ethyl(2-methoxyethyl)dimethylammonium ion, ethyl(3-methoxypropyl)dimethylammonium ion, and ethyl(dimethyl)(2-phenylethyl)ammonium ion.

[0063] Specific examples of the imidazolium ion, pyridinium ion, phosphonium ion, pyrrolidinium ion and phosphonium ion in the electrolyte include those mentioned above.

[0064] The cations that are electrolytes contained in the electrolytic solution of this embodiment are preferably protons, imidazolium ions, and pyrrolidinium ions, and the anions that are electrolytes are preferably perchlorate ions and sulfate ions.

[0065] Specific examples of the cathode electrolyte 106 used in the cathode electrolyte tank 105 of this embodiment include water, an aqueous sulfuric acid solution, an ionic liquid, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methanol, ethanol, 1-propanol, 2-propanol, acetone, tetrahydrofuran, 1,2-dimethoxyethane, acetonitrile, pyridine, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and these may be used alone or in combination of two or more. Preferred examples of the cathode electrolyte 106 include water, an aqueous sulfuric acid solution, an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0066] Specific examples of the anode electrolyte 116 used in the anode electrolyte tank 115 of this embodiment include water, an aqueous sulfuric acid solution, an ionic liquid, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methanol, ethanol, 1-propanol, 2-propanol, acetone, tetrahydrofuran, 1,2-dimethoxyethane, acetonitrile, pyridine, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. Preferred examples of the anode electrolyte 116 include water, an aqueous sulfuric acid solution, an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0067] Examples of the electrolyte membrane 102 in the ammonia production method of this embodiment include polymer electrolyte membranes, reinforced membranes, etc., and depending on the difference in the fixed charge structure within a single membrane, in addition to cation exchange membranes and anion exchange membranes, bipolar membranes and mosaic charged membranes are listed as composite charged membranes in which the structures of cation exchange membranes and anion exchange membranes exist within a single membrane, and these can be arbitrarily selected and used in the ammonia production apparatus of this embodiment. Specific examples of such electrolyte membranes include DuPont's Nafion Membrane (registered trademark), Solvay's Aquivion Membrane (registered trademark), AGC's Flemion Membrane (registered trademark), Asahi Kasei's Aciplex (registered trademark), Dow Membrane (registered trademark), sulfonated polyether ketone polymer membranes, sulfonated polyether sulfone polymer membranes, sulfonated polyether ether sulfone polymer membranes, sulfonated polysulfide polymer membranes, sulfonated polyphenylene polymer membranes, and perfluorosulfonyl methyl methacrylate membranes using a polytetrafluoroethylene (PTFE) porous body as a reinforcing material. Examples of such membranes include GoreSelect Membrane (registered trademark) from Gore Japan LLC, which is impregnated with a phosphoric acid polymer, a membrane reinforced with PTFE woven fabric, a membrane using a porous polyethylene (PE) or porous polypropylene (PP) as a reinforcing material (for example, as described in patent document WO98 / 20063), a fibril-reinforced membrane using PTFE fibrils (for example, as described in patent document US2001-026883A1 and non-patent document Industrial Materials, 2001, Vol. 49, p. 31), Neosepta (registered trademark) from Astom Corporation, Selemion Membrane (registered trademark) from AGC Corporation, Aciplex Membrane (registered trademark) from Asahi Kasei Corporation, Fumasep Membrane (registered trademark) from FUMATECH BWT GmbH, and fumapem Membrane (registered trademark) from FUMATECH BWT GmbH. When a cation exchange membrane is used for the electrolyte membrane 102 in the ammonia production method of this embodiment, Nafion membrane (registered trademark) from DuPont, Aquivion membrane (registered trademark) from Solvay, and Gore Select membrane (registered trademark) from Gore Japan LLC are preferred, and when an anion exchange membrane is used, FAP-450 membrane and FAA-3 membrane from Fumasep membrane (registered trademark) from FUMATECH BWT GmbH, ASVN membrane and AHO membrane from Selemion membrane (registered trademark) from AGC are preferred.The electrolyte membrane 102 in the method for producing ammonia according to the present embodiment is preferably a cation exchange membrane such as a Nafion membrane (registered trademark) or an Aquivion membrane (registered trademark).

[0068] In the method for producing ammonia according to this embodiment, the reaction temperature is preferably −40° C. to 200° C., more preferably −10° C. to 120° C., and even more preferably 0° C. to 100° C. The electrolysis apparatus can be started from room temperature. The reaction atmosphere may be a pressurized atmosphere by providing a back pressure valve in the nitrogen supply pipe, or may be a normal pressure atmosphere. The reaction time is not particularly limited, but may usually be set in the range of several tens of minutes to several tens of hours. The reaction can be carried out continuously, but can also be stopped midway; for example, the reaction can be stopped after several hours and then restarted.

[0069] The ammonia production method and electrolysis apparatus serving as the production apparatus of this embodiment will be described below. As examples, Fig. 1 shows an ammonia electrolysis apparatus (No. 1) 100 for producing ammonia, Fig. 2 shows an ammonia electrolysis apparatus (No. 2) 200 for producing ammonia, Fig. 3 shows an ammonia electrolysis apparatus (No. 3) 300 for producing ammonia, Fig. 4 shows an ammonia electrolysis apparatus (No. 4) 400 for producing ammonia, and Fig. 5 shows an ammonia electrolysis apparatus (No. 5) 500 for producing ammonia.

[0070] The ammonia electrolysis device (part 1) 100 ( FIG. 1 ) of this embodiment is an ammonia production device capable of producing ammonia from nitrogen molecules through an electrolytic reaction. The ammonia production device includes a cathode 108, an anode 118, and a membrane electrode assembly 131 in which a cathode catalyst layer 103 and an anode catalyst layer 113 are integrated via an electrolyte membrane 102. The cathode catalyst layer 103 is bonded to one side of the electrolyte membrane 102, and a cathode current collector 104 is disposed on its outer side. The anode catalyst layer 113 is bonded to the other side of the electrolyte membrane 102, and an anode current collector 114 is disposed on its outer side. The current collector has flow paths for circulating gas, electrolytic solution, and reaction solution. The reaction solution refers to a mixture of a product of an electrolytic reaction in the device with the gas and electrolytic solution. The cathode catalyst layer 103 includes a metal complex and a cathode solid catalyst, and the anode catalyst layer 113 includes an anode solid catalyst. The manufacturing apparatus (first) 100 includes a cathode-side gas, electrolyte, and reaction solution flow path 136 that comes into solid-liquid-gas contact with the cathode 108 of the membrane electrode assembly 131, and a cathode electrolyte tank 105 that stores the cathode electrolyte 106; and an anode-side gas, electrolyte, and reaction solution flow path 135 that comes into solid-liquid-gas contact with the anode 118 of the membrane electrode assembly 131, and an anode electrolyte tank 115 that stores the anode electrolyte 116. In the present invention, when hydrogen gas is supplied to the anode, it can be supplied from a hydrogen cylinder 127 via a hydrogen cylinder regulator 128 and a hydrogen gas mass flow controller 129 through a pipe 121. When an electrolyte is not used, the hydrogen gas supplied from the pipe 121 connected to the anode electrolyte tank 115 comes into solid-gas contact with the anode 118. When an electrolyte is used, the hydrogen gas supplied from the pipe 121 connected to the anode electrolyte tank 115 comes into solid-liquid-gas contact with the anode 118. The device is equipped with a power source (power supply device 101) that supplies electrons to the cathode 108, a proton source that supplies protons to the cathode 108, and a means for supplying nitrogen gas to the cathode electrolyte 106 and the cathode 108. The proton source can be provided by the electrolyte membrane 102, the cathode electrolyte 106, the cathode catalyst layer 103, the anode electrolyte 116, or the anode catalyst layer 113.Nitrogen gas is supplied from a nitrogen cylinder 122 via a nitrogen cylinder regulator 123 and a nitrogen gas mass flow controller 124 through a pipe 121. When nitrogen gas is being supplied, the three-way cock 302 is not connected to the electrolyte and reaction solution recovery tank 201. Hydrogen gas can be supplied to the anode 118 from a hydrogen cylinder 127 via a hydrogen cylinder regulator 128 and a hydrogen gas mass flow controller 129 through a pipe 121. Ammonia produced at the cathode 108 can be collected in a cathode electrolyte tank 105 that stores the cathode electrolyte 106 and a dilute sulfuric acid aqueous solution tank 125 for ammonia collection. The cathode electrolyte 106 can be collected in the electrolyte and reaction solution recovery tank 201, and the next cathode electrolyte 106 can be sent from the storage tank 202 to the cathode electrolyte tank 105 by a liquid feed pump 303. The by-produced hydrogen and unreacted nitrogen pass through pipe 121, pass through a dilute sulfuric acid aqueous solution tank 125 for capturing ammonia, and are discharged to the outside through a draft device 126. Since the illustration is an example, the two-way cock 301 is shown in a representative position, but cocks for protecting devices inside the apparatus, such as a regulator and a mass flow controller, can be attached to the pipe.

[0071] The ammonia electrolysis apparatus (3) 300 ( FIG. 3 ) of this embodiment is an ammonia production apparatus capable of producing ammonia from nitrogen molecules by an electrolytic reaction, and is configured by adding a pipe 305, a three-way cock 307, and a three-way cock 308 to the ammonia electrolysis apparatus (1) 100. Differences from the ammonia electrolysis apparatus (1) 100 will be described. When hydrogen gas by-produced at the cathode 108 is supplied to the anode 118 according to the present invention, the ammonia capture dilute sulfuric acid aqueous solution tank 125 and the pipe 305 are connected by a three-way cock 306, and the pipe 305 and the mass flow controller 129 are connected by a three-way cock 307. This allows the mixed gas (nitrogen and hydrogen mixed gas) that has passed through the ammonia capture dilute sulfuric acid aqueous solution tank to be supplied to the anode electrolyte tank 115 and the anode 118, and the hydrogen gas in the mixed gas comes into solid-gas contact with the anode 118. The anode electrolyte 116 can also be used in this case. The anode electrolyte 116 can be recovered in the electrolyte and reaction solution recovery tank 205, and the next anode electrolyte 116 can be sent from the storage tank 206 to the anode electrolyte tank 115 by a liquid feed pump 303. The by-produced hydrogen and unreacted nitrogen pass through a pipe 121 and a dilute sulfuric acid aqueous solution tank 125 for capturing ammonia, and can be discharged to the outside via a draft device 126 using a three-way cock 302, or can be sent to the anode 118 via a pipe 305 according to the present invention. Since the illustration is an example, the two-way cock 301 is shown in a representative position, but cocks for protecting devices within the apparatus, such as a regulator and a mass flow controller, can be attached to the pipe.

[0072] The ammonia electrolysis device (part 2) 200 of this embodiment is an ammonia production device capable of producing ammonia from nitrogen molecules through an electrolytic reaction. The ammonia production device includes a cathode 108, an anode 118, and a membrane electrode assembly 131 in which a cathode catalyst layer 103 and an anode catalyst layer 113 are integrated via an electrolyte membrane 102. The cathode catalyst layer 103 is bonded to one side of the electrolyte membrane 102, and a cathode-side separator 204 and a cathode current collector 104 are disposed on the outer side thereof. The anode catalyst layer 113 is bonded to the other side of the electrolyte membrane 102, and an anode-side separator 214 and an anode current collector 114 are disposed on the outer side thereof. The separator and the current collector are provided with flow paths for circulating gas, electrolytic solution, and reaction solution. The reaction solution refers to a mixture of a product of the electrolytic reaction in the device with the gas and electrolytic solution. The cathode catalyst layer 103 comprises a metal complex and a cathode solid catalyst, and the anode catalyst layer 113 comprises an anode solid catalyst. The manufacturing apparatus (part 2) 200 comprises a cathode-side flow path 136 for gas, electrolyte, and reaction solution that comes into solid-liquid-gas contact with the cathode 108 of the membrane electrode assembly 131, and anode-side flow path 135 for gas, electrolyte, and reaction solution that comes into solid-liquid-gas contact with the anode 118 of the membrane electrode assembly 131. When hydrogen gas is supplied to the anode, hydrogen gas can be supplied from a hydrogen cylinder 127 through a hydrogen cylinder regulator 128, a hydrogen gas mass flow controller 129, and a gas humidifier 304 and then through a pipe 121. When the gas humidifier is set to non-humidification, hydrogen gas supplied from a pipe 121 connected to a flow path 135 for the anode-side gas, electrolytic solution, and reaction solution comes into solid-gas contact with the anode 118, and when the gas humidifier is set to humidification, hydrogen gas supplied from a pipe 121 connected to a flow path 135 for the anode-side gas, electrolytic solution, and reaction solution comes into solid-liquid-gas contact with the anode 118. The device is equipped with a power source (power supply device 101) that supplies electrons to the cathode 108, a proton source that supplies protons to the cathode 108, and a means for supplying nitrogen gas to the cathode 108.Examples of proton sources include the electrolyte membrane 102, the cathode electrolyte 106, the cathode catalyst layer 103, the anode electrolyte 116, and the anode catalyst layer 113. Nitrogen gas is supplied from a nitrogen cylinder 122 via a nitrogen cylinder regulator 123, a nitrogen gas mass flow controller 124, a gas humidifier 304, a two-way cock 301, and a three-way cock 302 through a pipe 121; humidified nitrogen controlled by a relative humidity value can also be supplied. When nitrogen gas is being supplied, the three-way cock 302 is not connected to the recovery tank 201 for the electrolyte and reaction solution. The gas humidifier 304 can be used to switch between non-humidified and humidified modes. Hydrogen gas is supplied to the anode 118 via a hydrogen cylinder 127, a hydrogen cylinder regulator 128, a hydrogen gas mass flow controller 129, and a gas humidifier 304, through a pipe 121. Humidified hydrogen controlled by relative humidity can also be supplied. The ammonia produced at the cathode 108 can be recovered in a dilute sulfuric acid aqueous solution tank 125 for ammonia capture and an electrolyte and reaction solution recovery tank 201. A liquid transfer pump 303 can transfer the electrolyte and reaction solution to the cathode 108. The by-product hydrogen and unreacted nitrogen pass through the pipe 121, pass through the dilute sulfuric acid aqueous solution tank 125 for ammonia capture, and are discharged to the outside via a draft device 126. Cocks can be attached to the pipes to protect the regulator, mass flow controller, and other internal equipment.

[0073] The ammonia electrolysis apparatus (4) 400 ( FIG. 4 ) of this embodiment is an ammonia production apparatus capable of producing ammonia from nitrogen molecules by an electrolytic reaction, and is configured by adding a pipe 305, a three-way cock 307, and a three-way cock 308 to the ammonia electrolysis apparatus (2) 200. Differences from the ammonia electrolysis apparatus (2) 200 will be described. When hydrogen gas by-produced at the cathode 108 is supplied to the anode 118 according to the present invention, the dilute sulfuric acid aqueous solution tank 125 for ammonia absorption and the pipe 305 are connected by the three-way cock 306, and the pipe 305 and the mass flow controller 129 are connected by the three-way cock 307. This allows the mixed gas (mixed gas of nitrogen and hydrogen) that has passed through the dilute sulfuric acid aqueous solution tank for ammonia absorption to be supplied to the anode electrolyte tank 115 and the anode 118, and the hydrogen gas in the mixed gas comes into solid-gas contact with the anode 118. The anode electrolyte 116 can also be used in this case. The anode electrolyte 116 can be collected in the electrolyte and reaction solution recovery tank 205. The next anode electrolyte 116 can be sent from the storage tank 206 to the anode-side gas, electrolyte, and reaction solution flow path 135 using a liquid feed pump 303, and then sent to the recovery tank 205. By connecting the recovery tank 205 and the storage tank 206, the anode electrolyte 116 can also be circulated using the liquid feed pump 303. Hydrogen gas can be directly supplied to the anode 118 by supplying it from a hydrogen cylinder 127 via a hydrogen cylinder regulator 128, a hydrogen gas mass flow controller 129, a gas humidifier 304, a two-way cock 301, and a three-way cock 302 through piping 121. Humidified hydrogen controlled by the relative humidity can also be supplied. Ammonia generated at the cathode 108 can be collected in the dilute sulfuric acid aqueous solution tank 125 for ammonia collection and the electrolyte and reaction solution recovery tank 201. A liquid feed pump 303 can feed the electrolytic solution and the reaction solution to the cathode 108. The by-produced hydrogen and unreacted nitrogen pass through a pipe 121 and a dilute sulfuric acid aqueous solution tank 125 for capturing ammonia, and can be discharged to the outside via a draft device 126 using a three-way cock 302, or can be sent to the anode 118 via a pipe 305 according to the present invention.Cocks can be attached to the piping to protect devices inside the apparatus, such as regulators and mass flow controllers. By closing the three-way cock 302 of the ammonia electrolysis apparatus (No. 4) 400 ( FIG. 4 ) of this embodiment after introducing the reactant gas and the electrolyte into the anode-side and cathode-side flow paths, the cathode catalyst layer and the anode catalyst layer can be pressurized with the reactant gas and the electrolyte, respectively, and the electrolytic reaction can be promoted.

[0074] The ammonia electrolysis apparatus (no. 5) 500 ( FIG. 5 ) of this embodiment is an ammonia production apparatus that can produce ammonia from nitrogen molecules by an electrolytic reaction, and is an apparatus that is configured by adding two two-way cocks 308 and two two-way cocks 309 to the ammonia electrolysis apparatus (no. 3) described above ( FIG. 3 ). By closing the two-way cocks 308 on the anode side and the cathode side, introducing the reactant gas and the electrolyte, and then closing the two-way cock 309, the electrolyte tank and the cathode catalyst layer on the cathode side and the electrolyte tank and the anode catalyst layer on the anode side can be pressurized with the reactant gas and the electrolyte, respectively, and the electrolytic reaction can be promoted.

[0075] The cathode current collector 104 and the anode current collector 114 in the manufacturing apparatus of this embodiment may be made of, for example, carbon, a metal, an oxide, a metal-plated surface, an alloy containing two or more metals, an oxide containing two or more metals, stainless steel, indium tin oxide, indium zinc oxide, etc. Among these, metals include titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, rhodium, silver, tantalum, tungsten, osmium, iridium, indium, platinum, gold, etc., and oxides include titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, niobium pentoxide, molybdenum oxide, ruthenium oxide, rhodium oxide, silver oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, indium oxide, platinum oxide, gold oxide, etc.

[0076] The shape of the current collector is not particularly limited as long as it allows gas and electrolyte to pass through, and examples thereof include perforated, wire, rod, plate, foil, mesh, woven fabric, nonwoven fabric, expanded, porous, foam, etc. To prevent corrosion during production by electrolysis, it is also possible to use a current collector that has been gold-plated or the like.

[0077] In the electrolysis device of this embodiment, nitrogen gas can be supplied from a nitrogen cylinder 122 via a nitrogen cylinder regulator 123, a nitrogen gas mass flow controller 124, and a gas humidifier 304, with the flow rate controlled to provide humidified nitrogen managed based on the relative humidity. For example, nitrogen gas can be supplied by bubbling it into the electrolyte in the cathode electrolyte tank 105 in FIGS. 1 , 3, and 5 and the anode electrolyte tank 115 in FIGS. 2 and 4. Alternatively, nitrogen gas can be supplied directly to the cathode catalyst layer 103 through a hole in the cathode current collector 104, as shown in FIGS. 2 and 4. In the electrolysis device (2) 200 and the electrolysis device (4) 400, humidified nitrogen gas with a set relative humidity can also be supplied.

[0078] The electrolytic reaction for producing ammonia in the cathode catalyst layer 103 in the electrolysis device of this embodiment will be described. The catalyst of this embodiment causes a reaction to occur in which ammonia is produced from three elements: electrons supplied from the power supply device 101, nitrogen gas supplied to the cathode 108, and a proton source supplied to the cathode 108. When the environment in which the catalyst is placed is acidic, the reaction formula is "N ２ +6e － +6H ＋ →2NH ３ " or "N ２ +6e － +6H ３ O ＋ →2NH ３ +6H ２ O", and when the environment in which the catalyst body is placed is alkaline, "N ２ +6e － +6H ２ O → 2NH ３ +6OH － " can be written formally as ".

[0079] While ammonia is produced in the cathode catalyst layer 103, hydrogen is also produced as a by-product due to the reaction of hydroxonium ions or water and electrons in the cathode catalyst layer. This by-product hydrogen can also be dissociated on a solid catalyst or catalyst support. For example, on a platinum catalyst, which is a metal catalyst, adsorbed hydrogen dissociates homolytically into hydrogen atoms, while on zinc oxide, which is a metal oxide, adsorbed hydrogen dissociates heterolytically into protons and hydrides, as described on page 358 of the non-patent document, Schreiber-Atkins Inorganic Chemistry (Vol. 1), 6th Edition (2016, Japanese translation). It is speculated that the activated hydrogen atoms, protons, and hydrides on the solid catalyst promote the reaction that produces ammonia.

[0080] The ammonia produced at the cathode 108 can be sent to a dilute sulfuric acid aqueous solution tank 125 for capturing ammonia together with by-produced hydrogen and unreacted nitrogen, and in the electrolysis device (first) 100 and the electrolysis device (third) 300, the ammonia can also be captured in the electrolyte used in the cathode electrolyte tank 105. In this case, the electrolyte used in the cathode electrolyte tank 105 is preferably water or a dilute sulfuric acid aqueous solution from the viewpoint of recovery and reuse. The efficiency of ammonia capture can be improved by circulating the electrolyte in the cathode electrolyte tank 105 with a pump. For example, by connecting the recovery tank 201 and the storage tank 202, the cathode electrolyte 106 and the cathode reaction solution can be circulated by a liquid feed pump 303.

[0081] In the electrolysis device of this embodiment, ammonia is produced in the cathode catalyst layer 103, and the mixed gas composed of by-produced hydrogen and unreacted nitrogen can be selectively captured by using water or a dilute sulfuric acid solution, as described above. Therefore, it is possible to simultaneously extract the mixed gas of by-produced hydrogen and nitrogen, and hydrogen, which is useful as an energy carrier, can also be obtained in this embodiment. For safety reasons, the by-produced hydrogen can also be discharged to the outside through the draft device 126. As in the present invention, ammonia can be efficiently produced from nitrogen molecules by providing hydrogen molecules by means of feeding hydrogen gas produced at the cathode to the anode.

[0082] Putty or a sealant may be used at the connection portions between the gas pipe and the electrolyte tank to prevent gas or liquid leakage.

[0083] The electrolytic reaction in the anode catalyst layer 113 in the electrolysis device of this embodiment will be described. A reaction occurs in which electrons and protons are generated from the supplied hydrogen by the catalyst of the anode 118, and the reaction formula is "H ２ →2e － +2H ＋ The generated protons pass through the electrolyte membrane 102 or the electrolyte solution and move to the cathode 108, and the electrons pass through the anode current collector 114 and move to the power supply device 101. In this electrolysis device, while paying attention to the hydrogen concentration and oxygen concentration, it is also possible to supply electrons and protons by stopping the supply of hydrogen and supplying water to the anode catalyst layer 113. In this case, a reaction occurs in which oxygen, electrons, and protons are generated from water, and the reaction formula is "2H ２ O → O ２ +4e － +4H ＋ The generated protons pass through the electrolyte membrane 102 or the electrolyte solution to the cathode 108, and the electrons pass through the anode current collector 114 to the power supply 101. The generated oxygen can be released to the atmosphere while partially dissolved in the water in the anode electrolyte tank 115. Alternatively, the oxygen can be forcibly expelled by bubbling nitrogen gas into the anode electrolyte tank 115, and hydrogen can be supplied again. When water is supplied to the anode catalyst layer 113, the generated oxygen can be released to the atmosphere while partially dissolved in the water in the anode electrolyte tank 115 or the anode-side gas, electrolyte, and reaction solution flow paths. Alternatively, the supply of water to the anode catalyst layer 113 can be stopped and hydrogen can be supplied again. The electrolysis device (3) 300 and the electrolysis device (4) 400 can selectively use hydrogen gas from the hydrogen cylinder 127 or hydrogen gas by-produced at the cathode 108.

[0084] The anode catalyst layer 113 in the electrolysis device of this embodiment includes a catalyst support, an electrolyte, and a gas diffusion layer in addition to a solid catalyst. In this specification, the anode catalyst layer 113 including the anode solid catalyst, the catalyst support, the electron conductor, the electrolyte, and the gas diffusion layer may be referred to as a gas diffusion electrode 133.

[0085] The anode solid catalyst is defined as the solid catalyst in the anode catalyst layer 113 of the electrolytic device of this embodiment. Examples of the anode solid catalyst include the same as those described for the solid catalyst and cathode solid catalyst in the ammonia production method of this embodiment, and specific examples include metals such as iridium (IV) oxide powder catalyst, iridium oxide catalyst, platinum catalyst, gold catalyst, silver catalyst, ruthenium catalyst, iridium catalyst, rhodium catalyst, palladium catalyst, osmium catalyst, tungsten catalyst, lead catalyst, iron catalyst, chromium catalyst, cobalt catalyst, nickel catalyst, manganese catalyst, vanadium catalyst, molybdenum catalyst, gallium catalyst, and aluminum catalyst, as well as alloys thereof. Of these, the anode solid catalyst is preferably an iridium (IV) oxide powder catalyst, an iridium oxide catalyst, or a platinum catalyst. Furthermore, from the viewpoint of efficiently carrying out the electrolysis reaction both when water is supplied to the anode catalyst layer 113 and when hydrogen gas is supplied to the anode catalyst layer 113, it is also possible to combine an iridium oxide catalyst with a platinum catalyst, and to use a combination of an iridium oxide (IV) powder catalyst with a platinum catalyst.

[0086] The catalyst support in the anode catalyst layer 113 of this embodiment may be responsible for electron conduction and is not particularly limited as long as it can support the catalyst of this embodiment. Examples of the catalyst support include carbon black, carbon materials, metal mesh, metal foam, metal oxides, and composite oxides.

[0087] Examples of carbon black include channel black, furnace black, thermal black, acetylene black, ketjen black, and ketjen black EC. Examples of carbon materials include activated carbon obtained by carbonizing and activating various carbon-containing materials, coke, natural graphite, artificial graphite, and graphitized carbon. Examples of metal mesh include metal meshes of nickel or titanium. Examples of metal foams include aluminum, magnesium, titanium, zinc, iron, tin, lead, and alloys containing these. Examples of the metal oxide include aluminum oxide, zirconium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, niobium pentoxide, molybdenum oxide, ruthenium oxide, rhodium oxide, silver oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, indium oxide, platinum oxide, gold oxide, magnesium oxide, and silica. Examples of the composite oxide include silica-alumina and silica-magnesia. Among these, as the catalyst support, carbon black, Ketjenblack, Ketjenblack EC, nickel metal mesh, titanium metal mesh, titanium oxide, and metal foam are preferred because of their high specific surface area and excellent electronic conductivity, and titanium metal mesh, titanium oxide, and metal foam are more preferred because of their excellent durability.

[0088] The electrolyte in the anode catalyst layer 113 of this embodiment is not particularly limited as long as it is capable of ion conduction. Examples include the same electrolytes as those described for the electrolyte in the cathode catalyst layer 103 of this embodiment. Specific examples include, when a cation exchange membrane is used for the electrolyte membrane, fluorine-based sulfonic acid polymers, hydrocarbon-based sulfonic acid polymers, and partially fluorinated hydrocarbon-based sulfonic acid polymers, such as DuPont's Nafion (registered trademark), Solvay's Aquivion (registered trademark), AGC's Flemion (registered trademark), and Asahi Kasei's Aciplex (registered trademark). Among these, the electrolyte is preferably one that is capable of proton conduction, with Nafion, Aquivion, Flemion, and Aciplex being preferred. A mixture of the above electrolytes may be used, and it is preferable to include a perfluoroacid-based polymer such as Nafion. When an anion exchange membrane is used for the electrolyte membrane, it is preferable to use one that is capable of conducting hydroxide ions, with FAA-3-SOLUT-10 and AS-4 being preferred.

[0089] The gas diffusion layer in the anode catalyst layer 113 of this embodiment is not particularly limited as long as it is responsible for electron conduction, gas diffusion, and electrolyte diffusion. Examples include the same materials as those described for the gas diffusion layer in the cathode catalyst layer 103 of this embodiment, and carbon paper is preferred. Specific examples include TGP-H-060, TGP-H-090, TGP-H-120, TGP-H-060H, TGP-H-090H, and TGP-H-120H from Toray Industries, Inc., EC-TP1-030T, EC-TP1-060T, EC-TP1-090T, and EC-TP1-120T from Electrochem, Inc., and 22BB, 28BC, 36BB, and 39BB from SIGRACET. Among these, TGP-H-060, TGP-H-090, TGP-H-060H, TGP-H-090H, and EC-TP1-060T are preferred for the gas diffusion layer.

[0090] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0091] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0092] Example 1 1. Preparation of an Electrolytic Device for Producing Ammonia A cathode catalyst layer 103, which is a catalyst layer for producing ammonia, was prepared as follows. The catalyst ink 1A used for the cathode 108 is an ink for applying the cathode solid catalyst of this embodiment to the cathode catalyst layer 103. Catalyst ink 1A was prepared using a carbon black-supported platinum catalyst (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., platinum content: 46.6 wt %, product name "TEC10E50E") as the solid catalyst, deionized water, ethanol, and a Nafion dispersion solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "5% Nafion dispersion solution DE520 CS type") as the electrolyte. Hereinafter, the carbon black-supported platinum catalyst may be abbreviated as a carbon-supported platinum catalyst. A carbon-supported platinum catalyst, deionized water, ethanol, and Nafion dispersion were added to a glass vial in this order, and the resulting dispersion was irradiated with ultrasound for 30 minutes using a Microtec Nichion ultrasonic homogenizer, Smurth NR-50M, at an output of 40%, to prepare catalyst ink 1A. Next, this catalyst ink 1A was applied to carbon paper (manufactured by Toray Industries, Inc., product name "TGP-H-060H") fixed to a hop plate heated to 80°C, and the ethanol and water were allowed to dry. The amount of application was 1 cm. ２ The amount of platinum applied was adjusted to 1.0 mg per electrode. In this way, a gas diffusion electrode 133 (hereinafter sometimes abbreviated as "GDE") containing Nafion as the electrolyte and a carbon-supported platinum catalyst as the solid catalyst was fabricated. Specifically, the gas diffusion electrode 133 was a 2.8 × 2.8 cm electrode coated with 7.8 mg of platinum catalyst, which was a solid catalyst. ２ The gas diffusion electrode 133 was a square, and was designated "GDE-Cathode-1A."

[0093] Next, catalyst ink 1B was prepared by applying the metal complex of this embodiment to the cathode catalyst layer 103. A solution of rac-dimethylsilylbis(1-indenyl)zirconium dichloride (7.1 mg, 16 μmol) as the metal complex in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (2.4 mL) was used to prepare catalyst ink 1B. This catalyst ink 1B (20 μL) was applied to the gas diffusion electrode 133 "GDE-Cathode-1A" to prepare the cathode catalyst layer 103. Specifically, the gas diffusion electrode 133, which is the cathode catalyst layer 103, was a 2.8 × 2.8 cm electrode coated with a platinum catalyst (7.8 mg) and rac-dimethylsilylbis(1-indenyl)zirconium dichloride (0.13 μmol), which are solid catalysts. ２ The gas diffusion electrode 133 was a square, and was designated "GDE-Cathode-1."

[0094] The proportion of Nafion (hereinafter abbreviated as ionomer) in the above-mentioned catalyst ink 1A will now be described. Catalyst ink 1A was prepared so that the proportion (wt%) of ionomer calculated using the following formula was 28 wt%: Ionomer proportion (wt%) = [ionomer solids (wt) / [(carbon-supported platinum catalyst (wt) + ionomer solids (wt))] x 100

[0095] Specifically, when the ionomer was Nafion, the amount of the carbon-supported platinum catalyst was 100.0 mg, the amount of the Nafion dispersion was 837 μL, the amount of deionized water was 0.6 mL, and the amount of ethanol was 5 mL. The Nafion solid content in the Nafion dispersion (837 μL) was 38.9 mg.

[0096] The anode catalyst layer 113 was fabricated as follows. The catalyst ink 1A described in the cathode catalyst layer 103 was prepared in the same manner and applied in the same manner to fabricate a gas diffusion electrode 133, which is the anode catalyst layer 113 containing Nafion as the electrolyte and a carbon-supported platinum catalyst as the solid catalyst. Specifically, the gas diffusion electrode 133, which is the anode catalyst layer 113, was fabricated as a 2.8 × 2.8 cm ... ２The gas diffusion electrode 133 was a square, and was designated "GDE-Anode-1."

[0097] [Electrolysis Device (Part 1)] A membrane electrode assembly (hereinafter sometimes abbreviated as "MEA") consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was fabricated as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (membrane thickness: 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-1" serving as a cathode catalyst layer was disposed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-1" serving as an anode catalyst layer was disposed on the other side. Then, the upper and lower plates were thermocompression-bonded under the conditions of a temperature of 132°C, a load of 5.4 kN, and a compression-bonding time of 240 seconds to fabricate a membrane electrode assembly "MEA-1."

[0098] Stainless steel current collectors 104 and 114, each having 25 circular holes of 2.5 mm in diameter, were attached to both sides of the obtained "MEA-1" together with a Teflon (registered trademark) sheet serving as a gasket 134, to an electrolytic cell, thereby assembling the electrolysis device (part 1) 100 shown in FIG. 1 .

[0099] 2. Production of Ammonia Using the Electrolysis Apparatus for Ammonia Production (Part 1) assembled as described above, ammonia was produced by electrolysis under the following conditions. Temperature of the apparatus body: 25 to 28°C (room temperature). Power supply 101: Voltage and current were measured using a Versa STAT4 power supply from Princeton Applied Research. Cathode electrolyte tank 105: Nitrogen was bubbled into an aqueous sulfuric acid solution (0.02 mol / L, 6 mL) at 10 mL / min. Anode electrolyte tank 115: Hydrogen gas was flowed at 5 mL / min. Dilute sulfuric acid aqueous solution tank 125 for ammonia capture: Aqueous sulfuric acid solution (0.02 mol / L, 10 mL). Electrolysis conditions: Constant-potential electrolysis was performed at -2.3 V for 1 hour.

[0100] Ammonia was quantified using a Thermo Scientific Dionex ion chromatography (IC) system, Dionex Integration, manufactured by Thermo Corp. The sulfuric acid aqueous solution in the dilute sulfuric acid aqueous solution tank 125 for ammonia capture and the sulfuric acid aqueous solution in the cathode electrolyte tank 105 were collected, and the amount of ammonia was quantified to determine the amount of ammonia produced.

[0101] The amount of ammonia produced in this example was 1.21 (μmol).

[0102] Example 2 1. Preparation of an electrolysis device for producing ammonia The cathode catalyst layer 103 was prepared as follows. The catalyst ink 2A ​​used for the cathode 108 is an ink for applying the cathode solid catalyst of this embodiment to the cathode catalyst layer 103. The catalyst ink 2A ​​was prepared using a carbon black-supported platinum catalyst (manufactured by Tanaka Kikinzoku Kogyo K.K., platinum content: 46.5 wt %, product name "TEC10E50E") as the solid catalyst, 2-propanol (manufactured by Junsei Chemical Co., Ltd.), and a Nafion dispersion solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "5% Nafion dispersion solution DE520 CS type") as the electrolyte. Catalyst ink 2A ​​was prepared by adding a carbon-supported platinum catalyst, a Nafion dispersion, and 2-propanol, in that order, to a glass vial and irradiating the dispersion with ultrasonic waves for 30 minutes using an AS ONE Corporation ultrasonic cleaner ASU-6 with the oscillation power set to High. The proportion of Nafion (hereinafter abbreviated as "ionomer") in the above-mentioned catalyst ink 2A ​​will be described. Catalyst ink 2A ​​was prepared so that the proportion (wt%) of ionomer calculated from the above formula was 28 wt%. Specifically, the amount of carbon-supported platinum catalyst was 100 mg, the amount of Nafion dispersion was 837 μL (the amount of Nafion solids in the dispersion was 38.9 mg), and the amount of 2-propanol was 2.5 mL. Catalyst ink 2A ​​was applied using the following procedure. Carbon paper (manufactured by Toray Industries, product name "TGP-H-060H") was attached to a fixture so that the surface to be coated could be set to a 6.8 cm x 6.8 cm square, and the coating was carried out using an applicator. The entire amount of the prepared catalyst ink 2A ​​was used for coating, and the solvent and 2-propanol in the Nafion dispersion solution were dried, leaving a 1 cm area of ​​the coated surface.２ Specifically, the gas diffusion electrode 133 was a 2.8×2.8 cm electrode coated with a platinum catalyst (7.8 mg) as a solid catalyst. ２ The gas diffusion electrode 133 was a square, and was designated "GDE-Cathode-2A."

[0103] Next, catalyst ink 2B was prepared by applying the metal complex of this embodiment to the cathode catalyst layer 103. Catalyst ink 2B was prepared by dissolving rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride (6.8 mg, 16 μmol) as the metal complex in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (2.4 mL). This catalyst ink 2B (20 μL) was applied to the gas diffusion electrode 133 "GDE-Cathode-2A" to prepare the cathode catalyst layer 103. Specifically, the gas diffusion electrode 133, which is the cathode catalyst layer 103, is a 2.8 × 2.8 cm 2 electrode coated with a platinum catalyst (7.8 mg) and rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride (0.13 μmol). ２ The gas diffusion electrode 133 was a square, and was designated "GDE-Cathode-2."

[0104] The anode catalyst layer 113 was fabricated as follows. The catalyst ink 2A ​​described in the cathode catalyst layer 103 was prepared in the same manner and applied in the same manner to fabricate a gas diffusion electrode 133, which is the anode catalyst layer 113 containing Nafion as the electrolyte and a carbon-supported platinum catalyst as the solid catalyst. Specifically, the gas diffusion electrode 133, which is the anode catalyst layer 113, was fabricated as a 2.8 × 2.8 cm ... ２ The gas diffusion electrode 133 was a square, and was designated "GDE-Anode-2."

[0105] [Electrolysis Device (Part 2)] A membrane electrode assembly consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was produced as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (film thickness 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-2" serving as a cathode catalyst layer was placed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-2" serving as an anode catalyst layer was placed on the other side, and then thermocompression bonding was performed under conditions of a top and bottom plate temperature of 132°C, a load of 5.4 kN, and a compression bonding time of 240 seconds to produce a membrane electrode assembly "MEA-2."

[0106] A platinum-plated titanium separator 214 was attached to the anode side of the obtained "MEA-2," and a carbon separator 204 was attached to the cathode side together with a Teflon (registered trademark) sheet serving as a gasket 134. Gold-plated current collectors 104 and 114 were then attached and sandwiched from both sides to assemble the electrolysis device (part 2) 200 shown in Figure 2. The separators have flow paths 135 and 136 through which gas, electrolyte, reaction solution, etc. flow.

[0107] 2. Production of Ammonia Using the Electrolysis Apparatus for Producing Ammonia (Part 2) assembled as described above, ammonia was produced by electrolysis under the following conditions. Temperature of the apparatus body: 80°C. Power supply 101: Voltage and current were measured using a Versa STAT4 power supply from Princeton Applied Research. Cathode catalyst layer 103: Humidified nitrogen (relative humidity 95%) was flowed at 10 mL / min. Anode catalyst layer 113: Humidified hydrogen (relative humidity 95%) was flowed at 5 mL / min. Dilute sulfuric acid aqueous solution tank 125 for capturing ammonia: Sulfuric acid aqueous solution (0.02 mol / L, 10 mL). Electrolysis conditions: Constant-potential electrolysis was performed at -2.3 V for 1 hour.

[0108] An aqueous sulfuric acid solution (0.02 mol / L, 6 mL) was added via a liquid feed pump 303 to the aqueous sulfuric acid solution in the dilute aqueous sulfuric acid solution tank 125 for capturing ammonia and to the flow path 136 for the cathode-side gas, electrolytic solution, and reaction solution. The aqueous sulfuric acid solution was recovered from the cathode via a pipe 121 into a recovery tank 201 for the electrolytic solution and reaction solution on the cathode side, and the amount of ammonia was determined by quantifying the amount of ammonia produced using the method described in Example 1.

[0109] The amount of ammonia produced in this example was 2.02 (μmol).

[0110] [Comparative Example 1] The same electrolysis device (part 1) as in Example 1 was prepared, and the same experimental operation as in Example 1 was carried out, except that hydrogen was not supplied to the anode electrolyte tank and the anode catalyst layer, and water (6 mL) was added instead. The result of this example was that the amount of ammonia produced was 0.32 (μmol).

[0111] In comparison with Comparative Example 1 and Experimental Example 1, the efficiency of ammonia production was improved by about four times in the device of this example by providing hydrogen molecules from the means for supplying hydrogen gas at the anode.

[0112] Example 3 1. Fabrication of an electrolysis device for producing ammonia "GDE-Cathode-1" and "GDE-Anode-1", which are gas diffusion electrodes identical to those in Example 1, were fabricated.

[0113] [Electrolysis Device (Part 3)] An "MEA" consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was fabricated as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (film thickness 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-1" serving as a cathode catalyst layer was disposed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-1" serving as an anode catalyst layer was disposed on the other side. After that, they were thermocompression-bonded under the conditions of a top and bottom plate temperature of 132°C, a load of 5.4 kN, and a compression-bonding time of 240 seconds to fabricate a membrane electrode assembly "MEA-1."

[0114] Stainless steel current collectors 104 and 114, each having 25 circular holes of 2.5 mm in diameter, were attached to both sides of the obtained "MEA-1" together with a Teflon (registered trademark) sheet serving as a gasket 134, to an electrolytic cell, thereby assembling the electrolysis device (part 3) 300 shown in FIG. 3 .

[0115] 2. Production of Ammonia Using the Electrolysis Apparatus for Ammonia Production The electrolysis of ammonia was carried out under the following conditions using the electrolysis apparatus (No. 3) for producing ammonia assembled as described above. The valves and connections within the apparatus were adjusted so that the gas flow during operation of the electrolysis apparatus (No. 3) 300 was as shown by the arrows in Figure 6. Apparatus body temperature: 25-28°C (room temperature). Power supply 101: Voltage and current were measured using a Versa STAT4 power supply from Princeton Applied Research. Cathode electrolyte tank 105: Nitrogen was bubbled through an aqueous sulfuric acid solution (0.02 mol / L, 6 mL) at a rate of 10 mL / min. Anode electrolyte tank 115: Hydrogen gas generated at the cathode was supplied to the anode via a connection via piping 305. Anode electrolyte 116 was not used. Dilute sulfuric acid aqueous solution tank 125 for capturing ammonia: sulfuric acid aqueous solution (0.02 mol / L, 10 mL) Electrolysis conditions: constant potential electrolysis was carried out at −2.0 V for 1 hour.

[0116] The amount of ammonia was determined by the method described in Example 1. The amount of ammonia produced in this example was 0.94 (μmol).

[0117] Example 4 1. Fabrication of an electrolysis device for producing ammonia "GDE-Cathode-2" and "GDE-Anode-2", which are gas diffusion electrodes identical to those in Example 2, were fabricated.

[0118] [Electrolysis Device (Part 4)] A membrane electrode assembly consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was fabricated as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (membrane thickness 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-2" serving as a cathode catalyst layer was placed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-2" serving as an anode catalyst layer was placed on the other side, and then the upper and lower plates were thermocompression-bonded under conditions of a temperature of 132°C, a load of 5.4 kN, and a compression-bonding time of 240 seconds to fabricate a membrane electrode assembly "MEA-2."

[0119] A platinum-plated titanium separator 214 was attached to the anode side of the obtained "MEA-2," and a carbon separator 204 was attached to the cathode side together with a Teflon (registered trademark) sheet serving as a gasket 134. Gold-plated current collectors 104 and 114 were then attached and sandwiched from both sides to assemble the electrolysis device (No. 4) 400 shown in Figure 4. The separators have flow paths 135 and 136 through which gas, electrolyte, reaction solution, etc. flow.

[0120] 2. Production of Ammonia Using the Electrolysis Apparatus for Ammonia Production The electrolysis apparatus (No. 4) for ammonia production assembled as described above was used to produce ammonia by electrolysis under the following conditions. The valves and connections within the apparatus were adjusted so that the gas flow during operation of the electrolysis apparatus (No. 4) 400 was as shown by the arrows in Figure 7. Apparatus body temperature: 80°C. Power supply 101: Voltage and current were measured using a Versa STAT4 power supply manufactured by Princeton Applied Research. Cathode catalyst layer 103: Humidified nitrogen (relative humidity 95%) was flowed at 10 mL / min. Anode catalyst layer 113: Hydrogen gas generated at the cathode was delivered to the anode via piping 305. Dilute sulfuric acid aqueous solution tank 125 for ammonia capture: Sulfuric acid aqueous solution (0.02 mol / L, 10 mL). Electrolysis conditions: Constant-potential electrolysis was performed at -2.3 V for 1 hour.

[0121] The amount of ammonia was determined by the method described in Example 2. The amount of ammonia produced in this example was 1.31 (μmol).

[0122] [Comparative Example 2] The same electrolysis device (No. 3) as in Example 3 was prepared, and the same experimental operation as in Example 3 was carried out, except that hydrogen was not supplied to the anode electrolyte tank and the anode catalyst layer, and water (6 mL) was added instead. The result of this example was that the amount of ammonia produced was 0.27 (µmol).

[0123] In comparison with Comparative Example 2 and Example 3, the efficiency of ammonia production in the device of this example was improved by approximately three times by providing hydrogen molecules by sending hydrogen gas generated at the cathode to the anode.

[0124] Example 5 1. Fabrication of an electrolysis device for producing ammonia The same gas diffusion electrodes as those in Example 2, "GDE-Cathode-2A" and "GDE-Anode-2", were fabricated.

[0125] Next, catalyst ink 5B was prepared by applying the metal complex of this embodiment to the cathode catalyst layer 103. A solution of bis(cyclopentadienyl)titanium(IV) dichloride (4.0 mg, 16 μmol) as the metal complex in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (2.4 mL) was used to prepare catalyst ink 5B. This catalyst ink 5B (20 μL) was applied to the gas diffusion electrode 133 "GDE-Cathode-2A" to prepare the cathode catalyst layer 103. Specifically, the gas diffusion electrode 133, which is the cathode catalyst layer 103, was a 2.8 × 2.8 cm electrode coated with a platinum catalyst (7.8 mg) and bis(cyclopentadienyl)titanium(IV) dichloride (0.13 μmol), which are solid catalysts. ２ The gas diffusion electrode 133 was a square, and was designated "GDE-Cathode-5."

[0126] [Electrolysis Device (Part 3)] An "MEA" consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was fabricated as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (film thickness 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-5" serving as a cathode catalyst layer was disposed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-2" serving as an anode catalyst layer was disposed on the other side. After that, the upper and lower plates were thermocompression-bonded under the conditions of a temperature of 132°C, a load of 5.4 kN, and a compression-bonding time of 360 seconds to fabricate a membrane electrode assembly "MEA-5."

[0127] Stainless steel current collectors 104 and 114, each having 25 circular holes of 2.5 mm in diameter, were attached to both sides of the obtained "MEA-5" together with a Teflon (registered trademark) sheet serving as a gasket 134, to an electrolytic cell, thereby assembling the electrolysis device (part 3) 300 shown in FIG. 3 .

[0128] 2. Production of Ammonia Using the Electrolysis Apparatus for Ammonia Production Assembled as Above, the electrolysis apparatus (No. 3) for producing ammonia was used to produce ammonia by electrolysis under the following conditions. The valves and connections within the apparatus were adjusted so that the gas flow during operation of the electrolysis apparatus (No. 3) 300 was as shown by the arrows in Figure 6. Apparatus body temperature: 25-28°C (room temperature). Power supply 101: Voltage and current were measured using a Versa STAT4 power supply manufactured by Princeton Applied Research. Cathode electrolyte tank 105: Nitrogen was bubbled through an aqueous sulfuric acid solution (0.02 mol / L, 6 mL) at a rate of 10 mL / min. Anode electrolyte tank 115: Hydrogen gas generated at the cathode was delivered to the anode via piping 305. The anode electrolyte 116 used an aqueous sulfuric acid solution (0.02 mol / L, 6 mL), and hydrogen gas generated at the cathode was bubbled through the solution together with nitrogen. Dilute sulfuric acid aqueous solution tank 125 for capturing ammonia: sulfuric acid aqueous solution (0.02 mol / L, 10 mL) Electrolysis conditions: constant potential electrolysis was carried out at −2.3 V for 1 hour.

[0129] The amount of ammonia was determined by the method described in Example 1. The amount of ammonia produced in this example was 1.43 (μmol).

[0130] Example 6 1. Fabrication of an electrolysis device for producing ammonia "GDE-Cathode-5", which is the same gas diffusion electrode as in Example 5, and "GDE-Anode-2", which is the same gas diffusion electrode as in Example 2, were fabricated.

[0131] [Electrolysis Device (No. 5)] A membrane electrode assembly consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was produced as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (membrane thickness 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-5" serving as a cathode catalyst layer was placed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-2" serving as an anode catalyst layer was placed on the other side. After that, the upper and lower plates were thermocompression-bonded under the conditions of a temperature of 132°C, a load of 5.4 kN, and a compression-bonding time of 360 seconds to produce a membrane electrode assembly "MEA-6."

[0132] Stainless steel current collectors 104 and 114, each having 25 circular holes of 2.5 mm in diameter, were attached to both sides of the obtained "MEA-6" together with a Teflon (registered trademark) sheet serving as a gasket 134, to an electrolytic cell, thereby assembling the electrolysis device (No. 5) 500 shown in FIG. 5 .

[0133] 2. Production of ammonia by electrolysis apparatus Using the electrolysis apparatus (No. 5) for producing ammonia assembled as described above, ammonia was produced by electrolysis under the following conditions. During operation of the electrolysis apparatus (No. 5) 500, in addition to the operation of flowing gas, the two-way cock 308 was closed on the anode side and the cathode side, reactant gas and electrolyte were introduced, and then the two-way cock 309 was closed. Temperature of the apparatus body: 25 to 28°C (room temperature) Power supply 101: Voltage and current were measured using a Versa STAT4 manufactured by Princeton Applied Research. Cathode electrolyte tank 105: Nitrogen was bubbled into a sulfuric acid aqueous solution (0.02 mol / L, 6 mL) at 10 mL / min for 8 minutes, and then the two-way stopcock 308 was closed for 30 seconds. After that, the two-way stopcock 309 was closed for 1 minute 30 seconds, and then nitrogen was bubbled again. This operation was repeated 6 times within 1 hour. Anode electrolyte tank 115: Hydrogen gas was flowed into a 3 mL / min tank for 8 minutes, and then the two-way stopcock 308 was closed for 30 seconds. After that, the two-way stopcock 309 was closed for 1 minute 30 seconds, and then hydrogen was again flowed. This operation was repeated 6 times within 1 hour. Electrolysis conditions: Constant-potential electrolysis was performed at -2.3 V for 1 hour.

[0134] The amount of ammonia was determined by the method described in Example 1. The amount of ammonia produced in this example was 1.95 (μmol).

[0135] Example 7 1. Preparation of an electrolysis device for producing ammonia "GDE-Cathode-5", which is the same gas diffusion electrode as in Example 5, and "GDE-Anode-2", which is the same gas diffusion electrode as in Example 2, were prepared.

[0136] [Electrolysis Device (Part 4)] A membrane electrode assembly consisting of an electrolyte membrane 102, a cathode catalyst layer 103, and an anode catalyst layer 113 was produced as follows. The ion exchange membrane used for the electrolyte membrane 102 was DuPont's Nafion 212 membrane (registered trademark) (film thickness 50 μm, 5 cm × 5 cm). A gas diffusion electrode 133 "GDE-Cathode-5" serving as a cathode catalyst layer was placed on one side of the ion exchange membrane, and a gas diffusion electrode 133 "GDE-Anode-2" serving as an anode catalyst layer was placed on the other side. After that, the upper and lower plates were thermocompression-bonded under the conditions of a temperature of 132°C, a load of 5.4 kN, and a compression-bonding time of 240 seconds to produce a membrane electrode assembly "MEA-7."

[0137] A platinum-plated titanium separator 214 was attached to the anode side of the obtained "MEA-7," and a carbon separator 204 was attached to the cathode side together with a Teflon (registered trademark) sheet serving as a gasket 134. Gold-plated current collectors 104 and 114 were then attached and sandwiched from both sides to assemble the electrolysis device (No. 4) 400 shown in Figure 4. The separators have flow paths 135 and 136 through which gas, electrolyte, reaction solution, etc. flow.

[0138] 2. Production of Ammonia Using the Electrolysis Apparatus for Ammonia Production The electrolysis apparatus (No. 4) for producing ammonia assembled as described above was used to produce ammonia by electrolysis under the following conditions. While adjusting the valves and connections within the apparatus so that the gas flow during operation of the electrolysis apparatus (No. 4) 400 conformed to the flow indicated by the arrows in FIG. 7, the three-way valve 302 of the electrolysis apparatus (No. 4) 400 (FIG. 4) was used to introduce the reactant gas and electrolyte into the anode-side and cathode-side flow paths, and then the valve was closed, repeatedly pressurizing the cathode catalyst layer and the anode catalyst layer with the reactant gas and electrolyte. Apparatus body temperature: 80°C. Power supply 101: Voltage and current were measured using a Versa STAT4 power supply from Princeton Applied Research. Cathode catalyst layer 103: Humidified nitrogen (relative humidity 95%) was flowed at 10 mL / min for 8 minutes. The two three-way valves 302 of the cathode catalyst layer were closed to apply pressure, and after 2 minutes, humidified nitrogen was again flowed. This operation was repeated 6 times within 1 hour. Anode catalyst layer 113: Hydrogen gas generated at the cathode was sent to the anode via piping 305 for 8 minutes. The two three-way valves 302 of the anode catalyst layer were closed to apply pressure, and after 2 minutes, hydrogen gas generated at the cathode was again sent. This operation was repeated 6 times within 1 hour. Dilute sulfuric acid aqueous solution tank 125 for ammonia capture: Sulfuric acid aqueous solution (0.02 mol / L, 10 mL). Electrolysis conditions: Constant-potential electrolysis was performed at -2.3 V for 1 hour.

[0139] The amount of ammonia was determined by the method described in Example 2. The amount of ammonia produced in this example was 1.57 (μmol).

[0140] Example 8 1. Fabrication of an electrolysis device for producing ammonia An electrolysis device for producing ammonia similar to that of Example 7 was fabricated.

[0141] 2. Production of Ammonia by Electrolysis Apparatus Ammonia was produced by electrolysis under the following conditions using the same electrolysis apparatus for producing ammonia as in Example 7. The operation of adjusting the valves and connections within the electrolysis apparatus (No. 4) 400 so that the gas flow during operation conformed to the flow indicated by the arrows in Figure 7 was carried out. In parallel with this, the three-way valve 302 of the electrolysis apparatus (No. 4) 400 (Figure 4) was used to introduce the reactant gas and electrolyte into the anode-side and cathode-side flow paths, and then the valve was closed, repeatedly pressurizing the cathode catalyst layer and the anode catalyst layer with the reactant gas and electrolyte. Apparatus body temperature: 80°C. Power supply 101: Voltage and current were measured using a Versa STAT4 power supply from Princeton Applied Research. Cathode catalyst layer 103: Humidified nitrogen (relative humidity 95%) was flowed at 50 mL / min for 9 minutes and 30 seconds. The two three-way valves 302 of the cathode catalyst layer were closed to apply pressure, and after 30 seconds, humidified nitrogen was again flowed. This operation was repeated six times over one hour. Anode catalyst layer 113: Hydrogen gas generated at the cathode was sent to the anode via piping 305 for 9 minutes and 30 seconds. The two three-way valves 302 of the anode catalyst layer were closed to apply pressure, and after 30 seconds, hydrogen gas generated at the cathode was again sent. This operation was repeated six times over one hour. Dilute sulfuric acid aqueous solution tank 125 for ammonia capture: Sulfuric acid aqueous solution (0.02 mol / L, 10 mL). Electrolysis conditions: Constant-potential electrolysis was performed at -2.3 V for one hour.

[0142] The amount of ammonia was determined by the method described in Example 2. The amount of ammonia produced in this example was 1.88 (μmol).

[0143] The present invention can be used in a method for producing ammonia.

[0144] 100 Ammonia electrolysis device (part 1) 200 Ammonia electrolysis device (part 2) 300 Ammonia electrolysis device (part 3) 400 Ammonia electrolysis device (part 4) 500 Ammonia electrolysis device (part 5) 101 Power supply device 102 Electrolyte membrane 103 Cathode catalyst layer (catalyst layer for producing ammonia) 104 Cathode current collector 105 Cathode electrolyte tank 106 Cathode electrolyte 108 Cathode (cathode catalyst layer and cathode current collector) 113 Anode catalyst layer 114 Anode current collector 115 Anode electrolyte tank 116 Anode electrolyte 118 Anode (anode catalyst layer or anode current collector) 121 Piping 122 Nitrogen cylinder 123 Nitrogen cylinder regulator 124 Nitrogen gas mass flow controller 125 Dilute sulfuric acid aqueous solution tank for ammonia collection 126 Draft device 127 Hydrogen cylinder 128 Hydrogen cylinder regulator 129 Hydrogen gas mass flow controller 130 Back pressure valve 131 Membrane electrode assembly 132 Cathode membrane electrode assembly 133 Gas diffusion electrode 134 Gasket 135 Anode side gas, electrolyte, and reaction solution flow path 136 Cathode side gas, electrolyte, and reaction solution flow path 141 Electrolysis cell 201 Cathode side electrolyte and reaction solution recovery tank 202 Cathode side electrolyte and reaction solution storage tank 204 Cathode side separator 205 Anode side electrolyte and reaction solution recovery tank 206 Anode side electrolyte and reaction solution storage tank 214 Anode side separator 301 Two-way cock 302 Three-way cock 303 Liquid feed pump 304 Gas humidifier 305 Piping (piping for utilizing hydrogen produced as a by-product at the cathode at the anode) 306 Three-way cock 307 Three-way cock 308 Two-way cock 309 Two-way cock

Claims

1. A method for producing ammonia using nitrogen molecules as a raw material in a production apparatus that performs an electrolytic reaction, by supplying electrons from a power source, protons from a proton source, and nitrogen molecules from a means for supplying nitrogen gas in the presence of a metal complex and a solid catalyst at a cathode, and by supplying hydrogen molecules from a means for supplying hydrogen gas at an anode.

2. The means for supplying hydrogen gas at the anode comprises: A means for feeding hydrogen gas generated at the cathode to the anode is provided. The method for producing ammonia according to claim 1 .

3. 2. The method for producing ammonia according to claim 1, wherein the metal complex is a compound capable of forming a nitrogen complex when a nitrogen molecule is coordinated to a metal at a catalyst center; the solid catalyst is a metal catalyst, a transition metal catalyst, a noble metal catalyst, an alloy catalyst, an oxide catalyst, or a combination thereof; and the proton source is at least one selected from the group consisting of an electrolyte membrane, an electrolytic solution, a catalyst layer, and an electrolyte in the catalyst layer.

4. The method for producing ammonia according to claim 1 , wherein the metal complex is a metallocene compound or a half-metallocene compound.

5. 2. The method for producing ammonia according to claim 1, wherein the metal complex is bis(cyclopentadienyl)titanium dichloride, bis(cyclopentadienyl)zirconium dichloride, rac-dimethylsilylbis(1-indenyl)zirconium dichloride, or rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride.

6. The method for producing ammonia according to claim 1 , wherein the solid catalyst comprises platinum, gold, palladium, or zinc oxide.

7. The cathode has a cathode catalyst layer bonded to one side of the electrolyte membrane, and a cathode collector on the outside. an anode having an anode catalyst layer bonded to the other side of the electrolyte membrane and an anode current collector disposed on the outside thereof; the cathode having a cathode catalyst layer and a cathode current collector; the anode having an anode catalyst layer and an anode current collector; the cathode having a cathode electrolyte tank capable of solid-liquid-gas contact; the anode having an anode electrolyte tank capable of solid-liquid-gas contact; means for feeding hydrogen gas to the anode; a power source for supplying electrons to the cathode; a proton source for supplying protons to the cathode; and means for supplying nitrogen gas to the cathode electrolyte tank, the cathode electrolyte, or the cathode;

8. 8. The apparatus for producing ammonia according to claim 7, wherein the means for feeding hydrogen gas to the anode comprises means for feeding hydrogen gas produced at the cathode to the anode.

9. an ammonia producing apparatus in which ammonia is produced from nitrogen molecules by an electrolytic reaction, the apparatus comprising: a cathode having a cathode catalyst layer bonded to one side of an electrolyte membrane and a cathode current collector disposed on the outside thereof; and an anode having an anode catalyst layer bonded to the other side of the electrolyte membrane and an anode current collector disposed on the outside thereof; the cathode comprising a cathode catalyst layer and a cathode current collector; the anode comprising an anode catalyst layer and an anode current collector; the cathode comprising a flow path allowing solid-liquid-gas contact; the anode comprising a flow path allowing solid-liquid-gas contact; a means for feeding hydrogen gas to the anode; a power source for supplying electrons to the cathode; a proton source for supplying protons to the cathode; and a means for supplying nitrogen gas to a cathode electrolyte tank, the cathode electrolyte, or the cathode;

10. 10. The apparatus for producing ammonia according to claim 9, wherein the means for feeding hydrogen gas to the anode comprises means for feeding hydrogen gas produced at the cathode to the anode.