Electrochemical reaction apparatus and operation method thereof

Abstract

To improve the utilization efficiency of a carbon dioxide.SOLUTION: An electrochemical reaction apparatus comprises: an electrochemical reaction structure including a cathode, an anode, a diaphragm between the cathode and the anode, a cathode chamber, and an anode chamber; a first flow path through which a first fluid flows, being connected to the inlet of the cathode chamber; a second flow path through which a second fluid flows; a third flow path through which a third fluid flows; a fourth flow path through which a fourth fluid flows; at least one of the controllers selected from a group consisting of a first flow-controller, a second flow-controller, a first pressure controller, a second pressure controller, a temperature controller, and a power supply, and including at least the first flow-controller; a gas-liquid separator arranged in the middle of the fourth flow path; a first flow meter for measuring the flow rate of the third fluid; a second flow meter for measuring the flow rate of the fourth fluid; and a control device that measures the sum of the flow rate of the first fluid, the flow rate of the third fluid, and the flow rate of the fourth fluid, controls at least one of the controllers according to the measured sum, and adjusts the difference of pressure between the cathode chamber and the anode chamber.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to an electrochemical reactor. [Background technology]

[0002] In recent years, there are concerns about the depletion of fossil fuels such as oil and coal, and expectations are growing for sustainable renewable energy. From the perspective of such energy issues and environmental issues, development of Power to Chemicals (P2C) technology is underway to electrochemically reduce carbon dioxide using renewable energy such as sunlight to create a storable chemical energy source. Electrochemical reaction devices such as carbon dioxide reactors including electrolysis devices that realize P2C technology include an anode that oxidizes water (H2O) to generate oxygen (O2), and a cathode that reduces carbon dioxide (CO2) to generate carbon compounds. The anode and cathode of the carbon dioxide reactor are connected to a power source derived from renewable energy such as solar power generation, hydroelectric power generation, wind power generation, and geothermal power generation.

[0003] The cathode of the carbon dioxide reactor is, for example, immersed in water containing dissolved carbon dioxide, or is arranged so as to be in contact with the carbon dioxide flowing through a flow path. The cathode obtains a reduction potential for carbon dioxide from a power source derived from renewable energy, and reduces the carbon dioxide to produce carbon compounds such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH3OH), methane (CH4), ethanol (C2H5OH), ethane (C2H6), ethylene (C2H4), formaldehyde (HCHO), ethylene glycol (C2H6O2), acetic acid (CH3COOH), and propanol (C3H7OH). The anode is arranged so as to be in contact with an electrolyte solution containing water, and generates oxygen and hydrogen ions (H + In such a carbon dioxide reaction apparatus, there is a demand for improving the utilization efficiency of carbon dioxide, and further the utilization efficiency and value of the reduction product of carbon dioxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-506165 [Patent Document 2] JP 2018-070936 A [Patent Document 3] Patent Publication No. 2021-46574 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the embodiments of the present invention is to increase the efficiency of carbon dioxide utilization. [Means for solving the problem]

[0006] The electrochemical reaction device of the embodiment includes an electrochemical reaction structure including a cathode having a reduction catalyst that promotes a reduction reaction to reduce carbon dioxide to produce carbon compounds, an anode having an oxidation catalyst that promotes an oxidation reaction to oxidize water to produce oxygen, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode, and an anode chamber facing the anode, a first flow path connected to an inlet of the cathode chamber and through which a first fluid containing carbon dioxide to be supplied to the cathode chamber flows, a second flow path connected to an inlet of the anode chamber and through which a second fluid containing water to be supplied to the anode chamber flows, a third flow path connected to an outlet of the cathode chamber and through which a third fluid discharged from the cathode chamber and containing the produced carbon compounds flows, a fourth flow path connected to an outlet of the anode chamber and through which a fourth fluid discharged from the anode chamber and containing water and the produced oxygen flows, a first flow regulator that adjusts the flow rate of the first fluid flowing through the first flow path, and a second flow regulator that adjusts the flow rate of the second fluid flowing through the second flow path. at least one regulator including at least a first flow regulator, selected from the group consisting of a pressure regulator for regulating the pressure of the third flow path, a first pressure regulator for regulating the pressure of the fourth flow path, a temperature regulator for regulating the temperature of the electrochemical reaction structure, and a power source for regulating the current or voltage supplied to the electrochemical reaction structure; a gas-liquid separator provided midway through the fourth flow path for treating the fourth fluid and separating a liquid including water from the fourth fluid; and a flow rate controller for measuring the flow rate of the third fluid flowing through the third flow path. The system includes a first flow meter, a second flow meter that measures the flow rate of the processed fourth fluid flowing through the fourth flow path, and a control device connected to each of the at least one regulator, the first flow meter, and the second flow meter, and that measures the sum of the flow rate of the first fluid flowing through the first flow path, the flow rate of the third fluid flowing through the third flow path, and the flow rate of the processed fourth fluid flowing through the fourth flow path, and controls the at least one regulator in accordance with the value of the measured sum to adjust the pressure difference between the cathode chamber and the anode chamber. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing a configuration example of an electrochemical reaction device according to an embodiment; [Diagram 2]FIG. 2 is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment. [Diagram 3] FIG. 2 is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment. [Figure 4] FIG. 2 is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment. [Diagram 5] FIG. 2 is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment. [Figure 6] FIG. 2 is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described with reference to the drawings. In each embodiment shown below, substantially the same components are denoted by the same reference numerals, and some of the descriptions thereof may be omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each part, etc. may differ from the actual ones.

[0009] In this specification, unless otherwise specified, "connect" may include not only a direct connection but also an indirect connection.

[0010] Fig. 1 is a schematic diagram showing a configuration example of an electrochemical reaction device. Fig. 1 shows a configuration example of an electrochemical reaction device 1. The electrochemical reaction device 1 has an electrochemical reaction structure 10, a flow path P1, a flow path P2, a flow path P3, a flow path P4, a flow regulator 21, a flow regulator 22, a humidifier 30, a pressure regulator 41, a pressure regulator 42, a dehydrator 51, a gas-liquid separator 52, a flow meter 61, a flow meter 62, a power source 70, and a control device 80.

[0011] The electrochemical reaction structure 10 includes a cathode 11 , an anode 12 , a membrane 13 , a flow path plate 14 , a flow path plate 15 , a current collector 16 , and a current collector 17 .

[0012] The cathode 11 is, for example, a reduction electrode for performing a reduction reaction of at least one reduction target (substance to be reduced). The at least one reduction target includes, for example, carbon dioxide. The cathode 11 reduces, for example, carbon dioxide supplied as a gas or carbon dioxide contained in a first electrolytic solution (cathode solution) to generate a carbon compound. Examples of the carbon compound include carbon monoxide, formic acid, methanol, methane, ethanol, ethane, ethylene, formaldehyde, ethylene glycol, acetic acid, propanol, and the like. The cathode 11 may cause a side reaction of generating hydrogen by a reduction reaction of water in addition to the reduction reaction of carbon dioxide.

[0013] The cathode 11 has, for example, a reduction catalyst that promotes a reduction reaction that reduces carbon dioxide to produce a carbon compound. The reduction catalyst can be formed, for example, using a material that reduces the activation energy for reducing carbon dioxide. In other words, the reduction catalyst can be formed, for example, using a material that reduces the overvoltage that occurs when carbon dioxide is reduced to produce a carbon compound.

[0014] The cathode 11 can be formed, for example, using a metal material or a carbon material. Examples of the metal material include metals such as gold, aluminum, copper, silver, platinum, palladium, zinc, mercury, indium, nickel, and titanium, and alloys containing the metals. Examples of the carbon material include graphene, carbon nanotubes (CNTs), fullerene, and Ketjen black. The cathode 11 is not limited to these materials, and may be formed, for example, using a metal complex such as a Ru complex or a Re complex, or an organic molecule having an imidazole skeleton or a pyridine skeleton. The cathode 11 may be formed using a mixture of a plurality of materials. The cathode 11 may have a structure in which a reduction catalyst having a shape such as a thin film, a lattice, a particle, or a wire is provided on a conductive substrate. The type of carbon compound generated by the reduction reaction also varies depending on the type of the reduction catalyst.

[0015] The anode 12 is, for example, an oxidation electrode for carrying out an oxidation reaction of at least one oxidation target (substance to be oxidized). The at least one oxidation target includes, for example, water. The anode 12 oxidizes, for example, the oxidation target, such as a substance or ions, in a second electrolyte (anode solution) to generate oxygen.

[0016] The anode 12 has an oxidation catalyst that promotes an oxidation reaction that oxidizes water to produce oxygen. The oxidation catalyst can be formed using, for example, a material that reduces the activation energy when an object to be oxidized is oxidized, in other words, a material that reduces the reaction overvoltage. Examples of oxidation reactions at the anode 12 include a reaction that oxidizes water to produce oxygen or hydrogen peroxide, and a reaction that oxidizes chloride ions (Cl - ) to produce chlorine, and the oxidation of carbonate ions or bicarbonate ions to produce carbon dioxide.

[0017] Examples of the oxidation catalyst include metal materials. Examples of the metal materials include ruthenium, iridium, platinum, cobalt, nickel, iron, manganese, tantalum, zirconium, etc. Examples of the metal materials include binary metal oxides, ternary metal oxides, quaternary metal oxides, etc. Examples of the binary metal oxides include 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), etc. Examples of the ternary metal oxides include nickel-iron oxide (Ni-Fe-O), nickel-cobalt oxide (Ni-Co-O), lanthanum-cobalt oxide (La-Co-O), nickel-lanthanum oxide (Ni-La-O), strontium-iron oxide (Sr-Fe-O), etc. Examples of quaternary metal oxides include lead-ruthenium-iridium oxide (Pb-Ru-Ir-O) and lanthanum-strontium-cobalt oxide (La-Sr-Co-O). The oxidation catalyst is not limited to these materials, and may be formed using metal hydroxides containing metals such as cobalt, nickel, iron, and manganese, or metal complexes such as ruthenium complexes and iron complexes. The oxidation catalyst may also be formed by mixing a plurality of materials.

[0018] The anode 12 may be formed using a composite material including both an oxidation catalyst and a conductive material. Examples of the conductive material include carbon materials such as carbon black, activated carbon, fullerene, carbon nanotubes, graphene, ketjen black, and diamond; transparent conductive oxides such as indium tin oxide (ITO), zinc oxide (ZnO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), and antimony-doped tin oxide (ATO); metals such as copper, aluminum, titanium, nickel, silver, tungsten, cobalt, and gold; and alloys including at least one of these metals. The anode 12 may include a structure having an oxidation catalyst having a shape such as a thin film, a lattice, a particle, or a wire on a conductive substrate. The conductive substrate can be formed using a metal material including, for example, titanium, a titanium alloy, or stainless steel.

[0019] The diaphragm 13 is provided between the cathode 11 and the anode 12. The diaphragm 13 can separate the cathode chamber 140 and the anode chamber 150. The diaphragm 13 is capable of blocking hydrogen ions (H + ) and hydroxide ions (OH - ), hydrogen carbonate ion (HCO3 - ), carbonate ion (CO3 2- ) can move. An electrochemical reaction cell having a two-chamber structure can be formed by the diaphragm 13. The diaphragm 13 may be provided in contact with the cathode 11 and the anode 12.

[0020] The diaphragm 13 can be formed, for example, using a membrane that allows anions or cations to pass selectively. This allows the composition of the second electrolytic solution in contact with the anode 12 to be different from the composition of the first electrolytic solution in contact with the cathode 11, and further allows the reduction reaction or the oxidation reaction to be promoted by differences in ionic strength, pH, and the like. The diaphragm 13 may have a function of allowing some ions contained in the electrolytic solution in which the cathode 11 and the anode 12 are immersed to pass through, that is, a function of blocking one or more types of ions contained in the electrolytic solution. This allows, for example, the pH and the like to be different between the two electrolytic solutions. In addition, with regard to blocking of ions, a diaphragm that does not completely block some ions but is effective to the extent of limiting the amount of movement of ion species may be used.

[0021] The diaphragm 13 can be formed using an ion exchange membrane such as NeoSepta (registered trademark) from Astom Corporation, Selemion (registered trademark), Aciplex (registered trademark) from Asahi Glass Co., Ltd., Fumasep (registered trademark) and fumapem (registered trademark) from Fumatech Corporation, Nafion (registered trademark) which is a fluororesin obtained by sulfonating and polymerizing tetrafluoroethylene from DuPont Corporation, lewabrane (registered trademark) from LANXESS Corporation, IONSEP (registered trademark) from IONTECH Corporation, Mustang (registered trademark) from PALL Corporation, ralex (registered trademark) from mega Corporation, Gore-Tex (registered trademark) from Gore-Tex Corporation, Sustainion (registered trademark) from DIOXIDEMATERIALS Corporation, and PiperION (registered trademark) from Versogen Corporation. The ion exchange membrane may be formed using a membrane having a basic skeleton of a hydrocarbon, for example. The anion exchange membrane may be formed using a membrane having an amine group, for example. When there is a pH difference between the first and second electrolytic solutions, the pH of each electrolytic solution can be stably maintained when the diaphragm 13 is formed using a bipolar membrane in which a cation exchange membrane and an anion exchange membrane are laminated.

[0022] The diaphragm 13 may be formed using a material such as a fluorine-based resin, such as silicone resin, perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyethersulfone (PES), a ceramic porous membrane, a filler filled with a glass filter, agar, or the like, an insulating porous body, such as zeolite or an oxide, etc. In particular, a hydrophilic porous membrane is preferable as a material for the diaphragm 13 because it can suppress clogging due to air bubbles.

[0023] The cathode 11, the anode 12, and the diaphragm 13 are stacked to form an electrochemical reaction cell. The electrochemical reaction structure 10 may have a cell stack formed by stacking a plurality of electrochemical reaction cells. By forming a cell stack, the reaction amount of carbon dioxide per unit area increases, so that the amount of carbon compounds produced can be increased. The number of stacked electrochemical reaction cells is preferably, for example, 10 or more and 150 or less.

[0024] The flow path plate 14 forms a cathode chamber 140. The cathode chamber 140 is provided on the surface of the flow path plate 14 facing the cathode 11, and can form a cathode flow path. The cathode chamber 140 has an inlet for supplying a fluid to the cathode chamber 140, and an outlet for discharging the fluid from the cathode chamber 140. The surface shape of the cathode flow path is not particularly limited, but is, for example, serpentine.

[0025] The flow path plate 15 forms an anode chamber 150. The anode chamber 150 is provided on the surface of the flow path plate 15 facing the anode 12, and can form an anode flow path. The anode chamber 150 has an inlet for supplying a fluid to the anode chamber 150, and an outlet for discharging the fluid from the anode chamber 150. The surface shape of the anode flow path is not particularly limited, but is, for example, serpentine.

[0026] The electrolytic reactions such as oxidation and reduction reactions by the electrochemical reaction structure 10 are preferably carried out at a temperature between room temperature (e.g., 25°C) and 100°C, at which the electrolyte does not vaporize. The temperature is preferably between 60°C and 95°C, and more preferably between 60°C and 80°C. In order to maintain a temperature below room temperature, a cooling device such as a chiller is required, which may reduce the energy efficiency of the overall system. At temperatures above 100°C, the water in the electrolyte turns into steam, increasing the resistance and reducing the efficiency of electrolysis.

[0027] The current density of the cathode 11 is not particularly limited, but in order to increase the amount of reduction product produced per unit area, a high current density is preferable. 2 More than 1.5A / cm 2 Preferably less than 300 mA / cm 2 More than 700mA / cm 2 Less than 100mA / cm 2 Below 1.5A / cm, the amount of reduction product generated per unit area is low, and a large area is required. 2 Above this value, the side reaction of hydrogen generation increases and the concentration of reduction products decreases.

[0028] If Joule heat increases due to an increase in current density, the temperature will rise above an appropriate level, so a cooling mechanism may be provided on the electrochemical reaction structure 10 or in its vicinity. The cooling mechanism may be water-cooled or air-cooled. Even if the temperature of the electrochemical reaction structure 10 is higher than room temperature, it may be left at that temperature as long as it is 100° C. or lower.

[0029] The flow path P1 is connected to the inlet of the cathode chamber 140. The flow path P1 allows a cathode supply fluid to flow to the cathode chamber 140. The cathode supply fluid contains carbon dioxide. The cathode supply fluid may be a gas containing gaseous carbon dioxide or a first electrolyte containing carbon dioxide.

[0030] The flow path P1 may be connected to a carbon dioxide supply source. The carbon dioxide supply source may have a carbon dioxide capture device or may be connected to the carbon dioxide capture device. Carbon dioxide gas from the carbon dioxide capture device can be supplied to the flow path P1, for example, directly or after being temporarily stored. Examples of the carbon dioxide supply source include, for example, thermal power plants, facilities having various incinerators and combustion furnaces such as garbage incinerators, steel mills, facilities having blast furnaces, etc. The carbon dioxide supply source is not limited to these facilities and may be other factories that generate carbon dioxide.

[0031] The flow path P2 is connected to the inlet of the anode chamber 150. The flow path P2 allows the anode supply fluid to flow through the anode chamber 150. The anode supply fluid includes water or a second electrolyte. The flow path P2 may be connected to an anode solution supply source. The anode solution supply source may supply, for example, the second electrolyte used in the anode supply fluid.

[0032] The flow path P3 is connected to the outlet of the cathode chamber 140. The flow path P3 allows a cathode exhaust fluid discharged from the cathode chamber 140 to flow. The cathode exhaust fluid contains carbon compounds and hydrogen produced by the reduction reaction at the cathode 11, and a portion of the carbon dioxide gas contained in the cathode supply fluid or a portion of the first electrolytic solution.

[0033] The flow path P4 is connected to the outlet of the anode chamber 150. The flow path P4 allows the flow of an anode exhaust fluid discharged from the anode chamber 150. The anode exhaust fluid contains, for example, gaseous oxygen produced by an oxidation reaction in the anode 12, carbon dioxide moving from the cathode chamber 140 or the electrolyte, and water or a portion of the second electrolyte contained in the anode supply fluid.

[0034] When a gas (cathode gas) containing a substance to be reduced such as carbon dioxide is supplied to the cathode chamber 140, the electrochemical reaction structure 10 may have a second cathode chamber between the cathode 11 and the diaphragm 13, and the first electrolytic solution may be supplied to the second cathode chamber. Fig. 2 is a schematic diagram showing another configuration example of the electrochemical reaction device of the embodiment. As shown in Fig. 2, the electrochemical reaction device 1 may further have a flow path plate 18, a cathode chamber 180, a flow path P5, and a flow path P6.

[0035] The flow path plate 18 forms a cathode chamber 180. The cathode chamber 180 is provided on the surface of the flow path plate 18 facing the cathode 11, and can form a second cathode flow path. The cathode chamber 180 is disposed on the opposite side of the cathode 11 to the cathode chamber 140. The cathode chamber 180 has an inlet for supplying a fluid to the cathode chamber 180 and an outlet for discharging the fluid from the cathode chamber 180.

[0036] The flow path P5 is connected to the inlet of the cathode chamber 180. The flow path P5 can carry a second cathode supply fluid to be supplied to the cathode chamber 180. The second cathode supply fluid includes a first electrolyte. The first electrolyte may or may not include carbon dioxide. The flow path P5 can be connected to a catholyte supply source. The catholyte supply source can, for example, supply the first electrolyte used in the second cathode supply fluid. If the first electrolyte is the same as the second electrolyte, the flow path P5 can be connected to the above-mentioned anode solution supply source.

[0037] The flow path P6 is connected to the outlet of the cathode chamber 180. The flow path P6 allows the second cathode discharge fluid discharged from the cathode chamber 180 to flow. The second cathode discharge fluid contains carbon compounds and hydrogen produced by the reduction reaction at the cathode 11, and a first electrolytic solution. The second cathode discharge fluid may be reused by separating the gas component and the liquid component using a gas-liquid separator and then supplying the fluid to the flow path P5 as the first electrolytic solution. In this case, a pump may be further provided in another flow path connecting the flow path P5 and the flow path P6 or in the middle of the other flow path, and the separated liquid component may be returned to the flow path P5 by the pump.

[0038] The first electrolytic solution is preferably a solution having a high carbon dioxide absorption rate. The form of carbon dioxide in the first electrolytic solution is not necessarily limited to a dissolved state, and carbon dioxide in the form of bubbles may be mixed and present in the first electrolytic solution. Examples of the electrolytic solution containing carbon dioxide include aqueous solutions containing hydrogen carbonates or carbonates such as lithium hydrogen carbonate (LiHCO3), sodium hydrogen carbonate (NaHCO3), potassium hydrogen carbonate (KHCO3), cesium hydrogen carbonate (CsHCO3), sodium carbonate (Na2CO3), and potassium carbonate (K2CO3), phosphoric acid, boric acid, and the like. The electrolytic solution containing carbon dioxide may contain alcohols such as methanol and ethanol, or ketones such as acetone, or may be an alcohol solution or a ketone solution. The first electrolytic solution may be an electrolytic solution containing a carbon dioxide absorbent that reduces the reduction potential of carbon dioxide, has high ionic conductivity, and absorbs carbon dioxide.

[0039] The electrolytes such as the first electrolyte solution and the second electrolyte solution can be a solution containing water, for example, an aqueous solution containing any electrolyte. This solution is preferably an aqueous solution that promotes the oxidation reaction of water. The aqueous solution containing an electrolyte can be, for example, a solution containing phosphate ions (PO4 2- ), borate ion (BO3 3- ), sodium ion (Na + ), potassium ion (K + ), calcium ion (Ca 2+ ), lithium ion (Li + ), Cesium ion (Cs + ), magnesium ion (Mg 2+ ), chloride ion (Cl - ), hydrogen carbonate ion (HCO3 - ), carbonate ion (CO3 - ), hydroxide ion (OH - ) and the like.

[0040] The electrolyte described above is, for example, a mixture of a cation such as an imidazolium ion or a pyridinium ion and BF4 - or PF6- An ionic liquid or an aqueous solution thereof, which is composed of a salt with an anion such as ethanolamine, imidazole, pyridine, or the like and is in a liquid state over a wide temperature range, can be used. Further, other electrolyte solutions include amine solutions such as ethanolamine, imidazole, pyridine, or the like, or an aqueous solution thereof. Examples of amines include primary amines, secondary amines, and tertiary amines. These electrolyte solutions may have high ionic conductivity, a property of absorbing carbon dioxide, and a property of reducing reduction energy.

[0041] Examples of primary amines include methylamine, ethylamine, propylamine, butylamine, pentylamine, and hexylamine. The amine hydrocarbon may be substituted with an alcohol, a halogen, or the like. Examples of amines with substituted hydrocarbons include methanolamine, ethanolamine, and chloromethylamine. In addition, unsaturated bonds may be present. The same is true for secondary and tertiary amines.

[0042] Examples of secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, etc. The substituted hydrocarbon may be different. This is also true for tertiary amines. For example, examples of amines with different hydrocarbons include methylethylamine, methylpropylamine, etc.

[0043] Examples of the tertiary amine include trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trimethanolamine, triethanolamine, tripropanolamine, tributanolamine, trihexanolamine, methyldiethylamine, and methyldipropylamine.

[0044] Examples of the cation of the ionic liquid include a 1-ethyl-3-methylimidazolium ion, a 1-methyl-3-propylimidazolium ion, a 1-butyl-3-methylimidazole ion, a 1-methyl-3-pentylimidazolium ion, and a 1-hexyl-3-methylimidazolium ion.

[0045] The 2-position of the imidazolium ion may be substituted. Examples of cations substituted at the 2-position of the imidazolium ion include 1-ethyl-2,3-dimethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl-2,3-dimethylimidazolium ion, 1,2-dimethyl-3-pentylimidazolium ion, and 1-hexyl-2,3-dimethylimidazolium ion.

[0046] Examples of pyridinium ions include methylpyridinium, ethylpyridinium, propylpyridinium, butylpyridinium, pentylpyridinium, hexylpyridinium, etc. In both the imidazolium ion and the pyridinium ion, the alkyl group may be substituted, and an unsaturated bond may be present.

[0047] The anion is fluoride ion (F - ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), BF4 - , PF6 - , CF3COO - , CF3SO3 - , NO3 - , SCN - , (CF3SO2)3C - , bis(trifluoromethoxysulfonyl)imide, bis(trifluoromethoxysulfonyl)imide, bis(perfluoroethylsulfonyl)imide, etc. Zwitterions in which the cation and anion of the ionic liquid are connected by a hydrocarbon may also be used. A buffer solution such as a potassium phosphate solution may be supplied to the anode chamber 150 and the cathode chamber 180.

[0048] The second electrolyte contains water as the substance to be oxidized. The reactivity can be changed by changing the amount of water and the electrolyte components contained in the first and second electrolytes, and the selectivity of the reduced substance and the ratio of the generated substance can be changed. The first and second electrolytes may contain a redox couple as necessary. The redox couple can be Fe 3+ / Fe 2+ or IO 3- / I - etc.

[0049] The flow rate regulator 21 is provided midway through the flow path P1. The flow rate regulator 21 can adjust, for example, the flow rate of the cathode supply fluid flowing through the flow path P1. The flow rate regulator 21 may have, for example, a mass flow controller. The flow rate regulator 21 adjusts the flow rate of carbon dioxide introduced into the cathode chamber 140. The flow rate regulator 21 may have a function of adjusting the flow rate of the cathode supply fluid according to a control signal from the control device 80. The flow rate regulator 21 may, for example, measure the flow rate of the cathode supply fluid flowing through the flow path P1, and supply a data signal including data indicating the measured flow rate to the control device 80.

[0050] The flow rate regulator 22 is provided in the middle of the flow path P2. The flow rate regulator 22 can adjust, for example, the flow rate of the anode supply fluid flowing through the flow path P2. The flow rate regulator 22 may have, for example, a mass flow controller. The flow rate regulator 22 can also control the temperature of the electrochemical reaction structure 10 and move the gas generated in the anode chamber 150 to the flow path P4. The flow rate regulator 22 can measure, for example, the flow rate of the anode supply fluid flowing through the flow path P2 and supply the control device 80 with a data signal including data indicating the measured flow rate.

[0051] The humidifier 30 is provided in the middle of the flow path P1, before or after the flow rate regulator 21. The humidifier 30 can humidify the carbon dioxide gas in the cathode supply fluid. Examples of the humidifier 30 include humidifiers such as a bubbling type humidifier and a hollow fiber membrane type humidifier. As shown in FIG. 1, by disposing the humidifier 30 between the flow rate regulator 21 and the cathode chamber 140, it is possible to supply the cathode supply fluid containing carbon dioxide gas with an accurate supply amount to the cathode chamber 140 even after humidification. The electrochemical reaction device of the embodiment does not need to have the humidifier 30.

[0052] The cathode supply fluid containing humidified carbon dioxide gas may contain liquid in the form of mist or fume. The cathode supply fluid containing humidified carbon dioxide gas may contain water in a partially liquid state. In addition, the water may contain something that functions as a cathode solution, and may contain carbon dioxide as a substance to be reduced.

[0053] The pressure regulator 41 is provided in the middle of the flow path P3. The pressure regulator 41 can adjust the pressure in the cathode chamber 140 by controlling the pressure in the flow path P3. The pressure regulator 41 may have a function of adjusting the pressure in the cathode chamber 140 based on a control signal from the control device 80. The pressure regulator 41 may have a function of indirectly measuring the pressure in the cathode chamber 140 by measuring the pressure in the flow path P3.

[0054] The pressure regulator 42 is provided in the middle of the flow path P4. The pressure regulator 42 can adjust the pressure inside the anode chamber 150, for example, by controlling the pressure in the flow path P4. The pressure regulator 42 may have a function of adjusting the pressure in the anode chamber 150 based on a control signal from the control device 80. The pressure regulator 42 may have a function of indirectly measuring the pressure in the anode chamber 150 by measuring the pressure in the flow path P4.

[0055] The dehydrator 51 is provided in the middle of the flow path P3, for example, after the pressure regulator 41. The dehydrator 51 can, for example, process the cathode discharge fluid to separate water and the first electrolytic solution from the cathode discharge fluid. The dehydrator 51 may have a function of removing moisture in the exhaust gas by cooling or the like. By arranging the dehydrator 51 before the flowmeter 61, the flow rate of the gas containing carbon compounds in the cathode discharge fluid discharged from the cathode chamber 140 can be measured more accurately.

[0056] The gas-liquid separator 52 is provided midway through the flow path P4, for example, after the pressure regulator 42. The gas-liquid separator 52 can, for example, process the anode discharge fluid to separate liquids such as water and the electrolyte from the anode discharge fluid. The processed anode discharge fluid contains, for example, oxygen produced by an oxidation reaction in the anode 12 and carbon dioxide transferred from the cathode chamber 140. By providing the gas-liquid separator 52 before the flow meter 62, the flow rates of gases such as oxygen and carbon dioxide in the anode discharge fluid discharged from the anode chamber 150 can be measured more accurately.

[0057] The flow meter 61 is provided in the middle of the flow path P3, for example, at the rear of the dehydrator 51. The flow meter 61 can measure, for example, the flow rate of the treated cathode discharge fluid flowing through the flow path P3. The flow meter 61 can measure the total flow rate of gases such as carbon compounds, hydrogen, and unreacted carbon dioxide in the cathode discharge fluid.

[0058] The flow meter 62 is provided in the middle of the flow path P4, for example, after the gas-liquid separator 52. The flow meter 62 can measure, for example, the flow rate of the treated anode discharge fluid flowing through the flow path P4. The flow meter 62 can measure the total flow rate of gases such as oxygen and carbon dioxide in the anode discharge fluid.

[0059] The power source 70 can supply power to the electrochemical reaction structure 10, for example. The power source 70 is connected to the current collector 16 and the current collector 17, for example. The power source 70 can supply power to the electrochemical reaction structure 10 to cause an electrolytic reaction such as an oxidation reaction or a reduction reaction, and is electrically connected to the cathode 11 and the anode 12. The reduction reaction at the cathode 11 and the oxidation reaction at the anode 12 are performed using the electric energy supplied from the power source 70. The power source 70 and the current collector 16, and the power source 70 and the current collector 17 are connected by, for example, wiring. An electric device such as an inverter, a converter, or a battery may be installed between the electrochemical reaction structure 10 and the power source 70 as necessary. The driving method of the electrochemical reaction structure 10 may be a constant voltage method or a constant current method.

[0060] The power source 70 may be a normal commercial power source or a battery, or may be a power source that converts renewable energy into electrical energy and supplies it. Examples of such power sources include a power source that converts kinetic energy or potential energy such as wind power, water power, geothermal power, and tidal power into electrical energy, a power source such as a solar cell having a photoelectric conversion element that converts light energy into electrical energy, a power source such as a fuel cell or a storage battery that converts chemical energy into electrical energy, and a power source such as a device that converts vibration energy such as sound into electrical energy. The photoelectric conversion element has a function of performing charge separation by the energy of light such as irradiated sunlight. Examples of the photoelectric conversion element include a pin junction type solar cell, a pn junction type solar cell, an amorphous silicon solar cell, a multi-junction type solar cell, a single crystal silicon solar cell, a polycrystalline silicon solar cell, a dye-sensitized solar cell, and an organic thin film solar cell. The photoelectric conversion element may be laminated with at least one of the cathode 11 and the anode 12 inside the electrochemical reaction structure 10.

[0061] The power supply 70 can adjust, for example, the current or voltage supplied to the electrochemical reaction structure 10. The power supply 70 may have, for example, a power controller that adjusts the current or voltage supplied to the electrochemical reaction structure 10. The power supply 70 may have a function of adjusting the pressure in the cathode chamber 140 or the pressure in the anode chamber 150 by adjusting the current or voltage supplied to the electrochemical reaction structure 10 according to a control signal from the control device 80.

[0062] FIG. 3 is a schematic diagram showing another configuration example of the electrochemical reaction device of the embodiment. As shown in FIG. 3, the electrochemical reaction device 1 may further include a flow path P7 and a pump 90. The flow path P7 connects, for example, the gas-liquid separator 52 to the flow path P2 or the anode fluid supply source. The pump 90 is provided in the middle of the flow path P7. The gas-liquid separator 52 separates the anode discharge fluid into a liquid component such as the second electrolytic solution and a gas component such as oxygen, hydrogen, and carbon dioxide, and the liquid component is returned to the flow path P2 via the flow path P7 by the pump 90, thereby circulating the anode solution. The flow paths P1, P2, P3, P4, P5, P6, and P7 can be formed, for example, using piping.

[0063] FIG. 4 is a schematic diagram showing another configuration example of the electrochemical reaction device of the embodiment. As shown in FIG. 4, the electrochemical reaction device 1 may further include a temperature regulator 71. The temperature regulator 71 is directly or indirectly connected to the electrochemical reaction structure 10. The temperature regulator 71 can, for example, measure and adjust the temperature (for example, the external temperature) of the electrochemical reaction structure 10. The temperature regulator 71 may include a heater capable of heating the electrochemical reaction structure 10 or a cooler capable of cooling the electrochemical reaction structure 10. The temperature regulator 71 may measure at least one of the temperatures of the cathode chamber 140 and the anode chamber 150 and adjust these temperatures. The temperature regulator 71 may have a function of adjusting the pressure of the cathode chamber 140 and the pressure of the anode chamber 150 by adjusting at least one of the temperatures of the electrochemical reaction structure 10, the cathode chamber 140, and the anode chamber 150 according to a control signal from the control device 80.

[0064] The control device 80 is connected, for example, by wired or wireless connection to at least one of the flow regulators 21, 22, pressure regulators 41, 42, temperature regulator 71, and power supply 70. For example, as shown in Fig. 1, the control device 80 is connected, by wired or wireless connection, to each of the flow regulators 21, flow meter 61, and flow meter 62. The control device 80 can measure, for example, the sum of the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the treated cathode exhaust fluid flowing through the flow path P3, and the flow rate of the treated anode exhaust fluid flowing through the flow path P4, and adjust the operating conditions of the electrochemical reaction structure 10 according to the value of the measured sum. The control device 80 may control, for example, the pressure difference (differential pressure) between the cathode chamber 140 and the anode chamber 150 by controlling at least one of the flow regulator 21, the flow regulator 22, the pressure regulator 41, the pressure regulator 42, the temperature regulator 71, and the power supply 70 in accordance with the value of the above sum.

[0065] The control device 80 has hardware having an arithmetic unit such as a processor, for example. Each operation may be stored as an operation program in a computer-readable recording medium such as a memory, and each operation may be executed by appropriately reading the operation program stored in the recording medium by the hardware.

[0066] Fig. 5 is a schematic diagram showing another example of the configuration of the electrochemical reaction device of the embodiment. As shown in Fig. 5, the control device 80 may be further connected to at least one of the pressure regulator 41 and the pressure regulator 42 by wired or wireless connection. The control device 80 can, for example, measure the sum of the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the treated cathode discharge fluid flowing through the flow path P3, and the flow rate of the treated anode discharge fluid flowing through the flow path P4, and control at least one of the pressure regulators 41 and 42 according to the measured sum value to adjust the operating conditions of the electrochemical reaction structure 10.

[0067] FIG. 6 is a schematic diagram showing another configuration example of the electrochemical reaction device of the embodiment. As shown in FIG. 6, the control device 80 is connected to at least one of the pressure regulator 41 and the pressure regulator 42 by wired or wireless connection, and may not be connected to the flow rate regulator 22. The control device 80 can, for example, measure the sum of the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the treated cathode discharge fluid flowing through the flow path P3, and the flow rate of the treated anode discharge fluid flowing through the flow path P4, and control at least one of the pressure regulators 41 and 42 according to the measured sum to adjust the operating conditions of the electrochemical reaction structure 10. Note that the configurations shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 6 may be appropriately combined.

[0068] Next, an example of an operating method of the electrochemical reaction device 1 will be described. Here, a case will be described in which carbon dioxide is reduced to mainly produce carbon monoxide, and water is oxidized to produce oxygen. When a cathode supply fluid containing carbon dioxide is supplied to the cathode chamber 140, an anode supply fluid containing a second electrolytic solution is supplied to the anode chamber 150, and a voltage equal to or greater than the electrolysis voltage is applied between the cathode 11 and the anode 12 by power supply from the power source 70, an oxidation reaction of water occurs near the anode 12 in contact with the second electrolytic solution. As shown in the following formula (1), an oxidation reaction of water contained in the second electrolytic solution occurs, electrons are lost, and oxygen and hydrogen ions are produced. A part of the produced hydrogen ions moves to the cathode chamber 140 through the diaphragm 13. 2H2O → 4H + +O2+4e - …(1)

[0069] Hydrogen ions (H + ) reaches the vicinity of the cathode 11, and electrons (e - ) is supplied, a reduction reaction of carbon dioxide occurs. As shown in the following formula (2), hydrogen ions (H + ) and the electrons (e - ) carbon dioxide is reduced to carbon monoxide. 2CO2+4H+ +4e - → 2CO+2H2O …(2)

[0070] The gas component contained in the anode discharge fluid from the anode chamber 150 is mainly oxygen gas, as shown in the above formula (1). In the reaction at the cathode 11 and the anode 12, most of the carbon dioxide contained in the cathode supply fluid supplied to the cathode chamber 140 is reduced at the cathode 11, but some is converted into carbon dioxide or carbonate ions (CO3 2- ) and bicarbonate ion (HCO3 - ) and flow into the anode 12 side. When the pH of the anode solution (second electrolyte) becomes, for example, 6 or lower, the carbonate ions and bicarbonate ions that have migrated to the anode 12 side become present as carbon dioxide through a chemical equilibrium reaction, and a part of them dissolves in the anode solution. Such carbon dioxide gas that cannot be dissolved in the anode solution is contained together with oxygen gas in the anode exhaust fluid discharged from the anode chamber 150. Under typical operating conditions of the electrochemical reaction structure 10, the ratio of carbon dioxide gas to oxygen gas in the anode exhaust fluid may rise to, for example, 2:1.

[0071] The electrochemical reaction device of the embodiment can predict the state of the electrochemical reaction of the electrochemical reaction structure 10 by grasping the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the cathode discharge fluid (cathode discharge fluid treated by the dehydrator 51) flowing through the flow path P3, and the flow rate of the anode discharge fluid (anode discharge fluid treated by the gas-liquid separator 52) flowing through the flow path P4. Due to the reaction shown by the above formula (2), carbon dioxide is consumed on the cathode 11 side, but an equal amount of carbon compounds (here, carbon monoxide) is generated. Furthermore, an amount of carbon dioxide equal to the amount of carbon compounds generated moves to the anode 12 side. If the flow rate of carbon dioxide gas in the cathode supply fluid flowing through the flow path P1 is 100, when a current having a theoretical amount required to reduce 50 carbon dioxide gas is supplied from the power source 70 to the electrochemical reaction structure 10, the ratios of carbon dioxide, carbon monoxide, and hydrogen when the Faraday efficiency (FE) is 100%, 90%, 70%, and 50% are as shown in Table 1, for example. Data showing such a relationship is registered (recorded) in advance in the control device 80, and the operating conditions can be grasped by checking the difference between the registered data and the actual measured data, and by checking changes in the operating conditions over time.

[0072] [Table 1]

[0073] When the hydrogen generation reaction, which is a side reaction, progresses due to deterioration of the catalyst or flooding, which is a phenomenon in which the cathode catalyst is covered with water or electrolyte, the cathode discharge fluid changes so that the Faraday efficiency shown in Table 1 decreases from 100% to 90% or 70%. When 100 carbon dioxide flows through the flow path P3 and the Faraday efficiency decreases, the Faraday efficiency increases to 125 when the flow rate is 100% through the flow path P3, 130 when the flow rate is 90%, and 140 when the flow rate is 70%. Therefore, for example, the decrease in the Faraday efficiency can be confirmed by measuring the sum of the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the treated cathode discharge fluid flowing through the flow path P3, and the flow rate of the treated anode discharge fluid flowing through the flow path P4. In addition, the deterioration during long-term operation can be grasped by comparing the actual measurement data of these sums with the registered data of the control device 80.

[0074] The decrease in the faradaic efficiency due to deterioration during long-term operation causes a failure mode called cross leakage, in which, for example, gas substances move to either the cathode 11 side or the anode 12 side, or to each other. When the reduction products move from the cathode 11 side to the anode 12 side, the carbon compounds and hydrogen generated at the cathode 11 are oxidized at the anode 12 and converted to carbon dioxide and water. When hydrogen is generated, the hydrogen molecules are small, so cross leakage in which hydrogen moves through the diaphragm 13 increases, and the product changes from gas to liquid by being converted to water at the anode 12, and the sum of the flow rate of the treated cathode discharge fluid flowing through flow path P3 and the treated anode discharge fluid flowing through flow path P4 decreases. Table 2 shows the changes in the flow rate of the treated cathode discharge fluid and the treated anode discharge fluid when hydrogen is converted to water. When the faradic efficiency drops to 90% due to cross leakage, the sum of the flow rate of the treated cathode exhaust fluid flowing through flow path P3 and the flow rate of the treated anode exhaust fluid flowing through flow path P4 drops from 130 to 125. By utilizing this change, the increase or decrease in cross leakage during long-term operation can be detected and the operation can be controlled.

[0075] [Table 2]

[0076] For example, when operating at a Faraday efficiency of 90%, if the flow rate of the treated cathode exhaust fluid flowing through flow path P3 changes from 60 in Table 1 to 55 in Table 2 due to long-term operation, and the flow rate of the treated anode exhaust fluid flowing through flow path P4 remains unchanged from 70 in Table 1 to 70 in Table 2, the change in the cathode exhaust fluid as shown in Table 2 due to the occurrence of cross leakage can be detected, and the operating conditions of each component can be adjusted by a control signal from the control device 80.

[0077] As an example of a conventional electrochemical reaction device, it is known that the total flow rate of the fluid discharged from the cathode chamber or the anode chamber is detected, and the flow rate of carbon dioxide gas in the fluid supplied to the cathode chamber is adjusted in accordance with the detection result to adjust the carbon dioxide contained in the fluid discharged from the cathode chamber. However, in order to detect changes in electrolysis performance such as cross leakage and deterioration caused by long-term operation of the electrochemical reaction device, it is necessary to detect changes in the sum of the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the treated cathode discharge fluid flowing through the flow path P3, and the flow rate of the treated anode discharge fluid flowing through the flow path P4, as in the electrochemical reaction device of the embodiment.

[0078] There is an appropriate pressure balance between the cathode chamber 140 and the anode chamber 150, and the pressure is adjusted to an appropriate level by, for example, the pressure regulator 41 and the pressure regulator 42. When the pressure in the cathode chamber 140 is low, water or electrolyte may flow into the cathode 11 from the flow path P2. When too much water or electrolyte flows in, flooding occurs and the hydrogen generation reaction, which is a side reaction, proceeds. When the pressure in the cathode chamber 140 is high, water or electrolyte is not sufficiently supplied to the cathode 11, causing a problem of ion diffusion being hindered. The pressure in the cathode chamber 140 is preferably adjusted to a range of 0 PaG to 300 KPaG in gauge pressure. The pressure in the cathode chamber 140 can be adjusted by, for example, the pressure regulator 41. It is more preferable that the pressure in the cathode chamber 140 is adjusted to a range of 50 KPaG to 200 KPaG in gauge pressure. The pressure in the anode chamber 150 is preferably adjusted to a gauge pressure of 0 PaG or more and 300 KPaG or less. The pressure in the anode chamber 150 can be adjusted, for example, by the pressure regulator 42. The pressure in the anode chamber 150 is more preferably adjusted to a gauge pressure of 0 PaG or more and 200 KPaG or less. The pressure difference (differential pressure) between the cathode chamber 140 and the anode chamber 150 is preferably adjusted to a gauge pressure of 0 PaG or more and 150 KPaG or less. The pressure in the cathode chamber 140 is preferably higher than the pressure in the anode chamber 150. By adjusting the pressure difference between the cathode chamber 140 and the anode chamber 150 to within the above range, for example, a side reaction, such as a hydrogen generation reaction, can be suppressed.

[0079] When the control device 80 detects the occurrence of cross leakage from the cathode chamber 140 to the anode chamber 150, the control device 80 controls at least one of the flow rate regulators 21, 22, pressure regulators 41, 42, power supply 70, and temperature regulator 71 using a control signal from the control device 80 to control the operating conditions of the electrochemical reaction structure 10. The control device 80 may also compare first data indicating the measured sum with second data registered in the control device 80, and adjust the pressure difference by controlling the at least one regulator according to the comparison result. The control device 80 may also analyze a change over time in the measured sum, and adjust the pressure difference by controlling the at least one regulator according to the analysis result.

[0080] When cross leakage occurs, for example, the control device 80 can control the flow regulator 21 to increase the flow rate of the cathode supply fluid flowing through the flow path P1, thereby suppressing the hydrogen evolution reaction.

[0081] In the case where a cross leak occurs due to an increase in the hydrogen production reaction caused by a temperature rise, the control device 80 can control the flow regulator 22 to increase the flow rate of the anode supply fluid flowing through the flow path P2, thereby suppressing the temperature rise of the electrochemical reaction structure 10 and suppressing the hydrogen production reaction.

[0082] When cross leakage occurs due to an increase in the inflow of water from the anode 12 side to the cathode 11 caused by a change in pressure in the cathode chamber 140 or the anode chamber 150, water electrolysis can be suppressed by controlling the pressure regulator 41 to adjust the pressure in the cathode chamber 140 and by controlling the pressure regulator 42 to adjust the pressure in the anode chamber 150. In addition, by controlling the power supply 70 to reduce the value of the current or voltage supplied to the electrochemical reaction structure 10, a temperature rise in the electrochemical reaction structure 10 can be suppressed, and the hydrogen production reaction can be suppressed.

[0083] When cross leakage occurs, the heater of the temperature regulator 71 is controlled to lower the temperature of the electrochemical reaction structure 10, thereby suppressing the hydrogen evolution reaction.

[0084] The flow path P3 may be connected to a valuable resource production device. Examples of the valuable resource production device include a chemical synthesis device that produces valuable resources by chemical synthesis using a raw material such as carbon monoxide. Examples of valuable resources include methanol produced by a methanol production device, hydrocarbons produced by a Fischer-Tropsch reactor, synthetic gasoline, diesel, jet fuel, and olefin compounds produced by an olefin production device. By providing a valuable resource production device downstream of the electrochemical reaction structure 10, valuable resources with high added value can be produced from the product of the electrochemical reaction structure 10.

[0085] The type of chemical synthesis apparatus is not particularly limited as long as it can react and synthesize other substances from the reduction products generated in the cathode 11. Examples of reactions using the reduction products in the chemical synthesis apparatus include chemical reactions, electrochemical reactions, and biological conversion reactions using organisms such as algae, enzymes, yeast, and bacteria.

[0086] The flow path P3 may be connected to a product separator instead of a valuable resource production device. The product separator can separate carbon compounds such as carbon monoxide, which are products, by separating excess carbon dioxide from the cathode exhaust fluid or removing moisture from the cathode exhaust fluid. For example, when carbon monoxide gas is generated by the above formula (2) in the electrochemical reaction structure 10, a mixed gas containing the generated carbon monoxide gas and hydrogen gas as a by-product of the reduction reaction can be used as a raw material to produce methanol by methanol synthesis, or jet fuel, diesel, etc. by Fischer-Tropsch synthesis. Without being limited thereto, the flow path P3 may be connected to a tank for storing gas containing carbon compounds such as carbon monoxide, instead of a valuable resource production device.

[0087] The reduction product may contain hydrogen produced by electrolysis of carbon dioxide, carbon monoxide, and water. The hydrogen concentration can be adjusted as desired depending on the mode of use. When hydrogen is used in the chemical synthesis device, carbon dioxide may be separated from the cathode discharge fluid in order to use a mixture of carbon monoxide and hydrogen. When hydrogen is not used, only carbon monoxide is separated from the cathode discharge fluid. When methanol is produced, the hydrogen produced in the cathode 11 can be used as a valuable resource by adjusting the number of moles of hydrogen to about twice the number of moles of carbon monoxide. On the other hand, the concentration of hydrogen in the reduction product can be adjusted to a volume percentage of 0.1% or more and 5% or less in the cathode 11 by suppressing a side reaction of hydrogen depending on the reaction conditions. This allows the electrochemical reaction device to be used as a carbon monoxide production device that produces high-concentration carbon monoxide.

[0088] The configurations of the above-mentioned embodiments can be applied in combination with each other, and some of them can be replaced. Although several embodiments of the present invention have been described here, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the scope of the invention and its equivalents described in the claims.

[0089] The above embodiments can be summarized in the following technical solutions. (Technical proposal 1) an electrochemical reaction structure including a cathode having a reduction catalyst for promoting a reduction reaction in which carbon dioxide is reduced to produce a carbon compound, an anode having an oxidation catalyst for promoting an oxidation reaction in which water is oxidized to produce oxygen, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode, and an anode chamber facing the anode; a first flow path connected to an inlet of the cathode chamber, through which a first fluid containing carbon dioxide flows and which is supplied to the cathode chamber; a second flow path connected to an inlet of the anode chamber, through which a second fluid including water to be supplied to the anode chamber flows; a third flow path connected to an outlet of the cathode chamber, through which a third fluid that is discharged from the cathode chamber and contains the produced carbon compound flows; a fourth flow path connected to an outlet of the anode chamber, through which a fourth fluid discharged from the anode chamber and containing the water and the generated oxygen flows; at least one regulator selected from the group consisting of a first flow regulator for regulating the flow rate of the first fluid flowing through the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing through the second flow path, a first pressure regulator for regulating the pressure of the third flow path, a second pressure regulator for regulating the pressure of the fourth flow path, a temperature regulator for regulating the temperature of the electrochemical reaction structure, and a power source for regulating the current or voltage supplied to the electrochemical reaction structure, the regulator including at least the first flow regulator; a gas-liquid separator provided in the fourth flow path and configured to process the fourth fluid and separate a liquid including water from the fourth fluid; a first flowmeter that measures a flow rate of the third fluid flowing through the third flow path; a second flow meter for measuring a flow rate of the processed fourth fluid flowing through the fourth flow path; a control device connected to each of the at least one regulator, the first flow meter, and the second flow meter, for measuring a sum of a flow rate of the first fluid flowing through the first flow path, a flow rate of the third fluid flowing through the third flow path, and a flow rate of the treated fourth fluid flowing through the fourth flow path, and for controlling the at least one regulator in accordance with the measured value of the sum to adjust a pressure difference between the cathode chamber and the anode chamber; An electrochemical reaction device comprising: (Technical proposal 2) The electrochemical reaction device according to Technical Solution 1 further comprises a humidifier disposed in the middle of the first flow path for humidifying the carbon dioxide in the first fluid. (Technical proposal 3) The electrochemical reaction device according to Technical Scheme 1 or 2, further comprising a dehydrator provided in the middle of the third flow path and upstream of the first flow meter, for treating the third fluid and separating water from the third fluid. (Technical proposal 4) the control device controls the first flow regulator in accordance with the measured value of the sum to adjust the flow rate of the first fluid flowing through the first flow path, thereby adjusting the pressure difference; An electrochemical reaction device according to any one of technical solutions 1 to 3. (Technical proposal 5) The at least one regulator comprises: The first pressure regulator; The second pressure regulator; Including, the control device controls the first pressure regulator in accordance with the measured value of the sum to adjust the pressure of the third flow path, and controls the second pressure regulator in accordance with the measured value of the sum to adjust the pressure of the fourth flow path, thereby adjusting the pressure difference. An electrochemical reaction device according to any one of technical solutions 1 to 4. (Technical proposal 6) the at least one regulator includes the second flow regulator; the control device controls the second flow regulator in accordance with the measured value of the sum to adjust the flow rate of the second fluid flowing through the second flow path, thereby adjusting the pressure difference; An electrochemical reaction device according to any one of technical solutions 1 to 5. (Technical proposal 7) the at least one regulator includes the temperature regulator; the control device controls the temperature regulator in response to the measured value of the sum to adjust the temperature of the electrochemical reaction structure, thereby adjusting the pressure difference; An electrochemical reaction device according to any one of technical solutions 1 to 6. (Technical proposal 8) The temperature regulator includes a heater that heats the electrochemical reaction structure. The electrochemical reaction device described in Technical Proposal 7. (Technical proposal 9) the at least one regulator includes the power supply; the control device controls the power source in response to the measured value of the sum to adjust the current or voltage supplied to the electrochemical reaction structure, thereby adjusting the pressure difference. An electrochemical reaction device according to any one of technical solutions 1 to 8. (Technical proposal 10) the control device compares first data indicating the measured sum with second data registered in the control device, and adjusts the pressure difference by controlling the at least one regulator in accordance with a comparison result; An electrochemical reaction device according to any one of technical solutions 1 to 9. (Technical proposal 11) The control device analyzes a change over time in the measured sum, and adjusts the pressure difference by controlling the at least one regulator in response to the analysis result. The electrochemical reaction device according to any one of technical solutions 1 to 10. (Technical proposal 12) 1. A method for operating an electrochemical reactor, comprising: The electrochemical reaction device is an electrochemical reaction structure including a cathode having a reduction catalyst for promoting a reduction reaction in which carbon dioxide is reduced to produce a carbon compound, an anode having an oxidation catalyst for promoting an oxidation reaction in which water is oxidized to produce oxygen, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode, and an anode chamber facing the anode; a first flow path connected to an inlet of the cathode chamber, through which a first fluid containing carbon dioxide flows and which is supplied to the cathode chamber; a second flow path connected to an inlet of the anode chamber, through which a second fluid including water to be supplied to the anode chamber flows; a third flow path connected to an outlet of the cathode chamber, through which a third fluid that is discharged from the cathode chamber and contains the produced carbon compound flows; a fourth flow path connected to an outlet of the anode chamber, through which a fourth fluid discharged from the anode chamber and containing the water and the generated oxygen flows; at least one regulator selected from the group consisting of a first flow regulator for regulating the flow rate of the first fluid flowing through the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing through the second flow path, a first pressure regulator for regulating the pressure of the third flow path, a second pressure regulator for regulating the pressure of the fourth flow path, a temperature regulator for regulating the temperature of the electrochemical reaction structure, and a power source for regulating the current or voltage supplied to the electrochemical reaction structure, the regulator including at least the first flow regulator; a gas-liquid separator provided in the fourth flow path and configured to process the fourth fluid and separate a liquid including water from the fourth fluid; a first flowmeter that measures a flow rate of the third fluid flowing through the third flow path; a second flow meter for measuring a flow rate of the processed fourth fluid flowing through the fourth flow path; Equipped with The above operation method is supplying the first fluid to the cathode chamber, the second fluid to the anode chamber, and supplying a current or voltage to the electrochemical reaction structure, thereby reducing the carbon dioxide at the cathode to produce the carbon compound, and reducing the water at the anode to produce the oxygen; measuring a sum of a flow rate of the first fluid flowing through the first flow path, a flow rate of the third fluid flowing through the third flow path, and a flow rate of the treated fourth fluid flowing through the fourth flow path, and controlling the at least one regulator in accordance with the measured value of the sum to adjust a pressure difference between the cathode chamber and the anode chamber; A method for operating an electrochemical reactor. (Technical proposal 13) The pressure in the cathode chamber is adjusted to a range of 0 PaG to 300 KPaG. The pressure in the anode chamber is adjusted to 0 PaG or more and 300 KPaG or less. The pressure difference is adjusted to be between 0 PaG and 150 KPaG. The pressure in the cathode chamber is higher than the pressure in the anode chamber. A method for operating an electrochemical reactor as described in Technical Proposal 12. [Explanation of symbols]

[0090] 1...electrochemical reaction device, 10...electrochemical reaction structure, 11...cathode, 12...anode, 13...diaphragm, 14...flow path plate, 15...flow path plate, 16...current collector, 17...current collector, 18...flow path plate, 21...flow regulator, 22...flow regulator, 30...humidifier, 41...pressure regulator, 42...pressure regulator, 51...dehydrator, 52...gas-liquid separator, 61...flow meter, 62...flow meter, 70...power supply, 71...temperature regulator, 80...control device, 90...pump, 140...cathode chamber, 150...anode chamber, 180...cathode chamber, P1...flow path, P2...flow path, P3...flow path, P4...flow path, P5...flow path, P6...flow path, P7...flow path.

Claims

1. An electrochemical reaction structure including a cathode having a reduction catalyst for promoting a reduction reaction in which carbon dioxide is reduced to produce a carbon compound, an anode having an oxidation catalyst for promoting an oxidation reaction in which water is oxidized to produce oxygen, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode, and an anode chamber facing the anode; a first flow path connected to an inlet of the cathode chamber and through which a first fluid containing the carbon dioxide flows to be supplied to the cathode chamber; a second flow path connected to an inlet of the anode chamber, through which a second fluid containing the water to be supplied to the anode chamber flows; a third flow path connected to an outlet of the cathode chamber, through which a third fluid that is discharged from the cathode chamber and contains the produced carbon compound flows; a fourth flow path connected to an outlet of the anode chamber, through which a fourth fluid discharged from the anode chamber and containing the water and the generated oxygen flows; at least one regulator selected from the group consisting of a first flow regulator for regulating the flow rate of the first fluid flowing through the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing through the second flow path, a first pressure regulator for regulating the pressure of the third flow path, a second pressure regulator for regulating the pressure of the fourth flow path, a temperature regulator for regulating the temperature of the electrochemical reaction structure, and a power source for regulating the current or voltage supplied to the electrochemical reaction structure, the regulator including at least the first flow regulator; a gas-liquid separator provided in the fourth flow path and configured to process the fourth fluid and separate the water-containing liquid from the fourth fluid; a first flow meter that measures a flow rate of the third fluid flowing through the third flow path; a second flow meter for measuring a flow rate of the processed fourth fluid flowing through the fourth flow path; a control device connected to each of the at least one regulator, the first flow meter, and the second flow meter, for measuring a sum of a flow rate of the first fluid flowing through the first flow path, a flow rate of the third fluid flowing through the third flow path, and a flow rate of the processed fourth fluid flowing through the fourth flow path, and for controlling the at least one regulator in accordance with the measured value of the sum to adjust a pressure difference between the cathode chamber and the anode chamber; An electrochemical reaction device comprising:

2. 2. The electrochemical reaction device according to claim 1, further comprising a humidifier provided in the middle of the first flow path and configured to humidify the carbon dioxide in the first fluid.

3. 2. The electrochemical reaction device according to claim 1, further comprising a dehydrator provided in the third flow path and upstream of the first flow meter, for treating the third fluid and separating the water from the third fluid.

4. the control device controls the first flow regulator in response to the measured value of the sum to adjust the flow rate of the first fluid flowing through the first flow path, thereby adjusting the pressure difference. The electrochemical reaction device according to claim 1 .

5. The at least one regulator comprises: the first pressure regulator; the second pressure regulator; Including, the control device controls the first pressure regulator in accordance with the measured value of the sum to adjust the pressure of the third flow path, and controls the second pressure regulator in accordance with the measured value of the sum to adjust the pressure of the fourth flow path, thereby adjusting the pressure difference. The electrochemical reaction device according to claim 1 .

6. the at least one regulator includes the second flow regulator; the control device controls the second flow regulator in response to the measured value of the sum to adjust the flow rate of the second fluid flowing through the second flow path, thereby adjusting the pressure difference. The electrochemical reaction device according to claim 1 .

7. the at least one regulator includes the temperature regulator; the control device controls the temperature regulator in response to the measured value of the sum to adjust the temperature of the electrochemical reaction structure, thereby adjusting the pressure difference.

7. The electrochemical reaction device according to claim 1.

8. The temperature regulator includes a heater that heats the electrochemical reaction structure. The electrochemical reaction device according to claim 7.

9. the at least one regulator includes the power source; the control device controls the power source in response to the measured value of the sum to adjust the current or voltage supplied to the electrochemical reaction structure, thereby adjusting the pressure difference.

7. The electrochemical reaction device according to claim 1.

10. the control device compares first data indicating the measured sum with second data registered in the control device, and adjusts the pressure difference by controlling the at least one regulator in accordance with a comparison result; The electrochemical reaction device according to claim 1 .

11. The control device analyzes a change over time in the measured sum, and adjusts the pressure difference by controlling the at least one regulator in response to a result of the analysis. The electrochemical reaction device according to claim 1 .

12. 1. A method for operating an electrochemical reactor, comprising: The electrochemical reaction device is An electrochemical reaction structure including a cathode having a reduction catalyst for promoting a reduction reaction in which carbon dioxide is reduced to produce a carbon compound, an anode having an oxidation catalyst for promoting an oxidation reaction in which water is oxidized to produce oxygen, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode, and an anode chamber facing the anode; a first flow path connected to an inlet of the cathode chamber and through which a first fluid containing the carbon dioxide flows to be supplied to the cathode chamber; a second flow path connected to an inlet of the anode chamber, through which a second fluid containing the water to be supplied to the anode chamber flows; a third flow path connected to an outlet of the cathode chamber, through which a third fluid that is discharged from the cathode chamber and contains the produced carbon compound flows; a fourth flow path connected to an outlet of the anode chamber, through which a fourth fluid discharged from the anode chamber and containing the water and the generated oxygen flows; at least one regulator selected from the group consisting of a first flow regulator for regulating the flow rate of the first fluid flowing through the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing through the second flow path, a first pressure regulator for regulating the pressure of the third flow path, a second pressure regulator for regulating the pressure of the fourth flow path, a temperature regulator for regulating the temperature of the electrochemical reaction structure, and a power source for regulating the current or voltage supplied to the electrochemical reaction structure, the regulator including at least the first flow regulator; a gas-liquid separator provided in the fourth flow path and configured to process the fourth fluid and separate the water-containing liquid from the fourth fluid; a first flow meter that measures a flow rate of the third fluid flowing through the third flow path; a second flow meter for measuring a flow rate of the processed fourth fluid flowing through the fourth flow path; Equipped with The operating method includes: supplying the first fluid to the cathode chamber, the second fluid to the anode chamber, and supplying a current or voltage to the electrochemical reaction structure, thereby reducing the carbon dioxide at the cathode to produce the carbon compound, and reducing the water at the anode to produce the oxygen; measuring a sum of a flow rate of the first fluid flowing through the first flow path, a flow rate of the third fluid flowing through the third flow path, and a flow rate of the processed fourth fluid flowing through the fourth flow path, and controlling the at least one regulator in accordance with the measured value of the sum to adjust a pressure difference between the cathode chamber and the anode chamber; A method for operating an electrochemical reactor.

13. The pressure in the cathode chamber is adjusted to a range of 0 PaG to 300 KPaG, The pressure in the anode chamber is adjusted to 0 PaG or more and 300 KPaG or less, The pressure difference is adjusted to be equal to or greater than 0 PaG and equal to or less than 150 KPaG, The pressure in the cathode chamber is higher than the pressure in the anode chamber. A method for operating an electrochemical reactor according to claim 12.

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