Electrochemical reaction device and method for operating electrochemical reaction device

Abstract

The utilization efficiency of carbon dioxide is improved. This electrochemical reaction device is provided with: an electrochemical reaction structure provided with a cathode, an anode, a separator between the cathode and the anode, a cathode chamber, and an anode chamber; a first flow path connected to the inlet of the cathode chamber and through which a first fluid flows; 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; the at least one adjustor is selected from a group consisting of a first flow adjustor, a second flow adjustor, a first pressure adjustor, a second pressure adjustor, a temperature adjustor and a power supply, and at least comprises the first flow adjustor; a gas-liquid separator provided midway in 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 which 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, and controls the at least one adjuster to adjust the pressure difference between the cathode chamber and the anode chamber according to the value of the measured sum.

Description

[0001] This application is based on Japanese Patent Application No. 2023-149912 (filing date: September 15, 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] An embodiment of the present invention relates to an electrochemical reaction device. Background Art

[0003] In recent years, there is a concern about the depletion of fossil fuels such as oil and coal, and expectations for sustainable renewable energy have increased. From the perspective of such energy problems and environmental problems, the development of power-to-chemicals (P2C) technology that uses renewable energy such as sunlight to electrochemically reduce carbon dioxide to produce storable chemical energy is being promoted. Electrochemical reaction devices such as a carbon dioxide reaction device including an electrolysis device that implements P2C technology have, for example, 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 reaction device are connected to a power source from renewable energy such as solar power generation, hydroelectric power generation, wind power generation, and geothermal power generation.

[0004] The cathode of the carbon dioxide reaction device is immersed in water containing dissolved carbon dioxide, or is configured to contact carbon dioxide flowing in the flow path. The cathode reduces carbon dioxide to generate 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) by obtaining the reduction potential of carbon dioxide from a power source derived from renewable energy. The anode is configured to contact an electrolyte containing water to generate oxygen and hydrogen ions (H + ) In such a carbon dioxide reaction device, it is required to improve the utilization efficiency of carbon dioxide and the utilization efficiency and utilization value of the reduction product of carbon dioxide. Summary of the invention

[0005] A problem to be solved by the embodiments of the present invention is to improve the utilization efficiency of carbon dioxide.

[0006] The electrochemical reaction device of the embodiment comprises: an electrochemical reaction structure, which comprises a cathode, an anode, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode and an anode chamber facing the anode, the cathode having a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide to generate carbon compounds, and the anode having an oxidation catalyst that promotes an oxidation reaction of oxidizing water to generate oxygen; a first flow path connected to the inlet of the cathode chamber, for supplying a first fluid containing carbon dioxide to the cathode chamber; a second flow path connected to the inlet of the anode chamber, for supplying a second fluid containing water to the anode chamber; a third flow path connected to the outlet of the cathode chamber, for supplying a third fluid discharged from the cathode chamber and containing the generated carbon compounds; a fourth flow path connected to the outlet of the anode chamber, for supplying a fourth fluid discharged from the anode chamber and containing water and the generated oxygen; and at least one regulator selected from a first flow regulator that regulates the flow rate of the first fluid flowing in the first flow path, a second flow regulator that regulates the flow rate of the second fluid flowing in the second flow path. A group consisting of a second flow regulator for adjusting flow, a first pressure regulator for adjusting pressure in a third flow path, a second pressure regulator for adjusting pressure in a fourth flow path, a temperature regulator for adjusting temperature of an electrochemical reaction structure, and a power supply for adjusting current or voltage supplied to the electrochemical reaction structure, includes at least a first flow regulator; a gas-liquid separator disposed midway in the fourth flow path, for treating a fourth fluid and separating a liquid containing water from the fourth fluid; a first flow meter for measuring the flow of the third fluid flowing in the third flow path; a second flow meter for measuring the flow of the treated fourth fluid flowing in the fourth flow path; and a control device, which is respectively connected to at least one regulator, the first flow meter, and the second flow meter, measures the sum of the flow of the first fluid flowing in the first flow path, the flow of the third fluid flowing in the third flow path, and the flow of the treated fourth fluid flowing in the fourth flow path, and controls at least one regulator according to the measured sum to adjust the pressure difference between the cathode chamber and the anode chamber. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0008] Figure 2 It is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment.

[0009] Figure 3 It is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment.

[0010] Figure 4 It is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment.

[0011] Figure 5It is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment.

[0012] Figure 6 It is a schematic diagram showing another configuration example of the electrochemical reaction device according to the embodiment.

[0013] Description of Reference Numerals

[0014] 1…electrochemical reaction device, 10…electrochemical reaction structure, 11…cathode, 12…anode, 13…diaphragm, 14…flow plate, 15…flow plate, 16…current collector, 17…current collector, 18…flow 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 DETAILED DESCRIPTION

[0015] The following describes the embodiments with reference to the accompanying drawings. In the embodiments shown below, substantially the same components are sometimes labeled with the same reference numerals, and part of the description thereof is omitted. The accompanying drawings are schematic, and the relationship between thickness and plane dimensions, the ratio of thickness of each part, etc., are sometimes different from reality.

[0016] In addition, in this specification, "connected" may include not only direct connection but also indirect connection unless otherwise specified.

[0017] Figure 1 It is a schematic diagram showing a structural example of an electrochemical reaction device. Figure 1 The structure example of the electrochemical reaction device 1 is shown. 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 supply 70, and a control device 80.

[0018] The electrochemical reaction structure 10 includes a cathode 11 , an anode 12 , a separator 13 , a flow channel plate 14 , a flow channel plate 15 , a current collector 16 , and a current collector 17 .

[0019] The cathode 11 is, for example, a reduction electrode for performing a reduction reaction of at least one reduction object (substance to be reduced). The at least one reduction object includes, for example, carbon dioxide. The cathode 11 reduces, for example, carbon dioxide supplied as a gas or carbon dioxide contained in the first electrolyte (cathode solution) to generate carbon compounds. Examples of carbon compounds include carbon monoxide, formic acid, methanol, methane, ethanol, ethane, ethylene, formaldehyde, ethylene glycol, acetic acid, propanol, and the like. The cathode 11 sometimes generates a side reaction of generating hydrogen through a reduction reaction of water together with the reduction reaction of carbon dioxide.

[0020] The cathode 11 has, for example, a reduction catalyst that promotes a reduction reaction in which carbon dioxide is reduced to generate 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 when a carbon compound is generated by a reduction reaction of carbon dioxide.

[0021] The cathode 11 can be formed using, for example, a metal material or a carbon material. Examples of metal materials include metals such as gold, aluminum, copper, silver, platinum, palladium, zinc, mercury, indium, nickel, titanium, and alloys containing the metals. Examples of carbon materials include graphene, carbon nanotubes (Carbon Nanotube: CNT), fullerene, Ketjen black, and the like. In addition, the cathode 11 is not limited to these materials, and can also be formed using metal complexes such as Ru complexes or Re complexes, and organic molecules having an imidazole skeleton or a pyridine skeleton. The cathode 11 can also be formed using a mixture of multiple materials. For example, the cathode 11 can have a structure having a reduction catalyst in the shape of a thin film, a grid, a particle, a line, or the like on a conductive substrate. The type of carbon compound generated by the reduction reaction will also vary depending on the type of the reduction catalyst.

[0022] The anode 12 is, for example, an oxidation electrode for performing 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 the oxidation target such as a substance or ion in the second electrolyte (anode solution) to generate oxygen.

[0023] The anode 12 has, for example, an oxidation catalyst that promotes an oxidation reaction in which water is oxidized to generate oxygen. The oxidation catalyst can be formed, for example, using a material that reduces the activation energy when the oxidized object is oxidized, in other words, a material that reduces the reaction overvoltage. Examples of oxidation reactions at the anode 12 include oxidation of water to generate oxygen, hydrogen peroxide, and chloride ions (Cl - ) is oxidized to produce chlorine, and carbonate ions or bicarbonate ions are oxidized to produce carbon dioxide.

[0024] Examples of oxidation catalysts include metal materials. Examples of metal materials include ruthenium, iridium, platinum, cobalt, nickel, iron, manganese, tantalum, zirconium, etc. In addition, examples of metal materials include binary metal oxides, ternary metal oxides, quaternary metal oxides, etc. Examples of 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 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. As quaternary metal oxides, for example, lead-ruthenium-iridium oxide (Pb-Ru-Ir-O), lanthanum-strontium-cobalt oxide (La-Sr-Co-O), etc. are included. In addition, the oxidation catalyst is not limited to these materials, and the oxidation catalyst may be formed using metal complexes such as metal hydroxides, ruthenium complexes, and iron complexes containing metals such as cobalt, nickel, iron, and manganese. In addition, the oxidation catalyst may be formed by mixing a plurality of materials.

[0025] The anode 12 may also be formed using a composite material including an oxidation catalyst and a conductive material. Examples of conductive materials include carbon materials such as carbon black, activated carbon, fullerene, carbon nanotubes, graphene, Ketjen black, diamond, etc., transparent conductive oxides such as indium tin oxide (ITO), zinc oxide (ZnO), fluorine-doped tin oxide (Fluorine-doped Tin Oxide: FTO), aluminum-doped zinc oxide (Aluminum-doped Zinc Oxide: AZO), antimony-doped Tin Oxide (Antimony-doped Tin Oxide: ATO), copper, aluminum, titanium, nickel, silver, tungsten, cobalt, gold, etc., and alloys containing at least one of these metals. The anode 12 may include, for example, a structure having an oxidation catalyst in a thin film, lattice, particle, wire, etc. on a conductive substrate. The conductive substrate may be formed using, for example, a metal material including titanium, a titanium alloy, or stainless steel.

[0026] 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 can allow hydrogen ions (H + ), hydroxide ion (OH - ), bicarbonate ion (HCO3 - ), carbonate ions (CO3 2- ) plasma movement. An electrochemical reaction unit having a double chamber structure can be formed by the diaphragm 13. The diaphragm 13 can also be arranged in contact with the cathode 11 and the anode 12.

[0027] The diaphragm 13 can be formed, for example, using a membrane that can selectively allow anions or cations to flow. Thus, the composition of the second electrolyte in contact with the anode 12 can be different from the composition of the first electrolyte in contact with the cathode 11, and further, the reduction reaction and the oxidation reaction can be promoted by differences such as differences in ionic strength and pH. The diaphragm 13 can also have a function of allowing a portion of the ions contained in the electrolyte that immerses the cathode 11 and the anode 12 to pass through, that is, a function of shielding one or more ions contained in the electrolyte. Thus, for example, the pH and the like can be made different between the two electrolytes. In addition, regarding the shielding of ions, it can also be a diaphragm that does not completely shield a portion of the ions, but exerts its effect to the extent of limiting the amount of movement determined by the type of ions.

[0028] The diaphragm 13 can be formed by using, for example, ion exchange membranes such as Neosepta (registered trademark) of ASTOM, Selemion (registered trademark) and Aciplex (registered trademark) of Asahi Glass, Fumasep (registered trademark) and fumapem (registered trademark) of Fumatech, Nafion (registered trademark) of DuPont, lewabrane (registered trademark) of LANXESS, IONSEP (registered trademark) of IONTECH, Mustang (registered trademark) of PALL, ralex (registered trademark) of mega, Gore-Tex (registered trademark) of Gore-Tex, Sustainion (registered trademark) of DIOXIDETMATERIALS, and PiperION (registered trademark) of Versogen. The ion exchange membrane can be formed by using, for example, a membrane with hydrocarbon as the basic skeleton. The anion exchange membrane can be formed by using, for example, a membrane having an amine group. When there is a pH difference between the first electrolyte and the second electrolyte, the separator 13 is formed using a bipolar membrane in which a cation exchange membrane and an anion exchange membrane are stacked, so that the pH of each electrolyte can be stably maintained.

[0029] The diaphragm 13 can be formed using materials such as silicone resin, perfluoroalkoxyalkane (PFA), perfluoroethylene propylene copolymer (FEP), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyethersulfone (PES) and other fluorine-based resins, ceramic porous membranes, fillers filled with glass filters or agar, zeolites, oxides and other insulating porous bodies. In particular, hydrophilic porous membranes can suppress clogging caused by bubbles, so they are preferably used as the material of the diaphragm 13.

[0030] The cathode 11, the anode 12 and the separator 13 are stacked to form an electrochemical reaction unit. The electrochemical reaction structure 10 may also have a cell stack formed by stacking a plurality of electrochemical reaction units. By forming a cell stack, the reaction amount of carbon dioxide per unit area increases, thereby increasing the amount of carbon compound generated. The stacking number of multiple electrochemical reaction units is preferably, for example, 10 or more and 150 or less.

[0031] The flow path plate 14 forms a cathode chamber 140. The cathode chamber 140 is disposed 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 a fluid from the cathode chamber 140. The surface shape of the cathode flow path is not particularly limited, and is, for example, a serpentine shape.

[0032] The flow path plate 15 forms an anode chamber 150. The anode chamber 150 is disposed 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 a fluid from the anode chamber 150. The surface shape of the anode flow path is not particularly limited, and is, for example, a serpentine shape.

[0033] The electrolytic reactions such as oxidation reactions and reduction reactions achieved by the electrochemical reaction structure 10 are preferably carried out at a temperature above room temperature (e.g., 25°C) and below 100°C and at a temperature at which the electrolyte is not vaporized. The above temperature is preferably above 60°C and below 95°C, and more preferably above 60°C and below 80°C. In order to set the temperature below room temperature, a cooling device such as a cooler is required, and the overall energy efficiency of the system may be reduced. When the temperature exceeds 100°C, the water in the electrolyte turns into steam and increases the resistance, and the electrolytic efficiency may be reduced.

[0034] The current density of the cathode 11 is not particularly limited, but a higher current density is preferred in order to increase the amount of reduction product generated per unit area. The current density is preferably 100 mA / cm 2 Above and 1.5A / cm 2 Below, more preferably 300mA / cm 2 Above and 700mA / cm 2 When less than 100mA / cm 2 When the reduction product per unit area is low, a larger area is required. 2 , the side reaction of producing hydrogen increases and the concentration of the reduced product decreases.

[0035] When the Joule heat is increased by increasing the current density, the temperature will rise to a level above the appropriate level, so a cooling mechanism may be provided in or near the electrochemical reaction structure 10. The cooling mechanism may be water cooling or air cooling. Even when the temperature of the electrochemical reaction structure 10 is higher than room temperature, the temperature may be maintained as long as it is below 100°C.

[0036] The flow path P1 is connected to the inlet of the cathode chamber 140. The flow path P1 can flow a cathode supply fluid supplied 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.

[0037] Flow path P1 may also be connected to a carbon dioxide supply source. The carbon dioxide supply source may have a carbon dioxide separation and recovery device, and may also be connected to the carbon dioxide separation and recovery device. The carbon dioxide gas from the carbon dioxide separation and recovery device can be supplied to flow path P1 directly or after temporary storage, for example. Examples of carbon dioxide supply sources include various incinerators such as thermal power plants and waste incinerators, facilities with combustion furnaces, ironworks, facilities with smelting furnaces, etc. The carbon dioxide supply source is not limited to these facilities, and may also be other factories that produce carbon dioxide.

[0038] Flow path P2 is connected to the inlet of anode chamber 150. Flow path P2 can flow an anode supply fluid supplied to anode chamber 150. The anode supply fluid includes water or a second electrolyte. Flow path P2 can also be connected to an anode solution supply source. The anode solution supply source can, for example, supply a second electrolyte for the anode supply fluid.

[0039] The flow path P3 is connected to the outlet of the cathode chamber 140. The flow path P3 can flow the cathode exhaust fluid discharged from the cathode chamber 140. The cathode exhaust fluid contains carbon compounds and hydrogen generated by the reduction reaction at the cathode 11, and part of the carbon dioxide gas contained in the cathode supply fluid or part of the first electrolyte.

[0040] The flow path P4 is connected to the outlet of the anode chamber 150. The flow path P4 can flow the anode exhaust fluid discharged from the anode chamber 150. The anode exhaust fluid includes, for example, gaseous oxygen generated by the oxidation reaction at the anode 12, carbon dioxide moved from the cathode chamber 140 or the electrolyte, and water or a portion of the second electrolyte contained in the anode supply fluid.

[0041] When a gas (cathode gas) containing a reduction target such as carbon dioxide is supplied to the cathode chamber 140 , the electrochemical reaction structure 10 may include a second cathode chamber between the cathode 11 and the separator 13 , and the first electrolyte may be supplied to the second cathode chamber. Figure 2Schematic diagram showing another structural example of the electrochemical reaction device according to the embodiment. Figure 2 As shown, the electrochemical reaction device 1 may further include a flow path plate 18 , a cathode chamber 180 , a flow path P5 , and a flow path P6 .

[0042] The flow path plate 18 forms a cathode chamber 180. The cathode chamber 180 is disposed 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 chamber 140 of the cathode 11. The cathode chamber 180 has an inlet for supplying a fluid to the cathode chamber 180 and an outlet for discharging a fluid from the cathode chamber 180.

[0043] Flow path P5 is connected to the inlet of cathode chamber 180. Flow path P5 can supply a second cathode supply fluid supplied to cathode chamber 180. The second cathode supply fluid includes a first electrolyte. The first electrolyte may or may not include carbon dioxide. Flow path P5 can also be connected to a cathode solution supply source. The cathode solution supply source can, for example, supply a first electrolyte for the second cathode supply fluid. When the first electrolyte is the same as the second electrolyte, flow path P5 can also be connected to the above-mentioned anode solution supply source.

[0044] Flow path P6 is connected to the outlet of cathode chamber 180. Flow path P6 can flow the second cathode discharge fluid discharged from cathode chamber 180. The second cathode discharge fluid includes carbon compounds and hydrogen generated by the reduction reaction at cathode 11, and the first electrolyte. The second cathode discharge fluid can also be reused by supplying it to flow path P5 as the first electrolyte after separating the gas component from the liquid component using a gas-liquid separator. In this case, there may also be other flow paths connecting flow path P5 and flow path P6, and a pump in the middle of the other flow path, and the separated liquid component is returned to flow path P5 by the pump.

[0045] The first electrolyte is preferably a solution with a high absorption rate of carbon dioxide. The existence form of carbon dioxide in the first electrolyte is not necessarily limited to a dissolved state, and bubble-shaped carbon dioxide may also be mixed in the first electrolyte. As an electrolyte containing carbon dioxide, for example, an aqueous solution containing bicarbonates, carbonates, phosphoric acid, boric acid, etc. such as lithium bicarbonate (LiHCO3), sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), cesium bicarbonate (CsHCO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3) can be cited. The electrolyte containing carbon dioxide can include ketones such as alcohols such as methanol and ethanol, acetone, or an alcohol solution or a ketone solution. The first electrolyte can be an electrolyte containing a carbon dioxide absorbent that reduces the reduction potential of carbon dioxide, has high ion conductivity, and absorbs carbon dioxide.

[0046] The first electrolyte and the second electrolyte may be a solution containing water, for example, an aqueous solution containing any electrolyte. The solution is preferably an aqueous solution that promotes the oxidation reaction of water. Examples of aqueous solutions containing electrolytes include 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 - ), carbonate ions (CO3 - ), hydroxide ion (OH - ) etc.

[0047] As the above-mentioned electrolyte, for example, a solution containing cations such as imidazolium ions and pyridinium ions and BF4 can be used. - PF6 - Ionic liquids or their aqueous solutions which are composed of salts of anions such as ethanolamine, imidazole, pyridine, etc. and are in a liquid state within a wide temperature range. In addition, other electrolytes include amine solutions or their aqueous solutions such as ethanolamine, imidazole, pyridine, etc. As amines, primary amines, secondary amines, tertiary amines, etc. can be listed. These electrolytes can also have the following characteristics: high ion conductivity, the property of absorbing carbon dioxide, and reducing the reduction energy.

[0048] Examples of primary amines include methylamine, ethylamine, propylamine, butylamine, pentylamine, and hexylamine. Amine hydrocarbons may be substituted with alcohols, halogens, and the like. Examples of amine hydrocarbons substituted with amine hydrocarbons include methanolamine, ethanolamine, and chloromethylamine. In addition, unsaturated bonds may also exist. The same is true for secondary amines and tertiary amines as for these hydrocarbons.

[0049] As secondary amines, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, etc. can be cited. The substituted hydrocarbons may be different. This is also the case for tertiary amines. For example, as substances with different hydrocarbons, methylethylamine, methylpropylamine, etc. can be cited.

[0050] Examples of the tertiary amine include trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trimethanolamine, triethanolamine, tripropanolamine, tributanolamine, tributanolamine, methyldiethylamine, and methyldipropylamine.

[0051] Examples of the cation of the ionic liquid include 1-ethyl-3-methylimidazolium ion, 1-methyl-3-propylimidazolium ion, 1-butyl-3-methylimidazolium ion, 1-methyl-3-pentylimidazolium ion, and 1-hexyl-3-methylimidazolium ion.

[0052] 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.

[0053] Examples of the pyridinium ion include methylpyridinium, ethylpyridinium, propylpyridinium, butylpyridinium, pentylpyridinium, and hexylpyridinium. Both the imidazolium ion and the pyridinium ion may be substituted with an alkyl group and may have an unsaturated bond.

[0054] Examples of anions include fluoride ions (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. It can also be a gemini ion in which the cation and anion of the ionic liquid are connected by hydrocarbon. In addition, a buffer solution such as potassium phosphate solution can also be supplied to the anode chamber 150 and the cathode chamber 180.

[0055] The second electrolyte contains water as an oxidized object. The amount of water contained in the first and second electrolytes and the electrolyte components can be changed to change the reactivity, change the selectivity of the reducing substance, and change the ratio of the generated substances. The first and second electrolytes can contain a redox pair as needed. Examples of the redox pair include Fe 3+ / Fe 2+ ,IO 3- / I - wait.

[0056] The flow regulator 21 is disposed in the middle of the flow path P1. The flow regulator 21 is capable of adjusting the flow rate of the cathode supply fluid flowing in the flow path P1, for example. The flow regulator 21 may also include a mass flow controller, for example. The flow regulator 21 adjusts the flow rate of carbon dioxide introduced into the cathode chamber 140. The flow regulator 21 may also 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 regulator 21 may also measure the flow rate of the cathode supply fluid flowing in the flow path P1, for example, and supply a data signal containing data representing the measured flow rate to the control device 80.

[0057] The flow regulator 22 is disposed in the middle of the flow path P2. The flow regulator 22 can, for example, adjust the flow rate of the anode supply fluid flowing in the flow path P2. The flow regulator 22 can also include a mass flow controller, for example. The temperature of the electrochemical reaction structure 10 can also be controlled by the flow regulator 22, or the gas generated in the anode chamber 150 can be moved to the flow path P4. The flow regulator 22 can also, for example, measure the flow rate of the anode supply fluid flowing in the flow path P2, and supply a data signal containing data representing the measured flow rate to the control device 80.

[0058] The humidifier 30 is provided in the middle of the flow path P1 and before or after the flow regulator 21. The humidifier 30 can humidify the carbon dioxide gas in the cathode supply fluid. Examples of the humidifier 30 include bubbling humidifiers, hollow fiber membrane humidifiers, and the like. Figure 1 As shown, by arranging the humidifier 30 between the flow regulator 21 and the cathode chamber 140, even when humidification is performed, the cathode supply fluid containing carbon dioxide gas at an accurate supply amount can be supplied to the cathode chamber 140. The electrochemical reaction device of the embodiment may not include the humidifier 30.

[0059] The cathode supply fluid containing humidified carbon dioxide gas may also contain liquid in the state of mist or smoke. The cathode supply fluid containing humidified carbon dioxide gas may also partially contain liquid water. In addition, these water contents may contain substances that function as cathode solutions, and may also contain carbon dioxide as a substance to be reduced.

[0060] The pressure regulator 41 is provided in the middle of the flow path P3. The pressure regulator 41 can adjust the pressure of the cathode chamber 140 by controlling the pressure of the flow path P3. The pressure regulator 41 may also have a function of adjusting the pressure of the cathode chamber 140 according to a control signal from the control device 80. The pressure regulator 41 may also have a function of indirectly measuring the pressure of the cathode chamber 140 by measuring the pressure of the flow path P3.

[0061] The pressure regulator 42 is provided in the middle of the flow path P4. The pressure regulator 42 can adjust the pressure in the anode chamber 150 by controlling the pressure of the flow path P4, for example. The pressure regulator 42 may also have a function of adjusting the pressure of the anode chamber 150 according to a control signal from the control device 80. The pressure regulator 42 may also have a function of indirectly measuring the pressure of the anode chamber 150 by measuring the pressure of the flow path P4.

[0062] The dehydrator 51 is provided in the middle of the flow path P3, for example, at the rear stage of the pressure regulator 41. The dehydrator 51 can, for example, process the cathode exhaust fluid and separate water and the first electrolyte from the cathode exhaust fluid. The dehydrator 51 can also have a function of removing moisture from the exhaust gas by cooling, etc. By arranging the dehydrator 51 at the front stage of the flow meter 61, the flow rate of the gas containing carbon compounds in the cathode exhaust fluid discharged from the cathode chamber 140 can be measured more accurately.

[0063] The gas-liquid separator 52 is provided in the middle of the flow path P4, for example, in the post stage of the pressure regulator 42. The gas-liquid separator 52 can, for example, process the anode exhaust fluid and separate liquids such as water and electrolyte from the anode exhaust fluid. The processed anode exhaust fluid contains, for example, oxygen generated by the oxidation reaction at the anode 12 and carbon dioxide moving from the cathode chamber 140. By arranging the gas-liquid separator 52 in the front stage of the flow meter 62, the flow rate of gases such as oxygen and carbon dioxide in the anode exhaust fluid discharged from the anode chamber 150 can be measured more accurately.

[0064] The flow meter 61 is provided in the middle of the flow path P3, for example, in the rear stage of the dehydrator 51. The flow meter 61 can measure, for example, the flow rate of the cathode exhaust fluid after treatment flowing in 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 exhaust fluid.

[0065] The flow meter 62 is provided in the middle of the flow path P4, for example, in the subsequent stage of the gas-liquid separator 52. The flow meter 62 can measure, for example, the flow rate of the anode exhaust fluid being processed flowing in 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 exhaust fluid.

[0066] The power supply 70 can, for example, supply power to the electrochemical reaction structure 10. The power supply 70 is connected to, for example, the current collector 16 and the current collector 17. The power supply 70 can input power for electrolytic reactions such as oxidation reactions and reduction reactions into the electrochemical reaction structure 10, 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 carried out using the electric energy supplied from the power supply 70. The power supply 70 and the current collector 16 and the power supply 70 and the current collector 17 are connected, for example, by wiring. Electrical equipment such as inverters, converters, and batteries may also be provided between the electrochemical reaction structure 10 and the power supply 70 as needed. The driving method of the electrochemical reaction structure 10 may be a constant voltage method or a constant current method.

[0067] The power supply 70 can be a common commercial power supply or battery, etc., and can also be a power supply that converts renewable energy into electric energy and supplies it. As an example of such a power supply, a power supply that converts kinetic energy and potential energy such as wind power, water power, geothermal energy, tidal force into electric energy, a power supply such as a solar cell with a photoelectric conversion element that converts light energy into electric energy, a power supply such as a fuel cell, a storage battery, etc. that converts chemical energy into electric energy, and a device that converts vibration energy such as sound into electric energy can be cited. The photoelectric conversion element has the function of using the energy of light such as irradiated sunlight to separate charges. As an example of a photoelectric conversion element, pin junction solar cells, pn junction solar cells, amorphous silicon solar cells, multi-junction solar cells, monocrystalline silicon solar cells, polycrystalline silicon solar cells, dye-sensitized solar cells, organic thin film solar cells, etc. are included. In addition, the photoelectric conversion element can also be stacked with at least one of the cathode 11 and the anode 12 inside the electrochemical reaction structure 10.

[0068] The power supply 70 can, for example, adjust the current or voltage supplied to the electrochemical reaction structure 10. The power supply 70 can, for example, have a power controller that adjusts the current or voltage supplied to the electrochemical reaction structure 10. The power supply 70 can also have a function of adjusting the pressure of the cathode chamber 140 or the pressure of 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.

[0069] Figure 3 Schematic diagram showing another structural example of the electrochemical reaction device according to the embodiment. Figure 3As shown, the electrochemical reaction device 1 may also include a flow path P7 and a pump 90. The flow path P7, for example, connects the gas-liquid separator 52 to the flow path P2 or the anode fluid supply source. The pump 90 is disposed in the middle of the flow path P7. The anode discharge fluid is separated into liquid components such as the second electrolyte and gas components such as oxygen, hydrogen, and carbon dioxide by the gas-liquid separator 52. By returning the liquid components to the flow path P2 via the flow path P7 by the pump 90, the anode solution can be circulated. The flow paths P1, P2, P3, P4, P5, P6, and P7 can be formed, for example, using piping.

[0070] Figure 4 Schematic diagram showing another structural example of the electrochemical reaction device according to the embodiment. Figure 4 As shown, the electrochemical reaction device 1 may also have a temperature regulator 71. The temperature regulator 71 is directly or indirectly connected to the electrochemical reaction structure 10. The temperature regulator 71 is capable of measuring and adjusting the temperature (e.g., the appearance temperature) of the electrochemical reaction structure 10, for example. The temperature regulator 71 may also have a heater capable of heating the electrochemical reaction structure 10, and a cooler capable of cooling the electrochemical reaction structure 10. The temperature regulator 71 may also measure at least one of the temperature of the cathode chamber 140 and the temperature of the anode chamber 150, and adjust these temperatures. The temperature regulator 71 may also have the 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 temperature of the electrochemical reaction structure 10, the temperature of the cathode chamber 140, and the temperature of the anode chamber 150 according to a control signal from the control device 80.

[0071] The control device 80 is connected to 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 source 70, for example, by wired connection or wireless connection. Figure 1 As shown, the control device 80 is connected to the flow regulator 21, the flow meter 61 and the flow meter 62 respectively by wired connection or wireless connection. The control device 80 can, for example, measure the sum of the flow rate of the cathode supply fluid flowing in the flow path P1, the flow rate of the treated cathode exhaust fluid flowing in the flow path P3 and the flow rate of the treated anode exhaust fluid flowing in the flow path P4, and adjust the operating conditions of the electrochemical reaction structure 10 according to the measured sum value. The control device 80 can also control 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 according to the above-mentioned sum value, thereby controlling the pressure difference (differential pressure) between the cathode chamber 140 and the anode chamber 150, for example.

[0072] The control device 80 has hardware including a computing device such as a processor, for example. In addition, 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 using hardware.

[0073] Figure 5 Schematic diagram showing another structural example of the electrochemical reaction device according to the embodiment. Figure 5 As shown, the control device 80 may also be connected to at least one of the pressure regulator 41 and the pressure regulator 42 through a wired connection or a wireless connection. The control device 80 can, for example, measure the sum of the flow rate of the cathode supply fluid flowing in the flow path P1, the flow rate of the treated cathode exhaust fluid flowing in the flow path P3, and the flow rate of the treated anode exhaust fluid flowing in the flow path P4, and control at least one of the pressure regulator 41 and the pressure regulator 42 according to the measured sum value to adjust the operating conditions of the electrochemical reaction structure 10.

[0074] Figure 6 Schematic diagram showing another structural example of the electrochemical reaction device according to the embodiment. Figure 6 As shown, the control device 80 may also be connected to at least one of the pressure regulator 41 and the pressure regulator 42 by wired connection or wireless connection, and is not connected to the flow regulator 22. The control device 80 can, for example, measure the sum of the flow rate of the cathode supply fluid flowing in the flow path P1, the flow rate of the treated cathode exhaust fluid flowing in the flow path P3, and the flow rate of the treated anode exhaust fluid flowing in the flow path P4, and control at least one of the pressure regulator 41 and the pressure regulator 42 according to the measured sum value to adjust the operating conditions of the electrochemical reaction structure 10. In addition, Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 The structures shown respectively can also be combined appropriately.

[0075] Next, an example of the operation method of the electrochemical reaction device 1 is described. Here, a case where carbon dioxide is reduced to mainly generate carbon monoxide, and water is oxidized to generate oxygen is described. When a cathode supply fluid containing carbon dioxide is supplied to the cathode chamber 140, an anode supply fluid containing a second electrolyte is supplied to the anode chamber 150, and a voltage greater than the electrolysis voltage is applied between the cathode 11 and the anode 12 by power supply from the power supply 70, an oxidation reaction of water occurs near the anode 12 in contact with the second electrolyte. As shown in the following formula (1), an oxidation reaction of the water contained in the second electrolyte occurs, electrons are lost, and oxygen and hydrogen ions are generated. A portion of the generated hydrogen ions move to the cathode chamber 140 via the diaphragm 13.

[0076] 2H2O→4H + +O2+4e - … (1)

[0077] When the hydrogen ions (H + ) reaches the vicinity of the cathode 11 and electrons (e) are supplied from the power supply 70 to the cathode 11 - ), a reduction reaction of carbon dioxide occurs. As shown in the following formula (2), hydrogen ions (H + ) and the electrons (e - ), reducing carbon dioxide to produce carbon monoxide.

[0078] 2CO2+4H + +4e - →2CO+2H2O… (2)

[0079] As shown in the above formula (1), the gas component contained in the anode exhaust fluid from the anode chamber 150 is mainly oxygen. In the reaction between 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 a part of it is reduced as carbon dioxide or as carbonate ions (CO3 2- ), bicarbonate ion (HCO3 - ) and flows to the anode 12 side. When the pH of the anode solution (second electrolyte) is, for example, 6 or less, the carbonate ions and bicarbonate ions that have moved to the anode 12 side exist as carbon dioxide through a chemical equilibrium reaction, and a portion of them dissolves in the anode solution. Such carbon dioxide gas that cannot be completely dissolved in the anode solution is contained in the anode exhaust fluid discharged from the anode chamber 150 together with oxygen. Under the operating conditions of the general electrochemical reaction structure 10, the existence ratio of carbon dioxide gas to oxygen in the anode exhaust fluid sometimes rises to, for example, 2:1.

[0080] 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 in the flow path P1, the flow rate of the cathode discharge fluid (cathode discharge fluid treated by the dehydrator 51) flowing in the flow path P3, and the flow rate of the anode discharge fluid (anode discharge fluid treated by the gas-liquid separator 52) flowing in the flow path P4. Through the reaction shown in the above formula (2), an equal amount of carbon compound (here, carbon monoxide) is generated on the cathode 11 side to consume carbon dioxide. In addition, the same amount of carbon dioxide as the generated amount of carbon compound moves to the anode 12 side. If the flow rate of carbon dioxide gas in the cathode supply fluid flowing in the flow path P1 is set to 100, when the current having the theoretical amount required to reduce 50% of carbon dioxide gas is supplied from the power supply 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, for example, as shown in Table 1. By registering (recording) data indicating such a relationship in advance in the control device 80 and confirming the difference between the registered data and the actual measurement data and the change in the operating condition over time, the operating condition can be grasped.

[0081]

【Table 1

[0082]

[0083] When hydrogen generation reaction as a side reaction occurs due to deterioration of the catalyst, or a phenomenon in which the cathode catalyst is covered with water or electrolyte, i.e., overflow, etc., changes in the cathode exhaust fluid such as a decrease in Faraday efficiency from 100% to 90% and 70% are caused as shown in Table 1. When the carbon dioxide flowing through the flow path P3 at 100% decreases in Faraday efficiency, it increases to 125 when flowing through 100% of the flow path P3, increases to 130 when flowing through 90% of the flow path P3, and increases to 140 when flowing through 70% of the flow path P3. Therefore, for example, 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 exhaust fluid flowing through the flow path P3, and the flow rate of the treated anode exhaust fluid flowing through the flow path P4, the decrease in Faraday efficiency can be confirmed. In addition, by comparing the measured data of the sum with the registered data of the control device 80, the deterioration during long-term operation can be grasped.

[0084] The reduction in Faraday efficiency due to degradation during long-term operation, for example, causes a failure mode called cross leakage in which gaseous substances move to one of the cathode 11 side and the anode 12 side or to both sides. When the reduction product moves from the cathode 11 side to the anode 12 side, the carbon compound and hydrogen generated at the cathode 11 are oxidized at the anode 12 and converted into carbon dioxide and water. When hydrogen is generated, since hydrogen molecules are small, the cross leakage of hydrogen moving in the diaphragm 13 increases, and it is converted into water at the anode 12, whereby the product changes from gas to liquid, and the sum of the flow rate of the treated cathode exhaust fluid flowing in the flow path P3 and the flow rate of the treated anode exhaust fluid flowing in the flow path P4 decreases. The changes in the flow rate of the treated cathode exhaust fluid and the flow rate of the treated anode exhaust fluid when hydrogen is converted into water are shown in Table 2. When the Faraday efficiency is reduced to 90% due to cross leakage, the sum of the flow rate of the treated cathode exhaust fluid flowing in the flow path P3 and the flow rate of the treated anode exhaust fluid flowing in the flow path P4 decreases from 130 to 125. By utilizing this change, it is possible to sense the increase or decrease in the cross leakage during long-term operation and control the operation.

[0085]

Table 2

[0086]

[0087] For example, when operating at a Faraday efficiency of 90%, through long-term operation, the flow rate of the treated cathode exhaust fluid flowing in the flow path P3 changes from 60 in Table 1 to 55 in Table 2, and the flow rate of the treated anode exhaust fluid flowing in the flow path P4 remains unchanged from 70 in Table 1 to 70 in Table 2. In this case, the change in the cathode exhaust fluid as shown in Table 2 is sensed by the occurrence of cross leakage, and the operating conditions of each component can be adjusted according to the control signal from the control device 80.

[0088] As an example of a conventional electrochemical reaction device, there is known a technique for sensing the total flow rate of a fluid discharged from a cathode chamber or an anode chamber, and adjusting the flow rate of carbon dioxide gas in the fluid supplied to the cathode chamber in order to adjust the carbon dioxide contained in the fluid discharged from the cathode chamber according to the sensing result. However, in order to sense changes in electrolysis performance such as cross leakage and degradation caused by long-term operation of the electrochemical reaction device, it is necessary to sense changes in the sum of the flow rate of the cathode supply fluid flowing in the flow path P1, the flow rate of the treated cathode discharge fluid flowing in the flow path P3, and the flow rate of the treated anode discharge fluid flowing in the flow path P4, as in the electrochemical reaction device of the embodiment.

[0089] There is an appropriate pressure balance between the cathode chamber 140 and the anode chamber 150, for example, the pressure is adjusted to a suitable pressure by the pressure regulator 41 and the pressure regulator 42. When the pressure of the cathode chamber 140 is low, water or electrolyte sometimes flows into the cathode 11 from the flow path P2. When too much water or electrolyte flows in, overflow may occur, or a hydrogen generation reaction may be performed as a side reaction. When the pressure of the cathode chamber 140 is high, the problem of water or electrolyte not being fully supplied to the cathode 11 may be caused, thereby hindering ion diffusion. The pressure of the cathode chamber 140 is preferably adjusted to a range of 0PaG or more and 300KPaG or less according to the gauge pressure. The pressure of the cathode chamber 140 can be adjusted, for example, by the pressure regulator 41. The pressure of the cathode chamber 140 is more preferably adjusted to a range of 50KPaG or more and 200KPaG or less according to the gauge pressure. The pressure of the anode chamber 150 is preferably adjusted to a range of 0PaG or more and 300KPaG or less according to the gauge pressure. The pressure of the anode chamber 150 can be adjusted, for example, by the pressure regulator 42. The pressure of the anode chamber 150 is preferably adjusted to be greater than 0PaG and less than 200KPaG according to the gauge pressure. The pressure difference (differential pressure) between the cathode chamber 140 and the anode chamber 150 is preferably adjusted to be greater than 0PaG and less than 150KPaG according to the gauge pressure. The pressure of the cathode chamber 140 is preferably higher than the pressure of the anode chamber 150. By adjusting the pressure difference between the cathode chamber 140 and the anode chamber 150 to the above range, for example, a hydrogen generation reaction as a side reaction can be suppressed.

[0090] When the occurrence of cross leakage from the cathode chamber 140 to the anode chamber 150 is sensed by the control device 80, at least one of the flow regulator 21, the flow regulator 22, the pressure regulator 41, the pressure regulator 42, the power supply 70 and the temperature regulator 71 is controlled according to the control signal from the control device 80, thereby controlling the operating conditions of the electrochemical reaction structure 10. In addition, the control device 80 may also compare the first data representing the measured sum with the second data registered in the control device 80, and control the at least one regulator according to the comparison result, thereby adjusting the pressure difference. The control device 80 may also adjust the pressure difference by analyzing the change of the measured sum over time and controlling the at least one regulator according to the analysis result.

[0091] When cross leakage occurs, for example, the control device 80 controls the flow rate regulator 21 to increase the flow rate of the cathode supply fluid flowing in the flow path P1 , thereby suppressing the hydrogen generation reaction.

[0092] When the hydrogen generation reaction increases due to temperature rise and cross leakage occurs, the control device 80 controls the flow regulator 22 to increase the flow rate of the anode supply fluid flowing in the flow path P2, thereby suppressing the temperature rise of the electrochemical reaction structure 10 and suppressing the hydrogen generation reaction.

[0093] When the inflow of water from the anode 12 side to the cathode 11 increases due to the change in the pressure of the cathode chamber 140 or the pressure of the anode chamber 150, thereby generating cross leakage, the pressure regulator 41 is controlled to adjust the pressure of the cathode chamber 140, and the pressure regulator 42 is controlled to adjust the pressure of the anode chamber 150, thereby suppressing water electrolysis. In addition, by controlling the power supply 70 to reduce the value of the current or voltage supplied to the electrochemical reaction structure 10, the temperature rise of the electrochemical reaction structure 10 can be suppressed, and the hydrogen generation reaction can be suppressed.

[0094] When cross leakage occurs, the temperature of the electrochemical reaction structure 10 can be lowered by controlling the heater of the temperature regulator 71 , thereby suppressing the hydrogen generation reaction.

[0095] Flow path P3 may also be connected to a valuable substance manufacturing device. Examples of valuable substance manufacturing devices include chemical synthesis devices that generate valuable substances by chemical synthesis using raw materials such as carbon monoxide. Examples of valuable substances include methanol generated by a methanol manufacturing device, hydrocarbons generated by a Fischer-Tropsch reaction device, synthetic gasoline, light oil, jet fuel, olefin compounds generated by an olefin manufacturing device, etc. By arranging a valuable substance manufacturing device at the rear stage of the electrochemical reaction structure 10, valuable substances with high added value can be manufactured from the products of the electrochemical reaction structure 10.

[0096] The type of chemical synthesis device is not particularly limited as long as it can react / synthesize other substances from the reduction product generated at the cathode 11. Examples of reactions using the reduction product generated by the chemical synthesis device include chemical reactions, electrochemical reactions, and biological conversion reactions using organisms such as algae, enzymes, yeast, and bacteria.

[0097] The flow path P3 may also be connected to a product separator instead of being connected to a valuable substance manufacturing device. The product separator can separate carbon compounds such as carbon monoxide as a product by separating excess carbon dioxide from the cathode discharge fluid or removing moisture from the cathode discharge fluid. For example, when carbon monoxide gas is generated by the above formula (2) in the electrochemical reaction structure 10, methanol can be manufactured by methanol synthesis by using a mixed gas containing the generated carbon monoxide gas and hydrogen as a by-product of the reduction reaction as a raw material, or jet fuel, light oil, etc. can be manufactured by Fischer-Tropsch synthesis. Not limited to this, the flow path P3 may also be connected to a tank for storing gases containing carbon compounds such as carbon monoxide instead of being connected to a valuable substance manufacturing device.

[0098] The reduction product may include carbon dioxide, carbon monoxide, and hydrogen produced by the electrolysis of water. The hydrogen concentration can be adjusted arbitrarily according to the mode of use. In the case of using hydrogen in a chemical synthesis device, in order to use a mixture of carbon monoxide and hydrogen, carbon dioxide can also be separated from the cathode exhaust fluid for use. In the case of not using hydrogen, only carbon monoxide is separated from the cathode exhaust fluid. In the case of generating methanol, by adjusting the number of moles of hydrogen to about 2 times the number of moles of carbon monoxide, the hydrogen generated at the cathode 11 can be used as a valuable substance. On the other hand, at the cathode 11, the side reaction of hydrogen can also be suppressed by the reaction conditions, and the concentration of hydrogen in the reduction product can be adjusted in a range of more than 0.1% and less than 5% by volume percentage. Thus, the electrochemical reaction device can be used as a carbon monoxide manufacturing device for manufacturing high-concentration carbon monoxide.

[0099] 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.

[0100] The above embodiments can be summarized into the following technical solutions.

[0101] (Technical Solution 1)

[0102] An electrochemical reaction device, wherein the device comprises: an electrochemical reaction structure, which comprises a cathode, an anode, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode and an anode chamber facing the anode, the cathode having a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide to generate a carbon compound, and the anode having an oxidation catalyst that promotes an oxidation reaction of oxidizing water to generate oxygen; a first flow path connected to the inlet of the cathode chamber, through which a first fluid containing carbon dioxide supplied to the cathode chamber flows; a second flow path connected to the inlet of the anode chamber, through which a second fluid containing water supplied to the anode chamber flows; a third flow path connected to the outlet of the cathode chamber, through which a third fluid discharged from the cathode chamber and containing the generated carbon compound flows; a fourth flow path connected to the outlet of the anode chamber, through which a fourth fluid discharged from the anode chamber and containing the water and the generated oxygen flows; and at least one regulator selected from a first flow regulator that regulates the flow rate of the first fluid flowing in the first flow path, a second flow regulator that regulates the flow rate of the second fluid flowing in the second flow path. A group consisting of two flow regulators, a first pressure regulator for adjusting the pressure of the third flow path, a second pressure regulator for adjusting the pressure of the fourth flow path, a temperature regulator for adjusting the temperature of the electrochemical reaction structure, and a power supply for adjusting the current or voltage supplied to the electrochemical reaction structure, at least including the first flow regulator; a gas-liquid separator, which is arranged in the middle of the fourth flow path, processes the fourth fluid and separates the liquid containing water from the fourth fluid; a first flow meter, which measures the flow rate of the third fluid flowing in the third flow path; a second flow meter, which measures the flow rate of the treated fourth fluid flowing in the fourth flow path; and a control device, which is connected to the at least one regulator, the first flow meter and the second flow meter respectively, measures the sum of the flow rate of the first fluid flowing in the first flow path, the flow rate of the third fluid flowing in the third flow path and the flow rate of the treated fourth fluid flowing in the fourth flow path, and controls the at least one regulator according to the measured value of the sum to adjust the pressure difference between the cathode chamber and the anode chamber.

[0103] (Technical Solution 2)

[0104] The electrochemical reaction device according to claim 1 further comprises a humidifier provided in the middle of the first flow path to humidify carbon dioxide in the first fluid.

[0105] (Technical Solution 3)

[0106] The electrochemical reaction device according to claim 1 or 2 further comprises a dehydrator provided in the middle of the third flow path and before the first flow meter, and processes the third fluid to separate water from the third fluid.

[0107] (Technical Solution 4)

[0108] An electrochemical reaction device according to any one of Technical Solutions 1 to Technical Solutions 3, wherein the control device controls the first flow regulator according to the measured value of the sum to adjust the flow rate of the first fluid flowing in the first flow path, thereby adjusting the pressure difference.

[0109] (Technical Solution 5)

[0110] An electrochemical reaction device according to any one of Technical Solutions 1 to Technical Solutions 4, wherein the at least one regulator includes the first pressure regulator and the second pressure regulator, and the control device controls the first pressure regulator to adjust the pressure of the third flow path according to the measured value of the sum, and controls the second pressure regulator to adjust the pressure of the fourth flow path according to the measured value of the sum, thereby adjusting the pressure difference.

[0111] (Technical Solution 6)

[0112] An electrochemical reaction device according to any one of Technical Solutions 1 to 5, wherein the at least one regulator includes the second flow regulator, and the control device controls the second flow regulator according to the measured value of the sum to adjust the flow rate of the second fluid flowing in the second flow path, thereby adjusting the pressure difference.

[0113] (Technical Solution 7)

[0114] An electrochemical reaction device according to any one of Technical Solutions 1 to Technical Solutions 6, wherein the at least one regulator includes the temperature regulator, and the control device controls the temperature regulator according to the measured values ​​of the sum to adjust the temperature of the electrochemical reaction structure, thereby adjusting the pressure difference.

[0115] (Technical Solution 8)

[0116] According to the electrochemical reaction device described in Technical Solution 7, the temperature regulator includes a heater for heating the electrochemical reaction structure.

[0117] (Technical Solution 9)

[0118] An electrochemical reaction device according to any one of Technical Solutions 1 to 8, wherein the at least one regulator includes the power supply, and the control device controls the power supply according to the measured values ​​of the sum to adjust the current or voltage supplied to the electrochemical reaction structure, thereby adjusting the pressure difference.

[0119] (Technical Solution 10)

[0120] An electrochemical reaction device according to any one of Technical Solutions 1 to 9, wherein the control device compares the first data representing the measured sum with the second data registered in the control device, and controls at least one regulator based on the comparison result, thereby adjusting the pressure difference.

[0121] (Technical Solution 11)

[0122] An electrochemical reaction device according to any one of Technical Solutions 1 to 10, wherein the control device analyzes the changes in the measured sum over time and controls at least one regulator based on the analysis results, thereby adjusting the pressure difference.

[0123] (Technical Solution 12)

[0124] A method for operating an electrochemical reaction device, wherein the electrochemical reaction device comprises: an electrochemical reaction structure, which comprises a cathode, an anode, a diaphragm between the cathode and the anode, a cathode chamber facing the cathode and an anode chamber facing the anode, the cathode having a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide to generate carbon compounds, and the anode having an oxidation catalyst that promotes an oxidation reaction of oxidizing water to generate oxygen; a first flow path connected to an inlet of the cathode chamber for supplying a first fluid containing carbon dioxide to the cathode chamber; a second flow path connected to an inlet of the anode chamber for supplying a first fluid containing carbon dioxide to the anode chamber; a flow path for a second fluid containing water supplied to the anode chamber; a third flow path connected to the outlet of the cathode chamber and for a flow path for a third fluid discharged from the cathode chamber and containing the generated carbon compound; a fourth flow path connected to the outlet of the anode chamber and for a flow path for a fourth fluid discharged from the anode chamber and containing the water and the generated oxygen; at least one regulator selected from a first flow regulator for regulating the flow rate of the first fluid flowing in the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing in the second flow path, a first pressure regulator for regulating the pressure of the third flow path, and a pressure regulator for regulating the pressure of the third flow path. A group consisting of a second pressure regulator for adjusting the pressure of the fourth flow path, a temperature regulator for adjusting the temperature of the electrochemical reaction structure, and a power supply for adjusting the current or voltage supplied to the electrochemical reaction structure, comprising at least the first flow regulator; a gas-liquid separator, which is arranged in the middle of the fourth flow path and processes the fourth fluid to separate the liquid containing water from the fourth fluid; a first flow meter, which measures the flow rate of the third fluid flowing in the third flow path; and a second flow meter, which measures the flow rate of the treated fourth fluid flowing in the fourth flow path; the operation method comprises the following steps : The first fluid is supplied to the cathode chamber, the second fluid is supplied to the anode chamber, and an electric current or voltage is supplied to the electrochemical reaction structure, thereby reducing the carbon dioxide at the cathode to generate the carbon compound, and reducing the water at the anode to generate the oxygen, measuring the sum of the flow rate of the first fluid flowing in the first flow path, the flow rate of the third fluid flowing in the third flow path, and the flow rate of the treated fourth fluid flowing in the fourth flow path, and controlling the at least one regulator according to the measured value of the sum to adjust the pressure difference between the cathode chamber and the anode chamber.

[0125] (Technical Solution 13)

[0126] According to the operating method of the electrochemical reaction device described in Technical Solution 12, the pressure of the cathode chamber is adjusted to a range of greater than 0PaG and less than 300KPaG, the pressure of the anode chamber is adjusted to greater than 0PaG and less than 300KPaG, the pressure difference is adjusted to greater than 0PaG and less than 150KPaG, and the pressure of the cathode chamber is higher than the pressure of the anode chamber.

Claims

1. An electrochemical reaction device, characterized in that: have: An electrochemical reaction structure comprising a cathode, an anode, a separator between the cathode and the anode, a cathode chamber facing the cathode and an anode chamber facing the anode, wherein the cathode has a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide to generate a carbon compound, and the anode has an oxidation catalyst that promotes an oxidation reaction of oxidizing water to generate oxygen; a first flow path connected to the inlet of the cathode chamber and through which a first fluid containing the carbon dioxide supplied to the cathode chamber flows; a second flow path connected to the inlet of the anode chamber and through which a second fluid containing the water supplied to the anode chamber flows; a third flow path connected to the outlet of the cathode chamber and through which a third fluid discharged from the cathode chamber and containing the generated carbon compound flows; a fourth flow path connected to the outlet of the anode chamber and 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 in the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing in 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, including at least the first flow regulator; a gas-liquid separator disposed in the middle of the fourth flow path and processing the fourth fluid to separate a liquid containing water from the fourth fluid; a first flow meter for measuring a flow rate of the third fluid flowing in the third flow path; a second flow meter for measuring a flow rate of the treated fourth fluid flowing in the fourth flow path; as well as A control device is respectively connected to the at least one regulator, the first flow meter and the second flow meter, measures the sum of the flow rate of the first fluid flowing in the first flow path, the flow rate of the third fluid flowing in the third flow path and the flow rate of the treated fourth fluid flowing in the fourth flow path, and controls the at least one regulator according to the measured value of the sum to adjust the pressure difference between the cathode chamber and the anode chamber.

2. The electrochemical reaction device according to claim 1, characterized in that: The electrochemical reaction device further includes a humidifier provided in the middle of the first flow path and humidifying carbon dioxide in the first fluid.

3. The electrochemical reaction device according to claim 1 or 2, characterized in that: The electrochemical reaction device further includes a dehydrator provided in the middle of the third flow path and before the first flow meter, and processing the third fluid to separate water from the third fluid.

4. The electrochemical reaction device according to any one of claims 1 to 3, characterized in that: The control device controls the first flow rate regulator to adjust the flow rate of the first fluid flowing in the first flow path based on the measured value of the sum, thereby adjusting the pressure difference.

5. The electrochemical reaction device according to any one of claims 1 to 4, characterized in that: The at least one regulator includes the first pressure regulator and the second pressure regulator, The control device controls the first pressure regulator to adjust the pressure of the third flow path according to the measured value of the sum, and controls the second pressure regulator to adjust the pressure of the fourth flow path according to the measured value of the sum, thereby adjusting the pressure difference.

6. The electrochemical reaction device according to any one of claims 1 to 5, characterized in that: The at least one regulator comprises the second flow regulator, The control device controls the second flow rate regulator to adjust the flow rate of the second fluid flowing in the second flow path based on the measured value of the sum, thereby adjusting the pressure difference.

7. The electrochemical reaction device according to any one of claims 1 to 6, characterized in that: The at least one regulator includes the temperature regulator, The control device controls the temperature regulator based on the measured value of the sum to adjust the temperature of the electrochemical reaction structure, thereby adjusting the pressure difference.

8. The electrochemical reaction device according to claim 7, characterized in that: The temperature regulator includes a heater for heating the electrochemical reaction structure.

9. The electrochemical reaction device according to any one of claims 1 to 8, characterized in that: said at least one regulator comprising said power supply, The control device controls the power source based on the measured value of the sum to adjust the current or voltage supplied to the electrochemical reaction structure, thereby adjusting the pressure difference.

10. The electrochemical reaction device according to any one of claims 1 to 9, characterized in that: The control device compares first data indicating the measured sum with second data registered in the control device, and controls the at least one regulator based on the comparison result, thereby adjusting the pressure difference.

11. The electrochemical reaction device according to any one of claims 1 to 10, characterized in that: The control device analyzes the changes in the measured sum over time and controls the at least one regulator according to the analysis result, thereby adjusting the pressure difference.

12. A method for operating an electrochemical reaction device, characterized in that: The electrochemical reaction device comprises: An electrochemical reaction structure comprising a cathode, an anode, a separator between the cathode and the anode, a cathode chamber facing the cathode and an anode chamber facing the anode, wherein the cathode has a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide to generate a carbon compound, and the anode has an oxidation catalyst that promotes an oxidation reaction of oxidizing water to generate oxygen; a first flow path connected to the inlet of the cathode chamber and through which a first fluid containing the carbon dioxide supplied to the cathode chamber flows; a second flow path connected to the inlet of the anode chamber and through which a second fluid containing the water supplied to the anode chamber flows; a third flow path connected to the outlet of the cathode chamber and through which a third fluid discharged from the cathode chamber and containing the generated carbon compound flows; a fourth flow path connected to the outlet of the anode chamber and 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 in the first flow path, a second flow regulator for regulating the flow rate of the second fluid flowing in 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, including at least the first flow regulator; a gas-liquid separator disposed in the middle of the fourth flow path and processing the fourth fluid to separate a liquid containing water from the fourth fluid; a first flow meter for measuring a flow rate of the third fluid flowing in the third flow path; as well as a second flow meter for measuring a flow rate of the treated fourth fluid flowing in the fourth flow path; The operation method comprises the following steps: supplying the first fluid to the cathode chamber, supplying 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 generate the carbon compound, and reducing the water at the anode to generate the oxygen, The sum of the flow rate of the first fluid flowing in the first flow path, the flow rate of the third fluid flowing in the third flow path, and the flow rate of the treated fourth fluid flowing in the fourth flow path is measured, and the at least one regulator is controlled according to the measured value of the sum to adjust the pressure difference between the cathode chamber and the anode chamber.

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

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