Electrolytic apparatus and method for manufacturing an electrolytic apparatus

Abstract

This invention provides an electrolytic apparatus that enables the highly efficient production of reduction products through electrolytic reactions. [Solution] The electrolytic apparatus comprises a cathode, an anode, a cathode chamber in contact with the cathode and supplied with a gaseous substance to be reduced, an anode chamber in contact with the anode and supplied with a liquid or gaseous substance to be oxidized, and a diaphragm provided between the cathode and the anode. The cathode has a substrate and a catalyst layer. The catalyst layer has a metal complex that promotes a chemical reaction to reduce the substance to be reduced and produce a reduction product, an alcohol with a carbon content of 2 or less, or an aprotic solvent with a dielectric constant of 3.0 or more, a catalyst support that carries the metal complex and is conductive, and a binder that binds the metal complex to the substrate.

Description

Technical Field

[0001] Embodiments of the present invention relate to an electrolysis device and a method for manufacturing the electrolysis device.

Background Art

[0002] The annual global production volume of ammonia is approximately 140 million tons (1.4×10 11 kg), and the production volume continues to increase. Approximately 80% of the production volume is used as a raw material for fertilizers and is mainly converted into other nitrogen compounds such as urea, nitric acid, ammonium nitrate, ammonium sulfate, etc. On the other hand, the remaining 20% is used in the production of synthetic resins and fibers. In order to cope with the global population increase, the shortage of arable land, and food shortages due to the sophistication of diets, especially in emerging countries, the demand for ammonia is increasing. Furthermore, ammonia is attracting attention for use as an energy carrier because of its ease of handling, high energy density, and the fact that it does not emit carbon dioxide when used without containing carbon.

[0003] Currently, ammonia is industrially synthesized from hydrogen gas and nitrogen gas derived from fossil fuels such as petroleum, coal, and natural gas by a method called the Haber-Bosch process, which was invented about 100 years ago. This synthesis reaction requires severe conditions of high temperature (400 - 650°C) and high pressure (200 - 400 atm), and consumes 1.2% of the world's total energy, resulting in a large amount of carbon dioxide emissions. In order to form a sustainable society in the future, the development of alternative processes with low dependence on fossil fuels is desired.

[0004] Regarding such points, in an electrolysis method and an electrolysis apparatus for producing ammonia (NH3) by electrolyzing and reducing nitrogen (NH3), the development of a catalyst for generating ammonia from nitrogen at normal temperature and pressure has been underway. For example, as the catalyst, a molybdenum iodine complex having a PNP (2,6-bis(di-tert-butylphosphinomethyl)pyridine) ligand, alcohol or water as a proton source, and a halide (II) of a lanthanoid metal as a reducing agent, such as samarium (II) iodide, are used. It has been reported that by stirring a solution containing an organic low molecule as a solvent in the presence of nitrogen gas at normal temperature, up to 4350 equivalents of ammonia can be generated per catalyst. Also, a method has been reported in which a molybdenum iodine complex having a PNP ligand is used as the catalyst, and as the proton source, either the solution used in the cathode cell or both the electrolyte membrane and the solution used in the cathode cell are used.

[0005] In electrolytic devices that produce ammonia (NH3) by the reduction of nitrogen (N2) as described above, a method is used to support the catalyst on a gas diffusion electrode, which is a support, using an organic low-molecular-weight solvent (also called the catalyst support method) when preparing the cathode that generates ammonia by reducing nitrogen gas. However, because this organic low-molecular-weight solvent has relatively high adsorption selectivity to the support, it can reduce the amount of catalyst supported and increase the hydrophilicity of the support, causing a flattening phenomenon. These factors reduce the amount and efficiency of electrolytic products such as ammonia produced on the cathode side. Furthermore, when using a material that is deactivated by reacting with excess water, such as a molybdenum complex, as a catalyst, the catalytic reaction can proceed more efficiently by reducing the hydrophilicity of the cathode. Therefore, there is a need to optimize the solvent used in the cathode preparation process and the process itself, as well as the composition of the cathode, in order to achieve a cathode with high catalyst support and low hydrophilicity, thereby improving the production efficiency and recovery efficiency of electrolytic products such as ammonia. Such challenges are not limited to nitrogen electrolytic devices that produce ammonia by reduction of nitrogen, but are also required in electrolytic devices that have a cathode made using a catalyst-supported method and produce reduction products different from ammonia, such as water electrolytic devices that produce hydrogen (H2) by electrolyzing water (H2O), and carbon dioxide electrolytic devices that produce carbon compounds such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH3OH), and ethanol (C2H5OH) by electrolyzing carbon dioxide (CO2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-095640 [Patent Document 2] International Publication No. 2021 / 045206 [Patent Document 3] International Publication No. 2022 / 210987 [Patent Document 4] International Publication No. 2022 / 034927 [Patent Document 5] International Publication No. 2023 / 033185 [Non-patent literature]

[0007] [Non-Patent Document 1] Nature Communications 8: 14874, April 2017, doi:10.1038 / ncomms 14874 [Non-Patent Document 2] Nature, April 2019, Vol. 568(7753), p. 536-540 [Overview of the project] [Problems that the invention aims to solve]

[0008] The problem that this invention aims to solve is to provide an electrolytic apparatus capable of producing reduction products with high efficiency through electrolytic reactions. [Means for solving the problem]

[0009] The electrolytic apparatus of the embodiment comprises a cathode, an anode, a cathode chamber in contact with the cathode and supplied with a gaseous substance to be reduced, an anode chamber in contact with the anode and supplied with a liquid or gaseous substance to be oxidized, and a diaphragm provided between the cathode and the anode. The cathode has a substrate and a catalyst layer. The catalyst layer has a metal complex that promotes a chemical reaction to reduce the substance to be reduced and produce a reduction product, an alcohol with a carbon content of 2 or less, or an aprotic solvent with a dielectric constant of 3.0 or more, a catalyst support that carries the metal complex and is conductive, and a binder that binds the metal complex to the substrate. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of the structure of an electrolytic device. [Figure 2] This is a schematic diagram showing the first example of an electrochemical reaction unit. [Figure 3] This is a schematic diagram showing a second example of an electrochemical reaction unit. [Figure 4] This is a schematic diagram showing a third example of an electrochemical reaction unit. [Figure 5] This is a schematic cross-sectional diagram showing an example of a cathode structure. [Modes for carrying out the invention]

[0011] The electrolytic apparatus of the embodiment will be described below with reference to the drawings. In each embodiment shown below, substantially identical components are denoted by the same reference numerals, and their descriptions may be partially omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of the thickness of each part, etc., may differ from those in reality. Here, the electrolytic apparatus of the embodiment will be mainly described as a nitrogen electrolytic apparatus that produces ammonia (NH3) by reduction of nitrogen (N2), but the electrolytic apparatus of the embodiment is not limited to a nitrogen electrolytic apparatus. The electrolytic apparatus of the embodiment may be, for example, a water electrolytic apparatus that produces hydrogen (H2) by electrolyzing water (H2O), or a carbon dioxide electrolytic apparatus that produces carbon compounds such as carbon monoxide (CO), formic acid (HCOOH), and methanol (CH3OH) by electrolyzing carbon dioxide (CO2).

[0012] Figure 1 is a schematic diagram showing an example of the structure of an electrolytic apparatus according to an embodiment. Figure 1 shows a nitrogen electrolytic apparatus 1. The nitrogen electrolytic apparatus 1 is an ammonia production apparatus and comprises an electrochemical reaction unit (electrolytic cell) 5 having a first reaction vessel (electrolytic vessel for reduction reaction) 2 to which a gaseous substance to be reduced (e.g., nitrogen) is supplied, a second reaction vessel (electrolytic vessel for oxidation reaction) 3 to which a liquid or gaseous substance to be oxidized (e.g., an electrolyte containing water or water vapor) is supplied, and a diaphragm 4; a nitrogen supply unit 7 having a nitrogen supply section (supply device) 6 for supplying nitrogen to the cathode chamber; an ammonia collection section (ammonia collection unit) 9 having a collection section (collection device) 8 capable of collecting ammonia contained in the gas exhausted from the cathode chamber; an oxidized substance supply unit 11 for supplying electrolyte from an electrolyte storage tank 10 containing the electrolyte to the second reaction vessel 3; and an ammonia separation unit 13 having an ammonia separation section (separation device) 12 for separating ammonia contained in the electrolyte discharged from the second reaction vessel 3. The following provides a detailed description of each part.

[0013] Figure 2 shows a first example of an electrochemical reaction unit 5. The electrochemical reaction unit 5 shown in Figure 2 comprises a first reaction vessel (electrolytic cell for reduction reaction) 2 as a cathode chamber, a second reaction vessel (electrolytic cell for oxidation reaction) 3 as an anode chamber, a diaphragm 4 provided between the first reaction vessel 2 and the second reaction vessel 3, a cathode 14 located in the first reaction vessel 2 and used for the electrochemical reduction reaction, and an anode 15 located in the second reaction vessel 3 and used for the electrochemical oxidation reaction. These constitute an electrochemical reaction cell (electrolytic cell). The electrochemical reaction cell 5 uses hydrogen ions (H + ) and hydroxide ions (OH - The reactor is separated into a first reaction vessel 2 and a second reaction vessel 3 by a diaphragm 4 that allows ions such as ions to move. Gaseous nitrogen (N2) is supplied to the first reaction vessel 2 from a nitrogen supply unit 7 via piping. An electrolyte containing water (H2O) or water vapor (H2O) generated by the vaporization of the electrolyte is supplied to the second reaction vessel 3 from an oxidizing material supply unit 11 via piping.

[0014] Figure 3 shows a second example of the electrochemical reaction unit 5. The electrochemical reaction unit 5 shown in Figure 3 has a first flow channel plate 2a instead of a first reaction vessel 2 to which gaseous nitrogen, the substance to be reduced, is supplied, and a second flow channel plate 3a instead of a second reaction vessel 3 to which electrolyte or water vapor, the substance to be oxidized, is supplied. The first flow channel plate 2a has a first flow channel (also called the cathode flow channel) which serves as a cathode chamber facing the cathode 14 to which gaseous nitrogen, the substance to be reduced, is supplied. The second flow channel plate 3a has a second flow channel (also called the anode flow channel) which serves as an anode chamber facing the anode 15 to which electrolyte or water vapor, the substance to be oxidized, is supplied. The electrochemical reaction unit 5 shown in Figure 3 consists of a cathode 14 used for electrochemical reduction reactions, located next to the first channel plate 2a and a second channel plate 3a, sandwiched between the first channel plate 2a and a second channel plate 3a. An anode 15 used for electrochemical oxidation reactions is located next to the second channel plate 3a, and a diaphragm 4 is provided between the cathode 14 and anode 15. These constitute an electrochemical reaction cell (electrolytic cell). According to Figure 3, the distance between the cathode 14 and anode 15 is equal to the thickness of the diaphragm 4, which reduces electrical resistance and also facilitates the generation of hydrogen ions (H + ) and hydroxide ions (OH - This allows for rapid movement of the ammonia between each electrode. This reduces the power consumption of the electrolytic cell and increases the efficiency of ammonia production. Further explanations of the first flow channel plate 2a and the second flow channel plate 3a may be provided by referring to the explanations of the first reaction vessel 2 and the second reaction vessel 3 as appropriate.

[0015] Figure 4 shows a third example of the electrochemical reaction unit 5. The electrochemical reaction unit 5 shown in Figure 4 includes a third reaction vessel 16 supplied with an electrolyte solution (cathode solution) containing water, which is located between a first reaction vessel 2 supplied with gaseous nitrogen (N2) and a diaphragm 4. The first reaction vessel 2 and the third reaction vessel 16 are in contact via a porous cathode 14, and together they constitute a cathode chamber. The cathode chamber, which includes the first reaction vessel 2 and the third reaction vessel 16, is in contact with a second reaction vessel 3, which acts as an anode chamber, via a diaphragm 4 and a porous anode 15. According to the electrochemical reaction unit 5 shown in Figure 4, ammonia (NH3) produced by reducing gaseous nitrogen (N2) supplied to the first reaction vessel 2 can be dissolved in the electrolyte solution (cathode solution) supplied to the third reaction vessel 16 and extracted to the outside of the electrochemical reaction cell (electrolytic cell) 5. This makes it possible to increase the ammonia recovery efficiency.

[0016] The cathode 14 and anode 15 are connected to an external electrode. When current or voltage is supplied from the external electrode to the cathode 14 and anode 15, power is applied, a reduction reaction occurs in the cathode 14 and an oxidation reaction occurs in the anode 15. In the anode chamber, for example, water (H2O) in the electrolyte is oxidized at the anode 15, producing oxygen (O2) and hydrogen ions (H2O). + ) and electrons (e - In the cathode chamber, nitrogen (N2) is reduced by an ammonia-producing catalyst to produce ammonia (NH3). The nitrogen containing ammonia is led out of the cathode chamber via piping and continuously sent to the ammonia collection unit 9. In addition, some of the ammonia produced in the cathode chamber moves to the anode chamber through the diaphragm 4. The electrolyte or water vapor containing ammonia mixed with water in the anode chamber and oxygen produced at the anode 15 is led out of the anode chamber via piping and continuously or intermittently sent to the ammonia separation unit 13.

[0017] As described above, an electrolyte containing water (H2O) or water vapor is supplied to the anode chamber. The electrolyte may be an aqueous solution containing an electrolyte. Preferably, the electrolyte has high ionic conductivity and the electrolyte itself does not react. Examples of electrolytes contained in such electrolytes include lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium bromide (LiBr), sodium bromide (NaBr), potassium bromide (KBr), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), lithium nitrate (LiNO3), sodium nitrate (NaNO3), potassium nitrate (KNO3), lithium sulfate (Li2SO4), sodium sulfate (Na2SO4), potassium sulfate (K2SO4), lithium hydrogen sulfate (LiHSO4), sodium hydrogen sulfate (NaHSO4), potassium hydrogen sulfate (KHSO4), lithium peroxodisulfate (Li2S2O8), sodium peroxodisulfate (Na2S2O8), and potassium peroxodisulfate (K2S2O8). Examples include lithium phosphate (Li3PO4), sodium phosphate (Na3PO4), potassium phosphate (K3PO4), dilithium hydrogen phosphate (Li2HPO4), disodium hydrogen phosphate (Na2HPO4), dipotassium hydrogen phosphate (K2HPO4), lithium dihydrogen phosphate (LiH2PO4), sodium dihydrogen phosphate (NaH2PO4), potassium dihydrogen phosphate (KH2PO4), lithium bicarbonate (LiHCO3), sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), lithium carbonate (Li2CO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), lithium tetraborate (Li2B4O7), sodium tetraborate (Na2B4O7), potassium tetraborate (K2B4O7), lithium silicate (Li2SiO3), sodium silicate (Na2SiO3), potassium silicate (K2SiO3), and ionic liquids. Water is preferred as the solvent. The electrolyte concentration in the electrolyte solution is preferably in the range of, for example, 0.001 to 1 mol / L.

[0018] As the cation of the ionic liquid, ions such as imidazolium ion, pyridinium ion, pyrrolidinium ion, and piperidinium ion are used. Examples of imidazolium ions include 1-ethyl-3-methylimidazolium, 1-methyl-3-propylimidazolium, 1-butyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, 1-hexyl-3-methylimidazolium, etc. The 2-position of the imidazolium ion may be substituted. For example, 1-ethyl-2,3-dimethylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1,2-dimethyl-3-pentylimidazolium, 1-hexyl-2,3-dimethylimidazolium, etc. Examples of pyridinium ions include methylpyridinium, ethylpyridinium, propylpyridinium, butylpyridinium, pentylpyridinium, hexylpyridinium, etc. Examples of pyrrolidinium ions include ethyl-methylpyrrolidinium, methyl-propylpyrrolidinium, butyl-methylpyrrolidinium, methyl-pentylpyrrolidinium, hexyl-methylpyrrolidinium, etc. Examples of piperidinium ions include ethyl-methylpiperidinium, methyl-propylpiperidinium, butyl-methylpiperidinium, methyl-pentylpiperidinium, hexyl-methylpiperidinium, etc. The imidazolium ion, pyridinium ion, pyrrolidinium ion, and piperidinium ion may all have an alkyl group substituted or may have an unsaturated bond. As the cation of the ionic liquid, a cation used alone or in combination of a plurality is used.

[0019] As the anion of the ionic liquid, fluoride ion, chloride ion, bromide ion, iodide ion, acetate ion, nitrate ion, hydrogen sulfate ion, phosphate ion, dicyanamide ion, BF4 - , PF6 - , CF3COO - , CF3SO3 - , SCN - , (CF3SO2)3C -Examples include bis(trifluoromethoxysulfonyl)imide ions, bis(trifluoromethoxysulfonyl)imide ions, and bis(per-fluoroethylsulfonyl)imide ions. The anions of the ionic liquid can be single or in combination of multiple anions. Furthermore, a twinned ion may be formed by linking the cation and anion of the ionic liquid with a hydrocarbon. The above-mentioned ionic liquids may be used individually or in combination of two or more types.

[0020] The anode chamber contains an anode 15, and an electrolyte solution is supplied to it. When the hydrogen ion concentration of the electrolyte solution is 7 or less (pH ≤ 7), H2O is oxidized to O2 and H + On the other hand, when the hydrogen ion concentration of the electrolyte is greater than 7 (pH>7), OH - It is oxidized to produce O2 and H2O. Anode 15 is composed of a material that reduces the activation energy required to cause the oxidation reaction. In other words, anode 15 is H2O or OH - The anode 15 is composed of a material that reduces the overpotential when an oxidation reaction occurs to extract electrons. Examples of such constituent materials for the anode 15 include binary metal oxides such as platinum (Pt), manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), and ruthenium oxide (Ru-O); ternary metal oxides such as Ni-Co-O, La-Co-O, Ni-La-O, and Sr-Fe-O; quaternary metal oxides such as Pb-Ru-Ir-O and La-Sr-Co-O; or metal complexes such as Ru complexes or Fe complexes.

[0021] As described above, a cathode 14 is placed in the cathode chamber, and nitrogen gas is also supplied. For the reduction reaction to be carried out, it is preferable that the cathode 14 is made of a material that is conductive in order to transfer electrons supplied from the external electrode to the catalyst, has gas diffusivity in order to allow the material to be reduced to diffuse more quickly, and has a porous structure in order to support a larger amount of catalyst. Furthermore, it is even more preferable that it has low hydrophilicity in order to prevent the flooding phenomenon caused by the electrolyte moving from the anode chamber through the diaphragm 4. The hydrophilicity of the cathode 14 can be adjusted, for example, by the thickness of the cathode 14 or the constituent material.

[0022] Figure 5 is a schematic cross-sectional view showing an example of the structure of cathode 14. An example of cathode 14 includes a gas diffusion layer 141 that serves as the base material and a catalyst layer (also called a cathode catalyst layer) 142. Note that the structure of cathode 14 is not limited to the structure shown in Figure 5.

[0023] The gas diffusion layer 141 is formed using materials such as carbon paper, carbon cloth, carbon felt, glass cloth, or polymer porous membrane. The gas diffusion layer 141 may also include a layer called a multiporous layer (MPL) to improve gas diffusivity and water repellency.

[0024] The catalyst layer 142 is provided on the surface of the gas diffusion layer 141. Figure 5 shows an example in which the catalyst layer 142 is laminated on the gas diffusion layer 141, but is not limited to this. For example, at least a portion of the catalyst layer 142 may be formed on the surface of the gas diffusion layer 141 within the pores of the gas diffusion layer 141. The catalyst layer 142 has at least a material that acts as a reduction catalyst, a material that is responsible for conductivity, a material that acts as a catalyst support, and a material that plays a role in binding these together (a binder), and the same material may play multiple roles. Specifically, in addition to a reduction catalyst that reduces nitrogen to produce ammonia, it may also include an organic-inorganic composite material (a composite material of organic and inorganic materials) mainly composed of a carbon material as a conductor and catalyst support, for controlling the hydrophilicity of a second catalyst support and catalyst layer 142, or an organic polymer material for binding porous carbon material and inorganic oxide fine particles. The organic-inorganic composite material and organic polymer material may have ionic conductivity, thereby allowing hydrogen ions (H) to reach the reduction catalyst. + ) and hydroxide ions (OH - By improving the conductivity and supply of ions such as ), the reduction efficiency of nitrogen (N), i.e., the production efficiency of ammonia (NH3), can be increased.

[0025] The reduction catalyst (ammonia production catalyst) used in cathode 14 promotes the production of ammonia from nitrogen, and is not limited to, but may include, for example, a molybdenum complex. Examples of ammonia production catalysts include the molybdenum complexes (A) to (D) shown below.

[0026] A first example is a molybdenum complex having (A) N,N-bis(dialkylphosphinomethyl)dihydrobenzimidazolidene as the PCP ligand (where the two alkyl groups may be the same or different, and at least one hydrogen atom of the benzene ring may be substituted with an alkyl group, an alkoxy group, or a halogen atom).

[0027] A second example is a molybdenum complex having (B) 2,6-bis(dialkylphosphinomethyl)pyridine as the PNP ligand (where the two alkyl groups may be the same or different, and at least one hydrogen atom of the pyridine ring may be substituted with an alkyl group, an alkoxy group, or a halogen atom).

[0028] A third example is a molybdenum complex having a bis(dialkylphosphinomethyl)arylphosphine (where the two alkyl groups may be the same or different) as the (C)PPP ligand.

[0029] A fourth example is a molybdenum complex represented as (D)trans-Mo(N2)2(R1R2R3P)4 (where R1, R2, and R3 are alkyl or aryl groups that may be the same or different, and the two R3s may be linked together to form an alkylene chain).

[0030] In the molybdenum complex described above, the alkyl group may be, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a linear or branched alkyl group such as structural isomers thereof, or a cyclic alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group. The number of carbon atoms in the alkyl group is preferably 1 to 12, and more preferably 1 to 6. The alkoxy group may be, for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a hexyloxy group, or a linear or branched alkoxy group such as structural isomers thereof, or a cyclic alkoxy group such as a cyclopropoxy group, a cyclobutoxy group, a cyclopentoxy group, or a cyclohexyloxy group. The number of carbon atoms in the alkoxy group is preferably 1 to 12, and more preferably 1 to 6. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0031] Examples of molybdenum complexes of (A) include the molybdenum complex represented by the following formula (A1).

[0032] [ka] In the formula, R1 and R2 are alkyl groups which may be the same or different, X is an iodine atom, a bromine atom, or a chlorine atom, and at least one hydrogen atom on the benzene ring may be substituted with an alkyl group, an alkoxy group, or a halogen atom.

[0033] Examples of alkyl groups, alkoxy groups, and halogen atoms are the same as those already exemplified. Bulky alkyl groups (e.g., tert-butyl group or isopropyl group) are preferred for R1 and R2. The hydrogen atoms on the benzene ring are preferably unsubstituted, or the hydrogen atoms at positions 5 and 6 are preferably substituted with linear, cyclic, or branched alkyl groups having 1 to 12 carbon atoms.

[0034] Examples of molybdenum complexes of (B) include those represented by the following formulas (B1), (B2), and (B3).

[0035] [ka] In the formula, R1 and R2 are alkyl groups which may be the same or different, X is an iodine atom, a bromine atom, or a chlorine atom, and at least one hydrogen atom on the pyridine ring may be substituted with an alkyl group, an alkoxy group, or a halogen atom.

[0036] Examples of alkyl groups, alkoxy groups, and halogen atoms are the same as those already exemplified. Bulky alkyl groups (e.g., tert-butyl group or isopropyl group) are preferred for R1 and R2. The hydrogen atoms on the pyridine ring are preferably unsubstituted, or the hydrogen atom at position 4 is preferably substituted with a linear, cyclic, or branched alkyl group having 1 to 12 carbon atoms.

[0037] Examples of molybdenum complexes of (C) include the molybdenum complex represented by the following formula (C1).

[0038] [ka] In the formula, R1 and R2 are alkyl groups which may be the same or different, R3 is an aryl group, and X is an iodine atom, a bromine atom, or a chlorine atom.

[0039] Examples of alkyl groups include those already exemplified. Examples of aryl groups include phenyl, tolyl, xylyl, naphthyl groups, and those in which at least one of their cyclic hydrogen atoms is substituted with an alkyl or halogen atom. Examples of alkyl groups and halogen atoms include those already exemplified. Bulky alkyl groups (e.g., tert-butyl or isopropyl groups) are preferred for R1 and R2. A phenyl group is preferred for R3.

[0040] Examples of molybdenum complexes of (D) include the molybdenum complexes represented by the following formulas (D1) and (D2).

[0041] [ka] In the formula, R1, R2, and R3 are alkyl or aryl groups, which may be the same or different, and n is 2 or 3.

[0042] Examples of alkyl and aryl groups are the same as those already exemplified. In formula (D1), it is preferable that R1 and R2 are aryl groups (e.g., phenyl groups) and R3 is an alkyl group having 1 to 4 carbon atoms (e.g., a methyl group), or that R1 and R2 are alkyl groups having 1 to 4 carbon atoms (e.g., a methyl group) and R3 is an aryl group (e.g., a phenyl group). In formula (D2), it is preferable that R1 and R2 are aryl groups (e.g., phenyl groups) and n is 2.

[0043] The ammonia production catalyst (reduction catalyst) that promotes the production of ammonia from nitrogen may be, for example, a metallocene complex represented by the following formula (E1).

[0044] [ka] In the formula, M is a tetravalent metal ion, which is either titanium, zirconium, or hafnium. X1 and X2 are identical or different coordinating anions. The anion is Cl - , Br - , I - CH3 - , or OH - It is preferable that Cl - More preferably, metallocene complexes such as bis(cyclopentadienyl)titanium dichloride and bis(cyclopentadienyl)zirconium dichloride are preferred.

[0045] Furthermore, metal catalysts such as molybdenum, bismuth, iron, rhodium, ruthenium, titanium, and zirconium may be used as ammonia generation catalysts (reduction catalysts). These may be used individually or in combination of two or more types.

[0046] The conductive material included in the catalyst layer 142 is preferably a material that does not undergo reduction reactions as a catalyst itself. In other words, a material with a high overpotential for the reduction reactions of side reactions such as protons, water, and electrolytes is suitable, and carbon materials are mainly used. Examples of carbon materials (carbon particles) include channel black, furnace black, thermal black, acetylene black, activated carbon, natural graphite, artificial graphite, graphitized carbon, graphene, carbon nanotubes (CNTs), fullerene, Ketjenblack, and glassy carbon.

[0047] The catalyst support can support an ammonia-producing catalyst (reduction catalyst). The reduction catalyst is, for example, a metal complex. The catalyst support may be the carbon material mentioned above, or an organic-inorganic composite material. Examples of inorganic materials include magnesium oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, vanadium oxide, molybdenum oxide, tungsten oxide, tin oxide, zinc oxide, microporous three-dimensional aluminum silicate such as zeolites, and layered silicate minerals such as montmorillonite, bydelite, saponite, stevensite, and hectorite. Examples of organic-inorganic composite materials include metal-organic frameworks (MOFs) and materials in which organic molecules are inserted between sites or layers of an inorganic crystal structure. By using these materials as catalyst supports, the ammonia-producing catalyst can be immobilized at high density and efficiently. Therefore, a three-phase interface controlled cathode 14 capable of direct reaction with nitrogen (N2) can be realized. This significantly increases the efficiency of ammonia production in the gas phase.

[0048] By adsorbing and retaining the ammonia-producing catalyst on the surface of the catalyst support, it can be used as a catalyst support for nitrogen reduction reactions. For example, if the ammonia-producing catalyst is a molybdenum complex, a catalyst solution is prepared by dissolving the molybdenum complex in a solvent, and adsorption occurs on the surface of the catalyst support when the catalyst solution is brought into contact with the catalyst support. A characteristic of a catalyst support capable of suitably retaining the ammonia-producing catalyst is a specific surface area of ​​800 m² to increase the reaction area. 2 It is preferable that the amount is 1 / g or more.

[0049] The properties of catalyst supports can be evaluated by gas adsorption using a specific surface area measuring device. To measure the specific surface area, reversibly adsorbed inert gases (adsorbates) such as nitrogen, argon, and krypton are used. The measurement procedure involves placing the sample in a sample tube of known volume, removing any attached material from the sample by heating and vacuum drying, then introducing a fixed amount of adsorbate into the sample tube and bringing it into contact with the sample surface. The amount of adsorption increases over time until it stops increasing. This state is called the adsorption equilibrium state, the amount of adsorption is called the equilibrium adsorption amount, and the pressure is called the equilibrium pressure. The amount of adsorption can be determined by measuring the pressure change until the adsorption equilibrium state is reached. The specific surface area is calculated by determining the amount of the first adsorption layer from the amount of adsorbate adsorbed on the sample surface using the BET theory, and then determining the specific surface area value using the area occupied by one adsorbate molecule.

[0050] The more molybdenum-generating catalyst is contained in the catalyst layer 142, the greater the amount of ammonia produced in the gas phase. Therefore, by increasing the thickness of the catalyst layer 142 and the amount of catalyst support, a cathode 14 with a high ammonia production rate can be realized. On the other hand, if the catalyst layer 142 is thicker than necessary, the gas of the substance to be reduced supplied from the gas diffusion layer 141 will have difficulty reaching the surface side of the catalyst layer 142, and hydrogen will be produced by side reactions, reducing the ammonia production efficiency. For this reason, the thickness of the catalyst layer 142 is preferably 0.035 mm or more and 0.200 mm or less, and more preferably 0.050 mm or more and 0.150 mm or less. By adjusting the thickness of the catalyst layer 142 to 0.035 mm or more and 0.200 mm or less, the ammonia production efficiency can be increased.

[0051] The reduction catalyst is preferably a chemical reaction product of a metal complex that promotes a chemical reaction to reduce a target substance and produce a reduction product, and an alcohol or aprotic solvent with 2 or fewer carbon atoms. When the ammonia-producing catalyst, which is the reduction catalyst, is a molecular catalyst such as a molybdenum complex, the solubility of the molecular catalyst in the solvent and the affinity between the solvent and the catalyst support material affect the difficulty of adsorption. Solvents used to dissolve the molybdenum complex include methanol, ethanol, tetrahydrofuran, acetone, acetonitrile, and chloroform. Molybdenum complexes dissolve in methanol or ethanol, but do not dissolve in alcohols with more than 2 carbon atoms, such as propanol. They also dissolve readily in polar solvents such as tetrahydrofuran and do not dissolve in nonpolar solvents such as hexane. For this reason, the solvent is preferably an alcohol or aprotic solvent with 2 or fewer carbon atoms, and the relative permittivity ε of the aprotic solvent is preferably 3.0 or higher, and more preferably 20.0 or higher, at 20°C. The upper limit of the relative permittivity ε is not particularly limited, but is, for example, 50.0 or lower.

[0052] On the other hand, considering the interaction between the solvent and the molybdenum complex, and between the molybdenum complex and the catalyst support material, it is considered that adsorption to the catalyst support is more likely to proceed when the solvent has low solubility for the molybdenum complex. Furthermore, when a porous carbon material is used as the catalyst support, it is preferable to use a solvent with appropriate hydrophilicity to prevent the solvent from being preferentially adsorbed onto the carbon material. For this reason, it is preferable to use methanol as the solvent, which has a low boiling point and properties that balance appropriate hydrophilicity and solubility. For example, the temperature for adsorbing the molybdenum complex onto the porous carbon material is preferably 0 to 90°C, and more preferably 5 to 40°C, taking into account the decomposition temperature of the molybdenum complex and the boiling point of the solvent. If the time for adsorption of the molybdenum complex onto the porous carbon material is too short, adsorption may not be completed. On the other hand, if the adsorption time is too long, the ammonia production ability due to the reaction between the molybdenum complex and the solvent will decrease, and the workability will worsen. Therefore, the time for adsorbing the molybdenum complex onto the porous carbon material is preferably in the range of 0.5 to 48 hours, and more preferably 1 to 24 hours.

[0053] Next, a method for forming the cathode 14 in the manufacturing method of the electrolytic device will be described. When the ammonia generation catalyst is a molecular catalyst such as a molybdenum complex, methods for adsorbing the molecular catalyst onto the catalyst support include the drop-cast method, in which a molecular catalyst solution is prepared by dissolving the molecular catalyst in a solvent, and the molecular catalyst solution is dropped onto the catalyst support and the solvent is evaporated, as well as the immersion method, in which the molecular catalyst is supported by immersing the catalyst support in the molecular catalyst solution. The immersion method is preferred for the purpose of uniformly supporting the molecular catalyst on the catalyst support, and a cathode 14 with a large amount of catalyst can be produced by holding the molecular catalyst solution in which the catalyst support is immersed under reduced pressure or by holding it under ultrasonic irradiation using an ultrasonic generator.

[0054] Inorganic materials and organic-inorganic composite materials are thought to function as ion conductors in the catalyst layer 142 and also play a role in supplying the ions necessary for the ammonia generation catalyst reaction. When the hydrogen ion concentration of the electrolyte is 7 or less (pH ≤ 7), hydrogen ions (H + On the other hand, when the hydrogen ion concentration of the electrolyte is greater than 7 (pH>7), hydroxide ions (OH) are produced. - ) is supplied to the ammonia generation catalyst. By including an ion-conducting material in the catalyst layer 142, hydrogen ions (H) are supplied to the reduction catalyst. + ) and hydroxide ions (OH - This improves the transferability and supply of substances such as ). Consequently, it becomes possible to improve the reduction efficiency of nitrogen (N) and the initial reduction efficiency of nitrogen, thereby improving the production efficiency of ammonia (NH3).

[0055] The organic polymer material that binds the conductive material, the catalyst support bearing the reduction catalyst, and the gas diffusion layer 141 is preferably a water-insoluble polymer material that can maintain the catalyst layer structure even in a humid environment. Examples of such polymer materials include fluorine-based resins such as perfluoroalkoxyalkanes (PFA), perfluoroethylene propene copolymer (FEP), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE), as well as polystyrene, polyvinyl butyral, and poly(4-vinylpyridine). The polymer material used as a binder may also have ionic conductivity. Examples of ionic conductive polymer materials include Nafion®, a fluororesin obtained by sulfonating and polymerizing tetrafluoroethylene from DuPont, Sustainion® from Dioxide Materials, and PiperION® from Versogen.

[0056] The ratio of the mass of polymer materials in the catalyst layer 142 is preferably in the range of 0.1 to 0.5 relative to the total mass of the materials constituting the catalyst layer 142. Furthermore, the ratio of the mass of conductive materials is preferably in the range of 0.3 to 0.9 relative to the total mass of the materials constituting the catalyst layer 142. Within these ranges, ammonia generation can be promoted without causing a decrease in the binding properties or conductivity of the catalyst layer 142.

[0057] When the polymer material in the catalyst layer 142 is a water-repellent material such as polytetrafluoroethylene, a low-hydrophilic catalyst layer can be achieved by increasing the proportion of the polymer material in the catalyst layer 142. On the other hand, to increase the amount of catalyst supported, it is necessary to increase the proportion of the catalyst support in the catalyst layer 142. For example, the mass ratio of the catalyst support to the water-repellent polymer material is preferably in the range of 8:2 to 4:6, and more preferably in the range of 7:3 to 5:5. By adjusting the ratio of the catalyst support to the water-repellent polymer material to the above range, the efficiency of ammonia generation in the gas phase can be improved.

[0058] The catalyst layer 142 may contain an ionic liquid. By placing an ionic liquid on the surface of the catalyst support and suppressing the adhesion of excess moisture, it is possible to reduce hydrogen generation due to water reduction and promote the ammonia production reaction. The ionic liquid contained in the reduction catalyst can be made from the same material as that used for the electrolyte described above.

[0059] A membrane capable of selectively circulating anions or cations is used in the diaphragm 4 provided between the cathode chamber and the anode chamber of the electrochemical reaction unit 5. The membrane constituting such a diaphragm 4 is preferably a membrane polymer material having ion conductivity. Examples of ion-conducting polymer materials that can be used include ion exchange membranes such as Neosepta (registered trademark) from Astom, Celemion (registered trademark) from Asahi Glass, Aciplex (registered trademark) from Asahi Kasei, Fumasep (registered trademark) and fumapem (registered trademark) from Fumatech, Nafion (registered trademark), a fluororesin polymerized by sulfonating tetrafluoroethylene from DuPont, lewabrane (registered trademark) from LANXESS, IONSEP (registered trademark) from IONTECH, Mustang (registered trademark) from PALL, ralex (registered trademark) from mega, Gore-Tex (registered trademark) from Gore-Tex, Sustainion (registered trademark) from Dioxide Materials, and PiperION (registered trademark) from Versogen. The diaphragm 4 may be a composite membrane composed of an organic-inorganic composite material having ion conductivity and a polymer material that binds the organic-inorganic composite material together.

[0060] If the polymer material in the catalyst layer 142 or the material in the diaphragm 4 is an ion exchange membrane, the cathode 14 or diaphragm 4 may be immersed in an electrolyte solution to change the countercations and counteranions contained in the ion exchange membrane. Examples of electrolyte solutions for exchanging countercations include solutions containing ions such as lithium ions, sodium ions, potassium ions, cesium ions, and ammonium ions, and examples of electrolyte solutions for exchanging counteranions include solutions containing ions such as fluoride ions, chloride ions, bromide ions, and iodide ions. Note that the ions contained in the electrolyte solution are not limited to the above ions. By exchanging the counterions of such an ion exchange membrane, the water permeability of the ion exchange membrane can be controlled to promote ammonia production.

[0061] The nitrogen supply unit 7 is a unit that supplies gaseous nitrogen to the first reaction vessel (electrolytic cell for reduction reaction) 2 and is equipped with a nitrogen supply device 6. The nitrogen supplied from the nitrogen supply device 6 is, for example, nitrogen from the air, but is not limited to this. Since air contains about 21% oxygen, it is preferable to separate the oxygen from the air to be used beforehand and extract the nitrogen. When using nitrogen from the air, the nitrogen supply device 6 is equipped with an oxygen separation device that separates the oxygen from the air and extracts the nitrogen. The method for separating oxygen from the air in the oxygen separation device 6 can be, for example, a cryogenic separation method that uses the difference in boiling points, an adsorption separation method that uses the difference in adsorption characteristics of zeolite-based adsorbents for gas molecules, or a membrane separation method that uses the fact that the permeation rate of the membrane differs depending on the gas molecule, and can be appropriately selected according to cost and scale of the device, and is not particularly limited. The nitrogen supply unit 7 may further be equipped with a humidifier that humidifies the nitrogen extracted from the air. It is preferable to supply humidified nitrogen to the cathode chamber.

[0062] From the cathode chamber, nitrogen gas containing ammonia, hydrogen gas produced by a side reaction, and a portion of the electrolyte that has permeated the diaphragm (electrolyte membrane) 4 from the anode 15 are discharged. The discharge piping from the cathode chamber is connected to the ammonia collection unit 9. The ammonia collection unit 9 is a unit that collects ammonia contained in the exhaust gas discharged from the cathode chamber and is equipped with an ammonia collection device 8. The ammonia collection device 8 is not particularly limited, and for example, a device that selectively collects ammonia by contacting the exhaust gas with an aqueous solution (collection solution) with a pH of 0 to 7 for ammonia absorption can be used. With such an ammonia collection device 8, by-products such as hydrogen and unreacted nitrogen contained in the exhaust gas can be separated simultaneously.

[0063] The ammonia collected by the ammonia collection device 8 and a portion of the electrolyte that has permeated the diaphragm (electrolyte membrane) 4 from the anode 15 are contained in the collected liquid and are therefore sent to the ammonia separation device 19, which separates the ammonia from the collected liquid. The ammonia separation device 19 can be subjected to various methods, such as distillation or cryogenic separation, which utilize differences in boiling points; adsorption separation, which utilizes the differences in adsorption characteristics of zeolite-based adsorbents for gas molecules; or membrane separation, which utilizes the fact that the permeation rate of the membrane differs depending on the gas molecule. The ammonia separation device 19 can be appropriately selected according to cost, device size, etc., and is not particularly limited. The ammonia separation device 19 is equipped with piping for recovering the ammonia separated from the collected liquid.

[0064] When separating ammonia from a collected liquid by distillation, a distillation column is used as the ammonia separation apparatus 19. The distillation column is configured to separate ammonia, which has a boiling point lower than water, used as at least a portion of the collected liquid. In the distillation column, ammonia is separated from the supplied collected liquid by distillation using a conventional method. Specifically, the collected liquid is distilled under reduced pressure of 10-120 Torr (1333-15999 Pa), and ammonia is discharged from the piping at the top of the distillation column. The ammonia discharged from the piping is recovered in a tank or the like (not shown in the figure).

[0065] For ammonia separation, a stripping method may be applied, in which the collected liquid is brought into contact with vapor, and the ammonia in the collected liquid is recovered by transferring it to the vapor. In this case, the ammonia separation device 19 is equipped with a stripping tower whose interior is partitioned by a perforated plate, and the supplied collected liquid is configured to flow from the upper to the lower section of the stripping tower. The vapor flows from the lower section to the upper section and rises through the liquid that is blocked by the perforated plate. Upon contact between the collected liquid and the vapor, the ammonia in the collected liquid vaporizes and moves into the vapor section, and is discharged from the piping at the top of the tower. Furthermore, if a carbonate aqueous solution is used as the collected liquid, the ammonia in the collected liquid can be converted to ammonium bicarbonate, and by thermal decomposition using a pyrolysis device, ammonia and carbon dioxide can be separated and recovered. The water separated in the ammonia separation device 19 and a portion of the electrolyte that has permeated the diaphragm (electrolyte membrane) 4 from the anode 15 are sent back to the electrolyte storage tank 10 and reused as electrolyte (anode electrolyte) supplied to the anode chamber.

[0066] Next, additional configuration examples and modifications of the nitrogen electrolytic apparatus 1 of the embodiment will be described. A circulation mechanism such as a pump may be provided in the anode chamber. By promoting the circulation of the electrolyte with the circulation mechanism, ions (H) are generated between the anode chamber and the cathode chamber for the oxidation reaction. + yaOH - This can improve the circulation of the ions. Furthermore, flow channels may be provided in the first and second reaction vessels 2 and 3, and multiple circulation mechanisms may be provided. In addition, multiple (three or more) reaction vessel flow channels may be provided to reduce ion diffusion and circulate ions more efficiently. By creating a liquid flow with the circulation mechanism, it is possible to suppress the retention of generated bubbles on the electrode surface and the surface of the reaction vessel, thereby promoting the reaction.

[0067] The second reaction vessel 3 is connected to an electrolyte circulation unit. The electrolyte circulation unit may include at least an electrolyte storage tank 10, a liquid transfer pump 20, and circulation piping 24. The electrolyte circulation unit is a unit that circulates the electrolyte, which contains the generated ammonia, through the circulation piping 24 in order to take it out of the second reaction vessel 3 and to resupply the electrolyte to the second reaction vessel 3. The circulation piping 24 is provided with a liquid transfer pump 20 for circulating the electrolyte and an electrolyte storage tank 10 for storing the electrolyte and adjusting the electrolyte concentration, pH, etc. The electrolyte circulation unit is configured to circulate the electrolyte between the second reaction vessel 3 and the electrolyte storage tank 10 by the liquid transfer pump 20.

[0068] In Figure 1, the liquid transfer pump 20 is located in the circulation piping 24 that sends the electrolyte from the second reaction vessel 3 to the electrolyte storage tank 10. However, the liquid transfer pump 20 may also be located in the circulation piping 24 that sends the electrolyte from the electrolyte storage tank 10 to the second reaction vessel 3. The electrolyte circulation unit preferably includes an exhaust unit that exhausts excess nitrogen that did not dissolve in the electrolyte and gases produced by the oxidation reaction. As the exhaust unit, for example, piping equipped with a valve is used and is provided, for example, in the electrolyte storage tank 10. The electrolyte storage tank 10 functions as a gas-liquid separation tank, and oxygen (O2) produced by the oxidation reaction is separated from the electrolyte.

[0069] The ammonia separation unit 13 is a unit that recovers ammonia (NH3), a nitrogen reduction product, from the electrolyte. The ammonia separation unit 13 may include an ammonia separation device 12 that separates ammonia from the electrolyte, a three-way valve 22 that takes out at least a portion of the electrolyte circulating in the circulation pipe 24, a pipe 23 that sends the electrolyte taken out from the three-way valve 22 to the ammonia separation device 12, and a circulation pipe 24 that sends the electrolyte from which ammonia has been separated in the ammonia separation device 12 to the electrolyte storage tank 10. The three-way valve 22 is provided in the circulation pipe 24, and the ammonia separation unit 13 is connected to the electrolyte circulation unit via the three-way valve 22. The extraction of the electrolyte circulating in the circulation pipe 24 is not limited to the use of the three-way valve 22 provided in the circulation pipe 24, but may also be carried out by connecting a pipe with a valve to the electrolyte storage tank 10, and the configuration is not particularly limited. The ammonia separation device 12 is subjected to the same separation method as the ammonia separation device 19 and has a similar configuration.

[0070] Next, the process of producing ammonia using the nitrogen electrolysis apparatus (ammonia production apparatus) described above will be explained. First, as an initial step, humidified nitrogen gas is supplied to the cathode chamber. The electrolyte is supplied to the anode chamber. In this state, power is supplied to the cathode 14 and anode 15 from the external electrode.

[0071] The anode 15 and cathode 14 may be connected to an external power supply 17 via external electrodes. The external power supply 17 may be a normal commercial power supply or a battery, or it may be a power supply that converts renewable energy into electrical energy. Examples of such power supplies include power supplies that convert kinetic energy or potential energy such as wind power, hydropower, geothermal energy, and tidal power into electrical energy; power supplies such as solar cells that have photoelectric conversion elements that convert light energy into electrical energy; power supplies such as fuel cells and storage batteries that convert chemical energy into electrical energy; and devices that convert vibrational energy such as sound into electrical energy. The photoelectric conversion element has the function of separating charges using the energy of light such as irradiated sunlight. Examples of photoelectric conversion elements include pin junction solar cells, pn junction solar cells, amorphous silicon solar cells, multi-junction solar cells, monocrystalline silicon solar cells, polycrystalline silicon solar cells, dye-sensitized solar cells, organic thin-film solar cells, and perovskite solar cells.

[0072] By applying power to the cathode 14 and anode 15 from an external electrode, the anode 15 electrochemically reacts with water (H2O) or hydroxide ions (OH) in the electrolyte. - The following oxidation reaction occurs. For example, when the hydrogen ion concentration of the electrolyte is 7 or less (pH ≤ 7), H2O is oxidized to O2 and H based on the following equation (1). + Furthermore, if the hydrogen ion concentration of the electrolyte is greater than 7 (pH>7), OH is generated based on the following equation (2). - It is oxidized to produce O2 and H2O. 3H2O → 3 / 2O2 + 6H + +6e - …(1) 6OH - → 3 / 2O2 + 3H2O + 6e - …(2)

[0073] In the cathode chamber, nitrogen (N2) is reduced by an ammonia-producing catalyst to produce ammonia (NH3). The ammonia-producing catalyst is as described above. N2 is reduced by the conduction ion species of the diaphragm 4 according to equation (3) or equation (4) below to produce ammonia (NH3). N2 + 6H2O + 6e - → 2NH3 + 6OH - …(3) N2+6H + +6e - → 2NH3…(4)

[0074] The gas containing NH3 generated by the N2 reduction described above is sent to the ammonia collection unit 8, where ammonia is selectively collected by contacting the exhaust gas with an aqueous solution (collection liquid) with a pH of 0 to 7, as previously mentioned. At the same time, by-products such as hydrogen and unreacted nitrogen contained in the exhaust gas are separated. The collection liquid containing ammonia is sent to the ammonia separation unit 12, where ammonia is separated from the collection liquid.

[0075] A portion of the NH3 generated by N2 reduction is sent to the anode chamber via the diaphragm 4 and dissolved in the electrolyte. The electrolyte containing NH3 is sent to the electrolyte storage tank via the circulation piping, where oxygen (O2) is separated and then it is sent back to the anode chamber. By circulating the electrolyte through the circulation piping 24, the ammonia concentration in the electrolyte increases. At least a portion of the electrolyte with increased ammonia concentration is sent to the ammonia separation device 12 via the three-way valve 22, thereby separating ammonia from the electrolyte.

[0076] The supply of the electrolyte containing ammonia to the ammonia separation device 12 may be carried out continuously from the start of operation of the device, but it is preferable to carry it out intermittently once the concentration of ammonia in the electrolyte has become sufficiently high. That is, if the concentration of ammonia in the electrolyte is low, the energy required to recover ammonia from the electrolyte will be greater than the amount of energy stored in the ammonia, and the cost of producing ammonia will increase. To address this, by circulating the electrolyte through the circulation piping 24 via the second reaction vessel 3 and the electrolyte storage tank 10, an electrolyte containing a high concentration of ammonia can be obtained. It is preferable to send the electrolyte containing a high concentration of ammonia to the ammonia separation device 12. This allows for the efficient recovery of ammonia, which is a reduction product of N2. To improve the ammonia recovery efficiency, it is preferable to send the electrolyte containing ammonia at a concentration of 0.01 to 50% by mass to the ammonia separation device 12.

[0077] Temperature control mechanisms may be provided in the cathode and anode chambers to adjust the temperature of the electrolyte. By controlling the temperature using the temperature control mechanism, the catalytic performance can be controlled. For example, by making the temperature of the reaction system uniform, the performance of the catalyst can be stabilized. In addition, temperature rise can be prevented to stabilize the system. The reaction temperature in the electrochemical reaction cell 5 can be appropriately selected within the range of 5 to 95°C, taking into consideration that the electrolyte is an aqueous solution, the efficiency of the reaction, and economics. Preferably, it is around room temperature (10 to 60°C).

[0078] The electrochemical reaction cell 5 can obtain a larger reaction current by increasing the reaction area through the porous nature of its electrodes. The electrochemical reaction cell 5 may have an electrode structure in which a diaphragm 4 is sandwiched between a porous anode 15 and a porous cathode 14. That is, in the electrochemical reaction cell 5 shown in Figure 2, the porous anode 15 and the porous cathode 14 are arranged in contact with both sides of the diaphragm 4, respectively. The electrolyte is supplied to the side of the porous anode 15 opposite to the side in contact with the diaphragm 4. An ammonia-producing catalyst is placed on the side of the porous cathode 14 in contact with the diaphragm 4, and nitrogen is supplied to the side of the porous cathode 14 opposite to the side in contact with the diaphragm 4. The electrochemical reaction cell 5 may have a nitrogen supply pipe that supplies nitrogen to the ammonia-producing catalyst via the porous cathode 14 and the porous anode 15. A flow path may be provided in the path through which nitrogen flows. By providing multiple (three or more) gas flow paths, nitrogen can be uniformly distributed to the porous cathode 14.

[0079] The electrochemical reaction cell 5 may have an electrolyte between the porous cathode 14 and the diaphragm 4. That is, the electrochemical reaction cell 5 shown in Figure 4 can supply nitrogen from the side of the cathode 14 opposite to the ammonia-producing catalyst. In this way, the structure of the electrochemical reaction cell 5 can be modified in various ways. [Examples]

[0080] Next, we will describe the examples and their evaluation results.

[0081] [Cathode fabrication] The cathode was prepared by spray-coating a catalyst ink onto carbon paper with a carbon particle layer (MPL layer) formed on it. The catalyst ink used for the cathode was Ketjenblack (manufactured by Lion Specialty Chemicals, EC600JD, BET specific surface area: 1270 m²) as a support for the molybdenum complex. 2A catalyst ink was prepared using 0.3g of Ketjenblack, 0.2g of PTFE, 35mL of 2-propanol as a dispersion medium, and 35mL of pure water. In a glass vial, the Ketjenblack, PTFE, 2-propanol, and pure water were mixed and dispersed for 20 minutes using an ultrasonic homogenizer to prepare the catalyst ink. Next, the mixture was fixed to a metal plate and spray-coated onto carbon paper (Avcarb, MB-30 (product name)) heated to 90°C to form a catalyst layer. The catalyst layer was applied to the MPL layer side. At this time, the 1cm of the coated surface was 2 Each sample contained 2.2 mg of Ketjenbrak and 1.5 mg of PTFE. The electrodes were fired at 380°C in an argon atmosphere for 1 hour to bond the material, and then cut into 20 mm x 20 mm squares. The thickness of the catalyst layer was determined by subtracting the previously measured thickness of carbon paper from the thickness of the prepared electrodes. The thickness of the catalyst layer prepared under these conditions was 0.047 mm. Next, four electrodes with the catalyst layer formed were immersed in a sample bottle containing a catalyst solution (a solution of approximately 10 mg of molybdenum complex dissolved in 10 mL of methanol) prepared by dissolving molybdenum triiodide complex (with the PCP ligand 1,3-bis(ditter-butylphosphinomethylbenzimidazole-2-ylidene)) in methanol at room temperature in a nitrogen atmosphere, and the sample bottle was subjected to ultrasonic irradiation for 1 hour. After that, they were air-dried under a nitrogen stream to form cathodes (20 mm x 20 mm squares). The amount of supported molybdenum complex in the catalyst layer was quantified by X-ray fluorescence analysis and inductively coupled plasma emission spectroscopy. The mass ratio of Ketjenblack (KB) to PTFE (KB:PTFE) in the cathode was 5.9:4.1. The KB:PTFE ratio was measured over a 1 cm² area of ​​the coated surface. 2 It was calculated from the mass of KB and the mass of PTFE per unit area.

[0082] [Quantification of molybdenum complex content by X-ray fluorescence analysis and inductively coupled plasma emission spectroscopy] Cathodes for acquiring calibration curve data were prepared in advance, and the fluorescence X-ray intensity corresponding to the molybdenum atoms contained in the cathodes was measured. By performing inductively coupled plasma emission spectroscopy on the solution obtained by pressurized acid decomposition of the same sample, a calibration curve for the molybdenum atom weight corresponding to the fluorescence X-ray intensity was created. From the fluorescence X-ray intensity corresponding to the molybdenum atoms obtained by fluorescence X-ray analysis of the sample to be measured, the molybdenum atom weight contained in the cathodes was estimated using the calibration curve created above. The number of molybdenum atoms contained in the cathodes was calculated by dividing the molybdenum atom weight by the amount of molybdenum element. Since one molybdenum atom is contained in one molecule of the molybdenum complex, the amount of molybdenum complex was estimated using the number of molybdenum atoms as the number of molecules of the molybdenum complex. The amount of molybdenum complex per cathode estimated in this way was 2.26 μmol.

[0083] [Creating the Anode] The anode was fabricated by forming a mesh structure of Ti using an etching method, increasing the surface area of ​​the wire mesh (20mm x 20mm square), and then forming iridium oxide as an oxidation catalyst on the mesh.

[0084] [Fabrication of membrane electrode assemblies and N2 electrolytic cells] The experiment was conducted using the electrolytic cell configuration shown in Figure 3. A membrane electrode assembly (catalyst area 400 mm²) was constructed by stacking DuPont's Nafion® 117 membrane (25 mm x 25 mm square) as a diaphragm between the anode and cathode. 2 The following preparations were made. The Nafion117 membrane was pre-treated by boiling it for 1 hour in 3% hydrogen peroxide, 1M sulfuric acid, and pure water, respectively, and then immersing it in a 1M KOH solution. The cathode catalyst layer and the diaphragm were positioned in contact. The membrane electrode assembly was assembled into an N2 electrolytic cell by sandwiching it between titanium channels (serpentine, land width 0.4 mm, channel width 1.5 mm, channel depth 1 mm) via a Teflon gasket.

[0085] [Potential-constant electrolysis measurement (ammonia generation experiment)] A 0.1 M tripotassium phosphate solution was supplied as the electrolyte to the anode channel of the N2 electrolytic cell at a flow rate of 10 mL / min. The pH of the electrolyte was 11. Meanwhile, dry N2 gas (>99.99%) was supplied to the cathode channel at a flow rate of 80 mL / min. A power supply (Biologic VMP-300) was electrically connected to the cathode and anode from the outside of the cathode and anode channel plates, and a constant current of 1.6 A (current density 400 mA / cm²) was supplied. 2 A solution was applied for 15 minutes. 0.1M sulfuric acid was connected as a trap solution to the cathode channel outlet of the N2 electrolytic cell, and the reduction products generated from the cathode were collected and analyzed every 5 minutes.

[0086] [Method for determining ammonia] Ammonia was quantified using ion chromatography. The ammonia gas and ammonia-containing liquid discharged from the cathode channel outlet were all converted to ammonium ions by the sulfuric acid trap solution. The ammonium ions in the sulfuric acid trap solution were quantified using ion chromatography, for which a calibration curve had been prepared in advance using a specified volume of ammonium ion solution.

[0087] The partial current density and Faraday efficiency of ammonia production were calculated based on the current consumed in the cathode reduction reaction and the quantitative analysis of the reduction products. The partial current density corresponds to the ammonia production rate of the electrolytic cell, and the Faraday efficiency is expressed as the ratio of the amount of electricity required to produce the reduction products to the amount of electricity input. The Faraday efficiency of each analyzed reduction product was defined as the selectivity (%) of the product. In the N2 electrolytic cell prepared by the above method, the partial current density was 13.3 mA / cm². 2 The Faraday efficiency was 3.33%.

[0088] The amount of ammonia produced was estimated from the current density of the ammonia-producing portion, and the turn-over frequency (TOF) was estimated by dividing this by the amount of molybdenum complex contained in the cathode. In the N2 electrolytic cell prepared by the above method, the TOF was 294h ―1 These results are shown in Table 1.

[0089] (Example 2) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of ethanol. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 1.20 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 8.54 mA / cm². 2 The Faraday efficiency was 2.14%, and the time of flight (TOF) was 355h. ―1 These results are shown in Table 1.

[0090] (Example 3) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of tetrahydrofuran. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 2.38 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 13.1 mA / cm². 2 The Faraday efficiency was 3.28%, and the time of flight (TOF) was 274h. ―1 These results are shown in Table 1.

[0091] (Example 4) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of chloroform. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 1.44 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 8.97 mA / cm². 2 The Faraday efficiency was 2.24%, and the time of flight (TOF) was 309h. ―1 These results are shown in Table 1.

[0092] (Example 5) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of acetone. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 1.21 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 10.4 mA / cm². 2 The Faraday efficiency was 2.61%, and the time of flight (TOF) was 428 hours. ―1 These results are shown in Table 1.

[0093] (Example 6) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of acetonitrile. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 0.59 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 3.65 mA / cm². 2 The Faraday efficiency was 0.91%, and the time of flight (TOF) was 309h. ―1 These results are shown in Table 1.

[0094] (Comparative Example 1) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of 2-propanol. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 0.36 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 0.11 mA / cm². 2 The Faraday efficiency was 0.03%, and the time of flight (TOF) was 16 hours. ―1 These results are shown in Table 1.

[0095] (Comparative Example 2) The solvent in the catalyst solution was changed from 10 mL of methanol to the same volume of hexane. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the solvent of the catalyst solution. The amount of molybdenum complex per cathode was 0.19 μmol. Ammonia was attempted to be produced using this N2 electrolytic cell in the same manner as in Example 1. As a result, no ammonia was detected. These results are shown in Table 1.

[0096] According to Examples 1-6 and Comparative Examples 1 and 2, the molybdenum complex is readily soluble in C2 or less alcohols such as methanol and ethanol, or in polar solvents such as tetrahydrofuran, which increases the amount of cathode catalyst supported and thus increases the amount of ammonia produced. On the other hand, it does not dissolve in C3 or more alcohols such as 2-propanol or in nonpolar solvents such as hexane, which reduces the amount of cathode catalyst supported and thus decreases the amount of ammonia produced. For this reason, the dielectric constant ε of the aprotic solvent used as the solvent for the catalyst solution is preferably 3.0 or higher, and more preferably 20.0 or higher.

[0097] (Example 7) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2 A cathode was prepared containing 3.3 mg of Ketjenbrak and 2.2 mg of PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The thickness of the catalyst layer in the cathode was 0.100 mm. The KB:PTFE ratio was 6.0:4.0. The amount of molybdenum complex per cathode was 2.61 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 15.7 mA / cm². 2 The Faraday efficiency was 3.94%, and the time of flight (TOF) was 301h. ―1 These results are shown in Table 1.

[0098] (Example 8) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2A cathode was prepared containing 4.4 mg of Ketjenbrak and 3.0 mg of PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The thickness of the catalyst layer in the cathode was 0.149 mm. The KB:PTFE ratio was 5.9:4.1. The amount of molybdenum complex per cathode was 4.02 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 13.4 mA / cm². 2 The Faraday efficiency was 3.35%, and the time of flight (TOF) was 166h. ―1 These results are shown in Table 1.

[0099] (Example 9) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2 A cathode was prepared containing 1.1 mg of Ketjenbrak and 0.7 mg of PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The thickness of the catalyst layer in the cathode was 0.032 mm. The KB:PTFE ratio was 6.1:3.9. The amount of molybdenum complex per cathode was 1.20 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 9.91 mA / cm². 2 The Faraday efficiency was 2.48%, and the time of flight (TOF) was 410h. ―1 These results are shown in Table 1.

[0100] (Example 10) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2 A cathode was prepared containing 6.6 mg of Ketjenbrak and 4.5 mg of PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The thickness of the catalyst layer in the cathode was 0.210 mm. The KB:PTFE ratio was 5.9:4.1. The amount of molybdenum complex per cathode was 2.24 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 10.4 mA / cm². 2 The Faraday efficiency was 2.60%, and the time of flight (TOF) was 232h.―1 These results are shown in Table 1.

[0101] According to Examples 1, 7, 8, 9, and 10, a thicker cathode catalyst layer can support more molybdenum complexes, but beyond a certain thickness, the amount of complexes supported decreases. On the other hand, if the catalyst layer is thicker than necessary, the gas to be reduced supplied from the gas diffusion layer has difficulty reaching the surface of the catalyst layer, leading to hydrogen production by side reactions and a decrease in ammonia production efficiency. Therefore, a catalyst layer thickness of 0.035 to 0.200 mm is more preferable.

[0102] (Example 11) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2 A cathode was prepared containing 1.5 mg of Ketjenbrak and 2.2 mg of PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The thickness of the catalyst layer in the cathode was 0.046 mm. The KB:PTFE ratio was 4.0:6.0. The amount of molybdenum complex per cathode was 0.95 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 8.35 mA / cm². 2 The Faraday efficiency was 2.09%, and the time of flight (TOF) was 438h. ―1 These results are shown in Table 1.

[0103] (Example 12) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2 A cathode was prepared containing 2.9 mg of Ketjenbrak and 0.8 mg of PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The thickness of the catalyst layer in the cathode was 0.078 mm. The KB:PTFE ratio was 7.8:2.2. The amount of molybdenum complex per cathode was 1.78 μmol. Ammonia production was attempted using this N2 electrolytic cell in the same manner as in Example 1. As a result, the partial current density was 6.49 mA / cm². 2 The Faraday efficiency was 1.62%, and the time of flight (TOF) was 182h. ―1These results are shown in Table 1.

[0104] (Comparative Example 3) The cathode catalyst layer ink composition was changed, and the coated surface was measured over 1 cm. 2 A cathode was prepared using 3.7 mg of Ketjenblack per unit area, without adding PTFE. An N2 electrolytic cell was prepared in the same manner as in Example 1, except for the change in the cathode. The KB:PTFE ratio was 10:0. Using this N2 electrolytic cell, we attempted to produce ammonia in the same manner as in Example 1. As a result, the catalyst layer peeled off from the carbon paper during the molybdenum complex immersion process, and ammonia could not be produced. These results are shown in Table 1.

[0105] According to Examples 1, 11, 12 and Comparative Example 3, when the polymer material in the catalyst layer is a water-repellent material such as polytetrafluoroethylene, a low-hydrophilic catalyst layer can be realized by increasing the ratio of the polymer material in the catalyst layer. On the other hand, in order to increase the amount of catalyst supported, it is necessary to increase the ratio of the catalyst support in the catalyst layer, and in order to improve the efficiency of ammonia generation by the gas phase, the ratio of the catalyst support to the water-repellent polymer material is preferably in the range of 7.5:2.5 to 4:6, and more preferably in the range of 7:3 to 5:5.

[0106] TOF indicates the amount of ammonia produced by a single catalyst, and a higher TOF indicates that the catalyst is working efficiently. The same interpretation as in the paragraph above can be applied to TOF. That is, TOF can be increased by making at least one of the following materials or numerical ranges preferable: the type of catalyst solvent, the thickness of the catalyst layer, and the ratio of catalyst support to water-repellent polymer material.

[0107] [Table 1]

[0108] The configurations of each embodiment described above can be applied in combination, and can also be partially replaced. Although several embodiments of the present invention have been described here, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as described in the claims.

[0109] A technical proposal for the above-described embodiment is provided below. (Technical proposal 1) Cathode and, A-scatter, A cathode chamber is in contact with the aforementioned cathode and to which a gaseous substance to be reduced is supplied, An anode chamber, which is in contact with the anode and to which a liquid or gaseous substance to be oxidized is supplied, A diaphragm is provided between the cathode and the anode, It is equipped with, The cathode is, Substrate and Catalyst layer, It has, The catalyst layer is A metal complex that promotes a chemical reaction to reduce the target substance and produce a reduction product, Alcohols with a C2 or lower ratio, or a non-protic solvent with a dielectric constant of 3.0 or higher, A catalyst support that supports the aforementioned metal complex and is conductive, A binder that binds the metal complex and the substrate, Having, Electrolyzer. (Technical proposal 2) The cathode has a catalyst layer containing the reduction catalyst, The thickness of the catalyst layer is 0.035 mm or more and 0.200 mm or less. The electrolytic apparatus described in Technical Proposal 1. (Technical proposal 3) In the catalyst layer, the mass ratio of the catalyst support to the binder (catalyst support:binder) is in the range of 4:6 to 7.5:2.5. An electrolytic apparatus as described in Technical Proposal 1 or Technical Proposal 2. (Technical proposal 4) The catalyst support is a porous carbon material. An electrolytic device described in any one of Technical Proposal 1 to Technical Proposal 3. (Technical proposal 5) The aforementioned binder is an organic polymer material. An electrolytic apparatus described in any one of Technical Proposal 1 to Technical Proposal 4. (Technical proposal 6) The catalyst layer contains methanol. An electrolytic apparatus described in any one of Technical Proposal 1 to Technical Proposal 5. (Technical proposal 7) The aforementioned metal complex is a molybdenum complex that promotes a chemical reaction that reduces nitrogen to produce ammonia. An electrolytic apparatus described in any one of Technical Proposal 1 to Technical Proposal 6. (Technical proposal 8) A nitrogen supply unit comprising a nitrogen supply section for introducing gaseous nitrogen into the cathode chamber, An ammonia collection unit comprising an ammonia collection section for collecting ammonia contained in the waste from the cathode chamber, An ammonia separation unit comprising an ammonia separation section for separating ammonia from the electrolyte discharged from the anode chamber, It further possesses, The electrolytic device described in Technical Proposal 7. (Technical proposal 9) A circulation pipe for circulating the electrolyte supplied to the anode chamber outside the anode chamber, An electrolyte circulation unit comprising an electrolyte storage tank disposed in the aforementioned circulation piping for storing the electrolyte, The electrolytic apparatus described in Technical Proposal 8, further comprising the above. (Technical proposal 10) A method for manufacturing an electrolytic device, The electrolytic device is Cathode and, A-scatter, A cathode chamber is in contact with the aforementioned cathode and to which a gaseous substance to be reduced is supplied, An anode chamber, which is in contact with the anode and to which a liquid or gaseous substance to be oxidized is supplied, A diaphragm is provided between the cathode and the anode, It is equipped with, The cathode is, The catalyst is formed by a method comprising the steps of preparing a solution by mixing a metal complex, an alcohol with a carbon content of 2 or less or an aprotic solvent having a dielectric constant of 3.0 or more, a catalyst support, and a binder, and then forming a catalyst layer on a substrate using the solution. A method for manufacturing an electrolytic device. [Explanation of Symbols]

[0110] 1...Nitrogen electrolytic device, 2...First reaction vessel, 2a...First flow channel plate, 3...Second reaction vessel, 3a...Second flow channel plate, 4...Diaphragm, 5...Electrochemical reaction unit, 6...Nitrogen supply section, 7...Nitrogen supply unit, 8...Ammonia collection device, 9...Ammonia collection unit, 10...Electrolyte storage tank, 11...Oxidation target supply unit, 12...Ammonia separation device, 13...Ammonia separation unit, 14...Cathode, 15...Anode, 16...Third reaction vessel, 17...External power supply, 19...Ammonia separation device, 20...Liquid transfer pump, 22...Three-way valve, 23...Piping, 24...Circulation piping, 141...Gas diffusion layer, 142...Catalyst layer.

Claims

1. Cathode and, A-scatter, A cathode chamber is in contact with the aforementioned cathode and to which a gaseous substance to be reduced is supplied, An anode chamber, which is in contact with the anode and to which a liquid or gaseous substance to be oxidized is supplied, A diaphragm is provided between the cathode and the anode, It is equipped with, The cathode is, Substrate and Catalyst layer, It is equipped with, The catalyst layer is A metal complex that promotes a chemical reaction to reduce the target substance and produce a reduction product, Alcohols with a C2 or lower ratio, or a non-protic solvent with a dielectric constant of 3.0 or higher, A catalyst support that supports the aforementioned metal complex and is conductive, A binder that binds the substrate and the catalyst carrier, Having, Electrolyzer.

2. The thickness of the catalyst layer is 0.035 mm or more and 0.200 mm or less. The electrolytic apparatus according to claim 1.

3. In the catalyst layer, the mass ratio of the catalyst support to the binder (catalyst support:binder) is in the range of 4:6 to 7.5:2.

5. The electrolytic apparatus according to claim 1.

4. The catalyst support is a porous carbon material. The electrolytic apparatus according to claim 1.

5. The aforementioned binder is an organic polymer material. The electrolytic apparatus according to claim 1.

6. The catalyst layer contains methanol. The electrolytic apparatus according to claim 1.

7. The aforementioned metal complex is a molybdenum complex that promotes a chemical reaction that reduces nitrogen to produce ammonia. The electrolytic apparatus according to claim 1.

8. A nitrogen supply unit comprising a nitrogen supply section for introducing gaseous nitrogen into the cathode chamber, An ammonia collection unit comprising an ammonia collection section for collecting ammonia contained in the waste from the cathode chamber, An ammonia separation unit comprising an ammonia separation section for separating ammonia from the electrolyte discharged from the anode chamber, It further possesses, The electrolytic apparatus according to claim 7.

9. A circulation pipe for circulating the electrolyte supplied to the anode chamber outside the anode chamber, An electrolyte circulation unit comprising an electrolyte storage tank disposed in the aforementioned circulation piping for storing the electrolyte, The electrolytic apparatus according to claim 8, further comprising:

10. A method for manufacturing an electrolytic device, The electrolytic device is Cathode and, A-scatter, A cathode chamber is in contact with the aforementioned cathode and to which a gaseous substance to be reduced is supplied, An anode chamber, which is in contact with the anode and to which a liquid or gaseous substance to be oxidized is supplied, A diaphragm is provided between the cathode and the anode, It is equipped with, The cathode is, The catalyst is formed by a method comprising the steps of preparing a solution by mixing a metal complex, an alcohol with a C2 or less concentration or an aprotic solvent having a dielectric constant of 3.0 or more, a catalyst support, and a binder, and then forming a catalyst layer on a substrate using the solution. A method for manufacturing an electrolytic device.

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