Method for producing carbon monoxide or organic compounds

Abstract

To provide a method for producing an organic compound by reducing carbon dioxide efficiently at low cost. [Solution] A method for producing an organic compound in which carbon monoxide or an organic compound is obtained by electrolytic reduction of carbon dioxide in an electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte containing carbon dioxide, wherein the electrolyte contains an ionic liquid and water.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing carbon monoxide or organic compounds. [Background technology]

[0002] As one of the countermeasures against global warming in recent years, there is a demand for the development of carbon recycling technology, which regards carbon dioxide as a carbon resource, captures it, and reuses it as various carbon compounds.

[0003] As one such technique, it has been reported that carbon dioxide can be electrolytically reduced by applying a potential between an anode and a cathode in an inorganic electrolyte aqueous solution to produce lower hydrocarbons, lower alcohols, lower organic acids, and the like (see Non-Patent Document 1). It has also been reported that methane or ethylene can be produced by electrolytically reducing carbon dioxide using a Cu electrode as the cathode and a Pt electrode as the anode in a state in which carbon dioxide is dissolved in a KHCO3 aqueous solution by bubbling (see Non-Patent Document 2). Meanwhile, a method has been disclosed in which carbon dioxide is electrolytically reduced using a Cu electrode previously coated with cuprous halide as the cathode electrode (see Patent Document 1).

[0004] It has been reported that carbon dioxide can be dissolved in a KCl aqueous solution by bubbling, and then copper nanoparticles are electrodeposited in a copper sulfate aqueous solution onto a boron-doped diamond prepared using a microwave plasma CVD apparatus to form a copper-modified boron-doped diamond electrode. The copper-modified boron-doped diamond electrode is used as the cathode, and a platinum electrode is used as the anode, and carbon dioxide is electrolytically reduced to produce acetone and acetaldehyde along with ethanol (see Non-Patent Document 3).

[0005] It has been reported that ethanol can be obtained by electrolytic reduction of carbon dioxide using a cathode electrode and a platinum electrode as an anode electrode (see Non-Patent Document 4). Carbon dioxide is dissolved in an aqueous solution of KHCO3 by bubbling, and conductive carbon, PVDF (polyvinylidene fluoride resin), and N-methyl-2-pyrrolidone are mixed together to form a well-dissolved and dispersed slurry. The slurry is then applied to carbon paper and vacuum dried overnight at 80°C and 0.5 mTorr. A "nitrogen-doped ordered mesoporous carbon catalyst with mesopores" (nitrogen-doped catalyst preparation method omitted) is ultrasonically dispersed in an ethanol solution of Nafion (tetrafluoroethylene-perfluoroalkylsulfonic acid copolymer, trademark of Chemours) and applied to a cathode electrode and a platinum electrode as an anode electrode.

[0006] It has been reported that carbon monoxide can be obtained by electrolytic reduction of carbon dioxide dissolved in 1-butyl-3-methylimidazolium tetrafluoroborate, an imidazolium-based ionic liquid, by bubbling it into the liquid, using a gold electrode as the cathode and a platinum electrode as the anode (see Non-Patent Document 5). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-176129 [Non-patent literature]

[0008] [Non-Patent Document 1] Yoshio Hori, Handbook of fuel cells : fundamentals technology and applications. Volume 2, Chapter 48, 720-733 (2010) [Non-patent document 2] Y.Hori et al., Chem.Lett.15, 897-898(1986) [Non-patent document 3] Jiwanti et al., Electrochim. Acta, 266, 414-419 (2018). [Non-patent document 4] Y. Song et al., ChemSusChem, 13, 293-297(2020). [Non-patent document 5] Yongchun Fu et al., ChemElectroChem, 5, 748-752(2018). Summary of the Invention [Problem to be solved by the invention]

[0009] In these methods, since the electrolysis involves an aqueous solution, the generation of hydrogen at the cathode electrode is unavoidable, making it difficult to stably maintain a high current efficiency over a long period of time. Specifically, in the method described in Non-Patent Document 2, the faradaic efficiency for methane production is 65% at an electrolyte temperature of 0°C, and the faradaic efficiency for ethylene production is only 20% at an electrolyte temperature of 40°C, requiring complex operations such as temperature control. In addition, continued electrolysis over a long period of time reduces the faradaic efficiency, necessitating electrode replacement, and other problems that make the operation complicated.

[0010] In the method described in Patent Document 1, the duration of electrolysis can be extended slightly by using pretreated electrodes, but only by a few hours. Furthermore, the method requires complex pretreatment of the electrodes, which still poses the problem of complicated operations.

[0011] In the method described in Non-Patent Document 3, a high Faradaic efficiency of 15% for acetone production is temporarily achieved by further modifying boron-doped carbon, which is already expensive, with Cu nanoparticles. However, the electrodes are very expensive, and the Cu nanoparticles fall off over time, making it difficult to perform electrolysis while maintaining a high Faradaic efficiency for a long period of time.

[0012] The method described in Non-Patent Document 4 uses a cathode electrode with a sophisticated pore structure prepared through a complex process, thereby achieving a high faradaic efficiency of approximately 78% for ethanol production over 25 hours. However, there are problems in that the electrode catalyst is expensive, the pore structure collapses over time, and the catalytic activity decreases, making it difficult to perform electrolysis while maintaining a high faradaic efficiency for a long period of time.

[0013] In the method described in Non-Patent Document 5, expensive Au is used as the cathode electrode, and a high faradaic efficiency of 95% for carbon monoxide production is achieved in about 30 minutes. However, the electrode is very expensive and is strongly affected by the surface condition of the electrode, making it difficult to perform electrolysis while maintaining a high faradaic efficiency for a long period of time. Furthermore, because no aqueous solution is used, the electrolyte resistance is high and the current density is low, resulting in a low amount of carbon monoxide produced per unit time and low productivity.

[0014] An object of the present disclosure is to provide a method for producing carbon monoxide or an organic compound by reducing carbon dioxide simply and easily using low energy. [Means for solving the problem]

[0015] The present disclosure includes the following aspects. [1] A method for producing carbon monoxide or an organic compound, in which carbon dioxide is electrolytically reduced in an electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte containing carbon dioxide to obtain carbon monoxide or an organic compound, in which carbon dioxide is selectively reduced to carbon monoxide or a specific organic compound by applying a potential between the anode electrode and the cathode electrode. [2] A method for producing carbon monoxide or an organic compound, comprising electrolytically reducing carbon dioxide in an electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte containing carbon dioxide to obtain carbon monoxide or an organic compound, wherein the electrolyte contains an ionic liquid. [3] The method for producing carbon monoxide or an organic compound according to [2] above, wherein the electrolytic solution further contains water. [4] The method for producing carbon monoxide or an organic compound according to [2] or [3] above, wherein the ionic liquid is an imidazolium-based ionic liquid, an aromatic ionic liquid, a pyrrolidinium-based ionic liquid, an ammonium-based ionic liquid, a piperidinium-based ionic liquid, or a quaternary phosphonium-based ionic liquid. [5] The method for producing carbon monoxide or an organic compound according to any one of the above [2] to [4], wherein the ionic liquid is N,N-diethyl-N-(2-methoxyethyl)ammonium tetrafluoroborate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide. [6] The method for producing carbon monoxide or an organic compound according to any one of the above [2] to [5], wherein the electrolytic solution contains an additive. [7] The method for producing carbon monoxide or an organic compound according to any one of the above [2] to [6], wherein the additive comprises a supporting electrolyte or a basic catalyst. [8] The method for producing carbon monoxide or an organic compound according to [7] above, wherein the supporting electrolyte is KHCO3, KHPO4, LiBF4, LiPF6, LiClO4, LiAsF6, LiTf, LiTFSI, Li(CF3SO2)2N, K2CO3, Li2CO3, Na2CO3, or NaHCO3. [9] The method for producing carbon monoxide or an organic compound according to [7] or [8] above, wherein the supporting electrolyte is KHCO3.

[10] The method for producing carbon monoxide or an organic compound according to any one of the above [3] to [9], wherein the volume ratio of the ionic liquid to the total of water and the supporting electrolyte is 1:99 to 99:1.

[11] The method for producing carbon monoxide or an organic compound according to [7] above, wherein the basic catalyst is a hydroxide of an alkali metal or an alkaline earth metal.

[12] The method for producing carbon monoxide or an organic compound according to [7] or [8] above, wherein the basic catalyst is Ca(OH)2, LiOH, NaOH, KOH, or CsOH.

[13] The electrolytic reduction device further includes a reference electrode, and the reference electrode is Ag + The method for producing carbon monoxide or an organic compound according to any one of the above [2] to

[12] , wherein the cathode electrode is a Ag / Ag electrode, and the potential of the cathode electrode is −5.0 to −1.5 V.

[14] The method for producing carbon monoxide or an organic compound according to any one of the above [2] to

[13] , wherein the temperature of the electrolytic solution is 0 to 100°C.

[15] The method for producing carbon monoxide or an organic compound according to any one of the above [1] to

[14] , wherein the cathode electrode is a flat plate electrode.

[16] The method for producing carbon monoxide or an organic compound according to any one of [1] to

[15] above, wherein the anode electrode is a Pt, metal oxide, glassy carbon, or boron-doped diamond electrode, and the cathode electrode is a Cu, Ag, Fe, or Ni electrode.

[17] The method for producing carbon monoxide or an organic compound according to any one of the above [1] to

[16] , wherein the cathode electrode is an Ag, Cu or Fe electrode.

[18] The method for producing carbon monoxide or an organic compound according to any one of the above [1] to

[17] , wherein the cathode electrode is an Ag, Cu or Fe electrode, and the anode electrode is a Pt electrode.

[19] The method for producing carbon monoxide or an organic compound according to any one of [1] to

[18] above, wherein the organic compound is a hydrocarbon or an organic compound consisting of carbon, hydrogen, and oxygen.

[20] The hydrocarbon is C 1-10 The method for producing carbon monoxide or an organic compound according to

[19] above, wherein the organic compound is a hydrocarbon.

[21] The method for producing carbon monoxide or an organic compound according to

[19] above, wherein the organic compound consisting of carbon, hydrogen, and oxygen is an ether, a cyclic ether, an alcohol, or a carbonyl compound.

[22] The method for producing carbon monoxide or an organic compound according to any one of the above [2] to

[21] , wherein carbon monoxide or a predetermined organic compound is selectively produced by changing the potential of the cathode electrode.

[23] An electrolytic reduction device for producing carbon monoxide or an organic compound from carbon dioxide by electrolytic reduction, comprising an anode electrode, a cathode electrode, and an electrolytic cell containing an electrolyte containing carbon dioxide, wherein the carbon dioxide is selectively reduced to carbon monoxide or a specific organic compound by applying a potential between the anode electrode and the cathode electrode.

[24] The electrolytic reduction device according to

[22] above, wherein the cathode electrode is an Ag, Cu, or Fe electrode.

[25] The electrolytic reduction device according to

[22] or

[23] above, which selectively reduces carbon dioxide to carbon monoxide.

[26] The electrolytic reduction device according to any one of the above

[22] to

[24] , wherein the electrolytic solution has a water content of 5 mass % or less.

[27] The electrolytic reduction device according to any one of the above

[22] to

[26] , wherein the electrolytic solution is triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide.

[28] An electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte containing carbon dioxide, for producing carbon monoxide or an organic compound from carbon dioxide by electrolytic reduction, wherein the electrolyte contains an ionic liquid and water.

[29] The electrolytic reduction apparatus according to

[28] , wherein the ionic liquid is an imidazolium-based ionic liquid, an aromatic ionic liquid, a pyrrolidinium-based ionic liquid, an ammonium-based ionic liquid, a piperidinium-based ionic liquid, or a quaternary phosphonium-based ionic liquid.

[30] The electrolytic reduction apparatus according to

[28] or

[29] , wherein the ionic liquid is N,N-diethyl-N-(2-methoxyethyl)ammonium tetrafluoroborate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide.

[31] The electrolytic reduction device according to any one of the above

[28] to

[30] , wherein the electrolytic solution contains an additive.

[32] The electrolytic reduction apparatus according to

[31] above, wherein the additive includes a supporting electrolyte or a basic catalyst.

[33] The electrolytic reduction device according to

[32] above, wherein the supporting electrolyte is KHCO3, KHPO4, LiBF4, LiPF6, LiClO4, LiAsF6, LiTf, LiTFSI, Li(CF3SO2)2N, K2CO3, Li2CO3, Na2CO3, or NaHCO3.

[34] The electrolytic reduction apparatus according to the above

[32] or

[33] , wherein the supporting electrolyte is LiBF4.

[35] The apparatus for electrolytic reduction of hydrocarbons according to any one of the above

[28] to

[34] , wherein the volume ratio of the ionic liquid to the total of water and the supporting electrolyte is 75:25 to 25:75.

[36] The apparatus for electrolytic reduction of hydrocarbons according to the above

[32] , wherein the basic catalyst is a hydroxide of an alkali metal or an alkaline earth metal.

[37] The apparatus for electrolytic reduction of hydrocarbons according to

[36] above, wherein the basic catalyst is Ca(OH)2, LiOH, KOH, NaOH, or CsOH.

[38] The electrolytic reduction device according to any one of the above

[28] to

[37] , wherein the cathode electrode is a flat plate electrode.

[39] The electrolytic reduction apparatus according to any one of the above

[28] to

[38] , wherein the anode electrode is a Pt, metal oxide, glassy carbon, or boron-doped diamond electrode, and the cathode electrode is a Cu, Ag, Fe, or Ni electrode.

[40] The electrolytic reduction device according to any one of the above

[28] to

[39] , wherein the cathode electrode is an Ag, Cu or Fe electrode.

[41] The electrolytic reduction device according to any one of the above

[28] to

[40] , wherein the cathode electrode is an Ag, Cu or Fe electrode, and the anode electrode is a Pt electrode. [Effects of the Invention]

[0016] According to the electrolytic reduction method of the present disclosure, carbon dioxide can be reduced efficiently at low cost to produce carbon monoxide or an organic compound. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram schematically illustrating an experimental device used in an experiment. [Figure 2] 1 is a cyclic voltammogram illustrating the reduction behavior of carbon dioxide during electrolytic reduction carried out using electrolyte A. [Figure 3] FIG. 1 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolyte A, in comparison with a standard gas. [Figure 4] 1 is a cyclic voltammogram illustrating the reduction behavior of carbon dioxide during electrolytic reduction carried out using electrolyte B. [Figure 5] FIG. 1 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolyte B, in comparison with a standard gas. [Figure 6] FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution B at a cathode potential of −2.3 V. [Figure 7] FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution B at a cathode potential of −2.5 V. [Figure 8] FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution B at a cathode potential of −2.7 V. [Figure 9] FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution C at a cathode potential of −2.1 V. [Figure 10] FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution C at a cathode potential of −2.3 V. [Figure 11]FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution C at a cathode potential of −2.5 V. [Figure 12] FIG. 10 is a diagram showing a chromatogram obtained by gas chromatography analysis of the gas generated on the cathode electrode side during electrolytic reduction carried out using electrolytic solution C at a cathode potential of −2.7 V. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present disclosure will be described in detail below.

[0019] The present disclosure provides a method for producing carbon monoxide or an organic compound by electrolytic reduction of carbon dioxide in an electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte solution containing carbon dioxide, and the electrolytic reduction device.

[0020] The electrolytic reduction is usually carried out in an electrolytic cell, which may be any of a single-chamber type, a two-chamber type, a PEM (solid polymer membrane) type, a flow type, and a bipolar type.

[0021] The electrolytic reduction device used in the electrolytic reduction method includes an anode electrode, a cathode electrode, and an electrolyte solution containing carbon dioxide. The anode electrode and the cathode electrode are arranged so that at least a portion of them is in contact with the electrolyte solution. In such a device, by applying a potential between the anode electrode and the cathode electrode, carbon dioxide is reduced to an organic compound at the cathode electrode, causing a current to flow.

[0022] The anode electrode is not particularly limited, but examples thereof include electrodes of Pt, conductive metal oxides, glassy carbon, boron-doped diamond, etc. Examples of conductive metal oxide electrodes that can be used include transparent conductive electrodes called ITO electrodes, in which a mixed oxide of indium and tin is formed on glass, and DSA electrodes (trademark of De Nora Permelec Electrodes, Inc.), in which an oxide of a platinum group metal such as ruthenium or iridium is formed on a substrate such as titanium.

[0023] In a preferred embodiment, the anode electrode may be a Pt electrode. Use of a Pt electrode as the anode electrode improves the efficiency of electrolytic reduction, enabling stable electrolytic reduction over a long period of time.

[0024] The cathode electrode is not particularly limited, but examples include electrodes of Ag, Cu, Ni, Pb, Hg, Tl, Bi, In, Sn, Cd, Au, Zn, Pd, Ga, Ge, Ni, Fe, Pt, Pd, Ru, Ti, Cr, Mo, W, V, Nb, Ta, and Zr, and alloys thereof, as well as electrodes of carbon materials such as glassy carbon, pyrolytic graphite, plastic-formed carbon, and conductive diamond.

[0025] In a preferred embodiment, the cathode electrode may be a Cu, Ag, or Fe electrode, more preferably a Cu electrode. Use of a Cu electrode as the cathode electrode improves the efficiency of electrolytic reduction, enabling the production of the target carbon monoxide or organic compounds with less energy.

[0026] In a more preferred embodiment, the anode electrode is a Pt electrode, and the cathode electrode can be a Cu, Ag, or Fe electrode. Using a Pt electrode as the anode electrode and a Cu electrode as the cathode electrode improves the efficiency of electrolytic reduction, making it possible to produce the target carbon monoxide or organic compounds with less energy.

[0027] In one embodiment, the cathode electrode is a Cu electrode.

[0028] In another embodiment, the cathode electrode is an Ag electrode.

[0029] In another embodiment, the cathode electrode is an Fe electrode.

[0030] In a preferred embodiment, the anode electrode and / or the cathode electrode is a plate electrode. Preferably, the cathode electrode is a plate electrode, and more preferably, both the anode electrode and the cathode electrode are plate electrodes.

[0031] In one embodiment, the electrolyte solution includes an ionic liquid.

[0032] In one embodiment, the water content of the electrolyte solution is 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly may be substantially 0% by mass. By reducing the water content in the electrolyte as described above, composition changes due to evaporation of water in the electrolyte can be suppressed, and electrolysis can be continued for a long period of time without maintenance.

[0033] In another embodiment, the electrolyte solution contains at least an ionic liquid and water. When the electrolyte solution contains an ionic liquid and water, water and carbon dioxide are simultaneously electrolytically reduced on the cathode surface, allowing efficient production of organic compounds without the need for external hydrogen gas supply. Here, the ionic liquid refers to a salt having a melting point of 100°C or lower, i.e., an ionic substance consisting of a cation and an anion.

[0034] The ionic liquid may be an ionic liquid having a melting point of preferably 100°C or less, more preferably 40°C or less, and even more preferably 20°C or less. By using an ionic liquid having a melting point of 100°C or less, efficient electrolytic reduction can be achieved at room temperature, eliminating the need to heat the electrolyte during electrolytic reduction. In addition, ionic liquids with low melting points have low viscosity and high electrical conductivity (ionic conductivity), and therefore can reduce the electrolytic voltage when electrolysis is performed at the same current value, thereby increasing the production volume per unit time and energy efficiency.

[0035] Specifically, the ionic liquid may have a viscosity of 1000 mPa·s or less, preferably 300 mPa·s or less, and more preferably 300 mPa·s or less at 25°C. In addition, the ionic liquid may have a viscosity of 0.1 mPa·s or less at 25°C. -1 More than 1 mS·s, preferably -1 More preferably, 10 mS·s -1 The ionic liquid may have a viscosity of at least 1000 kJ / cm.

[0036] The ionic liquid preferably has a wide potential window, i.e., high redox resistance. In this production method, the use of an ionic liquid that is stable against the oxygen evolution reaction at the anode electrode and the carbon dioxide and water reduction reaction at the cathode electrode allows for efficient electroreduction over long periods of time. Redox resistance is evaluated by cyclic voltammetry and can be defined as the potential window, i.e., the potential range over which substantially no current flows. Specifically, the ionic liquid may have a potential window on the reduction side relative to a silver / silver chloride reference electrode (hereinafter the same), which is −2 V or less, preferably −2.5 V or less, and more preferably 3 V or less. The potential window on the oxidation side may be 2 V or more, preferably 2.5 V or more. Conducting electrolysis beyond the potential window can cause the ionic liquid to decompose, making it difficult to continue electrolysis for long periods of time. However, the optimal cathode potential setting varies depending on the electrolyte composition and the target product. Therefore, it is sufficient for the ionic liquid to have substantially no current flow when energized in an argon atmosphere without introducing carbon dioxide at the optimal setting. From the above viewpoints, an ionic liquid may be appropriately selected in terms of melting point, viscosity, electrical conductivity (ionic conductivity), and potential window, taking into account the target product, operating conditions, etc., and the type of ionic liquid is not limited to those exemplified.

[0037] The ionic liquid preferably has a high solubility of carbon dioxide. By using an ionic liquid with a high solubility of carbon dioxide, electrolytic reduction can be carried out more efficiently.

[0038] Examples of the ionic liquid include imidazolium-based ionic liquids, aromatic-based ionic liquids, pyrrolidinium-based ionic liquids, ammonium-based ionic liquids, piperidinium-based ionic liquids, and quaternary phosphonium-based ionic liquids.

[0039] The imidazolium-based ionic liquid is not particularly limited, but examples thereof include hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C1C6Im-NTf2), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C1C4Im-NTf2), 1-hexyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (C1C1Im-NTf2), 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (C1C1Im-NTf2), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C1C2Im-NTf2), 1-nonyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C1C8Im ―NTf2), 1-nonyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (C1C1C8Im―NTf2), 1-propyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (C1C1C3Im―NTf2), 1-ethyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide (EVIm―NTf2), 1,2-dimethyl-1-propylimidazolium bis(trifluoromethanesulfonyl)imide (DMPI-TFSI), 1,2-dimethyl-1-propylimidazolium tris(trifluoromethylsulfonyl)imide (DMPI-Me), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), 1-ethyl-3-methylimidazolium chloride (EMI-C l ), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI), 1-ethyl-3-methylimidazolium bis((perfluoroethyl)sulfonyl)imide (EMI-BETI), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMI-TfO), 1-ethyl-3-methylimidazolium trifluoroacetate (EMI-TA), 1-ethyl-3-methylimidazolium 2.3 hydrogen fluoride (EMI-F(HF) 2.3), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI), 1-ethyl-3-methylimidazolium hexafluorophosphate (EMI-PF6), 1-butyl-3-methylimidazolium tetrafluoroborate (BMI-BF4), 1-butyl-3-methylimidazolium trifluoroacetate (BMI-TA), 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6), 1-butyl-3-methylimidazolium bis(trifluoromethylimidazolium tetrafluoroborate) 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI-TFSI), 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (CMI-TFSI), 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (CMI-TFSI), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide (DMPI-TFSI), 1,2-dimethyl-3-propylimidazolium bismethide (DMPI-Me), and the like.

[0040] The aromatic ionic liquid is not particularly limited, but examples thereof include diphenylmethane diisocyanate bis(trifluoromethanesulfonyl)imide (MDI-TFSI).

[0041] The ammonium-based ionic liquid is not particularly limited, but examples thereof include N,N-diethyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEME-BF), trimethylpropylammonium bis(trifluoromethanesulfonyl)imide (TMPA-(CFSO)N), tetraethylammonium 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide (TEA-CFCO)(CFSO)N), N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide (DEME-TFSI), N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEME-NTF), and N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME-FSI).

[0042] The pyrrolidinium-based ionic liquid is not particularly limited, but examples thereof include N-methyl-N-propylpyrrolidinium hexafluorophosphate (P 13 -PF6), N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P 13 -TFSI), N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (P 13 -FSI), N-methyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (P 14 -FSI) etc.

[0043] The piperidinium-based ionic liquid is not particularly limited, but examples thereof include N-propyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide ([PMPip](CF3SO2)2N).

[0044] The quaternary phosphonium ionic liquid is not particularly limited, but for example, triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide (P 2225TFSI), triethyloctylphosphonium bis(trifluoromethanesulfonyl)imide (P 2228 -TFSI), tributylmethylphosphonium bis(trifluoromethanesulfonyl)imide (P 4441 -TFSI), triethylmethoxymethylphosphonium bis(trifluoromethanesulfonyl)imide (P 222 ( 1O1 )-TFSI) etc.

[0045] In a preferred embodiment, the ionic liquid may be N,N-diethyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEME-BF4) or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide (DEME-TFSI). By using DEME-BF4 or DEME-TFSI as the ionic liquid, the electrolytic reduction proceeds efficiently for a longer period of time.

[0046] The above ionic liquids may be used alone or in combination of two or more.

[0047] In one embodiment, the electrolyte consists of an ionic liquid and water.

[0048] The volume ratio of the ionic liquid to water in the electrolytic solution is preferably 1:99 to 99:1, more preferably 5:95 to 95:5, even more preferably 75:25 to 25:75, still more preferably 70:30 to 30:70, and particularly preferably 60:40 to 40:60. By setting the volume ratio of the ionic liquid to water within the above range, electrolytic reduction proceeds more efficiently.

[0049] In another embodiment, the electrolyte may contain additives in addition to the ionic liquid and water.

[0050] Examples of the additive include a supporting electrolyte that has the effect of increasing the electrical conductivity of the electrolyte, a basic catalyst, and an additive that has the effect of increasing the solubility of carbon dioxide in the electrolyte.

[0051] In one embodiment, the electrolyte solution comprises an ionic liquid, water, and a supporting electrolyte. By using an electrolyte solution comprising an ionic liquid, water, and a supporting electrolyte, electrolytic reduction proceeds stably and efficiently over a long period of time at a low cell voltage.

[0052] The supporting electrolyte is not particularly limited, but preferably contains a cation having a standard electrode potential that is so base as not to interfere with the electrolytic reduction of carbon dioxide or the electrolytic reduction of H2O, or is equivalent to the base.

[0053] The supporting electrolyte is not particularly limited, but examples thereof include alkali metal salts and alkaline earth metal salts, such as LiHCO3, NaHCO3, KHCO3, CsHCO3, KCl, KClO4, K2SO3, KHPO4, LiBF4, LiPF6, and LiClO 4、 LiAsF 6、 LiTf, LiTFSI, Li(CF3SO2)2N, K2CO 3、 Li2CO 3、 Examples include Na2CO3.

[0054] In a preferred embodiment, the supporting electrolyte may be KHCO. By using KHCO as the supporting electrolyte, the electrolytic reduction proceeds more efficiently.

[0055] The above supporting electrolytes may be used alone or in combination of two or more.

[0056] In a preferred embodiment, the combination of the ionic liquid and supporting electrolyte may be a combination of DEME-BF4 and KHCO3.

[0057] The supporting electrolyte is preferably added as an aqueous solution. The concentration of the aqueous solution may be preferably 0.01 to 10 mol / L, more preferably 0.01 to 5.0 mol / L, and even more preferably 0.05 to 0.5 mol / L. By adjusting the concentration of the aqueous solution of the supporting electrolyte to the above range, the electrolytic reduction proceeds more efficiently.

[0058] The volume ratio of the ionic liquid to water and supporting electrolyte (i.e., an aqueous solution of the supporting electrolyte) in the electrolytic solution may be preferably 75:25 to 25:75, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60. By setting the volume ratio of the ionic liquid to water and supporting electrolyte within the above range, electrolytic reduction proceeds more efficiently.

[0059] In one embodiment, the electrolytic solution comprises an ionic liquid, water, and a basic catalyst. By using an electrolytic solution comprising an ionic liquid, water, and a basic catalyst, electrolytic reduction proceeds efficiently.

[0060] Examples of the basic catalyst include hydroxides of alkali metals or alkaline earth metals, specifically LiOH, NaOH, KOH, RbOH, CsOH, Be(OH)2, Mg(OH)2, Ca(OH)2, Sr(OH)2, and Ba(OH)2.

[0061] In a preferred embodiment, the basic catalyst may be Ca(OH)2, LiOH, NaOH, KOH, or CsOH. By using Ca(OH)2, LiOH, NaOH, KOH, or CsOH as the basic catalyst, the electrolytic reduction proceeds more efficiently. In addition, the basic catalyst has the effect of increasing the solubility of carbon dioxide in the electrolyte, so the electrolytic reduction proceeds more efficiently.

[0062] The content of the basic catalyst in the electrolytic solution is preferably 1.0 × 10 relative to 100 molar parts of the total of the ionic liquid and water. -4 ~5.0 molar parts, more preferably 1.0 × 10 -3 to 1.0 molar part, more preferably 5.0 × 10 -3 The content of the basic catalyst may be in the range of 0.1 to 0.1 parts by mole. By setting the content of the basic catalyst in the range described above, the electrolytic reduction proceeds more efficiently.

[0063] In one embodiment, the electrolyte contains an ionic liquid and has a water content of 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly substantially 0% by mass. If the water content is too high, hydrogen generation by electrolytic reduction of water becomes the main reaction, resulting in a significant decrease in the yield of the target product. If the water content is too low, the resistance of the electrolyte increases, reducing the yield of all products and also reducing the yield of organic compounds containing hydrogen in their molecules. Therefore, it is necessary to maintain an optimal water content.

[0064] In one embodiment, the electrolyte does not contain the additive.

[0065] In one embodiment, the electrolyte contains an ionic liquid, has a water content of 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly substantially 0% by mass, and does not contain any of the additives.

[0066] The concentration of carbon dioxide in the electrolytic solution is not particularly limited, but is preferably a high concentration, and may be, for example, a saturated concentration.

[0067] The method for dissolving carbon dioxide in the electrolytic solution is not particularly limited, but examples thereof include bubbling carbon dioxide into the electrolytic solution, saturating the carbon dioxide in an electrolytic cell containing the electrolytic solution, stirring with a stirring device, stirring by ultrasonic irradiation, and using a flow electrolytic cell.

[0068] In the electrolytic reduction method of the present disclosure, carbon dioxide may be used in combination with other gases, such as argon, nitrogen, hydrogen, and water vapor.

[0069] The temperature of the electrolyte solution during electrolytic reduction is preferably 0 to 100°C, more preferably 0 to 80°C, even more preferably 10 to 50°C, and even more preferably 20 to 40°C. When the temperature of the electrolyte solution is near room temperature, there is no need to install a heating device for the electrolyte solution or a cooling device including a refrigerator, which allows for low equipment and operating costs. Furthermore, when the temperature is in the 40 to 100°C range, a simple heating device is required, but heating can reduce the viscosity of the electrolyte solution, thereby increasing its conductivity (ionic conductivity), allowing for a lower electrolytic voltage and an increased production volume per unit time. In the electrolytic reduction method of the present disclosure, even when the temperature of the electrolyte solution is set within the above-mentioned temperature range, electrolytic reduction proceeds efficiently, allowing for reduced energy costs.

[0070] The pressure during electrolytic reduction may be preferably atmospheric pressure to 0.5 MPa, for example, 0.1 MPa to 0.5 MPa, more preferably 0.1 MPa to 0.3 MPa, and even more preferably 0.1 MPa to 0.2 MPa. In the electrolytic reduction method of the present disclosure, even without pressurization or with only a small pressurization, electrolytic reduction proceeds efficiently and energy costs can be reduced.

[0071] The potential of the cathode electrode during electrolytic reduction may be preferably −5.0 V to −1.5 V, more preferably −5.0 V to −2.0 V, even more preferably −4.0 V to −2.0 V, still more preferably −3.0 V to −2.0 V, and particularly preferably −2.7 V to −2.3 V. Such a potential may be used when Ag + By setting the potential of the cathode electrode within the above range, the electrolytic reduction can proceed more efficiently, and the target compound can be obtained in good yield.

[0072] By the electrolytic reduction method of the present disclosure, carbon dioxide is reduced to obtain carbon monoxide or organic compounds.

[0073] Examples of the organic compounds include hydrocarbons and organic compounds composed of carbon, hydrogen, and oxygen.

[0074] The hydrocarbon may preferably be a hydrocarbon having 1 to 10 carbon atoms, more preferably a hydrocarbon having 1 to 6 carbon atoms, and even more preferably a hydrocarbon having 1 to 3 carbon atoms. The hydrocarbon may be linear or cyclic, straight-chain or branched-chain, saturated or unsaturated. In one embodiment, the hydrocarbon is linear. In another embodiment, the hydrocarbon is cyclic.

[0075] In a preferred embodiment, the chain hydrocarbon may be methane, ethane, ethylene, propane, or propene.

[0076] In a preferred embodiment, the cyclic hydrocarbon may be an alicyclic compound or an aromatic compound, specifically cyclohexane, cycloheptane, benzene, toluene, or xylene, and particularly preferably toluene.

[0077] The organic compounds consisting of carbon, hydrogen, and oxygen can be, for example, ethers, cyclic ethers, alcohols, and carbonyl compounds.

[0078] In one preferred embodiment, the organic compound consisting of carbon, hydrogen, and oxygen may be oxetanone, acetone, formaldehyde, or acetaldehyde having a hydrocarbon group with 1 to 3 carbon atoms (preferably a methyl group).

[0079] In one preferred embodiment, the organic compound consisting of carbon, hydrogen, and oxygen may be an alcohol, preferably an alcohol having 1 to 10 carbon atoms, more preferably an alcohol having 1 to 6 carbon atoms, and even more preferably an alcohol having 1 to 3 carbon atoms.

[0080] In one aspect, carbon dioxide is reduced to carbon monoxide by the electrolytic reduction method of the present disclosure. Conventional carbon monoxide production requires specialized and expensive electrode materials, such as metal nanoparticles. According to the method of the present disclosure, even when inexpensive copper or silver plates are used without the use of such expensive electrode materials, a Faraday efficiency comparable to that of expensive electrode materials can be achieved, allowing electrolysis to continue for extended periods without maintenance. Furthermore, total costs, including maintenance costs, can be reduced. In the electrolytic reduction method of the present disclosure, carbon dioxide is reduced to carbon monoxide even when an ionic liquid that does not contain an aqueous solution is used as the electrolyte. When an aqueous solution is not used, the electrolyte resistance is high, resulting in a reduced overall product yield. However, by using an appropriate ionic liquid, such as triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide, the reduction in yield can be minimized, and electrolysis can be continued for extended periods without maintenance, without being affected by composition changes due to water evaporation. Furthermore, a compact and inexpensive carbon dioxide decomposition device can be realized, eliminating the need for a device to maintain the composition of the electrolyte.

[0081] In another aspect, carbon dioxide is reduced to obtain alcohol, preferably ethanol, by the electrolytic reduction method of the present disclosure. Conventional methods require specialized and expensive electrode materials, such as nitrogen-doped ordered mesoporous carbon. The method of the present disclosure eliminates the need for such expensive electrode materials and allows electrolysis to continue for extended periods without maintenance, even when inexpensive silver plates are used.

[0082] In the electrolytic reduction method of the present disclosure, carbon dioxide can be selectively electrolytically reduced to a predetermined organic compound by adjusting the potential applied between the anode and cathode electrodes. For example, methane can be obtained by applying a certain potential, and ethane can be obtained by applying a different potential.

[0083] Therefore, the present disclosure also provides a method for electrolytic reduction of carbon dioxide in an electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte solution containing carbon dioxide, which can selectively electrolytically reduce carbon dioxide to carbon monoxide or a predetermined organic compound by applying a potential between the anode electrode and the cathode electrode.

[0084] For example, using a Cu electrode as the cathode electrode, a Pt electrode as the anode electrode, and a mixture of DEME-BF4 and KHCO3 aqueous solution as the electrolyte, applying a voltage of approximately -2.3 V between the anode electrode and the cathode electrode can produce methane, applying a voltage of approximately -2.5 V can produce propene, and applying a voltage of approximately -2.7 V can selectively produce ethane and ethylene.

[0085] As described above, in the method of the present disclosure for obtaining carbon monoxide or an organic compound by electrolytic reduction of carbon dioxide, the efficiency of reducing carbon dioxide to an organic compound, for example, the faradaic efficiency, is high. The faradaic efficiency of the electrolytic reduction in the method of the present disclosure can be preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more.

[0086] The method of the present disclosure is also advantageous in terms of durability, since it does not require high-temperature treatment, complicated electrode configurations, other catalysts, etc. For example, the method of producing carbon monoxide or an organic compound of the present disclosure, which obtains carbon monoxide or an organic compound by electrolytic reduction of carbon dioxide, prevents a decrease in reduction efficiency even when operated for preferably 100 hours or more, more preferably 150 hours or more.

[0087] Although the present invention has been described above, the present invention is not limited to the above and various modifications are possible within the scope of the present invention. [Example]

[0088] The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to these examples.

[0089] Figure 1 shows an outline of the experimental equipment used in this example. The experimental equipment includes an electrolytic cell 1, a carbon dioxide supply pipe 2, a working electrode WE as a cathode electrode, a counter electrode CE as an anode electrode, a reference electrode RE, and an exhaust pipe 3. The electrolytic cell 1 includes a cell body 11 and a lid 12 that closes the top opening of the cell body 11. The working electrode WE is a flat plate electrode, housed in a glass partition wall, and connected to a Ni conductor 4. The counter electrode CE is a Pt plate electrode, connected to a Ni conductor 4. The reference electrode RE is an Ag + The electrode is a silver / silver electrode, connected to a nickel conductor 4. The air supply pipe 2 branches into two branches, a first branch pipe 21 and a second branch pipe 22, in a Y-shape at the top, and both branch pipes 21 and 22 protrude from the top of the lid 12. The air supply pipe 2 has a cylindrical expanded diameter portion 23 at the other end of the branch pipe. An electrolyte 7 is present in the electrolytic cell 1, and the working electrode WE, counter electrode CE, reference electrode RE, and expanded diameter portion 23 are fixed in a state immersed in the electrolyte 7. The electrolyte was used at 25±2°C unless otherwise specified.

[0090] Example 1 DEME-BF4 as an ionic liquid and a KHCO3 aqueous solution (0.1 mol / L) were mixed at a volume ratio of 1:1 to obtain electrolyte A. As shown in Figure 1, the obtained electrolyte A was added to the cell body 11 of the electrolytic cell 1 to a height such that the electrodes WE, RE, and CE, as well as the expanded diameter portion 23, were immersed in the electrolyte A. A Cu plate electrode was used as the working electrode WE. The electrolytic cell 1 was sealed with the lid 12, and the working electrode WE, reference electrode RE, and counter electrode CE were connected to a potentiostat / galvanostat device (manufactured by Biologic). Carbon dioxide was supplied into the air inlet pipe 2 at a gas pressure of 0.1 MPa for 30 minutes via a carbon dioxide supply pipe (not shown) connected to the first branch pipe 21, and the carbon dioxide was bubbled from the lower end of the air inlet pipe 2 into the electrolyte A in the electrolytic cell 1. Next, the reduction behavior of carbon dioxide was observed by cyclic voltammetry, where a potential was applied between the working electrode WE and the counter electrode CE at a scan rate of 10 mV / s to measure the current density.

[0091] (Comparative Example 1) The same procedure as in Example 1 was carried out except that Ar was used instead of carbon dioxide.

[0092] (Comparative Example 2) The same procedure as in Example 1 was carried out except that DEME-BF4 was used instead of the electrolyte solution A.

[0093] The results of Example 1 and Comparative Examples 1 and 2 are shown in the graph in Figure 2. In the graph, the solid line represents the results of Example 1, the dashed line represents the results of Comparative Example 1, and the dotted line represents the results of Comparative Example 2. Figure 2 confirms that the electrolytic reduction of carbon dioxide proceeds within the potential window of DEME-BF. Specifically, in Comparative Example 2, where the electrolyte was DEME-BF only, the reduction current began to rise around -2.9 V, whereas in Example 1, where carbon dioxide was introduced using electrolyte A mixed with a KHCO aqueous solution, the reduction current began to flow around -2.0 V. Similarly, in Comparative Example 1, where Ar was used instead of carbon dioxide, the reduction current also began to flow around -2.0 V. These results indicate the generation of hydrogen through the reduction of HO, which is believed to be useful as a hydrogen source for the hydrocarbon gas in the present invention. Therefore, it can be seen that the formation of hydrocarbon gas through the electrolytic reduction of carbon dioxide proceeds without being affected by the reductive decomposition of DEME-BF.

[0094] Example 2 (Experiment 1) In the same manner as in Example 1, carbon dioxide was bubbled into the electrolytic solution A in the electrolytic cell 1, and then electrolysis was carried out for 30 minutes with the cathode potential kept constant at −2.1 V. After completion of electrolysis, the needle of the syringe 6 was inserted into the first branch pipe 21 through the rubber stopper 5 of the second branch pipe 22 to collect the gas in the air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was performed.

[0095] (Experiment 2) Electrolysis was carried out in the same manner as in Experiment 1, except that the cathode potential was kept constant at −2.8 V. After completion of the electrolysis, the gas in the air supply pipe 2 was collected in the same manner as in Experiment 1 and analyzed by gas chromatography (carrier gas: nitrogen).

[0096] Figure 3 compares the chromatograms obtained by gas chromatography analysis in Experiments 1 and 2 with the chromatograms of the reference gases hydrogen, carbon dioxide, and ethylene. As shown in Figure 3, in Experiment 1, where the cathode potential was -2.1 V, peaks were observed at the same positions as the peaks of hydrogen and carbon dioxide. On the other hand, in Experiment 2, where the cathode potential was -2.8 V, peaks were observed at the same positions as the peaks of hydrogen and carbon dioxide, as well as the peak at the same position as the peak of ethylene gas. These results confirmed that ethylene can be obtained selectively with high efficiency by adjusting the applied potential in the electrolytic reduction using the above-mentioned electrolyte A.

[0097] Example 3 DEME-BF4 as an ionic liquid and a KHCO3 aqueous solution (0.1 mol / L) were mixed at a volume ratio of 50:11 to obtain electrolyte solution B. The obtained electrolyte solution B was added to electrolytic cell 1 in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, a potential was applied between the working electrode WE and the counter electrode CE at a scan rate of 10 mV / s by cyclic voltammetry, and the current density was measured to observe the reduction behavior of carbon dioxide.

[0098] (Comparative Example 3) The same procedure as in Example 4 was carried out except that Ar was used instead of carbon dioxide.

[0099] The results of Example 3 and Comparative Example 3 are shown in the graph of Figure 4. In the graph, the solid line represents the results of Example 3, and the dashed line represents the results of Comparative Example 3. From Figure 4, it was confirmed that the electrolytic reduction of carbon dioxide proceeds at a potential less noble than approximately -2.0 V, even in electrolyte B. This potential indicates that the reduction of carbon dioxide proceeds without being affected by the reductive decomposition of DEME-BF4, as in Example 1.

[0100] Example 4 (Experiment 3) In the same manner as in Example 3, carbon dioxide was bubbled into the electrolytic solution B in the electrolytic cell 1, and then electrolysis was carried out for 60 minutes with the cathode potential kept constant at −1.9 V. After completion of electrolysis, the needle of the syringe 6 was inserted into the first branch pipe 21 through the rubber stopper 5 of the first branch pipe 21 to collect the gas in the air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was performed.

[0101] (Experiment 4) Electrolysis was carried out in the same manner as in Experiment 3, except that the cathode potential was kept constant at −2.1 V. After completion of electrolysis, the gas in the air supply pipe 2 was collected in the same manner as in Experiment 3 and analyzed by gas chromatography (carrier gas: nitrogen).

[0102] (Experiment 5) Electrolysis was carried out in the same manner as in Experiment 3, except that the cathode potential was kept constant at −2.5 V. After completion of the electrolysis, the gas in the air supply pipe 2 was collected in the same manner as in Experiment 3 and analyzed by gas chromatography (carrier gas: nitrogen).

[0103] (Experiment 6) Electrolysis was carried out in the same manner as in Experiment 3, except that the cathode potential was kept constant at −2.8 V. After completion of the electrolysis, the gas in the air supply pipe 2 was collected in the same manner as in Experiment 3 and analyzed by gas chromatography (carrier gas: nitrogen).

[0104] (Experiment 7) Electrolysis was carried out in the same manner as in Experiment 3, except that the cathode potential was kept constant at −3.1 V. After completion of the electrolysis, the gas in the air supply pipe 2 was collected in the same manner as in Experiment 3 and analyzed by gas chromatography (carrier gas: nitrogen).

[0105] FIG. 5 shows a comparison of the chromatograms obtained by gas chromatography analysis in Experiments 3 to 7 with the chromatograms of the reference gases hydrogen, carbon dioxide, and ethylene. As shown in FIG. 5, in Experiments 3, 4, 5, and 7, where the cathode potentials were −1.9 V, −2.1 V, −2.5 V, and −3.1 V, peaks identical to those of hydrogen and carbon dioxide were observed. On the other hand, in Experiment 6, where the cathode potential was −2.8 V, in addition to the peaks identical to those of hydrogen and carbon dioxide, a peak was also observed at the same position as that of ethylene gas. These results confirmed that ethylene can be obtained selectively with high efficiency by adjusting the applied potential in the electrolytic reduction using the above-mentioned electrolyte B.

[0106] Example 5 (Experiment 8) In the same manner as in Example 1, carbon dioxide was bubbled into the electrolytic solution A in the electrolytic cell 1, and then electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.3 V. After electrolysis was completed, the needle of the syringe 6 was inserted into the first branch pipe 21 through the rubber stopper 5 of the first branch pipe 21 to collect the gas in the air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was carried out. The obtained gas chromatogram is shown in FIG.

[0107] (Experiment 9) Electrolysis was carried out in the same manner as in Experiment 8, except that the cathode potential was kept constant at −2.5 V. After electrolysis was completed, the gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 8. The obtained gas chromatogram is shown in FIG.

[0108] (Experiment 10) Electrolysis was carried out in the same manner as in Experiment 8, except that the cathode potential was kept constant at −2.7 V. After electrolysis was completed, the gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 8. The obtained gas chromatogram is shown in FIG.

[0109] Chromatograms (Figures 6-8) obtained by gas chromatography analysis in Experiments 8-10 were compared with chromatograms of reference gases: hydrogen, carbon dioxide, methane, ethane, ethylene, and propene. As a result, in Experiment 8, where the cathode potential was -2.3 V, peaks identical to those of hydrogen and carbon dioxide were observed, as well as a peak at the same position as that of methane. In Experiment 9, where the cathode potential was -2.5 V, peaks identical to those of hydrogen and carbon dioxide were observed, as well as a peak at the same position as that of propene. In Experiment 10, where the cathode potential was -2.7 V, peaks identical to those of hydrogen and carbon dioxide were observed, as well as a peak at the same position as that of ethane and ethylene. These results confirmed that methane, ethane, ethylene, and propene can be obtained selectively and efficiently by adjusting the applied potential in electrolytic reduction using the above-mentioned electrolyte A.

[0110] Example 6 (Experiment 11) DEME-BF4 as an ionic liquid and water were mixed at a volume ratio of 50:50 to obtain electrolyte C. The obtained electrolyte C was added to an electrolytic cell in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was performed for 30 minutes with the cathode potential kept constant at -2.1 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was performed. The obtained gas chromatogram is shown in FIG. 9.

[0111] (Experiment 12) Electrolysis was carried out in the same manner as in Experiment 11, except that the cathode potential was kept constant at −2.3 V. After completion of the electrolysis, gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 11. The obtained gas chromatogram is shown in FIG.

[0112] (Experiment 13) Electrolysis was carried out in the same manner as in Experiment 11, except that the cathode potential was kept constant at −2.5 V. After completion of the electrolysis, gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 11. The obtained gas chromatogram is shown in FIG.

[0113] (Experiment 14) Electrolysis was carried out in the same manner as in Experiment 11, except that the cathode potential was kept constant at −2.7 V. After completion of the electrolysis, gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 11. The obtained gas chromatogram is shown in FIG.

[0114] The chromatograms obtained by the gas chromatography analysis in Experiments 11 to 14 were compared with the chromatograms of the reference gases hydrogen, carbon dioxide, methane, ethane, and 4-methyl-2-oxetanone. As a result, in Experiments 11, 13, and 14, where the cathode potentials were −2.1 V, −2.5 V, and −2.7 V, peaks identical to those of hydrogen and carbon dioxide were observed. On the other hand, in Experiment 12, where the cathode potential was −2.5 V, peaks identical to those of hydrogen and carbon dioxide were observed at the same positions as those of methane, ethane, and 4-methyl-2-oxetanone. These results confirmed that by adjusting the applied potential in the electrolytic reduction using the above-mentioned electrolyte C, methane, ethane, and 4-methyl-2-oxetanone could be obtained selectively with high efficiency.

[0115] Example 7 (Experiment 15) DEME-BF4 as an ionic liquid, water, and Ca(OH)2 were mixed in a molar ratio of 2.0:1.0:1.8×10-4 The electrolyte D was obtained by mixing the components so that the following was true: Electrolyte D. The obtained electrolyte D was added to an electrolytic cell of an electrolysis apparatus using a Cu plate electrode as the working electrode WE, in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.05 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was carried out. The analysis results are shown in Table 1 below.

[0116] The Faraday efficiency e can be calculated as follows: First, the volumetric ratio of the organic compounds contained in the collected gas is calculated from the total area of ​​the peaks obtained from the GC-MS analysis and the calibration curve. Next, the volume of the organic compounds generated is calculated from the volume of the gas phase in the collection container and the calculated volumetric ratio of the organic compounds in the gas. Finally, assuming that the generated organic compounds are in standard conditions, the Faraday efficiency e (%) is calculated using the following formula.

number

[0117] (Experiment 16) Electrolysis was carried out in the same manner as in Experiment 15, except that the cathode potential was kept constant at −2.85 V. After completion of electrolysis, gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 15. The analysis results are shown in Table 1 below.

[0118] (Experiment 17) Electrolysis was carried out in the same manner as in Experiment 15, except that the cathode potential was kept constant at -2.55 V and an Fe plate electrode was used as the working electrode WE. After completion of electrolysis, the gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 15. The analysis results are shown in Table 1 below.

[0119] (Experiment 18) Electrolysis was carried out in the same manner as in Experiment 15, except that the cathode potential was kept constant at -2.50 V and an Ag plate electrode was used as the working electrode WE. After completion of electrolysis, the gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 15. The analysis results are shown in Table 1 below.

[0120] Example 8 (Experiment 19) DEME-BF4 as an ionic liquid, water, and Ca(OH)2 were mixed in a molar ratio of 1.0:2.0:1.8×10 -4 The electrolyte solution E was obtained by mixing the components so that the following was true: Electrolyte E. The obtained electrolyte solution E was added to an electrolytic cell of an electrolysis apparatus using a Cu plate electrode as the working electrode WE, in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -1.80 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 1 below.

[0121] Example 9 (Experiment 20) DEME-BF4 as an ionic liquid, water, and KOH were mixed in a molar ratio of 2:1:0.001 to obtain electrolyte solution F. The obtained electrolyte solution F was added to an electrolytic cell of an electrolysis device using a Cu plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was performed for 30 minutes with the cathode potential kept constant at -1.76 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 1 below.

[0122] (Experiment 21) Electrolysis was carried out in the same manner as in Experiment 20, except that the cathode potential was kept constant at −2.16 V. After completion of electrolysis, gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 20. The analysis results are shown in Table 1 below.

[0123] Example 10 (Experiment 22) DEME-BF4 as an ionic liquid, water, and CsOH were mixed in a molar ratio of 2.0:1.0:3.7×10 -3 The electrolyte G was obtained by mixing the components so that the following was true: Electrolyte G. The obtained electrolyte G was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.55 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 1 below.

[0124] Example 11 (Experiment 23) DEME-BF4 as an ionic liquid and water were mixed at a molar ratio of 10:1 to obtain electrolyte solution H. The obtained electrolyte solution H was added to an electrolytic cell of an electrolysis apparatus using a Cu plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was performed for 30 minutes with the cathode potential kept constant at -1.85 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 1 below.

[0125] (Experiment 24) Electrolysis was carried out in the same manner as in Experiment 23, except that the cathode potential was kept constant at −2.45 V. After completion of electrolysis, gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 23. The analysis results are shown in Table 1 below.

[0126] Example 12 (Experiment 25) DEME-BF4 as an ionic liquid and water were mixed at a molar ratio of 20:1 to obtain electrolyte solution I. The obtained electrolyte solution I was added to an electrolytic cell of an electrolysis device using a Cu plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was performed for 30 minutes with the cathode potential kept constant at -1.96 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 1 below.

[0127] [Table 1]

[0128] Example 13 (Experiment 26) DEME-BF4 as an ionic liquid, water, and CsOH were mixed in a molar ratio of 10:1.0:4.0×10 -4 The electrolyte J was obtained by mixing the components so that the following was true: Electrolyte J. The obtained electrolyte J was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.65 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was carried out. The analysis results are shown in Table 2 below.

[0129] Example 14 (Experiment 27) DEME-BF4 as an ionic liquid, water, and NaOH were mixed in a molar ratio of 2.0:1.0:1.8×10 -4The electrolyte K was obtained by mixing the components so that the following was true: Electrolyte K. The obtained electrolyte K was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -3.00 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was carried out. The analysis results are shown in Table 2 below.

[0130] Example 15 (Experiment 28) DEME-BF4 as an ionic liquid, water, and CsOH were mixed in a molar ratio of 1.0:2.0:7.5×10 -4 The electrolyte L was obtained by mixing the components so that the following was true: Electrolyte L. The obtained electrolyte L was added to an electrolytic cell of an electrolysis apparatus using a Cu plate electrode as the working electrode WE, in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.00 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, and gas chromatography analysis (carrier gas: nitrogen) was carried out. The analysis results are shown in Table 2 below.

[0131] Example 16 (Experiment 29) DEME-BF4 as an ionic liquid, water, and CsOH were mixed in a molar ratio of 10:1.0:4.2×10 -4 The electrolyte M was obtained by mixing the components so that the following formula was obtained. The obtained electrolyte M was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, in the same manner as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -1.95 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 2 below.

[0132] Example 17 (Experiment 30) Electrolysis was carried out in the same manner as in Experiment 29, except that the cathode potential was kept constant at −2.75 V. After completion of electrolysis, gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 29. The analysis results are shown in Table 2 below.

[0133] Example 18 (Experiment 31) DEME-BF4 as an ionic liquid, water, and NaOH were mixed in a molar ratio of 2.1:2.0:2.0 × 10 -3 The electrolyte N was obtained by mixing the components so that the following was true: Electrolyte N. The obtained electrolyte N was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.80 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 2 below.

[0134] Example 19 (Experiment 32) DEME-BF4 as an ionic liquid, water, and LiOH were mixed in a molar ratio of 2.0:1.0:4.0×10 -3 The electrolyte solution O was obtained by mixing the components so that the following was true: Electrolyte O. The obtained electrolyte solution O was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.40 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 2 below.

[0135] Example 20 (Experiment 33) Electrolysis was carried out in the same manner as in Experiment 32, except that the cathode potential was kept constant at −3.05 V. After completion of electrolysis, gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 32. The analysis results are shown in Table 2 below.

[0136] Example 21 (Experiment 34) DEME-BF4 as an ionic liquid, water, and Ca(OH)2 were mixed in a molar ratio of 2.0:1.0:2.0 × 10 -4 The electrolyte P was obtained by mixing the components so that the following was true: Electrolyte P. The obtained electrolyte P was added to an electrolytic cell of an electrolysis apparatus using a Cu plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes with the cathode potential kept constant at -2.70 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 2 below.

[0137] Example 22 (Experiment 35) DEME-BF4 as an ionic liquid, water, and Ca(OH)2 were mixed in a molar ratio of 2.0:1.0:2.0 × 10 -4 The electrolyte P was obtained by mixing the components so that the following was true: Electrolyte P. The obtained electrolyte P was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, as in Example 1, and carbon dioxide was bubbled through. Next, electrolysis was carried out for 30 minutes at 80°C with the cathode potential kept constant at -2.60V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 2 below.

[0138] Example 23 (Experiment 36) Electrolysis was carried out in the same manner as in Experiment 35, except that the cathode potential was kept constant at −3.05 V. After completion of electrolysis, gas in the air inlet pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 35. The analysis results are shown in Table 2 below.

[0139] Example 24 (Experiment 37) P as an ionic liquid 2225 TFSI (triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide) was used as electrolyte Q. As in Example 1, electrolyte Q was added to an electrolytic cell of an electrolysis apparatus using an Ag plate electrode as the working electrode WE, and carbon dioxide was bubbled through. Next, electrolysis was performed for 60 minutes with the cathode potential kept constant at -3.20 V. After completion of electrolysis, the needle of syringe 6 was inserted into first branch pipe 21 through rubber stopper 5 of first branch pipe 21 to collect gas in air supply pipe 2, which was then analyzed by gas chromatography (carrier gas: nitrogen). The analysis results are shown in Table 2 below.

[0140] Example 25 (Experiment 38) Electrolysis was carried out in the same manner as in Experiment 37, except that the cathode potential was kept constant at −2.85 V. After completion of electrolysis, gas in the air supply pipe 2 was collected and analyzed by gas chromatography (carrier gas: nitrogen) in the same manner as in Experiment 37. The analysis results are shown in Table 2 below.

[0141] [Table 2] [Industrial Applicability]

[0142] The electrolytic reduction method of the present disclosure is useful in various fields, particularly in the environmental field, because it can convert carbon dioxide, which causes global warming, into useful carbon monoxide, organic compounds, and the like. [Explanation of symbols]

[0143] 1...Electrolytic cell 2...Gas supply pipe 3...Exhaust pipe 4…Conducting wire 5...Rubber stopper 6...Syringe 7...Electrolyte 11...tank body 12…Lid 21...First branch pipe section 22...Second branch pipe section 23... Expanded diameter part

Claims

1. A method for producing carbon monoxide or an organic compound (excluding butane, acetone, and aromatic compounds), comprising electrolytically reducing carbon dioxide to obtain carbon monoxide or an organic compound in an electrolytic reduction device having an anode electrode, a cathode electrode, and an electrolyte solution containing carbon dioxide, wherein the electrolyte solution contains an ionic liquid; the electrolyte solution contains an additive, the additive comprises a basic catalyst; The method for producing carbon monoxide or an organic compound, wherein the basic catalyst is Ca(OH) 2 , LiOH, NaOH, KOH, or CsOH.

2. The method for producing carbon monoxide or an organic compound according to claim 1 , wherein the electrolytic solution further contains water.

3. 3. The method for producing carbon monoxide or an organic compound according to claim 1, wherein the ionic liquid is an imidazolium-based ionic liquid, an aromatic-based ionic liquid, a pyrrolidinium-based ionic liquid, an ammonium-based ionic liquid, a piperidinium-based ionic liquid, or a quaternary phosphonium-based ionic liquid.

4. 4. The method for producing carbon monoxide or an organic compound according to claim 1, wherein the ionic liquid is N,N-diethyl-N-(2-methoxyethyl)ammonium tetrafluoroborate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide.

5. The method for producing carbon monoxide or an organic compound according to any one of claims 1 to 4, wherein the additive further comprises a supporting electrolyte.

6. The supporting electrolyte is KHCO ３ , KHPO ４ , LiBF ４ , LiPF ６ , LiClO ４ , LiAsF ６ , LiTf, LiTFSI, Li(CF ３ SO ２ ) ２ N.K. ２ CO ３ , Li ２ CO ３ , Na ２ CO ３ , or NaHCO ３ The method for producing carbon monoxide or an organic compound according to claim 5, wherein

7. The supporting electrolyte is KHCO ３ 7. The method for producing carbon monoxide or an organic compound according to claim 5 or 6,

8. 8. The method for producing carbon monoxide or an organic compound according to claim 5, wherein the volume ratio of the ionic liquid to the total of water and the supporting electrolyte is 1:99 to 99:

1.

9. The electrolytic reduction device further includes a reference electrode, and the reference electrode is Ag ＋ 9. The method for producing carbon monoxide or an organic compound according to claim 1, wherein the cathode electrode is a Ag / Ag electrode, and the potential of the cathode electrode is −5.0 to −1.5 V.

10. The method for producing carbon monoxide or an organic compound according to any one of claims 1 to 9, wherein the temperature of the electrolytic solution is 0 to 100°C.

11. The method for producing carbon monoxide or an organic compound according to any one of claims 1 to 10, wherein the cathode electrode is a flat plate electrode.

12. The method for producing carbon monoxide or an organic compound according to any one of claims 1 to 11, wherein the anode electrode is a Pt, metal oxide, glassy carbon, or boron-doped diamond electrode, and the cathode electrode is a Cu, Ag, Fe, or Ni electrode.

13. The method for producing carbon monoxide or an organic compound according to any one of claims 1 to 12, wherein the cathode electrode is an Ag, Cu, or Fe electrode.

14. 14. The method for producing carbon monoxide or an organic compound according to claim 1, wherein the cathode electrode is an Ag, Cu, or Fe electrode, and the anode electrode is a Pt electrode.

15. The method for producing carbon monoxide or an organic compound according to any one of claims 1 to 14, wherein the organic compound is a hydrocarbon or an organic compound composed of carbon, hydrogen, and oxygen.

16. The hydrocarbon is C １－１０ 16. The method for producing carbon monoxide or an organic compound according to claim 15, wherein the organic compound is a hydrocarbon.

17. 16. The method for producing carbon monoxide or an organic compound according to claim 15, wherein the organic compound consisting of carbon, hydrogen, and oxygen is an ether, a cyclic ether, an alcohol, or a carbonyl compound.

18. 18. The method for producing carbon monoxide or an organic compound according to claim 1, wherein carbon monoxide or a predetermined organic compound is selectively produced by changing the potential of the cathode electrode.

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