Carbon dioxide electrolysis device

Abstract

The present invention relates to a carbon dioxide electrolysis device. The present invention maintains the performance of an electrolytic cell. The carbon dioxide electrolysis device of the present invention comprises an electrolytic cell, wherein the electrolytic cell comprises: an anode for oxidizing water to generate oxygen, a cathode for reducing carbon dioxide to generate carbon compounds, a cathode flow path plate having a surface arranged in contact with the cathode and a cathode flow path arranged on the surface and facing the cathode, and a diaphragm arranged between the anode and the cathode. The surface has a hydrophilic region arranged in contact with the cathode and having a contact angle with water of less than 45 degrees.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-150307 (filing date: September 15, 2021). The entire contents of the above application are incorporated herein by reference. Technical Field

[0002] Embodiments of the present invention relate to a carbon dioxide electrolysis device. Background Art

[0003] In recent years, people have been concerned about the depletion of fossil fuels such as oil and coal, and expectations for sustainable renewable energy have been growing. Examples of renewable energy include solar power generation and wind power generation. However, they have the problem of difficulty in supplying electricity stably because the amount of power generated depends on weather and natural conditions. Therefore, attempts are being made to store the electricity generated by renewable energy in batteries to stabilize the electricity. However, when storing electricity, there are problems such as the cost of batteries and the loss of electricity during storage.

[0004] In this regard, the technology of using electricity generated by renewable energy to electrolyze water and produce hydrogen (H2) from water or electrochemically reduce carbon dioxide (CO2) to convert it into chemical substances (chemical energy) such as carbon compounds such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH3OH), methane (CH4), acetic acid (CH3COOH), ethanol (C2H5OH), ethane (C2H6), and ethylene (C2H4) has attracted much attention. When these chemical substances are stored in cylinders or tanks, compared with the case of storing electricity (electrical energy) in batteries, there is an advantage that the energy storage cost can be reduced and the storage loss is also small.

[0005] As a carbon dioxide electrolysis device, for example, a structure in which a cathode uses a silver (Ag) nanoparticle catalyst, the cathode is in contact with a cathode solution and CO2 gas, and the anode is in contact with an anode solution. As a specific structure of the electrolysis device, for example, a structure can be cited, which has: a cathode solution flow path configured along one surface of the cathode, a CO2 gas flow path configured along another surface of the cathode, an anode solution flow path configured along one surface of the anode, and a diaphragm configured between the cathode solution flow path and the anode solution flow path. Using an electrolysis device with such a structure, for example, when a constant current flows into the cathode and the anode, and a reaction such as generating CO from CO2 is carried out for a long time, there is a problem of degradation of cell performance over time such as a decrease in the amount of CO generated or an increase in the cell voltage. Therefore, a carbon dioxide electrolysis device capable of suppressing degradation of cell performance over time is being sought. Summary of the invention

[0006] Problems to be solved by the invention

[0007] The problem to be solved by the present invention is to maintain the performance of the electrolytic cell.

[0008] Means of solving problems

[0009] A carbon dioxide electrolysis device according to an embodiment includes an electrolytic cell, wherein the electrolytic cell includes:

[0010] an anode, which is used to oxidize water to generate oxygen,

[0011] a cathode for reducing carbon dioxide to form carbon compounds,

[0012] a cathode flow path plate having: a surface arranged in contact with the cathode and a cathode flow path arranged on the surface and facing the cathode, and

[0013] A separator is disposed between the anode and the cathode.

[0014] The surface has a hydrophilic region which is arranged in contact with the cathode and has a contact angle with water of less than 45 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a diagram showing the structure of the carbon dioxide electrolysis device according to the first embodiment.

[0016] Figure 2 Yes means Figure 1 A cross-sectional view of an electrolytic cell of a carbon dioxide electrolysis device is shown.

[0017] Figure 3 Yes means Figure 2 A diagram showing an example of an anode flow path of an electrolytic cell shown.

[0018] Figure 4 Yes means Figure 2 A diagram showing an example of a cathode flow path of an electrolytic cell shown.

[0019] Figure 5 Yes means Figure 2 FIG. 2 is a diagram showing another example of a cathode flow path of an electrolytic cell shown in FIG.

[0020] Figure 6 Yes means Figure 2 A diagram showing an example of a cathode flow path of an electrolytic cell shown.

[0021] Figure 7 Yes means Figure 2 A diagram of an example of a cathode of an electrolytic cell is shown.

[0022] Figure 8 Yes means Figure 2 A diagram of another example of a cathode of an electrolytic cell is shown.

[0023] Fig. 9 It is schematically indicated Figure 2 Diagram of the reaction at the cathode of an electrolytic cell shown.

[0024] Fig.10 It is a diagram showing the operation process of the carbon dioxide electrolysis device according to the first embodiment.

[0025] Fig.11 It is a diagram showing the updating process of the carbon dioxide electrolysis device according to the first embodiment.

[0026] Fig.12 It is a diagram for explaining the operation of the carbon dioxide electrolysis device according to the first embodiment.

[0027] Fig.13 Yes means Figure 2 FIG. 2 is a diagram showing another example of a cathode flow path of an electrolytic cell shown in FIG.

[0028] Fig.14 Yes means Figure 2 FIG. 2 is a diagram showing another example of a cathode flow path of an electrolytic cell shown in FIG.

[0029] Fig.15 Yes means Figure 2 FIG. 2 is a diagram showing another example of a cathode flow path of an electrolytic cell shown in FIG.

[0030] Fig.16 Yes means Figure 2 FIG. 2 is a diagram showing another example of a cathode flow path of an electrolytic cell shown in FIG.

[0031] Fig.17 Yes means Figure 2 A cross-sectional view of another example of the cathode flow path of the electrolytic cell shown.

[0032] Fig.18 Yes means Figure 2 A cross-sectional view of another example of the cathode flow path of the electrolytic cell shown.

[0033] Fig.19 It is a diagram showing a carbon dioxide electrolysis device according to a second embodiment.

[0034] Fig. 20 Yes means Fig.19 A cross-sectional view of an electrolytic cell of a carbon dioxide electrolysis device is shown.

[0035] Fig.21 Yes means Fig.19 FIG. 2 is a diagram showing another cross-sectional structure example of an electrolytic cell.

[0036] Fig. 22 Yes means Fig.19 FIG. 2 is a diagram showing another cross-sectional structure example of an electrolytic cell.

[0037] Fig.23This is a diagram showing the planar shape of the cathode flow path of Example 1.

[0038] Fig.24 This is a diagram showing the planar shape of the cathode flow path of Example 3.

[0039] Fig.25 This is a diagram showing the planar shape of the cathode flow path of Example 8.

[0040] (Explanation of symbols)

[0041] 1…electrolysis device, 1X…electrolysis device, 2…electrolysis cell, 2X…electrolysis cell, 10…anode portion, 11…anode, 11a…first surface, 11b…second surface, 12…anode flow path, 13…anode current collector plate, 14…flow path plate, 14a…welding pad, 20…cathode portion, 21…cathode flow path, 22…cathode, 22A…gas diffusion layer, 22B…cathode catalyst layer, 22C…porous layer, 22a…first surface, 22b…second surface, 23…cathode flow path , 24… cathode current collector plate, 25… flow path plate, 26… welding pad, 27… bridge portion, 28… flow path plate, 28a… surface, 29… welding pad, 30… diaphragm, 40… power supply control portion, 50… flow path plate, 50a… surface, 50b… surface, 51… flow path, 52… flow path, 100… anode solution supply system, 101… pressure control portion, 102… anode solution tank, 103… flow control portion, 104… reference electrode, 105… pressure gauge, 106… tank, 200…cathode solution supply system, 201…pressure control unit, 202…cathode solution tank, 203…flow control unit, 204…reference electrode, 205…pressure gauge, 206…gas component collection unit, 280…hydrophilic region, 281…concave and convex, 300…gas supply system, 301…CO2 gas storage cylinder, 302…flow control unit, 303…pressure gauge, 304…pressure control unit, 400…product collection system, 401…gas-liquid separation Isolation unit, 402…product collection unit, 500…control system, 501…reduction performance detection unit, 502…data collection / control unit, 503…update control unit, 504…analysis unit, 600…waste liquid collection system, 601…waste liquid collection tank, 700…update material supply unit, 710…gas substance supply system, 711…gas tank, 712…pressure control unit, 720…rinsing liquid supply system, 721…rinsing liquid tank, 722…flow control unit. DETAILED DESCRIPTION

[0042] Hereinafter, the carbon dioxide electrolysis device of the embodiment will be described with reference to the accompanying drawings. In each embodiment shown below, basically the same components are marked with the same symbols, and their descriptions are sometimes partially omitted. The accompanying drawings are schematic, and the relationship between thickness and plane size, the ratio of thickness of each part, etc. are sometimes different from the actual ones.

[0043] (First embodiment)

[0044] Figure 1 is a diagram showing the structure of a carbon dioxide electrolysis device according to a first embodiment. Figure 2 Yes means Figure 1 A cross-sectional view showing the structure of an electrolytic cell of an electrolytic device shown. Figure 1 The carbon dioxide electrolysis device 1 shown has: an electrolytic cell 2; an anode solution supply system 100 for supplying an anode solution to the electrolytic cell 2; a cathode solution supply system 200 for supplying a cathode solution to the electrolytic cell 2; a gas supply system 300 for supplying carbon dioxide (CO2) gas to the electrolytic cell 2; a product collection system 400 for collecting products generated by a reduction reaction in the electrolytic cell 2; a control system 500 for detecting the type and amount of the collected products and controlling the product and the renewal operation; a waste liquid collection system 600 for collecting waste liquid of the cathode solution and the anode solution; and a renewal material supply unit 700 for restoring the anode, cathode, etc. of the electrolytic cell 2. It should be noted that the components required for the renewal operation may not be provided.

[0045] like Figure 2 As shown, the electrolytic cell 2 includes an anode portion 10, a cathode portion 20 and a diaphragm 30. The anode portion 10 includes an anode 11, an anode flow path 12 (anode solution flow path), and an anode current collector plate 13. The cathode portion 20 includes a cathode flow path 21 (cathode solution flow path), a cathode 22, a cathode flow path (CO2 gas flow path) 23, and a cathode current collector plate 24. The diaphragm 30 is configured in a manner to separate the anode portion 10 from the cathode portion 20. The anode 11, the anode flow path (anode solution flow path) 12, the anode current collector plate 13, the cathode flow path 21, the cathode 22, the cathode flow path 23, the cathode current collector plate 24, and the diaphragm 30 may be stacked on top of each other. In addition, the cathode flow path 21 may be absent. The electrolytic cell 2 is sandwiched between a pair of support plates (not shown) and then fastened with bolts or the like. In Figure 1 and Figure 2 In the embodiment, a power supply control unit 40 is provided to allow current to flow through the anode 11 and the cathode 22. The power supply control unit 40 is connected to the anode 11 and the cathode 22 via a current introduction component. The power supply control unit 40 is not limited to a common system power supply and a battery, etc., and may also have a power supply for supplying power generated by renewable energy such as a solar cell or wind power generation. It should be noted that the power supply control unit 40 may have the above-mentioned power supply, and a power controller that adjusts the output of the above-mentioned power supply to control the voltage between the anode 11 and the cathode 22, etc.

[0046] The anode 11 is provided to oxidize a substance containing water or hydroxide to generate an oxidized product containing oxygen. The anode 11 causes water (H2O) in the anode solution as the electrolytic solution to undergo an oxidation reaction to generate oxygen (O2) and hydrogen ions (H +), or the hydroxide ions (OH - ) undergoes an oxidation reaction to generate an electrode (oxidation electrode) of oxygen (O2) and water (H2O). The anode 11 has a first surface 11a in contact with the diaphragm 30 and a second surface 11b facing the anode flow path 12. The first surface 11a of the anode 11 is in close contact with the diaphragm 30. The anode flow path 12 faces the anode 11 and supplies an anode solution as an electrolytic solution to the anode 11. It is composed of pits (grooves / recesses) provided in the flow path plate 14 (anode flow path plate). The anode solution flows in the anode flow path 12 in a manner in contact with the anode 11. The anode current collector plate 13 is electrically connected to the surface of the flow path plate 14 constituting the anode flow path 12 on the opposite side of the anode 11.

[0047] The flow plate 14 is provided with a solution inlet and a solution outlet (not shown), through which the anode solution is introduced and discharged by the anode solution supply system 100. The flow plate 14 is preferably made of a material with low chemical reactivity and high conductivity. Examples of such a material include metal materials such as Ti and SUS, and carbon. Figure 3 As shown, it is preferred to provide a plurality of pads (convex portions) 14a in the anode flow path 12. The pads 14a are provided for mechanical retention and electrical conduction. In order to make the flow of the anode solution uniform, the pads 14a are preferably provided in a staggered manner. With such pads 14a, the anode flow path 12 meanders. Furthermore, in order to properly discharge the anode solution mixed with oxygen (O2) gas, it is preferred to provide the pads 14a in a staggered manner in the anode flow path 12 so that the anode flow path 12 meanders.

[0048] The anode 11 is preferably mainly composed of a material that can oxidize water (H2O) to generate oxygen and hydrogen ions or hydroxide ions (OH - ) is oxidized to generate water and oxygen and a catalyst material (anode catalyst material) that can reduce the overvoltage of such a reaction. Such catalyst materials include: metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys or intermetallic compounds containing these metals, binary metal oxides such as 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), ruthenium oxide (Ru-O), lithium oxide (Li-O), and lanthanum oxide (La-O), ternary metal oxides such as Ni-Co-O, Ni-Fe-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, and metal complexes such as Ru complexes and Fe complexes.

[0049] The anode 11 has a structure that allows the anode solution and ions to move between the diaphragm 30 and the anode flow path 12, for example, a substrate with a porous structure such as a mesh material, a punching material, a porous body, a metal fiber sintered body, etc. The substrate can be composed of metal materials such as titanium (Ti), nickel (Ni), iron (Fe) or an alloy containing at least one of these metals (for example, SUS), or can be composed of the above-mentioned anode catalyst material. When an oxide is used as the anode catalyst material, it is preferred to attach or laminate the anode catalyst material on the surface of the substrate containing the above-mentioned metal material to form a catalyst layer. The anode catalyst material preferably has nanoparticles, nanostructures, nanowires, etc. to enhance the oxidation reaction. A nanostructure refers to a structure that forms nano-scale concave-convex structures on the surface of the catalyst material.

[0050] The cathode 22 is provided to reduce a substance containing carbon dioxide and generate a reduction product containing a carbon compound. The cathode 22 is an electrode (reduction electrode) that causes a reduction reaction of carbon dioxide (CO2) or a reduction reaction of a carbon compound generated thereby to generate carbon monoxide (CO), methane (CH4), ethane (C2H6), ethylene (C2H4), methanol (CH3OH), ethanol (C2H5OH), ethylene glycol (C2H6O2) and other carbon compounds. In the cathode 22, a side reaction of generating hydrogen (H2) due to a reduction reaction of water (H2O) sometimes occurs simultaneously with the reduction reaction of carbon dioxide (CO2). The cathode 22 has a first surface 22a facing the cathode flow path 21 and a second surface 22b facing the cathode flow path 23. The cathode flow path 21 is arranged between the cathode 22 and the diaphragm 30 in such a manner that the cathode solution as an electrolytic solution contacts the cathode 22 and the diaphragm 30.

[0051] The cathode flow path 21 faces the cathode 22 and is composed of an opening portion provided in a flow path plate 25 (cathode flow path plate). A solution inlet and a solution outlet (not shown) are provided in the flow path plate 25, and a cathode solution as an electrolytic solution is introduced and discharged through these solution inlet and solution outlets by a cathode solution supply system 200. The cathode solution circulates in the cathode flow path 21 in a manner in contact with the cathode 22 and the diaphragm 30. The flow path plate 25 constituting the cathode flow path 21 preferably uses a material with low chemical reactivity and no conductivity. As such a material, insulating resin materials such as acrylic resin, polyetheretherketone (PEEK), and fluororesin can be cited. The cathode flow path 21 will cause the cell resistance to increase, so the cathode flow path 21 may not be provided.

[0052] In the cathode 22, the reduction reaction of CO2 occurs mainly in the portion in contact with the cathode solution. Figure 4 As shown, it is preferred to use an opening with a large opening area in the cathode flow path 21. In order to improve mechanical retention and electrical connectivity, as shown in FIG. Figure 5As shown, a pad (convex portion) 26 may be provided in the cathode flow path 21. The pad 26 of the cathode flow path 21 is provided in the central portion of the cathode flow path 21 and is held on the flow path plate 25 by a bridge portion 27 thinner than the pad 26 so as not to hinder the circulation of the cathode solution in the cathode flow path 21. When the pad 26 is provided in the cathode flow path 21, it is preferred that the number of pads 26 is small in order to reduce the cell resistance.

[0053] Preferably, at least a portion of the pad 26 overlaps with the pad 14a of the flow path plate 14. Thus, a good electrical connection can be achieved, and the resistance of the electrolytic cell 2 can be reduced. In addition, good contact between the diaphragm 30 and the anode catalyst material and the cathode catalyst material can be achieved, which can not only reduce the resistance but also enable efficient reactions. In addition, it is preferred that at least a portion of the anode flow path 12 overlaps with the pad 26. Thus, a good electrical connection can be achieved, and the resistance of the electrolytic cell 2 can be reduced. In addition, good contact between the diaphragm 30 and the anode catalyst material and the cathode catalyst material can be achieved, which can not only reduce the resistance but also enable efficient reactions.

[0054] The cathode flow path 23 faces the cathode 22 and is composed of a pit (groove / recess) provided on a flow path plate (cathode flow path plate) 28. The flow path plate 28 constituting the cathode flow path 23 for the flow of gas containing carbon dioxide preferably uses a material with low chemical reactivity and high conductivity. As such a material, metal materials such as Ti and SUS, carbon, etc. can be cited. It should be noted that the flow path plate 14, the flow path plate 25 and the flow path plate 28 are provided with an inlet and outlet for a solution or gas, which are omitted from the figure, and a threaded hole for fastening, etc. In addition, before and after each flow path plate 14, 25, 28, a filler, which is omitted from the figure, is sandwiched as needed.

[0055] The flow path plate 28 is provided with a gas inlet and a gas outlet (not shown), through which CO2 gas or gas containing CO2 (which will be collectively referred to as CO2 gas) is introduced and discharged by the gas supply system 300. The CO2 gas flows in the cathode flow path 23 in a manner in contact with the cathode 22. Figure 6 As shown, it is preferred to provide a plurality of pads (convex portions) 29 in the cathode flow path 23. The pads 29 are provided for mechanical retention and electrical conduction. The pads 29 are preferably provided in a staggered manner, whereby the cathode flow path 23 meanders in the same manner as the anode flow path 12. The cathode current collector plate 24 is electrically connected to the surface of the flow path plate 28 on the opposite side to the cathode 22.

[0056] In the electrolytic cell 2 of the embodiment, by providing the pads 14a and 29 in the anode flow path 12 and the cathode flow path 23, the contact area between the anode 11 and the flow path plate 14 constituting the anode flow path 12 and the contact area between the cathode 22 and the flow path plate 28 constituting the cathode flow path 23 can be increased. In addition, by providing the pad 26 in the cathode flow path 21, the contact area between the cathode 22 and the flow path plate 25 constituting the cathode flow path 21 can be increased. Thus, the mechanical retention of the electrolytic cell 2 can be improved, and the electrical conduction between the anode current collector plate 13 and the cathode current collector plate 24 can be improved, and the reduction reaction efficiency of CO2 can be improved.

[0057] Furthermore, the surface 28a on the cathode 22 side of the flow path plate 28 has a hydrophilic region 280 in the region in contact with the cathode 22. The contact angle between the hydrophilic region 280 and water is greater than 0 degrees and less than 45 degrees. The contact angle is preferably less than 30 degrees, more preferably less than 15 degrees. The hydrophilic region 280 may not be permeable to gases such as carbon dioxide.

[0058] The contact angle between the other parts of the surface 28a and water may be 45 degrees or more and 180 degrees or less.

[0059] Figure 6 Although an example in which the hydrophilic region 280 is provided on the entire surface 28 a is shown, the present invention is not limited to this example, and the hydrophilic region 280 may be provided on at least a portion of the surface 28 a .

[0060] The hydrophilic region 280 can be formed, for example, by the following methods: a method of roughening the surface 28a by attaching carbon particles, a method of coating the surface 28a with a hydrophilic conductive polymer such as polyacetylene, polythiophene, polyaniline, polypyrrole, or a method of forming the flow path plate 28 from a hydrophilic material.

[0061] like Figure 7 As shown, the cathode 22 has a gas diffusion layer 22A and a cathode catalyst layer 22B disposed thereon. Figure 8 As shown in FIG. 2 , a porous layer 22C denser than the gas diffusion layer 22A may be disposed between the gas diffusion layer 22A and the cathode catalyst layer 22B. Fig. 9 As shown, the gas diffusion layer 22A is arranged on the cathode flow path 23 side, and the cathode catalyst layer 22B is arranged on the cathode flow path 21 side. The cathode catalyst layer 22B can enter the gas diffusion layer 22A. The cathode catalyst layer 22B preferably has catalyst nanoparticles or catalyst nanostructures. The gas diffusion layer 22A is composed of, for example, carbon paper or carbon cloth, and a hydrophobic treatment is applied. The porous layer 22C is composed of a porous body with a pore size smaller than that of the carbon paper or carbon cloth.

[0062] like Fig. 9As shown in the schematic diagram of , in the cathode catalyst layer 22B, the cathode solution or ions are supplied and discharged from the cathode flow path 21. In the gas diffusion layer 22A, CO2 gas is supplied from the cathode flow path 23, and the product of the reduction reaction of the CO2 gas is discharged. By pre-treatment of the gas diffusion layer 22A with appropriate hydrophobicity, the CO2 gas reaches the cathode catalyst layer 22B mainly through gas diffusion. The reduction reaction of CO2 and the reduction reaction of the carbon compounds generated thereby occur near the boundary between the gas diffusion layer 22A and the cathode catalyst layer 22B or near the cathode catalyst layer 22B that enters the gas diffusion layer 22A, and the gaseous product is mainly discharged from the cathode flow path 23, and the liquid product is mainly discharged from the cathode flow path 21.

[0063] The cathode catalyst layer 22B is composed of a catalyst material (cathode catalyst material) that can reduce carbon dioxide to carbon compounds, and reduce the carbon compounds generated thereby to carbon compounds as needed, and can reduce the overvoltage of such reactions. Examples of such materials include metals such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), and tin (Sn), metal materials such as alloys or intermetallic compounds containing at least one of these metals, carbon (C), graphene, CNT (carbon nanotube), fullerene, and ketjen black, and metal complexes such as Ru complexes and Re complexes. The cathode catalyst layer 22B can be in various shapes such as plate, mesh, wire, granular, porous, thin film, and island.

[0064] The cathode catalyst material constituting the cathode catalyst layer 22B preferably has a composite of nanoparticles of the above-mentioned metal material, nanostructures of the metal material, nanowires of the metal material, or nanoparticles of the above-mentioned metal material supported on carbon particles, carbon nanotubes, graphene, etc. By using catalyst nanoparticles, catalyst nanostructures, catalyst nanowires, catalyst nano-supported structures, etc. as cathode catalyst materials, the reaction efficiency of the reduction reaction of carbon dioxide at the cathode 22 can be improved.

[0065] The diaphragm 30 is provided between the anode 11 and the cathode 22. It is composed of an ion exchange membrane or the like that enables ions to move between the anode 11 and the cathode 22 and can separate the anode portion 10 from the cathode portion 20. As the ion exchange membrane, for example, a cation exchange membrane such as Nafion and Flemion, or an anion exchange membrane such as Neosepta and Selemion can be used. As described later, when an alkaline solution is used as the anode solution or the cathode solution, it is mainly assumed that hydroxide ions (OH -) moves, the diaphragm 30 is preferably composed of an anion exchange membrane. Among them, in addition to the ion exchange membrane, as long as it is a material that can move ions between the anode 11 and the cathode 22, a glass filter, a porous polymer membrane, a porous insulating material, etc. can also be applied to the diaphragm 30.

[0066] The anode solution and cathode solution as the electrolytic solution are preferably solutions containing at least water (H2O). Carbon dioxide (CO2) is supplied from the cathode flow path 23, so the cathode solution may contain carbon dioxide (CO2) or may not contain carbon dioxide (CO2). The anode solution and the cathode solution may be the same solution or different solutions. As the solution containing H2O used as the anode solution and the cathode solution, an aqueous solution containing any electrolyte can be cited. As the aqueous solution containing an electrolyte, for example, a solution containing hydroxide ions (OH - ), hydrogen ion (H + ), potassium ion (K + ), sodium ion (Na + ), lithium ion (Li + ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), nitrate ion (NO3 - ), sulfate ion (SO4 2- ), phosphate ion (PO4 2- ), borate ion (BO3 3- ) and bicarbonate ions (HCO3 - ) in an aqueous solution of at least one of the following. In order to reduce the resistance of the electrolytic solution, an alkaline solution containing an electrolyte such as potassium hydroxide or sodium hydroxide dissolved in high concentration is preferably used as the anode solution and the cathode solution.

[0067] In the cathode solution, a solution containing imidazole can be used. Ion or pyridine Ions and cations with BF4 - or PF6 - Ionic liquids or their aqueous solutions are salts formed by anions such as ethanolamine and imidazole and are liquid in a wide temperature range. Other cathode solutions include amine solutions such as ethanolamine, imidazole, pyridine, etc. or their aqueous solutions. The amine can be any of a primary amine, a secondary amine, and a tertiary amine.

[0068] An anode solution is supplied from an anode solution supply system 100 to the anode flow path 12 of the anode portion 10 as an electrolytic solution. The anode solution supply system 100 circulates the anode solution in such a manner that the anode solution flows in the anode flow path 12. The anode solution supply system 100 includes a pressure control unit 101, an anode solution tank 102, a flow control unit (pump) 103, a reference electrode 104, and a pressure gauge 105, and is configured to circulate the anode solution in the anode flow path 12. The anode solution tank 102 is connected to a gas component collection unit (not shown) that collects gas components such as oxygen (O2) contained in the circulating anode solution. The anode solution is introduced into the anode flow path 12 by controlling the flow rate and pressure in the pressure control unit 101 and the flow control unit 103.

[0069] The cathode solution is supplied from the cathode solution supply system 200 to the cathode flow path 21 of the cathode part 20. The cathode solution supply system 200 circulates the cathode solution in such a manner that the cathode solution flows in the cathode flow path 21. The cathode solution supply system 200 has a pressure control unit 201, a cathode solution tank 202, a flow control unit (pump) 203, a reference electrode 204 and a pressure gauge 205, and is configured to circulate the cathode solution in the cathode flow path 21. The cathode solution tank 202 is connected to a gas component collection unit 206 that collects gas components such as carbon monoxide (CO) contained in the circulating cathode solution. The cathode solution is introduced into the cathode flow path 21 by controlling the flow rate and pressure in the pressure control unit 201 and the flow control unit 203.

[0070] CO2 gas is supplied to the cathode flow path 23 from a gas supply system 300. The gas supply system 300 includes a CO2 gas tank 301, a flow control unit 302, a pressure gauge 303, and a pressure control unit 304. The CO2 gas is introduced into the cathode flow path 23 with the flow rate and pressure controlled in the flow control unit 302 and the pressure control unit 304. The gas supply system 300 is connected to a product collection system 400 that collects products in the gas flowing in the cathode flow path 23. The product collection system 400 includes a gas-liquid separation unit 401 and a product collection unit 402. Reduction products such as CO and H2 contained in the gas flowing in the cathode flow path 23 are accumulated in the product collection unit 402 via the gas-liquid separation unit 401.

[0071] The anode solution and the cathode solution circulate in the anode flow path 12 and the cathode flow path 21 during the electrolytic reaction operation as described above. During the renewal operation of the electrolytic cell 2 described later, the anode solution and the cathode solution are discharged into the waste liquid collection system 600 in a manner that the anode 11, the anode flow path 12, the cathode 22, the cathode flow path 21, etc. are exposed from the anode solution and the cathode solution. The waste liquid collection system 600 has a waste liquid collection tank 601 connected to the anode flow path 12 and the cathode flow path 21. The waste liquid of the anode solution and the cathode solution is collected in the waste liquid collection tank 601 by opening and closing a valve not shown in the figure. The opening and closing of the valve, etc. are uniformly controlled by the control system 500. The waste liquid collection tank 601 also serves as a collection part of the flushing liquid supplied from the renewal material supply unit 700. Furthermore, the gaseous substance containing a part of the liquid substance supplied from the renewal material supply unit 700 is also collected by the waste liquid collection tank 601 as needed.

[0072] The renewal material supply unit 700 is equipped with a gaseous substance supply system 710 and a flushing liquid supply system 720. It should be noted that the flushing liquid supply system 720 can be omitted according to circumstances. The gaseous substance supply system 710 has a gas tank 711 as a supply source of gaseous substances such as air, carbon dioxide, oxygen, nitrogen, argon, and a pressure control unit 712 that controls the supply pressure of the gaseous substance. The flushing liquid supply system 720 has a flushing liquid tank 721 as a supply source of flushing liquid such as water and a flow control unit (pump) 722 that controls the supply flow rate of the flushing liquid. The gaseous substance supply system 710 and the flushing liquid supply system 720 are connected to the anode flow path 12, the cathode flow path 21, and the cathode flow path 23 via piping. The gaseous substance and flushing liquid are supplied to each flow path 12, 21, and 23 by opening and closing valves not shown in the figure. The opening and closing of the valves are uniformly controlled by the control system 500.

[0073] A portion of the reduction product accumulated in the product collection unit 402 is sent to the reduction performance detection unit 501 of the control system 500. In the reduction performance detection unit 501, the generation amount and ratio of each product such as CO and H2 in the reduction product are detected. The generation amount and ratio of each product detected are input into the data collection / control unit 502 of the control system 500. Furthermore, the data collection / control unit 502 collects electrical data such as cell voltage, cell current, cathode potential, anode potential, and the internal pressure and pressure loss of the anode solution flow path and the cathode solution flow path as part of the cell performance of the electrolytic cell 2 and sends it to the update control unit 503.

[0074] In addition to the reduction performance detection unit 501, the data collection / control unit 502 is also electrically connected to the power supply control unit 40, the pressure control unit 101 and the flow control unit 103 of the anode solution supply system 100, the pressure control unit 201 and the flow control unit 203 of the cathode solution supply system 200, the flow control unit 302 and the pressure control unit 304 of the gas supply system 300, and the pressure control unit 712 and the flow control unit 722 of the renewal material supply unit 700 through a bidirectional signal line that is partially omitted in the figure, and they are uniformly controlled. It should be noted that a valve not shown in the figure is provided in each pipe, and the opening and closing operation of the valve is controlled by a signal from the data collection / control unit 502. The data collection / control unit 502 can control the operation of the above-mentioned components during electrolysis operation, for example.

[0075] The update control unit 503 is electrically connected to the power supply control unit 40, the flow control unit 103 of the anode solution supply system 100, the flow control unit 203 of the cathode solution supply system 200, the flow control unit 302 of the gas supply system 300, and the pressure control unit 712 and the flow control unit 722 of the update material supply unit 700 through a bidirectional signal line that is partially omitted in the figure, and they are uniformly controlled. It should be noted that a valve not shown in the figure is provided in each pipe, and the opening and closing operation of the valve is controlled by a signal from the update control unit 503. The update control unit 503 can control the operation of the above-mentioned components during electrolysis operation, for example. In addition, the update control unit 503 and the data collection / control unit 502 can be composed of one control unit.

[0076] The operation of the carbon dioxide electrolysis device 1 according to the embodiment will be described. Fig.10 As shown, the startup process S101 of the electrolysis device 1 is implemented. In the startup process S101 of the electrolysis device 1, the following work is performed. In the anode solution supply system 100, the pressure control unit 101 and the flow control unit 103 control the flow rate and pressure, and the anode solution is introduced into the anode flow path 12. In the cathode solution supply system 200, the pressure control unit 201 and the flow control unit 203 control the flow rate and pressure, and the cathode solution is introduced into the cathode flow path 21. In the gas supply system 300, the flow rate and pressure are controlled by the flow control unit 302 and the pressure control unit 304, and the CO2 gas is introduced into the cathode flow path 23.

[0077] Next, the electrolysis operation step S102 of CO2 is implemented. In the electrolysis operation step S102 of CO2, the power supply control unit 40 of the electrolysis device 1 that has implemented the start-up step S101 starts to apply the electrolysis voltage, and applies the voltage between the anode 11 and the cathode 22 to supply the current. When the current flows between the anode 11 and the cathode 22, the oxidation reaction near the anode 11 and the reduction reaction near the cathode 22 shown below occur. Here, the case where carbon monoxide (CO) is generated as a carbon compound is mainly described, but the carbon compound that is the reduction product of carbon dioxide is not limited to carbon monoxide, and can be other carbon compounds such as the above-mentioned organic compounds. In addition, as a reaction process of the electrolytic cell 2, it is considered that there is a process in which hydrogen ions (H + ) and the main generated hydroxide ions (OH - ) cases, but not limited to any one of these reaction processes.

[0078] First, the oxidation of water (H2O) to generate hydrogen ions (H + ) reaction process. When current is supplied between the anode 11 and the cathode 22 from the power supply control unit 40, an oxidation reaction of water (H2O) occurs at the anode 11 in contact with the anode solution. Specifically, as shown in the following formula (1), the H2O contained in the anode solution is oxidized to generate oxygen (O2) and hydrogen ions (H + ).

[0079] 2H2O→4H + +O2+4e - …(1)

[0080] H generated by the anode 11 + The electrons (e) move through the anode solution in the anode 11, the separator 30, and the cathode solution in the cathode flow path 21 and reach the vicinity of the cathode 22. The electrons (e) are supplied by the current supplied from the power supply control unit 40 to the cathode 22. - ) and H moving toward the cathode 22 + , a reduction reaction of carbon dioxide (CO2) is generated. Specifically, as shown in the following formula (2), CO2 supplied from the cathode flow path 23 to the cathode 22 is reduced to generate CO.

[0081] 2CO2+4H + +4e - →2CO+2H2O…(2)

[0082] Next, the process of reducing carbon dioxide (CO2) to generate hydroxide ions (OH -) is the reaction process. When current is supplied between the anode 11 and the cathode 22 from the power supply control unit 40, water (H2O) and carbon dioxide (CO2) are reduced near the cathode 22 to generate carbon monoxide (CO) and hydroxide ions (OH - ). Hydroxide ion (OH - ) diffuses toward the vicinity of the anode 11, as shown in the following formula (4), the hydroxide ion (OH - ) is oxidized to produce oxygen (O2).

[0083] 2CO2+2H2O+4e - →2CO+4OH - …(3)

[0084] 4OH - →2H2O+O2+4e - …(4)

[0085] In the reaction process of the cathode 22, as described above, it is considered that the reduction reaction of CO2 occurs near the boundary between the gas diffusion layer 22A and the cathode catalyst layer 22B. At this time, the cathode solution flowing in the cathode flow path 21 invades the gas diffusion layer 22A, or the cathode catalyst layer 22B becomes excessively hydrated, thereby causing the following undesirable phenomena: the amount of CO generated by the reduction reaction of CO2 is reduced, the cell voltage is increased, etc. Such a reduction in the cell performance of the electrolytic cell 2 is also caused by the following situations: the distribution deviation of ions and residual gas near the anode 11 and the cathode 22, the excess moisture of the cathode catalyst layer 22B, the electrolyte precipitation in the cathode 22 and the anode 11, and the electrolyte precipitation in the anode flow path 12 and the cathode flow path 21.

[0086] In addition, due to the electrolysis work, salt is sometimes precipitated on the cathode flow path 21 and the gas diffusion layer 22A, and due to the blockage of the flow path and the reduction of gas diffusivity, the performance of the pool is sometimes reduced. This is because ions move between the anode 11 and the cathode 22 via the diaphragm 30 or the ion exchange membrane, and the ions react with the gas components. For example, when the anode solution uses potassium hydroxide solution and the cathode gas uses carbon dioxide gas, potassium ions move from the anode 11 to the cathode 22, and the ions react with carbon dioxide to generate salts such as potassium bicarbonate and potassium carbonate. In the cathode flow path 21 and the gas diffusion layer 22A, when the above-mentioned salt is below the solubility, the above-mentioned salt is precipitated in the cathode flow path 21 and the gas diffusion layer 22A. Due to the occlusion of the flow path, the uniform gas flow in the entire pool is obstructed, and the pool performance is reduced. In particular, when multiple cathode flow paths 21 are set, the reduction of pool performance is significant. It should be noted that the performance of the pool itself can sometimes be improved by locally increasing the gas flow rate. This is because increasing the gas pressure increases the gas components supplied to the catalyst or increases the gas diffusivity, thereby improving the cell performance. In order to detect such a decrease in cell performance, step S103 is performed to determine whether the cell performance meets the required standard.

[0087] As described above, the data collection / control unit 502 collects the cell performance such as the amount and ratio of each product generated, the cell voltage of the electrolytic cell 2, the cell current, the cathode potential, the anode potential, the pressure inside the anode flow path 12, and the pressure inside the cathode flow path 21, etc., periodically or continuously. Furthermore, in the data collection / control unit 502, the required benchmarks of the cell performance are pre-set, and it is determined whether the collected data meets the set required benchmarks. When the collected data meets the set required benchmarks, the electrolysis of CO2 is not stopped (S104), and the electrolysis of CO2 is continued S102. When the collected data does not meet the set required benchmarks, the update work process S105 is implemented.

[0088] The cell performance collected by the data collection / control unit 502 is defined by, for example, the upper limit of the cell voltage when a constant current flows through the electrolytic cell 2, the lower limit of the cell current when a constant voltage is applied to the electrolytic cell 2, the Faraday efficiency of the carbon compound generated by the reduction reaction of CO2, and the like. Here, the Faraday efficiency is defined as the ratio of the current that contributes to the generation of the target carbon compound to the total current flowing through the electrolytic cell 2. In order to maintain the electrolysis efficiency, when the upper limit of the cell voltage when a constant current flows reaches 150% or more of the set value, preferably 120% or more, the updating work process S105 can be implemented. In addition, when the lower limit of the cell current when a constant voltage is applied reaches 50% or less of the set value, preferably 80% or less, the updating work process S105 can be implemented. In order to maintain the generation amount of the reduction product such as carbon compounds, when the Faraday efficiency of the carbon compound is 50% or less of the set value, preferably 80% or less, the updating work process S105 can be implemented.

[0089] The determination of cell performance is such as when at least one parameter of the cell voltage, cell current, the Faraday efficiency of the carbon compound, the pressure inside the anode flow path 12, and the pressure inside the cathode flow path 21 does not meet the required benchmark, it is determined that the cell performance does not meet the required benchmark, and the updating work process S105 is implemented. In addition, the required benchmark of the cell performance can be set by combining more than two of the above parameters. For example, when both the cell voltage and the Faraday efficiency of the carbon compound do not meet the required benchmark, the updating work process S105 can be implemented. The updating work process S105 is implemented when at least one of the cell performance does not meet the required benchmark. In order to stably implement the CO2 electrolysis work process S102, it is preferred to implement the updating work process S105 at intervals of more than 1 hour.

[0090] If only according to any one of the Faraday efficiency of cell voltage, cell current, carbon compound to judge the required benchmark of cell performance, then even if cell performance improves or does not change, when salt is precipitated in flow path or gas diffusion layer and output is reduced, sometimes it is judged to need to be updated.In electrolyzer, it is important to perceive the reduction of cell performance in advance and update work at the best time.Therefore, in the electrolyzer of embodiment, preferably by the pressure of cell (pressure inside anode flow path 12, pressure inside cathode flow path 21 etc.) is set as one of the parameters for defining required benchmark to perceive the precipitation of salt, update work.

[0091] In the case where the electrolytic cell 2 mainly generates CO, for example, if it is hydrogen, when it rises to at least 2 times, preferably 1.5 times or more of the normal level, it can be judged that the required standard of cell performance is not met. For example, if it is CO, when it drops to at least 0.8 times or less, preferably 0.9 times or less of the normal level, it can be judged that the required standard of cell performance is not met.

[0092] It is considered that the above-mentioned reference concentration is arbitrary because carbon compounds are generated and water is decomposed by the electrolytic cell 2. For example, when hydrogen and CO are generated at a ratio of 2:1 and the gas is passed through a reactor to produce methanol, the reference for the change in the concentration of the reduction product is different from the above-mentioned reference. When the concentration of hydrogen and carbon compounds rises to at least 1.3 times or more, preferably 1.1 times or more, or decreases to at least 0.8 times or less, preferably 0.9 or less, it can be judged that the required reference for the cell performance is not met.

[0093] When salt is detected, the salt is discharged by the flushing liquid, but if the amount of material movement does not change even if the salt is discharged, it can be determined that a leak has occurred in the electrolytic cell 2. The leakage of the electrolytic cell 2 is not limited to the leakage of the gas between the anode 11 and the cathode 22, and also includes, for example, the leakage of the gas between the cathode 22 and the cathode flow paths 21, 23. This gas leakage is easy to occur when the electrolytic cell 2 that precipitates salt is operated for a long time under the condition of high pressure in the cathode flow paths 21, 23.

[0094] The necessity of the renewal work is determined not only based on the salt perception caused by the change of the cell voltage, current value, and cell pressure, but also based on the gas-liquid separation performance between the anode 11 and the cathode 22 when the anode 11 and the cathode 22 are separated by the diaphragm 30, that is, the amount of liquid and gas moved between the anode 11 and the cathode 22, the amount of product, the voltage difference with the reference electrode, and the estimated value of the Faraday efficiency obtained from these parameters. The necessity of the renewal work can be determined by comprehensively judging the necessity of the renewal work based on the estimated Faraday efficiency of each parameter value and the parameters described later, and the combination of each value and the calculation method are arbitrary.

[0095] The necessity of the updating work can be judged based on the estimated overflow degree such as the data of each cell obtained by the operation method for detecting the overflow performance and the pressure change. In addition, the operation time of the electrolytic cell 2 can be considered. The operation time can be not only the operation time after the operation starts, but also the cumulative value of the operation time so far, or the duration, or the operation time after the updating work, or the calculated value of the cumulative voltage value and time, the current value and time multiplied together, etc., and its combination and calculation method are arbitrary. In addition, the calculated values ​​of these combinations are preferred because they take into account the differences in the operation methods of the electrolytic cell 2 compared with the judgment based only on the duration, etc. Furthermore, the change value of the current or voltage, the pH value of the electrolytic solution, the change value, the oxygen generation amount, and the change amount can also be used.

[0096] If the operation of judging the necessity of the updating work is performed and the judgment is made according to the parameters such as the cell voltage during the operation, the operation working time will be reduced, but it is preferred because the necessity of the updating work can be accurately judged. It should be noted that the judgment time of the necessity of the updating work at this time is preferably at least less than half of the updating working time, more preferably less than 1 / 4, and ideally less than 1 / 10. In addition, the parameters used to judge the necessity of the updating work collect the data of the electrolytic cell 2 through the electronic network, and the necessary parameters are derived through the data collection / control unit 502 and the analysis unit 504 of the multiple cells by big data analysis, machine learning and other analysis, so that the updating control unit 503 can update the required benchmark of the cell performance defined by each parameter to judge the necessity of the updating, and always perform the best updating work.

[0097] Update work step S105 is for example performed according to Fig.11 The process of the present invention is implemented as shown in the flowchart. First, the electrolysis voltage applied by the power supply control unit 40 is stopped to stop the reduction reaction of CO2 (S201). At this time, it is not necessary to stop the application of the electrolysis voltage. Then, the cathode solution and the anode solution are discharged from the cathode flow path 21 and the anode flow path 12 (S202). Then, the flushing liquid is supplied to the cathode flow path 21 and the anode flow path 12 (S203) for cleaning.

[0098] During the supply of the rinse liquid, a renewal voltage can be applied between the anode 11 and the cathode 22. Thus, ions and impurities attached to the cathode catalyst layer 22B can be removed. When the renewal voltage is applied to mainly perform oxidation treatment, impurities such as ions and organic matter attached to the catalyst surface are oxidized and removed. In addition, by performing this treatment in the rinse liquid, not only the catalyst can be renewed, but also the ions replaced in the ion exchange resin can be removed when the ion exchange membrane is used as the diaphragm 30.

[0099] The renewal voltage is preferably, for example, more than -2.5V and less than 2.5V. In order to use energy for the renewal work, the range of the renewal voltage is preferably as narrow as possible, for example, more preferably more than -1.5V and less than 1.5V. The renewal voltage can be applied cyclically to alternately carry out oxidation treatment and reduction treatment of ions or impurities. Thus, the regeneration of ion exchange resin and the regeneration of catalyst can be accelerated. In addition, the voltage of the electrolysis voltage equivalent value during the electrolysis work can be applied as the renewal voltage to carry out the renewal work. In this case, the formation of the power supply control unit 40 can be simplified.

[0100] Next, gas is supplied to the cathode flow path 21 and the anode flow path 12 (S204) to dry the cathode 22 and the anode 11. When the rinsing liquid is supplied to the cathode flow path 21 and the anode flow path 12, the saturation of the water in the gas diffusion layer 22A rises, and the output is reduced due to the diffusivity of the gas. By supplying gas, the saturation of water decreases, so the cell performance is restored and the renewal effect is improved. The gas is preferably supplied immediately after the rinsing liquid is circulated, preferably at least within 5 minutes after the rinsing liquid supply ends. This is because the saturation of water rises and the output is significantly reduced. For example, when the renewal work is performed every 1 hour, the output in the 5-minute renewal work is 0V or very little, so sometimes 5 / 60 of the output is lost.

[0101] When the above updating work is completed, the cathode solution is introduced into the cathode flow path 21, the anode solution is introduced into the anode flow path 12, and the CO2 gas is introduced into the cathode flow path 23 (S205). Then, the electrolysis voltage is applied between the anode 11 and the cathode 22 by the power supply control unit 40 to restart the CO2 electrolysis work (S206). It should be noted that if the application of the electrolysis voltage is not stopped in S201, the above restart work is not performed. The cathode solution and the anode solution can be discharged from each flow path 12, 21 using gas or flushing liquid.

[0102] The supply and flow of the flushing liquid (S203) are implemented to prevent the precipitation of the electrolyte contained in the cathode solution and the anode solution, and to clean the cathode 22, the anode 11 and each flow path 12, 21. Therefore, the flushing liquid is preferably water, more preferably water with a conductivity of 1 mS / m or less, and further preferably water with a conductivity of 0.1 mS / m or less. In order to remove precipitates such as electrolytes in the cathode 22 and the anode 11, etc., a low-concentration acidic flushing liquid such as sulfuric acid, nitric acid, and hydrochloric acid can be supplied, thereby dissolving the electrolyte. When using a low-concentration acidic flushing liquid, a process of supplying a water flushing liquid is implemented in a subsequent process. Before the gas supply process is performed, in order to prevent the additives contained in the flushing liquid from remaining, it is preferably implemented to supply a water flushing liquid. Figure 1 Although the rinse liquid supply system 720 having one rinse liquid tank 721 is shown, when a plurality of rinse liquids such as water and an acid rinse liquid are used, a corresponding plurality of rinse liquid tanks 721 are used.

[0103] In particular, for renewing ion exchange resins, acid or alkaline flushing solutions are preferred. This has the effect of replacing the protons, OH - Therefore, it is preferred that acid and alkaline rinse solutions are alternately circulated, combined with water having an electrical conductivity of 1 mS / m or less, and gas is supplied between the supply of multiple rinse solutions so that the rinse solutions do not mix with each other.

[0104] As a flushing liquid, water generated by the reaction can be used. For example, when CO is generated by reduction of CO2 and protons, water is generated. At this time, the water discharged from the cathode 22 can be separated by gas-liquid separation and stored for use. In this way, there is no need to resupply the flushing liquid from the outside, which is beneficial to the system. In addition, the reaction current can be increased by changing the potential, and the amount of water generated can be increased to supply the water to the cathode flow path 21. Thus, a tank for the generated water and piping, pumps, etc. for the flushing liquid are not required, which is an effective configuration in the system. In addition, by supplying an oxygen-containing gas to the cathode flow path 21 and applying a voltage, the electrolytic solution or flushing liquid of the anode 11 is hydrolyzed, and the protons or OH moving to the counter electrode are removed. -Ions are renewed by water generated by the catalyst. For example, in an electrolytic cell that uses a gold catalyst to reduce CO2 to CO, when Nafion is used as an ion exchange membrane, when air flows through the cathode 22 and a potential is applied to the cell to perform hydrolysis, the protons that move to the cathode 22 react with oxygen through the catalyst to generate water. Renewal work can be performed by this generated water. In addition, subsequently, a gas that does not contain oxygen is supplied to the cathode 22 or the supply of gas is stopped, thereby generating hydrogen, and a renewal work of drying the cathode 22 by the generated hydrogen can be performed. Thus, the catalyst can be renewed by the reducing power of protons and hydrogen.

[0105] The gas used in the gas supply and flow step S204 preferably includes at least one of air, carbon dioxide, oxygen, nitrogen and argon. Furthermore, it is preferred to use a gas with low chemical reactivity. From this point of view, it is preferred to use air, nitrogen and argon, and nitrogen and argon are more preferred. The supply of flushing liquid and gas for renewal is not limited to the cathode flow path 21 and the anode flow path 12, and flushing liquid and gas can also be supplied to the cathode flow path 23 to clean the surface of the cathode 22 in contact with the cathode flow path 23. In order to dry the cathode 22 also from the side of the surface in contact with the cathode flow path 23, it is effective to supply gas to the cathode flow path 23.

[0106] In the above, the case where the flushing liquid and gas for renewal are supplied to both the anode part 10 and the cathode part 20 is described, but the flushing liquid and gas for renewal can also be supplied to only one side of the anode part 10 or the cathode part 20. For example, the Faraday efficiency of the carbon compound varies according to the contact area between the cathode solution and CO2 in the gas diffusion layer 22A and the cathode catalyst layer 22B of the cathode 22. In this case, the Faraday efficiency of the carbon compound can be restored only by supplying the flushing liquid or gas for renewal to the cathode part 20. Depending on the type of electrolytic solution (anode solution and cathode solution) used, there is sometimes a tendency to precipitate easily on one side of the anode part 10 or the cathode part 20. Based on such a tendency of the electrolysis device 1, the flushing liquid and gas for renewal can be supplied to only one side of the anode part 10 or the cathode part 20. Furthermore, depending on the operating time of the electrolysis device 1, the cell performance can sometimes be restored by drying the anode 11 and the cathode 22. In this case, the gas for renewal can be supplied to only at least one side of the anode part 10 and the cathode part 20. The updating operation step S105 can be changed in various ways according to the operating conditions and trends of the electrolysis device 1 .

[0107] As described above, in the electrolysis device 1 of the first embodiment, it is determined whether to continue the CO2 electrolysis operation step S102 or whether to implement the renewal operation step S105 based on whether the cell performance of the electrolytic cell 2 meets the required standard. By supplying the flushing liquid and gas for renewal in the renewal operation step S105, the invasion of the cathode solution into the gas diffusion layer 22A, the excess water in the cathode catalyst layer 22B, the distribution deviation of ions and residual gas near the anode 11 and the cathode 22, the precipitation of electrolyte in the cathode 22, the anode 11, the anode flow path 12 and the cathode flow path 21, etc., which are the causes of the decline in cell performance, are removed. Therefore, by restarting the CO2 electrolysis operation step S102 after the renewal operation step S105, the cell performance of the electrolytic cell 2 can be restored. By repeating such a CO2 electrolysis operation step S102 and the renewal operation step S105 based on the required standard of cell performance, the CO2 electrolysis performance of the electrolysis device 1 can be maintained for a long time.

[0108] The salt precipitated in the cathode flow path 23 is more likely to precipitate in the front half of the flow path (the side close to the inlet IN in the length direction, the upstream side) than in the rear half of the flow path (the side close to the outlet OUT in the length direction, the downstream side). Therefore, by allowing a flushing liquid such as water to flow from the outlet OUT of the cathode flow path 23 to the inlet IN, the salt precipitated in the cathode flow path 23 can be effectively eluted. That is, on the outlet OUT side, the salt precipitation is small, and the salt concentration in the introduced flushing liquid is low. On the inlet IN side, the salt precipitation is large, and the salt concentration in the flushing liquid is high, so the salt can be effectively eluted with less flushing liquid. However, due to the flow of the flushing liquid, the water content of the gas diffusion layer increases, the diffusivity of carbon dioxide decreases, and the cell performance decreases. This phenomenon is called "flooding".

[0109] In the cathode flow path 23, overflow is likely to occur in the front half. This is because, in the front half of the cathode flow path 23, the humidity of the flow path is low, and salt precipitation is likely to occur. In addition, in the back half of the cathode flow path 23, the gas in the cathode flow path 23 is humidified by the water in the anode 11 and the water generated by the reaction, and the amount of salt precipitation is reduced. In some cases, liquid water is sometimes produced, and the salt is dissolved and discharged. Another reason is that since most of the CO2 gas reacts in the front half of the cathode flow path 23, the amount of CO2 gas is reduced in the back half of the cathode flow path 23, and the amount of salt precipitation is reduced.

[0110] In contrast, in the carbon dioxide electrolysis device of the first embodiment, the hydrophilic region 280 is formed on at least a portion of the surface 28a of the flow channel plate 28. Fig.12As shown by the arrow in , liquids such as water can move from the rear half of the cathode flow path 23 with a large amount of water to the front half. That is, water condensed in the rear half of the cathode flow path 23, water moved from the anode 11, and water generated by the reaction can move to the flow path plate of the hydrophilic region 280. Therefore, in the front half of the cathode flow path 23, the water moving through the hydrophilic region 280 is vaporized due to the temperature of the cell, and the gas in the cathode flow path 23 is humidified. In this way, by providing the hydrophilic region 280, the uniformity of the humidity in the cathode flow path 23 can be improved, and the inside of the cell can be humidified without providing a humidifier.

[0111] Water moves at the interface between the cathode catalyst layer 22B and the hydrophilic region 280 or inside the hydrophilic region 280. Thus, the uniformity of the water content in the cathode flow path 23 can be improved. In addition, the condensation of water in the cathode flow path 23 can be prevented, and the generation of droplets can be suppressed. Thus, the gas-liquid two-phase flow in the cathode flow path 23 can be prevented, the pressure loss in the cathode flow path 23 can be suppressed, the supply pressure of the gas can be reduced, and the system efficiency can be improved. In addition, when the cells are stacked to form a stack, the amount of gas supplied between the cells is uniform and the efficiency is good.

[0112] The gas diffusion layer 22A has hydrophobicity to improve the diffusivity of the gas. Since the mobility of water in the cathode catalyst layer 22B is poor, it is effective to move water through the hydrophilic region 280. In addition, by doing so, the humidification conditions inside the cell can be made uniform, and the surface uniformity of the reaction can be improved. In particular, when an electrolyte membrane is used, by making the humidification environment uniform, the drying of the membrane can be suppressed, and the ion movement at any position on the cell surface becomes optimal, which can improve the surface uniformity of the reaction.

[0113] like Fig.13 As shown, the hydrophilic region 280 may be provided only in the region (pad 29) between the flow path region including the inlet IN of the cathode flow path 23 and the flow path region including the outlet OUT on the surface 28a. The inlet IN of the cathode flow path 23 is one end of the length direction of the cathode flow path 23 on the surface 28a, and is connected to the gas inlet. The outlet OUT of the cathode flow path 23 is the other end of the length direction of the cathode flow path 23 on the surface 28a, and is connected to the gas outlet. A plurality of inlets IN and outlets OUT may be provided, respectively.

[0114] like Fig.14 As shown, the inlet IN and the outlet OUT of the cathode flow path 23 may be adjacent to each other on the surface 28a. In addition, the hydrophilic region 280 may be provided between the plurality of flow path regions of the cathode flow path 23 on the surface 28a, that is, in the pad 29. Fig.14 An example is shown in which the hydrophilic region 280 is provided between the inlet IN and the outlet OUT of the cathode flow path 23 on the surface 28 a .

[0115] like Fig.15 As shown, the planar shape of the cathode flow path 23 may be bilaterally symmetrical with respect to the center line M of the surface 28a. The inlet IN and the outlet OUT of the cathode flow path 23 may be adjacent to each other on the surface 28a. Fig.15 The example in which the hydrophilic region 280 is provided between the linear first flow path region including the inlet IN of the cathode flow path 23 and the linear second flow path region including the outlet on the surface 28 a is shown.

[0116] like Fig.16 As shown, the planar shape of the cathode flow path 23 may include a plurality of flow path regions extending in a curved shape. Fig.16 The example in which the hydrophilic region 280 is provided between a linear first channel region including the inlet IN of the cathode channel 23 and a linear second channel region including the outlet on the surface 28 a is shown.

[0117] When the cathode flow path 23 is hydrophilic, the cell resistance can be reduced and the cell performance can be improved by using a material with good electrical contact as the contact surface between the surface 28a and the cathode catalyst layer 22B. However, since the water movement path depends on the flow path length near the inlet IN and the outlet OUT of the cathode flow path 23, the water mobility is reduced. On the other hand, if Figures 13 to 16 As shown, when the hydrophilic region 280 is formed only in the pad 29, the movement of water does not depend on the flow path length near the inlet IN and the outlet OUT of the cathode flow path 23, so the salt precipitation can be effectively suppressed, and the humidity can be made uniform, thereby improving the surface uniformity of the cell surface reaction. In addition, the hydrophilic region 280 can be formed only in the region between the inlet IN and the outlet OUT of the cathode flow path 23. When the contact resistance increases and the cell performance deteriorates due to imparting hydrophilicity, it is preferred to form the hydrophilic region 280 only locally.

[0118] like Figures 14 to 16 As shown in FIG. 1 , by arranging the inlet IN and the outlet OUT of the cathode flow path 23 adjacent to each other, it is possible to promote the movement of water from the rear half to the front half of the cathode flow path 23, which is preferred. By making the distance between the inlet IN and the outlet OUT less than the square root of the catalyst area, the effect of promoting the movement of water can be enhanced. However, if they are very close, the gas in the cathode flow path 23 does not move through the gas diffusion layer 22A, so if they are too close, it is necessary to set the gas diffusion layer 22A with MPL, expand the width of the pad 29, etc., to prevent the gas from taking a shortcut.

[0119] A portion of the inner wall surface of the cathode flow path 23 can be processed to be hydrophilic. When the cathode flow path 23 is processed to be hydrophilic, the effect of preventing salt precipitation is high. However, when the cathode flow path 23 is not hydrophilic and has the effect of preventing salt precipitation, it is not necessarily processed to be hydrophilic. When the effect of preventing salt precipitation is low, a combination of supplying humidified CO2 and updating the salt eluent from the front half of the cathode flow path 23 can be performed. When the inlet IN and the outlet OUT of the cathode flow path 23 are arranged adjacent to each other, it has the effect of preventing salt precipitation, and the supply amount of the renewal liquid can be reduced and the number of renewals can be reduced. Therefore, overflow can be prevented even if the renewal work is performed. When humidified CO2 is supplied, the degree of humidification can be reduced, which is more preferable. The concentration of water in the humidified CO2 is, for example, 30% or more and 80% or less of the relative humidity at the reaction temperature. For example, when the cell temperature is 60°C, it can be operated under humidification at room temperature to around 40°C. At this time, the relative humidity is about 50 to 60%, which is preferable because the degree of humidification is small and overflow can be prevented.

[0120] like Fig.17 As shown, the surface of the hydrophilic region 280 may have concavoconvex 281. By making the hydrophilic region 280 have concavoconvex 281, the movement of water can be effectively promoted. When the arithmetic mean roughness of the hydrophilic region 280 is extremely large, since the gas takes a shortcut, the average roughness of the degree to which the concave portion is filled with water is preferably obtained. The surface roughness (width of each concavoconvex) of the hydrophilic region 280 is preferably above 0.01 μm and below 50 μm. The average roughness (arithmetic mean roughness) of the hydrophilic region 280 is more preferably above 10 nm and below 30 μm, and further preferably above 1 μm and below 10 μm. The maximum height of the hydrophilic region 280 is preferably above 1 μm and below 50 μm. Due to the concavoconvex 281, the surface tension becomes smaller, the concave portion is filled with water, and the gas does not penetrate, so it has the effect of suppressing the degradation of the pool performance caused by the gas taking a shortcut. The concavoconvex 281 can be formed, for example, by attaching carbon powder to the surface of the surface 28a.

[0121] like Fig.18 As shown, the hydrophilic region 280 can be provided on the entire flow path plate 28. This can be achieved, for example, by forming the flow path plate 28 from a hydrophilic porous body. The average pore size of the hydrophilic porous body is preferably greater than 0.1 μm and less than 10 μm. The porosity of the hydrophilic porous body is preferably greater than 30% and less than 80%. Other descriptions of the hydrophilic porous body can appropriately refer to the description of the hydrophilic region 280. The porosity can be measured, for example, using a mercury injection method, an Archimedes method, or a weight porosity method. The average pore size can be measured, for example, by observing the surface or cross-section using a scanning electron microscope, an optical microscope, or a laser microscope.

[0122] By forming a hydrophilic area 280 on the entire flow path plate 28, it is possible to promote the movement of water from the rear half to the front half of the cathode flow path 23, so that the inside of the pool is evenly humidified, and the inside of the pool can be humidified without providing a humidifier outside the pool. Furthermore, the water condensed in the flow path is absorbed by the hydrophilic porous body, and no condensation water is generated in the flow path, which can prevent the gas-liquid two-phase flow in the piping. When gas-liquid two-phase flow occurs, the pressure loss increases, and the balance between the movement in the pool and the movement between the pools of the stacked stack body is reduced, resulting in reduced performance. Furthermore, the pressure loss causes the gas supply pressure to increase, so the overall efficiency of the system decreases.

[0123] (Second embodiment)

[0124] Fig.19 is a diagram showing the structure of a carbon dioxide electrolysis device according to a second embodiment. Fig. 20 Yes means Fig.19 A cross-sectional view showing the construction of an electrolytic cell of the electrolytic device shown. Fig.19 The carbon dioxide electrolysis device 1X shown is similar to the carbon dioxide electrolysis device 1 of the first embodiment, and comprises: an electrolytic cell 2X, an anode solution supply system 100 for supplying an anode solution to the electrolytic cell 2X, a gas supply system 300 for supplying carbon dioxide (CO2) gas to the electrolytic cell 2X, a product collection system 400 for collecting products generated by a reduction reaction in the electrolytic cell 2X, a control system 500 for detecting the type and amount of the collected products and controlling and updating the products, a waste liquid collection system 600 for collecting waste liquid of the anode solution, and a renewal material supply unit 700 for restoring the anode and cathode of the electrolytic cell 2X.

[0125] Fig.19 The carbon dioxide electrolysis device 1X shown in the figure is similar to the carbon dioxide electrolysis device 1X except that the structure of the electrolytic cell 2X is different. Figure 1 The electrolysis devices 1 shown in the drawings have substantially the same structure. Fig. 20 As shown, the electrolytic cell 2X includes an anode portion 10, a cathode portion 20 and a diaphragm 30. The anode portion 10 includes an anode 11, an anode flow path 12 and an anode current collector plate 13. The cathode portion 20 includes a cathode 22, a cathode flow path 23 and a cathode current collector plate 24, and a cathode flow path 21 is not provided. Therefore, there may be no component for supplying a cathode solution to the cathode flow path 21. The power supply control unit 40 is connected to the anode 11 and the cathode 22 via a current introduction component.

[0126] The anode 11 preferably has a first surface 11a in contact with the diaphragm 30 and a second surface 11b facing the anode flow path 12. The first surface 11a of the anode 11 is in close contact with the diaphragm 30. The anode flow path 12 is composed of pits (grooves / recesses) provided on the flow path plate 14. The anode solution flows in the anode flow path 12 in a manner in contact with the anode 11. The anode collector plate 13 is electrically connected to the surface of the flow path plate 14 constituting the anode flow path 12 on the opposite side to the anode 11. The cathode 22 has a first surface 22a in contact with the diaphragm 30 and a second surface 22b facing the cathode flow path 23. The cathode flow path 23 is composed of pits (grooves / recesses) provided on the flow path plate 28. The cathode collector plate 24 is electrically connected to the surface of the flow path plate 28 constituting the cathode flow path 23 on the opposite side to the cathode 22.

[0127] The flow channel plate 28 has a hydrophilic region 280 similarly to the first embodiment. For the description of the hydrophilic region 280, the description of the first embodiment can be referred to as appropriate.

[0128] The gaseous material supply system 710 and the flushing liquid supply system 720 of the renewal material supply unit 700 are connected to the anode flow path 12 and the cathode flow path 23 via piping. The anode flow path 12 and the cathode flow path 23 are connected to the waste liquid collection system 600 via piping. The flushing liquid discharged from the anode flow path 12 and the cathode flow path 23 is recovered by the waste liquid collection tank 601 of the waste liquid collection system 600. The renewal gas discharged from the anode flow path 12 and the cathode flow path 23 is recovered by the waste gas collection tank not shown via the waste liquid collection system 600, or is released into the atmosphere. The constituent materials of each part are the same as those of the electrolysis device 1 of the first embodiment, and the details are as described above.

[0129] The cathode solution tank 202 has a function as a cathode discharge solution tank, which, for example, contains a liquid such as a flushing liquid discharged from the cathode flow path 23 during the renewal operation. In addition, the tank 106 can be connected to the cathode flow path 23 via the cathode solution tank 202 and the renewal material supply unit 700. Thus, when the liquid is contained in the tank 106, the liquid can be used as a flushing liquid.

[0130] In the electrolysis device 1X of the second embodiment, the startup process S101 of the electrolysis device 1X and the electrolysis work process S102 of CO2 are the same as those of the electrolysis device 1 of the first embodiment, except that the supply of the cathode solution is not implemented. It is to be noted that the reduction reaction of CO2 in the cathode 22 is carried out by the CO2 supplied from the cathode flow path 23 and the anode solution that permeates into the cathode 22 through the diaphragm 30. The determination process S103 for determining whether the required benchmark of the cell performance is met is also the same as that of the electrolysis device 1 of the first embodiment. When it is determined that the cell performance does not meet the required benchmark, the update work process S105 is implemented. In the electrolysis device 1X of the second embodiment, the update work process S105 is implemented as follows.

[0131] First, the CO2 reduction reaction is stopped. At this time, the application of the electrolysis voltage of the power control unit 40 can be maintained or stopped. Next, the anode solution is discharged from the anode flow path 12. Next, a rinse liquid is supplied from the rinse liquid supply system 720 to the anode flow path 12 and the cathode flow path 23 to clean the anode 11 and the cathode 22. During the supply of the rinse liquid, a renewal voltage can be applied between the anode 11 and the cathode 22 in the same manner as in the first embodiment. Next, gas is supplied from the gaseous substance supply system 710 to the anode flow path 12 and the cathode flow path 23 to dry the anode 11 and the cathode 22. The gas and rinse liquid used in the renewal work process are the same as in the first embodiment. After the above-mentioned renewal work is completed, the anode solution is introduced into the anode flow path 12, and the CO2 gas is introduced into the cathode flow path 23. Then, the CO2 electrolysis work is restarted. When the application of the electrolysis voltage of the power control unit 40 is stopped, it is restarted.

[0132] In the electrolysis device 1X of the second embodiment, whether to continue the CO2 electrolysis work or implement the renewal work is determined based on whether the cell performance of the electrolytic cell 2X meets the required benchmark. By supplying a flushing liquid or gas in the renewal work process, the following phenomena are eliminated: the deviation of the ion distribution near the anode 11 and the cathode 22 that causes the cell performance to decrease, the excess water in the cathode 22, the electrolyte precipitation in the anode 11 and the cathode 22, the flow path occlusion caused by this, etc. Therefore, by restarting the CO2 electrolysis work after the renewal work process, the cell performance of the electrolytic cell 2X can be restored. By repeating such CO2 electrolysis work and renewal work based on the required benchmark of the cell performance, the CO2 electrolysis performance of the electrolysis device 1X can be maintained for a long time.

[0133] When the liquid passes through the diaphragm 30 due to a relatively low pressure, for example, a hydrophilic polytetrafluoroethylene (PTFE) porous body is used, and only the flushing liquid is supplied to the anode flow path 12, and pressure is applied to the liquid at the anode outlet or the anode outlet is blocked by a valve not shown. Then, the flushing liquid flows to the cathode 22 through the diaphragm 30, and the flushing liquid flows out from the discharge port of the cathode 22. Thus, the cathode 22 and the anode 11 can be updated at the same time. This configuration is preferred because it does not require a device for circulating the flushing liquid in the cathode 22, so the device becomes compact and the system is simplified.

[0134] In addition, the pipe for introducing air gas can be connected to the cathode 22. During the renewal, the gas containing air can be supplied to the cathode 22, and the water electrolysis reaction can be performed by applying the renewal voltage between the anode 11 and the cathode 22. Oxygen is generated by the oxidation catalyst on the anode 11 side, and the generated protons move to the cathode 22 through the diaphragm 30 or the electrolyte membrane. In the cathode 22, the protons and the oxygen in the air react with each other through the cathode catalyst to generate water. The salt of the cathode can be dissolved and discharged by the generated water. In addition, since the generated water is pure water, the cathode 22 can be cleaned. At this time, the impurities in the cathode 22 can be reduced by the protons moved to the cathode 22, and the catalyst and parts can be regenerated. Since this structure does not require a device for supplying a flushing liquid to the cathode 22, the device becomes compact and the system can be simplified. In addition, when the air flowing to the cathode is stopped before the subsequent CO2 gas flows, the generated protons react with each other to generate hydrogen, and the generated water can also be squeezed out. Stopping the oxygen-containing gas before being squeezed out by CO2 makes the regeneration effect of the protons on the catalyst and parts more effective. This is because, due to the absence of oxygen, other catalysts that are difficult to reduce and various components of the cathode 22 are reduced. Specifically, there are impurity organic matter and metal oxides, etc. By subsequently supplying CO2 to react, a renewal effect can be expected.

[0135] The structure of the electrolytic cell 2X is not limited to Fig. 20 The structure shown. Fig.21 It is a schematic cross-sectional view showing another structural example of the electrolytic cell 2X. Fig.21 The electrolytic cell 2X shown with Fig. 20 The electrolytic cell 2X shown in the figure is different from the electrolytic cell 2X in that it includes a plurality of anodes 11, a plurality of cathodes 22, a plurality of diaphragms 30, and a flow channel plate 50. The different parts will be described below.

[0136] The respective anodes 11, the respective separators 30, and the respective cathodes 22 are sequentially stacked to form an electrolytic cell. For the description of the anodes 11, the separators 30, and the cathodes 22, the description of the first embodiment can be appropriately referred to.

[0137] The flow path plate 50 is provided between one of the plurality of anodes 11 and one of the plurality of cathodes 22. The flow path plate 50 has a flow path 51 provided on a surface 50a and a flow path 52 provided on a surface 50b. The flow path plate 50 is also referred to as a bipolar flow path plate.

[0138] The flow path 51 faces one of the plurality of anodes 11. The flow path 51 has a function as an anode flow path (anode solution flow path) for flowing an anode solution. For other descriptions of the flow path 51, the description of the anode flow path 12 can be appropriately referred to.

[0139] The flow path 52 faces one of the plurality of cathodes 22. The flow path 52 has a function as a cathode flow path (gas flow path) for flowing carbon dioxide. For other descriptions of the flow path 52, the description of the cathode flow path 23 can be appropriately referred to.

[0140] The flow channel plate 50 is formed of a hydrophilic porous body. The description of the hydrophilic porous body can refer to the description of the first embodiment as appropriate.

[0141] The flow path plate 50 forms a hydrophilic porous area between the flow path 51 and the flow path 52. As a result, the anode solution can move from the flow path 51 to the flow path 52 to humidify the flow path 52. Although it is a porous flow path plate, by making it hydrophilic, the surface tension becomes smaller, the porous inside is filled with water, and the gas does not pass through, so there is no gas leakage, and it can be used as a flow path plate. In addition, it can also effectively absorb condensed water and evenly humidify the inside of the pool. In addition, if cooling water is circulated inside or on the surface of the flow path plate 50, the cooling water can also achieve the same effect. Furthermore, the electrolyte component that moves from the anode 11 to the cathode 22 and precipitates can be returned to the anode 11. The electrolyte component of the anode solution moves to the cathode 22 due to the reaction, so there are problems such as its concentration reduction. By utilizing the hydrophilic porous body area, the electrolyte component can be returned from the cathode 22 to the anode 11, which can improve the stability of long-term operation.

[0142] like Fig. 22 As shown, the flow path 51 may also face another one of the plurality of cathodes 22. In this case, it is preferred that the inlet of the flow path 52 is closer to the outlet of the flow path 51 than the outlet of the flow path 52, and the outlet of the flow path 52 is closer to the outlet of the flow path 51 than the inlet of the flow path 52. Thus, water can move between the flow paths 51 and 52 to uniformly humidify the flow paths 51 and 52.

[0143] In addition, the configuration of the second embodiment can be appropriately combined with the configuration of the first embodiment. Figure 1 The electrolytic cell 2 shown is constructed as follows: Fig.21 or Fig. 22 The composition shown.

[0144] Example

[0145] (Example 1)

[0146] Assembly Figure 1 The electrolysis performance of carbon dioxide was investigated using the electrolysis device shown in the figure. First, a cathode in which carbon particles loaded with gold nanoparticles were coated on carbon paper provided with a porous layer was prepared by the following steps. A coating solution was prepared by mixing carbon particles loaded with gold nanoparticles with pure water, Nafion solution, and ethylene glycol. The average particle size of the gold nanoparticles was 8.7 nm, and the loading amount was 18.9% by mass. The coating solution was filled into a spray gun and sprayed on the carbon paper provided with a porous layer using nitrogen. After coating, it was rinsed with pure water under running water for 30 minutes, and then immersed in hydrogen peroxide to oxidize and remove organic matter such as ethylene glycol. It was cut into a size of 2×2 cm as a cathode. In addition, the coating amount of Au was estimated to be about 0.2 mg / cm based on the mixed amount of gold nanoparticles and carbon particles in the coating solution. 2 The anode used an electrode with IrO2 nanoparticles as a catalyst coated on a Ti nonwoven fabric. As the anode, an IrO2 / Ti mesh cut into 2×2 cm was used. The catalyst area was 2cm×2cm=4cm 2 The area of ​​the cathode catalyst layer 22B on the contact surface with the surface 28a is 4 cm 2 , the distance between the inlet IN and the outlet OUT is 0.8 cm, and the distance between the inlet IN and the outlet OUT / √the area of ​​the cathode catalyst layer 22B = 0.2.

[0147] like Figure 2 As shown, the electrolytic cell 2 is made by stacking the cathode collector plate 24, the cathode flow path 23 (flow path plate 28), the cathode 22, the cathode flow path 21 (flow path plate 25), the diaphragm 30, the anode 11, the anode flow path 12, and the anode collector plate 13 in order from top to bottom, sandwiched between support plates not shown in the figure, and further fastened with bolts. The diaphragm 30 uses an anion exchange membrane (trade name: Selemion). The IrO2 / Ti mesh of the anode 11 is in close contact with the anion exchange membrane. The thickness of the cathode flow path 23 is 1 mm. The flow path plate 28 is made of titanium. The cathode flow path 23 is made by cutting the flow path plate 28. The planar shape of the cathode flow path 23 is as shown Fig.23 As shown. The planar shape of the cathode flow path 23 is a serpentine shape with four bends. In addition, the cathode flow path 23 has four pairs of parallel flow path areas connected in parallel on the surface 28a. The width of the cathode flow path 23 is 1 mm. The depth of the flow path plate 28 of the cathode flow path 23 in the thickness direction is 1 mm. The width of the pad 29 is 1 mm.

[0148] The contact surface of the flow path plate 28 with the gas diffusion layer 22A has a hydrophilic region 280 having a surface roughness (width of each concave and convex) of 20 nm or more and 30 μm or less obtained by surface processing. The average roughness (arithmetic mean roughness) of the surface of the hydrophilic region 280 is about 4±1 μm. The contact angle between the hydrophilic region 280 and pure water is 20 degrees or more and 40 degrees or less. The contact angle between the other parts of the surface 28a of the flow path plate 28 and pure water is 45 degrees. It should be noted that the evaluation temperature is room temperature.

[0149] Assemble using the above electrolytic cell 2 Figure 1 The electrolysis device 1 shown in the figure is operated under the following conditions. CO2 gas is supplied to the cathode flow path 23 of the electrolysis cell 2 at 20 sccm, potassium hydroxide aqueous solution (concentration 1M KOH) is supplied to the cathode flow path 21 at a flow rate of 5 mL / min, and potassium hydroxide aqueous solution (concentration 1M KOH) is supplied to the anode flow path 12 at a flow rate of 20 mL / min. Then, the voltage is controlled by the power supply control unit at 200 mA / cm 2 A constant current density of 800 mA flows between the anode 11 and the cathode 22 to perform the electrolysis reaction of CO2, and the cell voltage at this time is measured and collected by the data collection / control unit. Furthermore, a part of the gas output from the cathode flow path 23 is collected, and the amount of CO gas generated by the reduction reaction of CO2 and the amount of H2 gas generated by the reduction reaction of water are analyzed by gas chromatography. The partial current density of CO or H2 collected and the ratio of the total current density to the partial current density (i.e., Faraday efficiency) are calculated by the data collection / control unit according to the gas generation. The results are shown in Table 1.

[0150] (Example 2)

[0151] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. The difference from Example 1 is that the hydrophilic carbon powder is attached only to the portion of the surface 28a of the flow path plate 28 that contacts the gas diffusion layer 22A to form a hydrophilic region 280. The surface roughness of the hydrophilic region 280 is greater than 20nm and less than 10μm, and the average roughness is about 3±1μm. The contact angle between the hydrophilic region 280 and pure water is greater than 10 degrees and less than 30 degrees. The contact angle between the other portions of the surface 28a of the flow path plate 28 and pure water is 45 degrees.

[0152] (Example 3)

[0153] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. Fig.24As shown, the inlet IN and the outlet OUT of the cathode flow path 23 are adjacent. The planar shape of the cathode flow path 23 is a serpentine shape with five bends. In addition, the cathode flow path 23 has six pairs of parallel flow path areas connected in parallel on the surface 28a. The area of ​​the cathode catalyst layer 22B on the contact surface with the surface 28a is 2cm×2cm=4cm 2 , the distance between the inlet IN and the outlet OUT is 0.4cm.

[0154] Distance between inlet IN and outlet OUT / √plane area of ​​cathode catalyst layer 22B=0.2 The other aspects are the same as those of Example 2.

[0155] (Example 4)

[0156] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. In the same manner as in Example 3, the inlet IN and the outlet OUT of the cathode flow path 23 were made adjacent to each other. In addition, the difference from Example 3 is that on the surface 28a, along the flow path area of ​​the portion from the inlet of the cathode flow path 23 to 1 / 3 of the total flow path length in the longitudinal direction, carbon powder was attached to the surface 28a of the flow path plate 28 to form a hydrophilic area 280.

[0157] (Example 5)

[0158] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. The difference from Example 1 is that the surface of the flow path plate 28 was processed to form a hydrophilic region 280 with a surface roughness of 2 μm and a maximum height of 20 μm. The average roughness of the hydrophilic region 280 was about 6±1 μm. At this time, the contact angle between the hydrophilic region 280 and pure water was 30 degrees.

[0159] (Example 6)

[0160] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. The difference from Example 1 is that there are multiple anodes 11 and multiple cathodes 22, the bipolar flow path plate is made of a hydrophilic porous carbon plate, and a flow path 51 facing one of the multiple cathodes is formed on one surface of the bipolar flow path plate, and a flow path 52 facing one of the multiple anodes is formed on the other surface. The average pore size of the hydrophilic porous carbon plate is greater than 10 nm and less than 1 μm, and the porosity is 30%. The contact angle of the hydrophilic porous carbon plate with pure water is less than 15 degrees.

[0161] (Example 7)

[0162] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. The difference from Example 1 is that the surface 28a of the flow path plate 28 and the area from the surface 28a of the inner wall surface of the cathode flow path 23 to 1 / 3 of the thickness of the flow path plate 28 were processed to form a hydrophilic region 280 with a surface roughness of 2 μm and a maximum height of 20 μm. The average roughness of the hydrophilic region 280 was about 6±1 μm. The contact angle of the hydrophilic region 280 with pure water was 30 degrees.

[0163] (Example 8)

[0164] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. Fig.25 As shown, the inlet IN and the outlet OUT of the cathode flow path 23 are adjacent to each other. The plane area of ​​the cathode catalyst layer 22B is 2 cm×2 cm=4 cm 2 , the distance between the inlet IN and the outlet OUT is 0.6 cm, and the distance between the inlet IN and the outlet OUT / √the plane area of ​​the cathode catalyst layer 22B = 0.3. The plane shape of the cathode flow path 23 is a serpentine shape with 5 bends. In addition, the cathode flow path 23 has 6 groups of 3 parallel flow path areas connected in parallel on the surface 28a.

[0165] (Comparative Example 1)

[0166] The carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was investigated. The difference from Example 1 is that the surface roughness of the surface 28a on the gas diffusion layer 22A side of the flow path plate 28 is less than 1 μm, and the average roughness is about 0.1 to 2 μm. The contact angle of the surface 28a with pure water is 45 degrees. Other than this, the same conditions were used.

[0167] (Comparative Example 2)

[0168] A carbon dioxide electrolysis device was assembled in the same manner as in Example 1, and the carbon dioxide electrolysis performance was examined. The difference from Example 1 was that the surface 28a was hydrophobicized with a conductive polymer. The contact angle of the surface with pure water was 90 degrees.

[0169] Table 1 shows the cell voltage, the Faraday efficiency of CO, and the Faraday efficiency of H2 collected about 5 hours after Examples 1 to 8, and Comparative Examples 1 and 2. In addition, the time until the cathode flow path 23 is blocked (the time until the pressure of the cathode flow path 23 exceeds 0.3MPa) is shown. 0.3MPa means that the flow path is blocked compared to the pressure loss of the flow path used for normal electrolysis. When the pressure of the cathode flow path 23 exceeds 0.3MPa, the flow rate immediately becomes 0. This is the same for both the comparative examples and the embodiments. When the cathode pressure exceeds 0.3MPa, the flow rate immediately becomes 0. Therefore, the time until the cathode flow path 23 is blocked is defined as the time when the cathode pressure exceeds 0.3MPa.

[0170] [Table 1]

[0171]

[0172] The results of Examples 1 to 8 and Comparative Examples 1 and 2 show that the time until the cathode flow path 23 is blocked can be extended by forming the hydrophilic region 280. In addition, it is found that the cell voltage and the Faraday efficiency of CO can be increased, thereby improving the electrolysis efficiency.

[0173] It should be noted that the above-mentioned embodiments can be combined and applied separately, or a part thereof can be replaced. Although several embodiments of the present invention are described here, these embodiments are only provided as examples and are not intended to limit the scope of the present invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, changes, etc. can be made without departing from the scope of the present invention. These embodiments and their variations are included in the scope and spirit of the present invention, and are also included in the invention described in the claims and their equivalents.

[0174] The above implementation modes can be summarized into the following technical solutions.

[0175] (Technical Solution 1)

[0176] A carbon dioxide electrolysis device, characterized in that it comprises an electrolytic cell, wherein the electrolytic cell comprises:

[0177] an anode, which is used to oxidize water to generate oxygen,

[0178] a cathode for reducing carbon dioxide to form carbon compounds,

[0179] a cathode flow path plate having: a surface arranged in contact with the cathode and a cathode flow path arranged on the surface and facing the cathode, and

[0180] a separator disposed between the anode and the cathode;

[0181] The surface has a hydrophilic region which is arranged in contact with the cathode and has a contact angle with water of less than 45 degrees.

[0182] (Technical Solution 2)

[0183] The carbon dioxide electrolysis device according to technical solution 1, wherein the cathode has:

[0184] a catalyst layer containing a reduction catalyst for reducing the carbon dioxide to generate the carbon compound, and

[0185] a gas diffusion layer disposed on the catalyst layer;

[0186] Wherein, the hydrophilic region is in contact with the gas diffusion layer.

[0187] (Technical Solution 3)

[0188] The carbon dioxide electrolysis device according to technical solution 1 or 2, wherein:

[0189] The cathode flow path comprises:

[0190] The first flow path region, and

[0191] a second flow path region spaced apart from the first flow path region;

[0192] The hydrophilic region is provided on the surface between the first flow path region and the second flow path region.

[0193] (Technical Solution 4)

[0194] The carbon dioxide electrolysis device according to claim 1 or 2, wherein the hydrophilic region extends on the surface along a region from the inlet of the cathode flow path to a portion that is 1 / 3 of the total flow path length in the longitudinal direction of the cathode flow path.

[0195] (Technical Solution 5)

[0196] The carbon dioxide electrolysis device described in Technical Solution 1 or 2, wherein the hydrophilic area is arranged on the entire surface.

[0197] (Technical Solution 6)

[0198] The carbon dioxide electrolysis device according to any one of claims 1 to 3, wherein the outlet of the cathode flow path is disposed adjacent to the inlet of the cathode flow path on the surface.

[0199] (Technical Solution 7)

[0200] The carbon dioxide electrolysis device according to any one of claims 1 to 6, wherein the hydrophilic region is a porous region having an average pore diameter of 0.1 μm or more and 10 μm or less.

[0201] (Technical Solution 8)

[0202] The carbon dioxide electrolysis device according to any one of claims 1 to 6, wherein the hydrophilic region is a concave-convex region having an arithmetic mean roughness of 10 nm or more and 30 μm or less.

[0203] (Technical Solution 9)

[0204] A carbon dioxide electrolysis device, characterized in that it comprises an electrolytic cell, wherein the electrolytic cell comprises:

[0205] a first anode for oxidizing water to generate oxygen,

[0206] a first cathode for reducing carbon dioxide to generate carbon compounds,

[0207] a first separator disposed between the first anode and the first cathode,

[0208] a second anode for oxidizing water to generate oxygen,

[0209] a second cathode for reducing carbon dioxide to generate carbon compounds,

[0210] a second separator disposed between the second anode and the second cathode, and

[0211] The first flow channel plate comprises:

[0212] a first surface disposed in contact with the first cathode,

[0213] a cathode flow path disposed on the first surface and facing the first cathode, and a second surface disposed in contact with the second anode,

[0214] an anode flow path disposed on the second surface and facing the second anode, and

[0215] The hydrophilic porous region is provided between the cathode flow path and the anode flow path, has a contact angle with water of less than 45 degrees, and has an average pore diameter of 0.01 μm or more and 10 μm or less.

[0216] (Technical Solution 10)

[0217] A carbon dioxide electrolysis device, characterized in that it comprises an electrolytic cell, wherein the electrolytic cell comprises:

[0218] a first anode for oxidizing water to generate oxygen,

[0219] a first cathode for reducing carbon dioxide to generate carbon compounds,

[0220] a first separator disposed between the first anode and the first cathode,

[0221] a second anode for oxidizing water to generate oxygen,

[0222] a second cathode for reducing carbon dioxide to generate carbon compounds,

[0223] a second separator disposed between the second anode and the second cathode, and

[0224] The second flow path plate comprises:

[0225] a first surface disposed in contact with the first cathode,

[0226] a first cathode flow path disposed on the first surface and facing the first cathode,

[0227] a second surface disposed in contact with the second cathode,

[0228] a second cathode flow path disposed on the second surface and facing the second cathode, and

[0229] The hydrophilic porous region is provided between the first cathode flow channel and the second cathode flow channel, has a contact angle with water of less than 45 degrees, and has an average pore diameter of 0.01 μm or more and 10 μm or less.

[0230] (Technical Solution 11)

[0231] The carbon dioxide electrolysis device described in technical solution 10, wherein:

[0232] The inlet of the second cathode flow path is closer to the outlet of the first cathode flow path than the outlet of the second cathode flow path.

[0233] The outlet of the second cathode flow path is closer to the outlet of the first cathode flow path than the inlet of the second cathode flow path.

[0234] (Technical Solution 12)

[0235] The carbon dioxide electrolysis device according to any one of technical solutions 1 to 8 further comprises:

[0236] a carbon dioxide supply unit for supplying carbon dioxide to the cathode;

[0237] an electrolytic solution supply unit for supplying an electrolytic solution containing water to at least one of the anode and the cathode;

[0238] a power supply control unit connected to the anode and the cathode and applying a voltage between the anode and the cathode;

[0239] The updating material supply unit comprises:

[0240] a gas supply unit that supplies a gaseous substance to at least one of the anode and the cathode, and

[0241] a flushing liquid supply unit for supplying flushing liquid to at least one of the anode and the cathode;

[0242] as well as

[0243] A control unit that stops supplying the carbon dioxide from the carbon dioxide supply unit, stops supplying the electrolytic solution from the electrolytic solution supply unit, and controls supplying a flushing solution from the renewal material supply unit to at least one of the anode and the cathode based on a required performance benchmark of the electrolytic cell.

Claims

1. A carbon dioxide electrolysis device, characterized in that: An electrolytic cell is provided, wherein the electrolytic cell comprises: an anode, which is used to oxidize water to generate oxygen, a cathode for reducing carbon dioxide to form carbon compounds, a cathode flow path plate having: a surface arranged in contact with the cathode and a cathode flow path arranged on the surface and facing the cathode, and a separator disposed between the anode and the cathode; wherein the surface has a hydrophilic region disposed in contact with the cathode and having a contact angle with water of less than 45 degrees, The cathode has: a catalyst layer containing a reduction catalyst for reducing the carbon dioxide to generate the carbon compound, and a gas diffusion layer disposed on the catalyst layer; Wherein, the hydrophilic region is in contact with the gas diffusion layer.

2. The carbon dioxide electrolysis device according to claim 1, wherein: The cathode flow path comprises: The first flow path region, and a second flow path region spaced apart from the first flow path region; The hydrophilic region is provided on the surface between the first flow path region and the second flow path region.

3. The carbon dioxide electrolysis device according to claim 1 or 2, wherein: The hydrophilic region extends on the surface along a region from the inlet of the cathode flow path to a portion that is 1 / 3 of the total flow path length in the longitudinal direction of the cathode flow path.

4. The carbon dioxide electrolysis device according to claim 1 or 2, wherein: The hydrophilic region is disposed over the entire surface.

5. The carbon dioxide electrolysis device according to claim 1 or 2, wherein: The outlet of the cathode flow path is disposed adjacent to the inlet of the cathode flow path on the surface.

6. The carbon dioxide electrolysis device according to claim 1 or 2, wherein: The hydrophilic region is a porous region having an average pore diameter of 0.1 μm or more and 10 μm or less.

7. The carbon dioxide electrolysis device according to claim 1 or 2, wherein: The hydrophilic region is a concavo-convex region having an arithmetic mean roughness of 10 nm or more and 30 μm or less.

8. A carbon dioxide electrolysis device, characterized in that: An electrolytic cell is provided, wherein the electrolytic cell comprises: a first anode for oxidizing water to generate oxygen, a first cathode for reducing carbon dioxide to generate carbon compounds, a first separator disposed between the first anode and the first cathode, a second anode for oxidizing water to generate oxygen, a second cathode for reducing carbon dioxide to generate carbon compounds, a second separator disposed between the second anode and the second cathode, and The first flow channel plate comprises: a first surface disposed in contact with the first cathode, a cathode flow path disposed on the first surface and facing the first cathode, a second surface disposed in contact with the second anode, an anode flow path disposed on the second surface and facing the second anode, and The hydrophilic porous region is provided between the cathode flow path and the anode flow path, has a contact angle with water of less than 45 degrees, and has an average pore diameter of 0.01 μm or more and 10 μm or less.

9. A carbon dioxide electrolysis device, characterized in that: An electrolytic cell is provided, wherein the electrolytic cell comprises: a first anode for oxidizing water to generate oxygen, a first cathode for reducing carbon dioxide to generate carbon compounds, a first separator disposed between the first anode and the first cathode, a second anode for oxidizing water to generate oxygen, a second cathode for reducing carbon dioxide to generate carbon compounds, a second separator disposed between the second anode and the second cathode, and The second flow path plate comprises: a first surface disposed in contact with the first cathode, a first cathode flow path disposed on the first surface and facing the first cathode, a second surface disposed in contact with the second cathode, a second cathode flow path disposed on the second surface and facing the second cathode, and The hydrophilic porous region is provided between the first cathode flow channel and the second cathode flow channel, has a contact angle with water of less than 45 degrees, and has an average pore diameter of 0.01 μm or more and 10 μm or less.

10. The carbon dioxide electrolysis device according to claim 9, wherein: The inlet of the second cathode flow path is closer to the outlet of the first cathode flow path than the outlet of the second cathode flow path. The outlet of the second cathode flow path is closer to the outlet of the first cathode flow path than the inlet of the second cathode flow path.

11. The carbon dioxide electrolysis device according to claim 1 or 2, further comprising: a carbon dioxide supply unit for supplying carbon dioxide to the cathode; an electrolytic solution supply unit for supplying an electrolytic solution containing water to at least one of the anode and the cathode; a power supply control unit connected to the anode and the cathode and applying a voltage between the anode and the cathode; The updating material supply unit comprises: a gas supply unit that supplies a gaseous substance to at least one of the anode and the cathode, and a flushing liquid supply unit for supplying flushing liquid to at least one of the anode and the cathode; as well as A control unit that stops supplying the carbon dioxide from the carbon dioxide supply unit, stops supplying the electrolytic solution from the electrolytic solution supply unit, and controls supplying a flushing solution from the renewal material supply unit to at least one of the anode and the cathode based on a required performance benchmark of the electrolytic cell.

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