Electrolysis device, electrolysis system, and method for operating electrolysis device

Abstract

The purpose of the present invention is to suppress the consumption of unwanted current in an electrolysis reaction of an electrolysis device. This electrolysis device is provided with: a first electrolysis unit that reduces an object to be reduced and oxidizes an object to be oxidized; a second electrolysis unit that reduces the object to be reduced and oxidizes the object to be oxidized; a first supply source for supplying a first fluid containing a gas of the object to be reduced to the first electrolysis unit and the second electrolysis unit; a second supply source that supplies a second fluid containing a liquid of the object to be oxidized to the first electrolysis unit and the second electrolysis unit; and at least one power supply that supplies a first power supply current to the first electrolysis unit and supplies a second power supply current to the second electrolysis unit. The at least one power supply sets the value of the first power supply current and the value of the second power supply current such that the current density of the current flowing through the second electrolysis unit when the object to be reduced is reduced is higher than the current density of the current flowing through the first electrolysis unit when the object to be reduced is reduced.

Description

[0001] This application is based on Japanese Patent Application No. 2023-151655 (filing date: September 19, 2023), and claims the benefit of priority from the above-mentioned application. This application incorporates the entire contents of the above-mentioned application by reference. Technical Field

[0002] Embodiments of the present invention relate to an electrolysis device and an electrolysis system. Background Art

[0003] In recent years, from the perspectives of both energy and environmental issues, it is expected that renewable energy such as solar power generation can be converted into electric energy for use, and that it can be stored and converted into a state that can be transported. In response to this expectation, research and development of artificial photosynthesis technology that uses sunlight to generate chemical substances, such as photosynthesis of plants, has been carried out. Through this technology, renewable energy can also be stored as storable fuel, and it is also expected to generate value by generating chemical substances that become industrial raw materials.

[0004] As a device for generating chemical substances using renewable energy sources such as solar power generation, it is known that there are electrolysis devices (electrochemical reaction devices) such as carbon dioxide electrolysis devices having, for example, a cathode for reducing carbon dioxide (CO2) produced by a power plant or a waste treatment plant and an anode for oxidizing water (H2O). In the cathode, for example, carbon dioxide is reduced to generate carbon compounds such as carbon monoxide (CO). In the case of realizing such an electrolysis device by a unit form (also referred to as an electrolysis unit), it is considered to be effective to realize it in a manner similar to a fuel cell such as a Polymer Electric Fuel Cell (PEFC). By directly supplying carbon dioxide to the catalyst layer of the cathode, the reduction reaction of carbon dioxide can be rapidly carried out. Furthermore, by forming a stack structure in which the electrolysis units are overlapped, it is possible to save space and efficiently carry out the reduction reaction. Summary of the invention

[0005] The technical problem to be solved by the present invention is to suppress unnecessary consumption of electric current in an electrolytic reaction of an electrolytic device.

[0006] The electrolysis device of the embodiment comprises: a first electrolysis unit for reducing a reduction target and oxidizing an oxidation target; a second electrolysis unit for reducing a reduction target and oxidizing an oxidation target; a first supply source for supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit; a second supply source for supplying a second fluid containing a liquid of the oxidation target to the first electrolysis unit and the second electrolysis unit; and at least one power supply for supplying a first power supply current to the first electrolysis unit and a second power supply current to the second electrolysis unit. The at least one power supply sets the value of the first power supply current and the value of the second power supply current so that the current density of the current flowing through the second electrolysis unit when reducing the reduction target is higher than the current density of the current flowing through the first electrolysis unit when reducing the reduction target. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram showing a configuration example of an electrolysis device according to an embodiment.

[0008] Figure 2 1 is a schematic perspective view showing a structural example of the unit structure 100 .

[0009] Figure 3 It is a schematic diagram showing a structural example of a membrane electrode assembly MEA.

[0010] Figure 4 1 is a schematic diagram showing a structural example of the cathode channel plate 14 .

[0011] Figure 5 1 is a schematic diagram showing a structural example of the anode channel plate 15 .

[0012] Figure 6 It is a schematic diagram showing a structural example of the cathode current collector 16 .

[0013] Figure 7 It is a schematic diagram showing a structural example of the anode current collector 17 .

[0014] Figure 8 1 is a schematic diagram showing a structural example of the insulating layer 18 .

[0015] Fig. 9 It is a schematic diagram for explaining the flow of the cathode fluid and the flow of the anode fluid in the unit structure 100 .

[0016] Fig.10 1 is a schematic perspective view showing a structural example of the unit structure 100 .

[0017] Fig.11 It is a schematic diagram showing a state in which impurities and reduction targets in the cathode fluid flow through each electrolytic unit 10 in series.

[0018] Fig.12This is a diagram showing an example of a graph showing the relationship between the current density flowing through the electrolytic cell 10, the cell voltage, and the Faraday efficiency.

[0019] Fig.13 It is a schematic diagram showing another example of the electrolysis device according to the embodiment.

[0020] Fig.14 It is a schematic diagram showing another example of the electrolysis device according to the embodiment.

[0021] Fig.15 It is a schematic diagram showing another example of the electrolysis device according to the embodiment.

[0022] Fig.16 It is a schematic diagram showing another example of the electrolysis device according to the embodiment.

[0023] (Explanation of Reference Numerals)

[0024] 1…electrolysis device, 10…electrolysis unit, 11…cathode, 12…anode, 13…diaphragm, 14…cathode flow path plate, 15…anode flow path plate, 16…cathode current collector, 17…anode current collector, 18…insulating layer, 19…piping, 20…cathode supply source, 30…anode supply source, 40…power supply, 41…power supply, 42…power supply, 100…unit structure, 130…support plate, 130a…opening, 131…opening, 140…cathode flow path, 141…opening, 150…anode flow path, 151…opening, 161…opening, 171…opening, 181…opening, MEA…membrane electrode assembly. DETAILED DESCRIPTION

[0025] Hereinafter, the electrolysis device of the embodiment will be described with reference to the accompanying drawings. In each embodiment shown below, the same reference numerals are sometimes given to substantially the same components, and a part of the description thereof is omitted. The accompanying drawings are schematic, and the relationship between thickness and plane size, the ratio of thickness of each part, etc. may be different from the actual ones.

[0026] In this specification, "connected" includes not only direct connection but also indirect connection unless otherwise specified. In addition, in this specification, "connected" includes not only physical connection but also electrical connection unless otherwise specified.

[0027] Figure 1 It is a schematic diagram showing a configuration example of an electrolysis device according to an embodiment. Figure 1 The electrolysis device 1 is shown as a configuration example. The electrolysis device 1 includes an electrolysis unit 10 that performs an electrolysis reaction, a cathode supply source 20 that supplies a cathode fluid, an anode supply source 30 that supplies an anode fluid, and a power source 40 that supplies power to the electrolysis unit 10 . Figure 1y represents the X-axis, the Y-axis, and the Z-axis. The X-axis, the Y-axis, and the Z-axis intersect each other perpendicularly. The Z-axis is along the thickness direction of the electrolytic cell 10. Figure 1 Indicates a portion of an XZ cross section including the X-axis and the Z-axis.

[0028] The electrolytic cell 10 includes a cathode 11, an anode 12, a separator 13, a cathode flow plate 14 having a cathode flow path 140, an anode flow plate 15 having an anode flow path 150, a cathode current collector 16, and an anode current collector 17. The cathode 11, the anode 12, and the separator 13 may be stacked to form a membrane electrode assembly MEA. In addition, the stacking order of the components of the electrolytic cell 10 is not limited to Figure 1 , for example, you can also follow Figure 1 The layers are stacked in the reverse order shown.

[0029] The electrolysis device 1 includes a plurality of electrolysis cells 10. The plurality of electrolysis cells 10 are stacked with an insulating layer 18 interposed therebetween to form a cell structure 100 such as a cell stack. Figure 2 1 is a perspective view schematically showing a structural example of the unit structure 100. The unit structure 100 further includes an insulating layer 18 between two stacked electrolytic units 10. The stacked electrolytic units 10 can be sandwiched by a pair of support plates and further fastened by bolts or the like. Figure 1 and Figure 2 The electrolytic units 10_1, 10_2, and 10_3 are shown as a plurality of electrolytic units 10, but the number of the electrolytic units 10 is not limited to 2 as long as it is 2 or more. Figure 1 and Figure 2 Quantity shown.

[0030] The cathode 11 is, for example, an electrode (reduction electrode) for generating a reduction reaction of at least one reduction object (substance to be reduced) and generating a reduction product. The at least one reduction object includes, for example, carbon dioxide or nitrogen. The cathode 11 is in contact with the diaphragm 13. The cathode 11 is an electrode (reduction electrode) for generating a reduction reaction of the reduction object and generating a reduction product. Examples of reduction objects include carbon dioxide, nitrogen, hydrogen, oxygen, reduction products, etc. Examples of reduction products include carbon compounds, ammonia, etc. Examples of carbon compounds include carbon monoxide (CO), methane (CH4), ethane (C2H6), etc. The reduction reaction at the cathode 11 may include a side reaction of generating hydrogen (H2) by generating a reduction reaction of water. In addition, the reduction reaction at the cathode 11 may also include a side reaction of generating water (H2O) by generating a reduction reaction of oxygen together with the reduction reaction of carbon dioxide.

[0031] Anode fluid and ions are supplied to cathode 11 from diaphragm 13, and cathode fluid is supplied to cathode 11 from cathode flow path 140. Cathode 11 may have a gas diffusion layer and a cathode catalyst layer disposed on the gas diffusion layer. Cathode 11 may also have a porous layer denser than the gas diffusion layer between the gas diffusion layer and the cathode catalyst layer. The gas diffusion layer is arranged on the cathode flow path 140 side, and the cathode catalyst layer is arranged on the diaphragm 13 side. The cathode catalyst layer may enter the gas diffusion layer. The cathode catalyst layer preferably has catalyst nanoparticles, catalyst nanostructures, etc. The gas diffusion layer may be composed of, for example, carbon paper, carbon cloth, etc., and a water-repellent treatment is performed. The porous layer is composed of a porous body having a pore size smaller than that of carbon paper and carbon cloth.

[0032] By performing appropriate water repellency treatment on the gas diffusion layer, the carbon dioxide gas reaches the cathode catalyst layer mainly through gas diffusion. The reduction reaction of carbon dioxide and the reduction reaction of the carbon compounds generated thereby occur near the boundary between the gas diffusion layer and the cathode catalyst layer or near the cathode catalyst layer that has entered the gas diffusion layer.

[0033] The cathode catalyst layer preferably includes a catalyst material (cathode catalyst material) that can reduce the overvoltage of the above-mentioned reduction reaction. 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), tin (Sn), alloys containing at least one of these metals, metal materials such as intermetallic compounds, carbon (C), graphene, CNT (carbon nanotubes), fullerene, carbon materials such as Ketjen black, metal complexes such as Ru complexes and Re complexes. The cathode catalyst layer can be applied in various shapes such as plate, mesh, wire, particle, porous, film, island, etc.

[0034] The cathode catalyst material constituting the cathode catalyst layer preferably comprises nanoparticles of the above-mentioned metal material, nanostructures of the metal material, nanowires of the metal material, or a composite formed by nanoparticles of the above-mentioned metal material supported on carbon materials such as carbon particles, carbon nanotubes, and graphene. 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 in the cathode 11 can be improved.

[0035] The anode 12 is disposed between the diaphragm 13 and the anode flow path 150 and is in contact with them. The anode 12 is used to oxidize water (H2O) in the anode solution contained in the anode fluid to generate oxygen (O2), hydrogen ions (H +) electrode, or for converting hydroxide ions (OH - ) is oxidized to produce oxygen and water.

[0036] The anode 12 preferably includes a catalyst material (anode catalyst material) that can reduce the overvoltage of the above-mentioned oxidation reaction. Such catalyst materials include, for example, metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys containing these metals, intermetallic compounds, 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.

[0037] The anode 12 has a structure that enables liquid and ions to move between the diaphragm 13 and the anode flow path 150, such as a mesh material, a punching material, a porous body, a metal fiber sintered body and other substrates with a porous structure. The substrate can be composed of metal materials such as titanium (Ti), nickel (Ni), iron (Fe), alloys containing at least one of these metals (such as SUS), etc., or it can be composed of the above-mentioned anode catalyst material. In the case of using an oxide as the anode catalyst material, it is preferred to attach or stack the anode catalyst material on the surface of the substrate composed of the above-mentioned metal material to form a catalyst layer. The anode catalyst material preferably has nanoparticles, nanostructures, nanowires, etc. on the basis of improving the oxidation reaction. The nanostructure is a structure with nano-scale concave and convex structures formed on the surface of the catalyst material. In addition, it is not necessary to set an oxidation catalyst at the anode 12. The oxidation catalyst layer arranged outside the anode 12 can also be electrically connected to the anode 12.

[0038] The diaphragm 13 is provided between the cathode 11 and the anode 12. The diaphragm 13 is configured to separate the cathode 11 from the anode 12. The diaphragm 13 includes an ion exchange membrane that can move ions between the cathode 11 and the anode 12 and can separate the cathode 11 from the anode 12. Examples of ion exchange membranes include cation exchange membranes such as Nafion and Flemion, and anion exchange membranes such as Neosepta, Selemion, and Sason. An alkaline solution is used as the electrolyte, mainly assuming that OH -In the case of movement of ions, the diaphragm 13 is preferably composed of an anion exchange membrane. In addition, a membrane with hydrocarbon as the basic skeleton or a membrane with an amine group can also be used to constitute the ion exchange membrane. However, in addition to the ion exchange membrane, as long as it is a material that can move ions between the cathode 11 and the anode 12, a salt bridge, a glass filter, a porous polymer membrane, a porous insulating material, etc. can also be applied to the diaphragm 13. However, if gas circulation occurs between the cathode 11 and the anode 12, a cyclic reaction caused by the reoxidation of the reduction product sometimes occurs. Therefore, it is preferred that the exchange of gas between the cathode 11 and the anode 12 is small. Therefore, it is necessary to pay attention when using a porous film as the diaphragm 13.

[0039] The cathode flow path plate 14 has a cathode flow path 140. The cathode flow path 140 faces the cathode 11. The cathode flow path 140 can supply a cathode fluid that is supplied to the cathode 11 and contains a reduction object. The cathode fluid may also contain water vapor by being humidified. The reduction product is mainly contained in the cathode fluid from the cathode flow path 140 and discharged. The reduction product differs depending on the type of reduction catalyst, etc. Together with such a gas product, water obtained by condensation of steam or steam contained in the humidified carbon dioxide gas is discharged from the cathode flow path 140.

[0040] The reduction products vary depending on the composition of the cathode fluid. When the cathode fluid contains carbon dioxide gas or humidified carbon dioxide gas, carbon monoxide gas and byproduct hydrogen and other reduction products are mainly generated. When the cathode fluid contains nitrogen gas, ammonia and other reduction products are mainly generated. When the cathode fluid contains impurity gases such as oxygen, oxygen is reduced to generate water as a reduction product.

[0041] The cathode flow path 140 is arranged on the surface of the cathode flow path plate 14. The cathode flow path plate 14 has a groove (recess) on the surface that forms the cathode flow path 140. The cathode flow path plate 14 is preferably formed using a material with low chemical reactivity and high conductivity. Examples of such materials include metal materials such as Ti, SUS, carbon, etc. In addition, the material of the flow path plate includes, for example, a material with low chemical reactivity and no conductivity. Examples of such materials include insulating resin materials such as acrylic resin, polyetheretherketone (PEEK), and fluororesin. In addition, the cathode flow path plate 14 has a threaded hole for fastening that is not shown in the figure. In addition, a packing (packing) that is omitted from the figure can also be sandwiched in front and behind each cathode flow path plate 14 as needed. In addition, the cathode flow path 140 can also be arranged on the cathode collector 16.

[0042] The cathode flow path 140 has an inlet and an outlet, and the cathode fluid is supplied from the cathode supply source 20 through the inlet, and the cathode fluid containing unreacted reduction objects and reduction products is discharged through the outlet. The cathode fluid flows in the cathode flow path 140 in a manner of contacting the cathode 11. The cathode fluid discharged from the cathode flow path 140 may also contain unreacted reduction objects, reduction products, etc.

[0043] The cathode flow path 140 may also have a pad in contact with the cathode 11 for electrical connection with the cathode 11. The shape of the cathode flow path 140 is not particularly limited as long as it is continuously connected, and for example, a serpentine shape formed by bending a long and narrow flow path can be cited. Thus, the cathode fluid flows uniformly on the surface of the cathode 11, so that a uniform reaction can be performed at the cathode 11, which is preferred.

[0044] The cathode fluid may be supplied in a dry state. In the case where the cathode fluid contains carbon dioxide gas, the carbon dioxide concentration of the cathode fluid supplied from the cathode supply source 20 to the cathode flow path 140 may not be 100%. A fluid containing a gas of carbon dioxide discharged from various facilities may also be used as the cathode fluid. In this case, the cathode fluid may contain an impurity gas. If the first gas contained in the cathode fluid is carbon dioxide gas, the second gas is, for example, a substance different from carbon dioxide such as oxygen or nitrogen. The concentration of the second gas is lower than that of the first gas, for example, preferably greater than 1 ppm and less than 100,000 ppm.

[0045] The cathode channel plate 14 is mainly formed of one member, but may be formed of a plurality of different members and these members may be stacked. Furthermore, by subjecting a part or the entire surface to surface treatment, a hydrophilic or water-repellent function may be imparted.

[0046] The anode flow path plate 15 has an anode flow path 150. The anode flow path 150 faces the anode 12. The anode flow path 150 allows an anode fluid supplied to the anode 12 to flow. The anode fluid includes, for example, a liquid such as an anode solution.

[0047] The anode solution preferably contains at least water (H 2 O). For example, when the reduction target is carbon dioxide, carbon dioxide is supplied from the cathode flow path 140 , so the anode solution may or may not contain carbon dioxide.

[0048] As the anode solution, an aqueous solution (electrolyte) containing metal ions can be used. As the aqueous solution, for example, a solution containing phosphate ions (PO4 2- ), borate ion (BO3 3- ), sodium ion (Na + ), potassium ion (K + ), calcium ions (Ca 2+ ), lithium ion (Li+ ), cesium ion (Cs + ), magnesium ion (Mg 2+ ), chloride ion (Cl - ), bicarbonate ion (HCO3 - ) etc. In addition, aqueous solutions containing lithium bicarbonate (LiHCO3), sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), cesium bicarbonate (CsHCO3), phosphoric acid, boric acid, etc. can also be used.

[0049] The anode flow path 150 is arranged on the surface of the anode flow path plate 15. The anode flow path plate 15 is used to supply the anode fluid to the anode 12, and has a groove (recess) on the surface that forms the anode flow path 150. The anode flow path plate 15 is preferably formed using a material with low chemical reactivity and high electrical conductivity. Examples of such materials include metal materials such as Ti and SUS, carbon, etc. In addition, the anode flow path 150 can also be arranged on the anode current collector 17. In addition, the material of the anode flow path plate 15 includes, for example, a material with low chemical reactivity and no electrical conductivity. Examples of such materials include insulating resin materials such as acrylic resin, polyetheretherketone (PEEK), and fluororesin. In addition, the anode flow path plate 15 has a threaded hole for fastening that is not shown in the figure.

[0050] The anode channel plate 15 is mainly formed of one member, but may be formed of a plurality of different members and these members may be stacked. Furthermore, by subjecting a part or the entire surface to surface treatment, a hydrophilic or water-repellent function may be imparted.

[0051] The anode flow path 150 has an inlet and an outlet, and the anode fluid is supplied from the anode supply source 30 through the inlet and discharged through the outlet. The anode fluid flows in the anode flow path 150 in a manner in contact with the anode 12. The anode fluid discharged from the anode flow path 150 may also contain unreacted oxidation objects, electrolyte, oxidation products, etc.

[0052] The anode flow path 150 may also have a pad in contact with the anode 12 for electrical connection with the anode 12. The shape of the anode flow path 150 is not particularly limited as long as it is continuously connected, and for example, a serpentine shape formed by bending a long and narrow flow path can be cited. Thus, the anode fluid flows uniformly on the surface of the anode 12, so a uniform reaction can be performed at the anode 12, which is preferred.

[0053] The cathode current collector 16 is electrically connected to the cathode 11. The cathode current collector 16 is in contact with the surface of the cathode flow path plate 14 on the opposite side of the cathode flow path 140. The cathode current collector 16 preferably includes a material with low chemical reactivity and high conductivity. Examples of such a material include metal materials such as Ti and SUS, and carbon.

[0054] The anode current collector 17 is electrically connected to the anode 12. The anode current collector 17 is in contact with the surface of the anode flow path plate 15 opposite to the anode flow path 150. The anode current collector 17 preferably includes a material having low chemical reactivity and high conductivity. Examples of such a material include metal materials such as Ti and SUS, and carbon.

[0055] The insulating layer 18 is provided between the two electrolytic cells 10. The insulating layer 18 is formed of materials such as silicone, a material covered with a fluororesin such as polytetrafluoroethylene (PTFE), an insulating resin material such as acrylic resin, polyetheretherketone (PEEK), or a fluororesin. The electrolytic device 1 may have a plurality of insulating layers 18.

[0056] The cathode supply source 20 can supply, for example, a cathode fluid to the electrolysis unit 10. The cathode supply source 20 is connected to the cathode flow path 140 of the electrolysis unit 10_1 via, for example, a pipe.

[0057] The anode supply source 30 can supply, for example, an anode fluid to the electrolysis unit 10. The anode supply source 30 is connected to the anode flow path 150 of the electrolysis unit 10_1 via, for example, a pipe.

[0058] The power supply 40 can supply power supply current to each of the plurality of electrolytic cells 10, for example. The power supply 40 is electrically connected to the cathode current collectors 16 of each of the plurality of electrolytic cells 10, for example, via wiring. The plurality of cathode current collectors 16 can also be electrically connected in parallel with each other. The power supply 40 is electrically connected to the anode current collectors 17 of each of the plurality of electrolytic cells 10, for example, via wiring. The plurality of anode current collectors 17 can also be electrically connected in parallel with each other.

[0059] Examples of the power supply 40 are not limited to conventional system power supplies and batteries, and may also include power sources that supply power generated by renewable energy such as solar cells and wind power generation. If renewable energy is used, it is environmentally preferred to effectively utilize the reduction object. The power supply 40 may also have a power controller that adjusts the output of the power supply 40 to control the voltage between the cathode 11 and the anode 12. In addition, the power supply 40 may also be arranged outside the electrolysis device 1. The power supply 40 can achieve the best operation of the electrolysis unit 10 by controlling the current or voltage supplied to each electrolysis unit 10, and improve the reaction efficiency of the reduction reaction of the reduction object in the cathode 11. In addition, by adjusting the current or voltage supplied to each electrolysis unit 10, the best operation of the electrolysis unit 10 can be achieved, and the reaction efficiency of the reduction reaction of the reduction object in the cathode 11 can be improved. Between the power supply 40 and the electrolysis unit 10 and the unit structure 100, there may also be an element for monitoring the current, such as a resistor element. Thus, the voltage can be controlled to achieve the best operation of the electrolysis unit 10 and improve the reaction efficiency of the reduction reaction in the cathode 11.

[0060] The cathode fluid and the anode fluid can be supplied to the plurality of electrolysis units 10 in a manner of flowing in series or in parallel. When the cathode fluid and the anode fluid are supplied to the plurality of electrolysis units 10 in a manner of flowing in series, the plurality of electrolysis units 10 may connect the plurality of cathode flow paths 140 in series and the plurality of anode flow paths 150 in series. Hereinafter, a structural example of each component of the electrolysis unit 10 in the case where the plurality of cathode flow paths 140 are connected in series and the plurality of anode flow paths 150 are connected in series will be described.

[0061] Figure 3 It is a schematic diagram showing a structural example of a membrane electrode assembly MEA. Figure 3 Represents an XY top view. The membrane electrode assembly MEA can be surrounded by a support plate 130. The support plate 130 has, for example, an opening 130a and an opening 131. The opening 130a is a space that penetrates the support plate 130 in the Z-axis direction and is provided with the membrane electrode assembly MEA. The opening 131 penetrates the support plate 130 in the Z-axis direction, for example, and is a through hole such as a through hole. The support plate 130 has a plurality of openings 131. The plurality of openings 131 are arranged around the opening 130a. One of the plurality of openings 131 can allow cathode fluid to flow. Another of the plurality of openings 131 can allow anode fluid to flow. Figure 3 The openings 131_1 and 131_2 are shown as the plurality of openings 131, but the number of the openings 131 is not limited to 2 as long as it is 2 or more. Figure 3 The number shown. The opening 131_1 allows the cathode fluid to flow. The opening 131_2 allows the anode fluid to flow. The support plate 130 is preferably formed using an insulating material, for example. In addition, the above structure is an example, and the plurality of openings 131 can be provided in other components such as the cathode 11 and the anode 12 instead of the support plate 130 as long as the cathode fluid and the anode fluid can pass through the layer including the membrane electrode assembly MEA without leakage.

[0062] Figure 4 1 is a schematic diagram showing a structural example of the cathode channel plate 14 . Figure 4 14 is an XY top view. The cathode flow path plate 14 has, for example, a cathode flow path 140 and an opening 141. The cathode flow path 140 is provided on the membrane electrode assembly MEA side of the cathode flow path plate 14, for example, Figure 4 As shown, it can be formed into a snake shape along the XY plane, or it can have other shapes. The opening 141, for example, penetrates the cathode flow path plate 14 along the Z-axis direction, for example, a through hole such as a through hole. The cathode flow path plate 14 has a plurality of openings 141. One of the plurality of openings 141 can allow the cathode fluid to flow. Another of the plurality of openings 141 can allow the anode fluid to flow. Figure 4 The opening 141_1, the opening 141_2, and the opening 141_3 are shown as the plurality of openings 141, but the number of the openings 141 is not limited to 2 as long as it is 2 or more. Figure 4 The cathode flow path 140 is connected to the opening 131_1. The opening 141_1 is, for example, provided on the opposite side of the formation surface of the cathode flow path 140, overlaps with one end of the cathode flow path 140, and is connected to the cathode flow path 140. The opening 141_2 is, for example, connected to the opening 131_2. The other end of the cathode flow path 140 overlaps with the opening 131_1, for example. The opening 141_1 allows the cathode fluid to flow. The opening 141_2 allows the anode fluid to flow.

[0063] Figure 5 1 is a schematic diagram showing a structural example of the anode channel plate 15 . Figure 5 15 is an XY top view. The anode flow path plate 15 has, for example, an anode flow path 150 and an opening 151. The anode flow path 150 may be, for example, Figure 5 The anode flow path plate 15 is shown as a serpentine shape along the XY plane, and may also have other shapes. The opening 151, for example, passes through the anode flow path plate 15 along the Z-axis direction, and is, for example, a through hole such as a through hole. The anode flow path plate 15 has a plurality of openings 151. One of the plurality of openings 151 can allow the cathode fluid to flow. Another of the plurality of openings 151 can allow the anode fluid to flow. Figure 5 The openings 151_1 and 151_2 are shown as the plurality of openings 151, but the number of the openings 151 is not limited to 2 as long as it is 2 or more. Figure 5 The number shown. The opening 151_1 is connected to the opening 131_1, for example. The opening 151_2 is provided on the opposite side of the surface where the anode flow path 150 is formed, overlaps with one end of the anode flow path 150, and is connected to the opening 131_2, for example. The opening 151_1 can allow the cathode fluid to flow. The opening 151_2 can allow the anode fluid to flow.

[0064] Figure 6 It is a schematic diagram showing a structural example of the cathode current collector 16 . Figure 6 It represents an XY top view. The cathode current collector 16 has, for example, an opening 161. The opening 161 penetrates the cathode current collector 16 along the Z-axis direction, and is, for example, a through hole such as a through hole. The cathode current collector 16 has a plurality of openings 161. One of the plurality of openings 161 can allow cathode fluid to flow. Another of the plurality of openings 161 can allow anode fluid to flow. Figure 6 The openings 161_1 and 161_2 are shown as the plurality of openings 161, but the number of the openings 161 is not limited to 2 as long as it is 2 or more. Figure 6 The number shown. The opening 161_1 is connected to the opening 141_1, for example. The opening 161_2 is connected to the opening 141_2, for example. The opening 161_1 can be used for the cathode fluid to flow. The opening 161_2 can be used for the anode fluid to flow.

[0065] Figure 7It is a schematic diagram showing a structural example of the anode current collector 17 . Figure 7 It represents an XY top view. The anode current collector 17 has, for example, an opening 171. The opening 171 penetrates the anode current collector 17 along the Z-axis direction, and is, for example, a through hole such as a through hole. The anode current collector 17 has a plurality of openings 171. One of the plurality of openings 171 can allow cathode fluid to flow. Another of the plurality of openings 171 can allow anode fluid to flow. Figure 7 The openings 171_1 and 171_2 are shown as the plurality of openings 171, but the number of the openings 171 is not limited to 2 as long as it is 2 or more. Figure 7 The number shown. The opening 171_1 is connected to the opening 151_1, for example. The opening 171_2 is connected to the opening 151_2, for example. The opening 171_1 can be used for the cathode fluid to flow. The opening 171_2 can be used for the anode fluid to flow.

[0066] Figure 8 1 is a schematic diagram showing a structural example of the insulating layer 18 . Figure 8 18 is an XY top view. The insulating layer 18 has, for example, an opening 181. The opening 181 penetrates the insulating layer 18 along the Z-axis direction, and is, for example, a through hole such as a through hole. The insulating layer 18 has a plurality of openings 181. One of the plurality of openings 181 can allow cathode fluid to flow. Another of the plurality of openings 181 can allow anode fluid to flow. Figure 8 The openings 181_1 and 181_2 are shown as the plurality of openings 181, but the number of the openings 181 is not limited to 2 as long as it is 2 or more. Figure 8 The number shown. The opening 181_1 is connected to the opening 171_1, for example. The opening 181_2 is connected to the opening 171_2, for example. The opening 181_1 can be used for the cathode fluid to flow. The opening 181_2 can be used for the anode fluid to flow.

[0067] When multiple electrolytic units 10 are stacked with an insulating layer 18 therebetween, the positions of the multiple openings 131, the multiple openings 141, the multiple openings 151, the multiple openings 161, the multiple openings 171, and the multiple openings 181 may also be different between the electrolytic units 10_2n-1 (n is a natural number) of odd-numbered stages such as the electrolytic unit 10_1 and the electrolytic units 10_2n (n is a natural number) of even-numbered stages such as the electrolytic unit 10_2. For example, between the odd-numbered electrolytic units 10_2n-1 (n is a natural number) and the even-numbered electrolytic units 10_2n (n is a natural number), the positions of the openings 131_1 and 131_2, the positions of the openings 141_1 and 141_2, the positions of the openings 151_1 and 151_2, the positions of the openings 161_1 and 161_2, the positions of the openings 171_1 and 171_2, and the positions of the openings 181_1 and 181_2 may also have a symmetrical relationship respectively. In addition, according to the shape of the flow path, between the electrolytic units 10_2n-1 (n is a natural number) of odd-numbered stages and the electrolytic units 10_2n (n is a natural number) of even-numbered stages, the positions of the openings 131_1 and 131_2, the positions of the openings 141_1 and 141_2, the positions of the openings 151_1 and 151_2, the positions of the openings 161_1 and 161_2, the positions of the openings 171_1 and 171_2, and the positions of the openings 181_1 and 181_2 may have an asymmetric relationship, respectively. In addition, in the case of having a gasket, a plurality of openings may also be formed on the gasket to allow the cathode fluid and the anode fluid to pass through.

[0068] Reference Fig. 9 and Fig.10 The flow of the cathode fluid and the flow of the anode fluid in each electrolysis cell 10 when the cathode fluid and the anode fluid are supplied to the plurality of electrolysis cells 10 in series flow will be described. Fig. 9 and Fig.10 It is a schematic diagram for explaining the flow of the cathode fluid and the flow of the anode fluid in each electrolysis unit 10 . Fig. 9 and Fig.10 The solid arrows shown represent the flow of cathode fluid. Fig. 9 and Fig.10 The solid arrows shown represent the flow of the anode fluid.

[0069] In the first-stage electrolysis unit 10_1 and other odd-numbered electrolysis units 10_2n-1, the cathode fluid is as follows: Fig. 9 As shown, the cathode flow path 140 moves from one end to the other end through the opening 161_1, through the opening 141_1, through the opening 131_1, through the opening 151_1, through the opening 171_1, through the opening 181_1, thereby being able to move to the electrolytic unit 10 of the next stage.

[0070] In the odd-numbered electrolysis unit 10_2n-1, the anode fluid is as follows Fig. 9 As shown, the anode flow path 150 moves from one end to the other end through the opening 161_2, through the opening 141_2, through the opening 131_2, through the opening 151_2, through the opening 171_2, through the opening 181_2, thereby being able to move to the electrolytic unit 10 of the next stage.

[0071] In the electrolytic unit 10_1 of the second stage and the electrolytic units 10_2n of the even-numbered stages, as shown in FIG. Fig.10 As shown, the cathode fluid moves from one end of the cathode flow path 140 to the other end through the opening 161_1, through the opening 141_1, through the opening 131_1, through the opening 151_1, through the opening 171_1, through the opening 181_1, and thus can move to the electrolytic unit 10 of the next stage.

[0072] In the odd-numbered electrolysis unit 10_2n-1, the anode fluid is as follows Fig. 9 As shown, the anode flow path 150 moves from one end to the other end through the opening 161_2, through the opening 141_2, through the opening 131_2, through the opening 151_2, through the opening 171_2, through the opening 181_2, thereby being able to move to the electrolytic unit 10 of the next stage.

[0073] Next, an example of the operation method of the electrolysis device 1 will be described. Here, the case where carbon monoxide is generated as a carbon compound will be mainly described, but the reduction product of carbon dioxide is not limited to carbon compounds.

[0074] First, the oxidation of water (H2O) to generate hydrogen ions (H + ). A cathode fluid is supplied from the cathode supply source 20 to the cathode flow path 140, and an anode fluid is supplied from the anode supply source 30 to the anode flow path 150. If a current is supplied from the power supply 40 between the cathode 11 and the anode 12, an oxidation reaction of water (H2O) occurs at the anode 12 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 + ).

[0075] 2H2O→4H + +O2+4e - …(1)

[0076] The H generated at the anode 12 + The electrolyte in the anode flow path 150 moves through the diaphragm 13 and reaches the vicinity of the cathode 11. The electrons (e -) and H moved to the vicinity of the cathode 11 + , a reduction reaction of carbon dioxide is generated. Specifically, as shown in the following formula (2), carbon dioxide supplied from the cathode 11 flow path to the cathode 11 is reduced to generate carbon monoxide. In addition, as shown in the following formula (3), hydrogen ions accept electrons to generate hydrogen. At this time, hydrogen can be generated simultaneously with carbon monoxide.

[0077] CO2+2H + +2e - →CO+H2O…(2)

[0078] 2H + +2e - →H2…(3)

[0079] Next, the carbon dioxide (CO2) is mainly reduced to generate hydroxide ions (OH - ) is described below. When current is supplied from a power source between the cathode 11 and the anode 12, water (H2O) and carbon dioxide (CO2) are reduced near the cathode 11 to generate carbon monoxide (CO) and hydroxide ions (OH - ). In addition, as shown in the following formula (5), water accepts electrons to generate hydrogen. In this case, hydrogen can be generated simultaneously with carbon monoxide. The hydroxide ions (OH - ) diffuses to the vicinity of the anode 12, as shown in the following formula (6), the hydroxide ion (OH - ) is oxidized to produce oxygen (O2).

[0080] 2CO2+2H2O+4e - →2CO+4OH - …(4)

[0081] 2H2O+2e - →H2+2OH - …(5)

[0082] 4OH - →2H2O+O2+4e - …(6)

[0083] Such an electrolysis unit 10 is not only used exclusively for reducing carbon dioxide, but can also produce a reduction product and hydrogen in an arbitrary ratio, for example, by generating carbon monoxide and hydrogen at a ratio of 1:2 and producing methanol in the subsequent chemical reaction.

[0084] Hydrogen is a cheap and easily available raw material from the electrolysis of water and fossil fuels, so the ratio of hydrogen does not need to be high. From these viewpoints, it is preferred from the economic and environmental viewpoints that the ratio of carbon monoxide to hydrogen is at least 1 or more, preferably 1.5 or more.

[0085] Next, the reaction process when oxygen (O2) is mainly reduced to generate water (H2O) is described. When current is supplied from a power source between the cathode 11 and the anode 12, oxygen (O2) is reduced near the cathode 11 as shown in the following formula (7) to generate water (H2O). At this time, water can be generated simultaneously with carbon monoxide and hydrogen, but it is believed that due to the difference in reduction potential, oxygen reduction mainly proceeds. As shown in the following formula (8), the water in the electrolyte is oxidized to generate oxygen (O2) and protons (H + ), the protons (H + ) diffuses from the vicinity of the anode 12. In addition, hydrogen peroxide (H2O2) may also be generated as an intermediate product or product. In addition, the oxygen reduction reaction may occur in either an acidic or alkaline environment, taking into account 2-electron reduction and 4-electron reduction.

[0086] O2+4H + +4e - →2H2O…(7)

[0087] 2H2O→O2+4H + +4e - …(8)

[0088] Such an electrolysis unit 10 is not only dedicated to the reduction of carbon dioxide, but can also reduce impurity gases such as oxygen and nitrogen even if they are mixed therein.

[0089] In the case of a nitrogen electrolysis device, ammonia can be generated by reducing nitrogen at the cathode 11. Regarding other structures of the nitrogen electrolysis device, the structure of the electrolysis device 1 can be appropriately referred to. In this case, the impurity gas of the cathode fluid is not nitrogen.

[0090] When cathode fluid is supplied from cathode supply source 20 to unit structure 100 and the reduction object is reduced in electrolysis unit 10 to generate reduction product, in the case where cathode fluid contains gas of reduction object such as carbon dioxide, nitrogen and gas of impurities such as oxygen, current is consumed in the reduction of the impurity gas, so current is consumed in vain accordingly. Furthermore, the current used to reduce the reduction object is reduced accordingly, the amount of carbon dioxide reduced becomes less, and sometimes the Faraday efficiency of reduction products such as carbon compounds and ammonia is reduced. In the existing electrolysis device, cathode fluid and anode fluid and power supply current are supplied to the unit stack in a manner that flows in series, so it is difficult to control the current supply amount of the first-stage electrolysis unit where the reduction of impurity gas mainly occurs. In addition, in order to realize an electrolysis device with high electrolysis efficiency, it is necessary to operate the electrolysis device with low power consumption.

[0091] In contrast, the electrolysis device of the embodiment supplies a first power supply current to a first group of electrolysis cells 10 including the first-stage electrolysis cells 10, and supplies a second power supply current to a second group of electrolysis cells 10 including at least one of the lower-stage and subsequent electrolysis cells 10. Figure 1 In the electrolysis device 1 shown, by connecting a plurality of electrolysis cells 10 in parallel to a power supply 40, current can be supplied individually to each electrolysis cell 10. Without being limited thereto, a first power supply current may be supplied to a first group of electrolysis cells 10 including electrolysis cells 10 of the first to X-th stages (X is a natural number greater than or equal to 2), and a second power supply current may be supplied to a second group of electrolysis cells 10 including at least one of the electrolysis cells 10 of the X+1th stage and thereafter.

[0092] Fig.11 This is a schematic diagram showing how impurities such as oxygen and reduction targets such as carbon dioxide in the cathode fluid flow through the electrolysis units 10 in series. Fig.12 This is a diagram showing an example of a graph showing the relationship between the current density flowing through the electrolytic cell 10, the cell voltage, and the Faraday efficiency. Fig.12 The solid line curve shown represents the relationship between the cell voltage of the electrolysis cell 10 supplied with the mixed gas of the carbon dioxide-containing gas and the oxygen gas and the current density of the current flowing through the electrolysis cell 10 . Fig.12 The dashed curve shown represents the relationship between the cell voltage of the electrolysis cell 10 supplied with the single gas of carbon dioxide and the current density of the current flowing through the electrolysis cell 10 . Fig.12 The dashed-dotted curve shown represents the relationship between the Faraday efficiency of carbon monoxide in the electrolysis cell 10 supplied with the single gas of carbon dioxide and the current density of the current flowing through the electrolysis cell 10 . Fig.12 The double-dashed line curve shown represents the relationship between the Faraday efficiency of carbon monoxide in the electrolysis cell 10 supplied with the mixed gas containing carbon dioxide gas and oxygen and the current density of the current flowing through the electrolysis cell 10 .

[0093] When the current density of the current flowing through the electrolysis unit 10 is low, the current is mainly consumed in the production of water based on oxygen reduction, and the production of carbon monoxide based on the reduction of carbon dioxide does not proceed. On the other hand, when the current density of the current flowing through the electrolysis unit 10 is high, the current is mainly consumed in the production of carbon monoxide, and the production of carbon monoxide proceeds. This is believed to be because oxygen is preferentially reduced near the inlet of the cathode flow path 140 of the electrolysis unit 10, the oxygen concentration decreases, and after the middle of the cathode flow path 140, carbon dioxide is mainly reduced, which becomes a preferred environment. Fig.11 , Fig.12 As shown, at 100mA / cm 2 The following low current density range ( Fig.12In the range A), oxygen reduction is prioritized, and current is consumed mainly in water generation based on oxygen reduction, and carbon monoxide generation based on carbon dioxide reduction is not performed. 2 The range of high current density above ( Fig.12 In range B), the reduction of carbon dioxide is primarily prioritized, and the current is consumed primarily in the generation of carbon monoxide based on the reduction of carbon dioxide.

[0094] Therefore, the first power supply current is supplied so that the current flowing through the first-stage electrolytic cell 10 (electrolytic cell 10_1) has a low current density. The current density at this time is, for example, 1 mA / cm 2 Above and 150mA / cm 2 As a result, oxygen reduction is preferentially performed in the electrolysis unit 10 of the first stage. As a result, in the electrolysis unit 10 of the first stage, most of the impurities in the cathode fluid are reduced, so the composition of the cathode fluid flowing in the electrolysis unit 10 of the next stage and thereafter is mainly only the gas of the reduction object. Here, the area of ​​the electrolysis unit 10 of the first stage is the same as the area of ​​the electrolysis unit 10 of the next stage and thereafter, but the areas of the plurality of electrolysis units 10 are not necessarily the same. The area of ​​the electrolysis unit 10 includes, for example, the area of ​​the overlapping portion of the cathode 11 and the cathode flow path 140, the area of ​​the overlapping portion of the anode 12 and the anode flow path 150, and the like.

[0095] Furthermore, the second power supply current is supplied so that the current flowing through the electrolytic cells 10 of the next stage and later has a high current density. The current density at this time is, for example, 150 mA / cm 2 The upper limit of the current density is not particularly limited, and is, for example, 1000 mA / cm 2 As follows. Thus, in the electrolysis unit 10 after the next stage, more reduction objects can be reduced, and further, the composition of the cathode fluid supplied to the electrolysis unit 10 after the next stage can be substantially composed only of the gas of the reduction object, so that the electrolysis unit 10 that consumes current in the reduction of impurities can be left only in the electrolysis unit 10 of the first stage, and the consumption of unnecessary current in the electrolysis reaction such as the reduction reaction of impurities can be suppressed. Thus, an electrolysis device that operates with low power consumption can be provided. Oxygen and other impurity gases are sometimes also supplied to the electrolysis units 10 after the second stage. In this case, in the electrolysis device of the embodiment, the power supply current can be supplied from the power supply 40 as follows: the current density of the current flowing in each of the electrolysis units 10 of the second group including at least one of the electrolysis units 10 after the next stage is higher than the current density of the current flowing in each of the electrolysis units 10 of the first group including the electrolysis unit 10_1 of the first stage and at least one of the electrolysis units 10 after the second stage. In addition, as Fig.12As shown, the reduction potential of carbon dioxide gas is higher than that of oxygen.

[0096] Fig.13 It is a schematic diagram showing another example of the electrolysis device according to the embodiment. Fig.13 1 shows another structural example of the electrolysis device 1. Fig.13 As shown, the electrolysis device 1 may also share one cathode current collector 16 and one anode current collector 17 for a plurality of electrolysis units 10 . Fig.13 The example in which the electrolytic unit 10_2 and the electrolytic unit 10_3 are provided between a cathode current collector 16 and an anode current collector 17, and the anode flow plate 15 in the electrolytic unit 10_2 is electrically connected to the cathode flow plate 14 in the electrolytic unit 10_3 is shown. According to the above structure, the number of cathode current collectors 16 and anode current collectors 17 can be reduced, so the manufacturing cost and thickness of the unit structure 100 can be suppressed.

[0097] Fig.14 It is a schematic diagram showing another example of the electrolysis device according to the embodiment. Fig.14 1 shows another structural example of the electrolysis device 1. Fig.14 As shown, the electrolysis device 1 may also have a power source 41 and a power source 42 .

[0098] The power source 41 is electrically connected to the first group of electrolytic cells 10 including the first-stage electrolytic cells 10. The power source 41 can supply a first power current to the first-stage electrolytic cells 10. The other descriptions of the power source 41 can refer to the descriptions of the power source 40 as appropriate.

[0099] The power source 42 is electrically connected to the second group of electrolytic cells 10, which includes at least one of the electrolytic cells 10 of the next stage and the next stage of the electrolytic cells 10 of the first group. The power source 42 can supply the second power supply current to the next stage and the next stage of the electrolytic cells 10. The other descriptions of the power source 42 can refer to the description of the power source 40 as appropriate.

[0100] When the above-mentioned area of ​​the electrolytic cells 10 of the first group and the above-mentioned area of ​​the electrolytic cells 10 of the second group are the same, the values ​​of the first power supply current and the second power supply current are adjusted by the power supply 41 and the power supply 42 so that the current density of the current flowing through the electrolytic cells 10 of the second group is higher than the current density of the current flowing through the electrolytic cells 10 of the first group. According to the above-mentioned structure, for example, the first power supply current and the second power supply current that become the optimal current density can be set and supplied according to the cell voltage of each of the electrolytic cells 10 of the first group and the electrolytic cells 10 of the second group. At this time, when it is difficult to predict the voltage, the optimal current density can be adjusted by providing a resistor between the electrolytic cells 10 of the first group and the electrolytic cells 10 of the second group and connecting a current monitor to each electrolytic cell 10. In addition, the cell voltage of each electrolytic cell 10 can also be controlled to supply the current. In addition, the reduction product can also be selectively changed by controlling the voltage and current of the electrolytic cells 10 of the second group. Here, the area of ​​the electrolytic cells 10 of the first group is the same as the area of ​​the electrolytic cells 10 of the second group, but the areas of the plurality of electrolytic cells do not necessarily have to be the same. In this case, the current density of the first power supply current and the current density of the second power supply current are adjusted by power supplies 41 and 42 so that the current density flowing through the second group of electrolytic cells 10 is higher than the current density flowing through the first group of electrolytic cells 10.

[0101] Fig.15 It is a schematic diagram showing another example of the electrolysis device according to the embodiment. Fig.15 1 shows another structural example of the electrolysis device 1. Fig.15 As shown, the electrolysis device 1 may also have: a power supply 41; and a power supply 42, and have: a piping 19a for separating the electrolysis units 10 of the first group from the electrolysis units 10 of the second group, and supplying cathode fluid from the electrolysis units 10 of the first group to the electrolysis units 10 of the second group; and a piping 19b for supplying cathode fluid from the electrolysis units 10 of the first group to the electrolysis units 10 of the second group.

[0102] The piping 19a connects the cathode flow path 140 of the final electrolysis unit 10 of the first group with the cathode flow path 140 of the primary electrolysis unit 10 of the second group. The piping 19b connects the anode flow path 150 of the final electrolysis unit 10 of the first group with the anode flow path 150 of the primary electrolysis unit 10 of the second group. The piping 19a and the piping 19b can be formed using, for example, a metal material or an insulating material. Through the above structure, the distance between the electrolysis unit 10 of the first group and the electrolysis unit 10 of the second group can be separated. Thus, for example, even in a narrow installation space, space can be efficiently utilized.

[0103] Fig.16 It is a schematic diagram showing another example of the electrolysis device according to the embodiment. Fig.161 shows another structural example of the electrolysis device 1. Fig.16 As shown, the electrolysis device 1 may also have a power supply 41 and a power supply 42, so that the cathode fluid is supplied from the cathode supply source 20 to the plurality of electrolysis units 10 in parallel, and the anode fluid is supplied from the anode supply source 30 to the plurality of electrolysis units 10 in parallel. The cathode flow path 140 of the first group of electrolysis units 10 and the cathode flow path 140 of the second group of electrolysis units 10 may be connected in parallel, for example. The anode flow path 150 of the first group of electrolysis units 10 and the anode flow path 150 of the second group of electrolysis units 10 may be connected in parallel, for example. Through the above structure, it is possible to set the optimal current and gas composition and its gas flow rate according to each cell voltage of the first group of electrolysis units 10 and the second group of electrolysis units 10 and make them flow. At this time, when it is difficult to predict the voltage, by setting a resistor between the first group of electrolysis units 10 and the second group of electrolysis units 10 and connecting a current monitor to each electrolysis unit 10, the optimal current density can be adjusted. In addition, the cell voltage of each electrolysis unit 10 may be controlled to supply current. Furthermore, the reduction product may be selectively changed by controlling the voltage and current of the electrolytic unit 10 of the second group.

[0104] When the cathode fluid contains a first gas of a reduction target and a second gas of an impurity, and the second gas is nitrogen, the first group of electrolysis units 10 can reduce nitrogen to produce ammonia, and the second group of electrolysis units 10 can reduce the reduction target such as carbon dioxide to produce reduction products such as carbon compounds.

[0105] The cathode 11 in the first group of electrolysis units 10 may have a first catalyst, and the cathode 11 in the second group of electrolysis units 10 may have a second catalyst. The first catalyst is different from the second catalyst. An example of the first catalyst is platinum or its alloy. An example of the second catalyst is gold. By selecting the best catalyst for each electrolysis unit 10 according to the main product, the electrolysis efficiency of the electrolysis device can be further improved.

[0106] The electrolysis device 1 can also be applied to an electrolysis system, for example. The electrolysis system can also include a control device, for example. Through the control device, for example, the power supply voltage or power supply current from the power supply 40 can be controlled. In addition, through the control device, for example, the flow rate of the cathode fluid from the cathode supply source 20 can be controlled. And, through the control device, for example, the flow rate of the anode fluid from the anode supply source 30 can be controlled. The control device includes, for example: hardware with a computing device such as a processor. In addition, each action can also be stored as an action program in a recording medium such as a computer-readable memory, and the action program stored in the recording medium can be appropriately read out by hardware to perform each action.

[0107] The above-mentioned configuration examples of the electrolysis device 1 can be combined as appropriate.

[0108] In addition, the structures of the above-mentioned embodiments can be used in combination, and a part of them can also be replaced. Here, several embodiments of the present invention are described, but these embodiments are proposed as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, replacements, changes, etc. can be made without departing from the scope of the main purpose of the invention. These embodiments and their variations are included in the scope and main purpose of the invention, and are also included in the invention described in the claims and the scope of their equivalents.

[0109] The above embodiments can be summarized into the following technical solutions:

[0110] (Technical Solution 1)

[0111] An electrolysis device, comprising:

[0112] A first electrolytic unit reduces the reduction target and oxidizes the oxidation target;

[0113] a second electrolysis unit, reducing the reduction target and oxidizing the oxidation target;

[0114] a first supply source for supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit;

[0115] a second supply source that supplies a second fluid containing a liquid of the oxidation target to the first electrolysis unit and the second electrolysis unit; and

[0116] at least one power supply for supplying a first power supply current to the first electrolysis unit and a second power supply current to the second electrolysis unit,

[0117] The at least one power supply sets the value of the first power supply current and the value of the second power supply current so that the current density of the current flowing through the second electrolytic cell when reducing the reduction object is higher than the current density of the current flowing through the first electrolytic cell when reducing the reduction object.

[0118] (Technical Solution 2)

[0119] According to the electrolysis device described in technical solution 1,

[0120] The first electrolysis unit has:

[0121] A first membrane electrode assembly having a first cathode, a first anode, and a first separator between the first cathode and the first anode;

[0122] a first cathode flow path plate having a first cathode flow path facing the first cathode; and

[0123] A first anode flow path plate having a first anode flow path facing the first anode,

[0124] The second electrolysis unit has:

[0125] A second membrane electrode assembly having a second cathode, a second anode, and a second separator between the second cathode and the second anode;

[0126] a second cathode flow path plate having a second cathode flow path facing the second cathode; and

[0127] A second anode flow path plate having a second anode flow path facing the second anode,

[0128] The electrolysis device further comprises:

[0129] a first cathode current collector electrically connected to the first cathode and the at least one power source;

[0130] a first anode current collector electrically connected to the first anode and the at least one power source;

[0131] a second cathode current collector electrically connected to the second cathode and the at least one power source; and

[0132] The second anode current collector is electrically connected to the second anode and the at least one power source.

[0133] (Technical Solution 3)

[0134] According to the electrolysis device described in technical solution 2,

[0135] The second cathode flow path is connected in series with the first cathode flow path.

[0136] (Technical Solution 4)

[0137] According to the electrolysis device described in technical solution 2,

[0138] The second cathode flow path is connected in parallel with the first cathode flow path.

[0139] (Technical Solution 5)

[0140] The electrolysis device according to any one of technical solutions 2 to 4,

[0141] comprising a power source that supplies the first power source current to the first electrolytic cell via the first cathode current collector and the first anode current collector, and supplies the second power source current to the second electrolytic cell via the second cathode current collector and the second anode current collector,

[0142] The first cathode current collector, the first anode current collector, the second cathode current collector, and the second anode current collector are electrically connected to the at least one power source.

[0143] (Technical Solution 6)

[0144] The electrolysis device according to any one of technical solutions 2 to 4,

[0145] The at least one power source comprises:

[0146] a first power source that supplies the first power source current to the first electrolytic cell via the first cathode current collector and the first anode current collector; and

[0147] The second power supply supplies the second power supply current to the second electrolytic cell via the second cathode current collector and the second anode current collector.

[0148] (Technical Solution 7)

[0149] The electrolysis device according to any one of technical solutions 1 to 6,

[0150] The first fluid comprises a first gas and a second gas,

[0151] The first gas is carbon dioxide gas,

[0152] The second gas is a gas of a substance different from the carbon dioxide,

[0153] The first electrolysis unit and the second electrolysis unit reduce the carbon dioxide and reduce the substance,

[0154] The reduction potential of the carbon dioxide is higher than the reduction potential of the substance.

[0155] (Technical Solution 8)

[0156] According to the electrolysis device described in technical solution 7,

[0157] The substance is oxygen.

[0158] (Technical Solution 9)

[0159] According to the electrolysis device described in technical solution 7,

[0160] The substance is nitrogen.

[0161] (Technical Solution 10)

[0162] The electrolysis device according to any one of technical solutions 7 to 9,

[0163] A concentration of the second gas in the first fluid is greater than or equal to 1 ppm and less than or equal to 100,000 ppm.

[0164] (Technical Solution 11)

[0165] The electrolysis device according to any one of technical solutions 2 to 6,

[0166] A third electrolytic unit is further provided between the second cathode current collector and the second anode current collector,

[0167] The third electrolysis unit has:

[0168] The third cathode;

[0169] The third anode;

[0170] a third diaphragm, located between the third cathode and the third anode;

[0171] A third cathode flow path plate having a third cathode flow path facing the third cathode; and

[0172] a fourth anode flow path plate having a third anode flow path facing the third anode,

[0173] The third cathode is electrically connected to the second anode, or the third anode is electrically connected to the second cathode.

[0174] (Technical Solution 12)

[0175] The electrolysis device according to any one of technical solutions 2 to 7 further comprises:

[0176] a first pipe connecting the first electrolytic unit and the second electrolytic unit and supplying the first fluid from the first cathode flow path to the second cathode flow path; and

[0177] The second pipe connects the first electrolysis unit and the second electrolysis unit, and supplies the second fluid from the first anode flow path to the second anode flow path.

[0178] (Technical Solution 13)

[0179] The electrolysis device according to any one of technical solutions 2 to 6 and technical solution 12,

[0180] The first cathode has a first catalyst,

[0181] The second cathode has a second catalyst,

[0182] The first catalyst is different from the second catalyst.

[0183] (Technical Solution 14)

[0184] The electrolysis device according to any one of technical solutions 2 to 6, technical solutions 12 and technical solutions 13,

[0185] The first fluid comprises carbon dioxide gas,

[0186] The first electrolysis unit reduces carbon dioxide in the first cathode to generate carbon compounds,

[0187] The second electrolysis unit reduces carbon dioxide in the second cathode to generate the carbon compound.

[0188] (Technical Solution 15)

[0189] The electrolysis device according to any one of technical solutions 2 to 6, technical solutions 12 and technical solutions 13,

[0190] The first fluid comprises nitrogen,

[0191] The first electrolysis unit reduces nitrogen in the first cathode to produce ammonia,

[0192] The second electrolysis unit reduces nitrogen in the second cathode to produce ammonia.

[0193] (Technical Solution 16)

[0194] The electrolysis device according to any one of technical solutions 2 to 15,

[0195] The first electrolysis unit comprises:

[0196] A first membrane electrode assembly having the first cathode, the first anode and the first diaphragm;

[0197] A first support plate surrounds the first membrane electrode assembly and has a first opening and a second opening;

[0198] a first cathode flow path plate having the first cathode flow path connected to the first opening, a third opening connected to the first cathode flow path, and a fourth opening connected to the second opening;

[0199] a first anode flow path plate having the first anode flow path connected to the second opening, a fifth opening connected to the first opening, and a sixth opening connected to the first anode flow path;

[0200] The first cathode current collector has a seventh opening connected to the third opening and an eighth opening connected to the fourth opening;

[0201] The first anode current collector has a ninth opening connected to the fifth opening and a tenth opening connected to the sixth opening;

[0202] The second electrolysis unit comprises:

[0203] A second membrane electrode assembly having the second cathode, the second anode and the second separator;

[0204] a second supporting plate, surrounding the second membrane electrode assembly, and having an eleventh opening and a twelfth opening;

[0205] a second cathode flow path plate having the second cathode flow path connected to the eleventh opening, a thirteenth opening connected to the second cathode flow path, and a fourteenth opening connected to the twelfth opening;

[0206] a second anode flow path plate having the second anode flow path connected to the twelfth opening, a fifteenth opening connected to the eleventh opening, and a sixteenth opening connected to the second anode flow path;

[0207] The second cathode current collector has a seventeenth opening connected to the thirteenth opening and an eighteenth opening connected to the fourteenth opening; and

[0208] The second anode current collector has a nineteenth opening connected to the fifteenth opening and a twentieth opening connected to the sixteenth opening.

[0209] (Technical Solution 17)

[0210] The electrolysis device according to technical solution 16 further includes an insulating layer, which is arranged between the first electrolysis unit and the second electrolysis unit and has a twenty-first opening connecting the ninth opening and the fourteenth opening and a twenty-second opening connecting the tenth opening and the thirteenth opening.

[0211] (Technical Solution 18)

[0212] An electrolysis system comprises an electrolysis device according to any one of technical solutions 1 to 17.

[0213] (Technical Solution 19)

[0214] A method for operating an electrolysis device,

[0215] The electrolysis device comprises:

[0216] A first electrolytic unit reduces the reduction target and oxidizes the oxidation target;

[0217] a second electrolysis unit, reducing the reduction target and oxidizing the oxidation target;

[0218] a first supply source for supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit;

[0219] a second supply source that supplies a second fluid containing a liquid of the oxidation target to the first electrolysis unit and the second electrolysis unit; and

[0220] at least one power supply for supplying a first power supply current to the first electrolysis unit and a second power supply current to the second electrolysis unit,

[0221] The operation method is as follows:

[0222] supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit, and supplying a second fluid containing a liquid of the oxidation target to the first electrolysis unit and the second electrolysis unit;

[0223] supplying the first power supply current to the first electrolytic cell to reduce the reduction target, and supplying the second power supply current to the second electrolytic cell to reduce the reduction target; and

[0224] The current density of the current flowing through the second electrolytic cell when reducing the reduction target is higher than the current density of the current flowing through the first electrolytic cell when reducing the reduction target.

Claims

1. An electrolysis device comprising: A first electrolytic unit reduces the reduction target and oxidizes the oxidation target; a second electrolysis unit, reducing the reduction target and oxidizing the oxidation target; a first supply source for supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit; a second supply source for supplying a second fluid containing the oxidizable object as a liquid to the first electrolysis unit and the second electrolysis unit; as well as at least one power supply for supplying a first power supply current to the first electrolysis unit and a second power supply current to the second electrolysis unit, The at least one power supply sets the value of the first power supply current and the value of the second power supply current so that the current density of the current flowing through the second electrolytic cell when reducing the reduction object is higher than the current density of the current flowing through the first electrolytic cell when reducing the reduction object.

2. The electrolysis device according to claim 1, The first electrolysis unit has: A first membrane electrode assembly having a first cathode, a first anode, and a first separator between the first cathode and the first anode; A first cathode flow path plate having a first cathode flow path facing the first cathode; as well as A first anode flow path plate having a first anode flow path facing the first anode, The second electrolysis unit has: A second membrane electrode assembly having a second cathode, a second anode, and a second separator between the second cathode and the second anode; A second cathode flow path plate having a second cathode flow path facing the second cathode; as well as A second anode flow path plate having a second anode flow path facing the second anode, The electrolysis device further comprises: a first cathode current collector electrically connected to the first cathode and the at least one power source; a first anode current collector electrically connected to the first anode and the at least one power source; a second cathode current collector electrically connected to the second cathode and the at least one power source; as well as The second anode current collector is electrically connected to the second anode and the at least one power source.

3. The electrolysis device according to claim 2, The second cathode flow path is connected in series with the first cathode flow path.

4. The electrolysis device according to claim 2, The second cathode flow path is connected in parallel with the first cathode flow path.

5. The electrolysis device according to any one of claims 2 to 4, The at least one power source includes a power source that supplies the first power source current to the first electrolytic cell via the first cathode current collector and the first anode current collector, and supplies the second power source current to the second electrolytic cell via the second cathode current collector and the second anode current collector, The first cathode current collector, the first anode current collector, the second cathode current collector, and the second anode current collector are electrically connected to the power source.

6. The electrolysis device according to any one of claims 2 to 4, The at least one power source comprises: a first power source, supplying the first power source current to the first electrolytic unit via the first cathode current collector and the first anode current collector; as well as The second power supply supplies the second power supply current to the second electrolytic cell via the second cathode current collector and the second anode current collector.

7. The electrolysis device according to any one of claims 1 to 6, The first fluid comprises a first gas and a second gas, The first gas is carbon dioxide gas, The second gas is a gas of a substance different from the carbon dioxide, The first electrolysis unit and the second electrolysis unit reduce the carbon dioxide and reduce the substance, The reduction potential of the carbon dioxide is higher than the reduction potential of the substance.

8. The electrolysis device according to claim 7, The substance is oxygen.

9. The electrolysis device according to claim 7, The substance is nitrogen.

10. The electrolysis device according to any one of claims 7 to 9, A concentration of the second gas in the first fluid is greater than or equal to 1 ppm and less than or equal to 100,000 ppm.

11. The electrolysis device according to any one of claims 2 to 6, A third electrolytic unit is further provided between the second cathode current collector and the second anode current collector, The third electrolysis unit has: The third cathode; The third anode; a third separator between the third cathode and the third anode; A third cathode flow path plate having a third cathode flow path facing the third cathode; as well as a fourth anode flow path plate having a third anode flow path facing the third anode, The third cathode is electrically connected to the second anode, or the third anode is electrically connected to the second cathode.

12. The electrolysis device according to any one of claims 2 to 7, further comprising: a first pipe connecting the first electrolytic unit and the second electrolytic unit and supplying the first fluid from the first cathode flow path to the second cathode flow path; and The second pipe connects the first electrolysis unit and the second electrolysis unit, and supplies the second fluid from the first anode flow path to the second anode flow path.

13. The electrolysis device according to any one of claims 2 to 6 and 12, The first cathode has a first catalyst, The second cathode has a second catalyst, The first catalyst is different from the second catalyst.

14. The electrolysis device according to any one of claims 2 to 6, 12, and 13, The first fluid comprises carbon dioxide gas, The first electrolysis unit reduces carbon dioxide in the first cathode to generate carbon compounds, The second electrolysis unit reduces carbon dioxide in the second cathode to generate the carbon compound.

15. The electrolysis device according to any one of claims 2 to 6, 12, and 13, The first fluid comprises nitrogen, The first electrolysis unit reduces nitrogen in the first cathode to produce ammonia, The second electrolysis unit reduces nitrogen in the second cathode to produce ammonia.

16. The electrolysis device according to any one of claims 2 to 6 and 12 to 15, The first electrolysis unit comprises: A first membrane electrode assembly having the first cathode, the first anode and the first diaphragm; A first support plate surrounds the first membrane electrode assembly and has a first opening and a second opening; a first cathode flow path plate having the first cathode flow path connected to the first opening, a third opening connected to the first cathode flow path, and a fourth opening connected to the second opening; a first anode flow path plate having the first anode flow path connected to the second opening, a fifth opening connected to the first opening, and a sixth opening connected to the first anode flow path; The first cathode current collector has a seventh opening connected to the third opening and an eighth opening connected to the fourth opening; The first anode current collector has a ninth opening connected to the fifth opening and a tenth opening connected to the sixth opening; The second electrolysis unit comprises: A second membrane electrode assembly having the second cathode, the second anode and the second separator; a second supporting plate, surrounding the second membrane electrode assembly, and having an eleventh opening and a twelfth opening; a second cathode flow path plate having the second cathode flow path connected to the eleventh opening, a thirteenth opening connected to the second cathode flow path, and a fourteenth opening connected to the twelfth opening; a second anode flow path plate having the second anode flow path connected to the twelfth opening, a fifteenth opening connected to the eleventh opening, and a sixteenth opening connected to the second anode flow path; The second cathode current collector has a seventeenth opening connected to the thirteenth opening and an eighteenth opening connected to the fourteenth opening; as well as The second anode current collector has a nineteenth opening connected to the fifteenth opening and a twentieth opening connected to the sixteenth opening.

17. The electrolysis device according to claim 16, The device further includes an insulating layer provided between the first electrolytic unit and the second electrolytic unit and having a twenty-first opening connecting the ninth opening and the fourteenth opening and a twenty-second opening connecting the tenth opening and the thirteenth opening.

18. An electrolysis system comprising the electrolysis device according to any one of claims 1 to 17.

19. A method for operating an electrolysis device, The electrolysis device comprises: A first electrolytic unit reduces the reduction target and oxidizes the oxidation target; a second electrolysis unit, reducing the reduction target and oxidizing the oxidation target; a first supply source for supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit; a second supply source for supplying a second fluid containing the oxidizable object as a liquid to the first electrolysis unit and the second electrolysis unit; as well as at least one power supply for supplying a first power supply current to the first electrolysis unit and a second power supply current to the second electrolysis unit, The operation method is as follows: supplying a first fluid containing a gas of the reduction target to the first electrolysis unit and the second electrolysis unit, and supplying a second fluid containing a liquid of the oxidation target to the first electrolysis unit and the second electrolysis unit; supplying the first power supply current to the first electrolytic unit to reduce the reduction target, and supplying the second power supply current to the second electrolytic unit to reduce the reduction target; as well as The current density of the current flowing through the second electrolytic cell when reducing the reduction target is higher than the current density of the current flowing through the first electrolytic cell when reducing the reduction target.

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