Electrolysis device and method for controlling the electrolysis device

Abstract

To suppress lowering of electrolytic efficiency of an electrolytic apparatus.SOLUTION: An electrolytic apparatus includes: an electrolytic cell having a cathode flow passage, an anode flow passage, a cathode, an anode, and a diaphragm between the cathode flow passage and the anode flow passage; an anode supply flow passage; an anode discharge flow passage; a cathode supply flow passage; a cathode discharge flow passage for allowing cathode fluid to flow therein; first, second and third pressure detectors for measuring the pressures of the cathode supply flow passage, the cathode discharge flow passage and the anode supply flow passage; first and second pressure controllers for controlling the pressures of the cathode flow passage and the anode flow passage; a first gas-liquid separator for separating a reduction product from the cathode fluid; a gas detector for measuring the concentration of the separated reduction product; and an arithmetic device for performing arithmetic processing of calculating the values of the pressures of the anode flow passage and the cathode flow passage, on the basis of the measured concentration and pressures, controlling the first and second pressure controllers, and thereby adjusting the pressures of the anode flow passage and the cathode flow passage to the calculated values.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to an electrolysis device and a method for controlling the electrolysis device. [Background technology]

[0002] In recent years, various electrolysis technologies have been attracting attention as attempts at decarbonization, such as carbon dioxide electrolysis, which electrochemically reduces carbon dioxide (CO2) and converts it into chemical substances (chemical energy) such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH3OH), methane (CH4), ethanol (C2H5OH), ethane (C2H6), and ethylene (C2H4), and ammonia synthesis electrolysis, which synthesizes ammonia through an electrochemical reaction using nitrogen as a raw material. Electrolysis cells, which have two chambers separated by a diaphragm, have the problem that part of the cathode gas containing the product moves from the cathode channel to the anode channel, where it is reoxidized at the anode or moves with the electrolyte and is discharged from the anode channel, lowering the recovery rate of the produced gas and the electrolysis efficiency of the electrolysis device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-23047 [Patent Document 2] Japanese Patent Application Publication No. 2019-56135 [Patent Document 3] Patent Publication No. 2021-46574 [Patent Document 4] Japanese Patent Application Publication No. 58-94767 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to suppress a decrease in the electrolysis efficiency of an electrolysis device. [Means for solving the problem]

[0005] The electrolysis device of the embodiment includes an electrolysis cell having a cathode flow path through which a first cathode fluid containing a first substance flows, an anode flow path through which a first anode fluid containing a second substance flows, a cathode facing the cathode flow path and reducing the first substance to produce a reduction product, an anode facing the anode flow path and oxidizing the second substance to produce an oxidation product, and a diaphragm provided between the cathode flow path and the anode flow path; an anode supply flow path connected to the inlet of the anode flow path and through which an anode solution containing the second substance flows, an anode discharge flow path connected to the outlet of the anode flow path and through which a second anode fluid containing the oxidation product flows, a cathode supply flow path connected to the inlet of the cathode flow path and through which a cathode gas containing the first substance flows, a cathode discharge flow path connected to the outlet of the anode flow path and through which the second cathode fluid containing the reduction product flows, and a cathode supply a first pressure detector that measures the pressure in the cathode discharge flow path; a third pressure detector that measures the pressure in the anode supply flow path; a first pressure controller that controls the pressure in the cathode flow path; a second pressure controller that controls the pressure in the anode flow path; a first gas-liquid separator that separates reduction products from the second cathode fluid; a gas detector that measures the concentration of the separated reduction products; and a computing device that performs a calculation to calculate the respective values ​​of the pressure in the anode flow path and the pressure in the cathode flow path based on the measured concentrations, the measured pressure in the cathode supply flow path, the measured pressure in the cathode discharge flow path, and the measured pressure in the anode supply flow path, and controls the first pressure controller and the second pressure controller to adjust the pressure in the anode flow path and the pressure in the cathode flow path to the values ​​calculated by the calculation. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration example of an electrolysis device according to a first embodiment. [Figure 2] 1 is a schematic diagram illustrating a structural example of an electrolysis cell 101 according to a first embodiment. [Figure 3] 10 is a diagram showing the required pressure range for the pressure on both sides of the diaphragm 113. FIG. [Figure 4] FIG. 1 is a schematic diagram showing an example of the configuration of an electrolysis cell 101 according to a second embodiment. [Figure 5] FIG. 10 is a schematic diagram showing another example of the configuration of the electrolysis cell 101 in the second embodiment. [Figure 6] FIG. 1 is a schematic diagram showing a configuration example of an electrolysis device according to an embodiment. [Figure 7] FIG. 10 is a graph showing the time variation of the total faradaic efficiency. [Figure 8] FIG. 10 is a diagram showing the change over time in the flow rate of reduction products measured at the outlet of the cathode flow channel 111. [Figure 9] 10 is a diagram showing the change over time of the difference between the pressure at the inlet and the pressure at the outlet of the cathode flow channel 111. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, electrolysis devices according to embodiments will be described with reference to the drawings. In each embodiment, substantially identical components are denoted by the same reference numerals, and some of their descriptions may be omitted. The drawings are schematic, and the relationship between the thickness of each component and its planar dimensions, the thickness ratio of each component, etc. may differ from the actual ones.

[0008] In this specification, unless otherwise specified, the term "connect" may include not only direct connection but also indirect connection.

[0009] (First embodiment) Fig. 1 is a schematic diagram showing a configuration example of an electrolysis device according to Embodiment 1. The electrolysis device 1 shown in Fig. 1 includes a drive unit 1a and a drive control unit 1b.

[0010] The driving unit 1 a has an electrolysis unit 100 , a cathode supply unit 200 , a cathode discharge unit 300 , an anode supply unit 400 , and an anode discharge unit 500 .

[0011] The electrolysis unit 100 includes an electrolysis cell 101, a temperature controller 103, and a power supply .

[0012] The cathode supply unit 200 includes a cathode gas supply source 201 , a flow rate controller 202 , a humidifier 203 , and a pressure detector 204 .

[0013] The cathode exhaust section 300 includes a pressure controller 301 , a gas-liquid separator 302 , a flow rate detector 303 , a pressure detector 304 , and a gas detector 305 .

[0014] The anode supply unit 400 includes an anode solution supply source 401 , a flow rate controller 402 , and a pressure detector 403 .

[0015] The anode exhaust section 500 includes a pressure controller 501 , a gas-liquid separator 502 , a flow rate detector 503 , and a gas detector 504 .

[0016] The drive control unit 1b includes a control unit 600. The control unit 600 controls the driving of each component of the drive unit 1a. The control unit 600 includes, for example, a calculation device 601.

[0017] Fig. 2 is a schematic diagram showing an example of the structure of an electrolytic cell 101 according to the first embodiment. The electrolytic cell 101 shown in Fig. 2 includes a cathode flow path 111, an anode flow path 112, a diaphragm 113, a cathode 114, an anode 115, a cathode supply flow path 116, a cathode supply flow path 117, a cathode discharge flow path 118, an anode supply flow path 119, and an anode discharge flow path 120. Each flow path may be connected to a pump as necessary.

[0018] A first cathode fluid containing a substance to be reduced flows through the cathode flow channel 111. The cathode flow channel 111 is formed, for example, in a first storage section capable of storing the substance to be reduced. The substance to be reduced is stored in the cathode flow channel 111, for example, as a first electrolytic solution containing the substance. The first cathode fluid may contain a first electrolytic solution. The first electrolytic solution functions as a cathode solution and contains the substance to be reduced. When carbon dioxide is reduced, the cathode solution contains carbon dioxide, which is the substance to be reduced. When nitrogen is reduced, the cathode solution contains nitrogen, which is the substance to be reduced. The substance to be reduced present in the first electrolytic solution does not need to be in a gaseous form, and may be a dissolved substance to be reduced or carbonate ions (CO3 2- ) and bicarbonate ions (HCO3 - The first electrolytic solution may contain hydrogen ions or hydroxide ions, and is preferably an aqueous solution.

[0019] A first anode fluid containing a substance to be oxidized flows through the anode flow channel 112. The anode flow channel 112 is formed in a second container that can contain, for example, a second electrolyte solution or water vapor containing the substance to be oxidized. The second electrolyte solution functions as an anode solution, and contains, for example, water (HO) or chloride ions (Cl) as the substance to be oxidized. - ), carbonate ions (CO3 2- ) and bicarbonate ions (HCO3 - The second electrolytic solution may be an aqueous solution of an alcohol, an aqueous solution of an organic substance such as an amine, or the like.

[0020] By changing the amount of water and the components of the first and second electrolytic solutions, the reactivity can be changed, and the selectivity of the substance to be reduced and the ratio of the chemical substances produced can be changed. The first and second electrolytic solutions may contain a redox couple as needed. Examples of the redox couple include Fe 3+ / Fe 2+ or IO3 - / I - Examples include:

[0021] The first and second containers may be made of, for example, quartz glass, acrylic resin (PMMA), polystyrene (PS), or the like. A light-transmitting material may be used for a portion of the cathode channel 111 and the anode channel 112, with the remaining portion made of a resin material. Examples of resin materials include polyether ether ketone (PEEK), polyamide (PA), polyvinylidene fluoride (PVDF), polyacetal (POM) (copolymer), polyphenylene ether (PPE), acrylonitrile-butadiene-styrene copolymer (ABS), polypropylene (PP), polyethylene (PE), and the like. The first and second containers may have spaces for accommodating gases contained in the reactants and products.

[0022] The pressure in the first and second storage compartments is preferably set to a pressure at which the substance to be reduced does not liquefy, and is preferably adjusted, for example, within a range of 0.1 MPa to 6.4 MPa. If the pressure in the storage compartments is less than 0.1 MPa, the reduction reaction efficiency of the substance to be reduced may decrease. If the pressure in the storage compartments exceeds 6.4 MPa, the cathode gas may liquefy, and the reduction reaction efficiency of the substance to be reduced may decrease. Note that the pressure difference between the first and second storage compartments may cause damage to the diaphragm 113. For this reason, the pressure difference between the first and second storage compartments (differential pressure) is preferably set to 1 MPa or less.

[0023] The lower the temperature of the electrolyte, the greater the amount of the substance to be reduced that dissolves. However, from the perspective of electrolysis, low temperatures are disadvantageous because they increase the solution resistance and the theoretical voltage of the reaction. On the other hand, a high electrolyte temperature reduces the amount of carbon dioxide that dissolves, but is advantageous for electrolysis. For this reason, the operating temperature condition of the electrolytic cell 101 is preferably in the medium temperature range, for example, from ambient temperature to the boiling point of the electrolyte. When the electrolyte is an aqueous solution, a temperature of 10°C to 100°C is preferred, and 25°C to 80°C is more preferred. Note that when a cathode gas containing carbon dioxide is supplied to the cathode flow channel 111 and water vapor is supplied to the anode flow channel 112, operation at higher temperatures is possible. In this case, the operating temperature is determined taking into account the heat resistance of components such as the diaphragm 113. When the diaphragm 113 is an ion exchange membrane or the like, the operating temperature is a maximum of 180°C. When the diaphragm 113 is a porous polymer membrane such as Teflon (registered trademark), the maximum temperature is 300°C.

[0024] The first and second electrolytic solutions may contain different substances, or may be the same electrolytic solution containing the same substance. When the first and second electrolytic solutions contain the same substance and the same solvent, the first and second electrolytic solutions may be considered to be a single electrolytic solution. The pH of the first electrolytic solution may be higher than the pH of the second electrolytic solution. This allows ions such as hydrogen ions and hydroxide ions to move more easily through the diaphragm 113. Furthermore, the liquid junction potential difference caused by the pH difference can effectively promote the oxidation-reduction reaction.

[0025] The first electrolyte solution is preferably a solution with a high absorption rate of the substance to be reduced. The existence form of the substance to be reduced in the first electrolyte solution is not necessarily limited to a dissolved state, and the substance to be reduced may be present in the form of bubbles mixed in the first electrolyte solution. When the substance to be reduced contains carbon dioxide, examples of the first electrolyte solution include aqueous solutions containing bicarbonates or carbonates such as lithium bicarbonate (LiHCO3), sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), cesium bicarbonate (CsHCO3), sodium carbonate (Na2CO3), and potassium carbonate (K2CO3), phosphoric acid, boric acid, etc. When the substance to be reduced contains nitrogen, examples of the first electrolyte solution include aqueous solutions containing potassium sulfate (K2SO4), potassium hydrogen sulfate (KHSO4), etc. The carbon dioxide-containing electrolyte solution may contain alcohols such as methanol, ethanol, and acetone, or may be an alcohol solution. The first electrolytic solution may be an electrolytic solution containing a carbon dioxide absorbent that lowers the reduction potential of carbon dioxide, has high ionic conductivity, and absorbs carbon dioxide.

[0026] The second electrolytic solution can be a solution using water (H2O), 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- ), hydrogen ions (H + ), sodium ions (Na + ), potassium ions (K + ), calcium ions (Ca 2+ ), lithium ion (Li + ), cesium ions (Cs + ), magnesium ions (Mg 2+ ), chloride ions (Cl - ), bicarbonate ion (HCO3 - ), carbonate ions (CO3 - ), hydroxide ion (OH - ), sulfate ions (SO4 - ) and the like.

[0027] The electrolyte solution described above is a solution containing a cation such as an imidazolium ion or a pyridinium ion and BF4 - and PF6 - An ionic liquid or an aqueous solution thereof, which is composed of a salt with an anion such as ammonium hydroxide, ammonium nitrate, or the like and remains in a liquid state over a wide temperature range, can be used. Other examples of the electrolyte include solutions of amines such as ethanolamine, imidazole, and pyridine, or aqueous solutions thereof. Examples of amines include primary amines, secondary amines, and tertiary amines. These electrolytes may have high ionic conductivity, the ability to absorb the substance to be reduced, and the ability to reduce the reduction energy.

[0028] Examples of primary amines include methylamine, ethylamine, propylamine, butylamine, pentylamine, and hexylamine. The hydrocarbon amine may be substituted with an alcohol, a halogen, or the like. Examples of substituted hydrocarbon amines include methanolamine, ethanolamine, and chloromethylamine. An unsaturated bond may also be present. The same applies to secondary and tertiary amines.

[0029] Examples of secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, and dipropanolamine. The substituted hydrocarbon may be different. This also applies to tertiary amines. For example, examples of amines with different hydrocarbons include methylethylamine and methylpropylamine.

[0030] Examples of tertiary amines include trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trimethanolamine, triethanolamine, tripropanolamine, tributanolamine, trihexanolamine, methyldiethylamine, and methyldipropylamine.

[0031] 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-methylimidazolium ion, a 1-methyl-3-pentylimidazolium ion, and a 1-hexyl-3-methylimidazolium ion.

[0032] The imidazolium ion may be substituted at the 2-position. Examples of cations substituted at the 2-position of the imidazolium ion include a 1-ethyl-2,3-dimethylimidazolium ion, a 1,2-dimethyl-3-propylimidazolium ion, a 1-butyl-2,3-dimethylimidazolium ion, a 1,2-dimethyl-3-pentylimidazolium ion, and a 1-hexyl-2,3-dimethylimidazolium ion.

[0033] Examples of pyridinium ions include methylpyridinium, ethylpyridinium, propylpyridinium, butylpyridinium, pentylpyridinium, hexylpyridinium, etc. Both the imidazolium ion and the pyridinium ion may have a substituted alkyl group and may have an unsaturated bond.

[0034] The anion is fluoride ion (F - ), chloride ions (Cl - ), bromide ion (Br - ), iodide ion (I - ), BF4 - , PF6 - , CF3COO - , CF3SO 3- , NO3 - , SCN - , (CF3SO2)3C - Examples of suitable ionic liquids include bis(trifluoromethoxysulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and the like. Zwitterions in which the cation and anion of an ionic liquid are connected by a hydrocarbon may also be used. A buffer solution such as a potassium phosphate solution may also be supplied to the cathode flow channel 111 and the anode flow channel 112.

[0035] The diaphragm 113 is provided between the cathode flow channel 111 and the anode flow channel 112, and separates the cathode flow channel 111 from the anode flow channel 112. The diaphragm 113 is a membrane that separates hydrogen ions (H + ), hydroxide ion (OH - ), carbonate ions (CO3 2- ), bicarbonate ion (HCO3 - ) and other ions can be transferred.

[0036] The diaphragm 113 is a membrane that allows selective passage of anions or cations. This allows the electrolyte solutions in contact with the cathode 114 and the anode 115 to contain different substances, and furthermore, differences in ionic strength, pH, etc. can promote reduction reactions and oxidation reactions. The diaphragm 113 can be used to separate the first and second electrolyte solutions. The diaphragm 113 may have the function of allowing some ions contained in the electrolyte solutions in which both electrodes are immersed to pass through, i.e., the function of blocking one or more types of ions contained in the electrolyte solutions. This allows, for example, the two electrolyte solutions to have different pH values.

[0037] Examples of ion exchange membranes that can be used as the diaphragm 113 include 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), a fluororesin obtained by sulfonating and polymerizing tetrafluoroethylene from DuPont Corporation, Lewabrane (registered trademark) from LANXESS, IONSEP (registered trademark) from IONTECH, Mustang (registered trademark) from PALL Corporation, Ralex (registered trademark) from Mega Corporation, and Gore-Tex (registered trademark) from Gore-Tex Corporation. The ion exchange membrane may also be formed using a membrane with a hydrocarbon skeleton or, for anion exchange, a membrane with an amine group. When there is a pH difference between the first and second electrolytic solutions, a bipolar membrane formed by stacking a cation exchange membrane and an anion exchange membrane can be used, maintaining the pH of each electrolytic solution stable.

[0038] As the diaphragm 113, in addition to an ion exchange membrane, for example, a silicone resin, a fluorine-based resin (perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyethersulfone (PES), etc., a ceramic porous membrane, a glass filter, a packing filled with agar or the like, an insulating porous body such as zeolite or an oxide, etc. can be used. In particular, a hydrophilic porous membrane is preferable as the diaphragm 113 because it does not become clogged with air bubbles.

[0039] The cathode 114 faces the cathode flow channel 111. The cathode 114 is an electrode (reduction electrode) that reduces a substance to be reduced to produce a reduction product. The cathode 114 is disposed inside the first housing and immersed in the first electrolytic solution. The cathode 114 includes, for example, a reduction catalyst for producing a reduction product by a reduction reaction of the substance to be reduced, or a reduction catalyst for producing ammonia by a reduction reaction of nitrogen. Examples of the reduction catalyst include a material that reduces the activation energy for reducing the cathode gas. In other words, examples of the reduction catalyst include a material that reduces the overvoltage that occurs when a reduction product is produced by a reduction reaction of the cathode gas.

[0040] The cathode 114 may be made of, for example, a metal material or a carbon material. Metal materials include, for example, gold, aluminum, copper, silver, platinum, palladium, zinc, mercury, indium, nickel, titanium, and bismuth, as well as alloys containing these metals. Carbon materials include, for example, graphene, carbon nanotubes (CNTs), fullerenes, and Ketjen black. The reduction catalyst is not limited to these, and may be, for example, a metal complex such as a Mo complex, a Ru complex, or a Re complex, a merocene complex, or an organic molecule having an imidazole or pyridine skeleton. The reduction catalyst may also be a mixture of multiple materials. The cathode 114 may have a structure in which a reduction catalyst is provided in the form of, for example, a thin film, a lattice, particles, or a wire on a conductive substrate.

[0041] The reduction products generated by the reduction reaction at the cathode 114 vary depending on the type of cathode gas and the type of reduction catalyst, and include, for example, carbon monoxide (CO), formic acid (HCOOH), methane (CH), methanol (CHOH), ethane (CH), ethylene (CH), ethanol (CHOH), formaldehyde (HCHO), and ethylene glycol (CHO). When the reduction target substance contains nitrogen, the reduction product includes ammonia (NH). In the cathode 114, a side reaction that generates hydrogen (H) may occur simultaneously with the reduction reaction of these reduction target substances.

[0042] The anode 115 faces the anode flow path 112. The anode 115 is an electrode (oxidation electrode) that oxidizes substances to be oxidized, such as substances and ions, in the second electrolyte solution. For example, the anode 115 oxidizes water to produce oxygen or hydrogen peroxide solution, or oxidizes chloride ions (Cl - ) to produce chlorine. The anode 115 is placed inside the second housing and immersed in the second electrolyte. The anode 115 contains an oxidation catalyst for the substance to be oxidized. As the oxidation catalyst, a material that reduces the activation energy when oxidizing the substance to be oxidized, in other words, a material that reduces the reaction overvoltage, is used.

[0043] Examples of oxidation catalysts include metals such as ruthenium, iridium, platinum, cobalt, nickel, iron, and manganese. Binary, ternary, and quaternary metal oxides can also be used. 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), and ruthenium oxide (Ru-O). Examples of ternary metal oxides include Ni-Fe-O, Ni-Co-O, La-Co-O, Ni-La-O, and Sr-Fe-O. Examples of quaternary metal oxides include Pb-Ru-Ir-O and La-Sr-Co-O. The oxidation catalyst is not limited to these, and metal hydroxides containing cobalt, nickel, iron, manganese, etc., and metal complexes such as Ru complexes and Fe complexes can also be used. Also, a mixture of multiple materials can be used.

[0044] The anode 115 may be a composite material containing both 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, 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 Cu, Al, Ti, Ni, Ag, W, Co, and Au; and alloys containing at least one of these metals. The anode 115 may have a structure in which an oxidation catalyst in the form of a thin film, lattice, particles, or wire is provided on a conductive substrate. The conductive substrate may be a metal material such as titanium, a titanium alloy, or stainless steel.

[0045] The cathode supply flow path 116 is connected to the inlet of the cathode flow path 111. A cathode gas containing a substance to be reduced flows through the cathode supply flow path 116. The electrolysis cell 101 is capable of supplying the cathode gas from the cathode supply flow path 116 to the cathode flow path 111. Although the cathode supply flow path 116 shown in FIG. 2 extends inside the first housing unit, the position of the cathode supply flow path 116 is not limited to the position shown in FIG. 2.

[0046] The cathode supply flow path 117 is connected to the inlet of the cathode flow path 111. The cathode solution flows through the cathode supply flow path 117. The electrolytic cell 101 can supply the cathode solution to the cathode flow path 111 via the cathode supply flow path 117. The cathode supply flow path 117 may be connected to an electrolyte supply source (not shown). The electrolyte supply source can supply a first electrolyte to the cathode flow path 111 via the cathode supply flow path 117. If the first electrolyte and the second electrolyte are the same electrolyte, the cathode supply flow path 117 may be connected to the anode supply flow path 119.

[0047] The cathode exhaust flow path 118 is connected to the outlet of the cathode flow path 111. A second cathode fluid that is discharged from the cathode flow path 111 and contains the reduction product and the first electrolytic solution flows through the cathode exhaust flow path 118. The electrolysis cell 101 is capable of discharging the second cathode fluid from the cathode flow path 111 via the cathode exhaust flow path 118.

[0048] The anode supply flow path 119 is connected to the inlet of the anode flow path 112. An anode solution containing a substance to be oxidized flows through the anode supply flow path 119. The electrolysis cell 101 can supply the anode solution containing a substance to be oxidized to the anode flow path 112 via the anode supply flow path 119.

[0049] The anode exhaust flow path 120 is connected to the outlet of the anode flow path 112. A second anode fluid, which is discharged from the anode exhaust flow path 120 and contains oxidation products and an anode solution, flows through the anode exhaust flow path 120. The electrolysis cell 101 can discharge the second anode fluid from the anode flow path 112 via the anode exhaust flow path 120.

[0050] The power supply 102 applies a voltage between the cathode 114 and the anode 115. The power supply 102 may be, for example, an AC power supply supplied from a power plant, a DC power supply via a converter circuit, or a variable power supply, i.e., a power supply that converts renewable energy into electrical energy and supplies the converted energy. Examples of such power supplies include power supplies that convert kinetic energy or potential energy such as wind power, hydroelectric power, geothermal power, and tidal power into electrical energy, power supplies such as solar cells that have photoelectric conversion elements that convert light energy into electrical energy, power supplies such as fuel cells and storage batteries that convert chemical energy into electrical energy, and devices that convert vibrational energy such as sound into electrical energy. Furthermore, the power supply 102 may have a power controller that controls the power supplies.

[0051] The temperature controller 103 has a temperature detector, a heater, and a cooling chiller, which are connected to the electrolytic cell 101. The temperature detector is a contact-type temperature detector or a radiation-type temperature detector. The temperature controller 103 may have a chiller inside the heater. The temperature controller 103 may have a heater and a chiller connected to the electrolytic cell 101. The temperature controller 103 has a control mechanism that compares the temperature of the electrolytic cell 101 measured by the temperature detector with a set value and brings the temperature of the electrolytic cell 101 closer to the set value by heating with the heater or cooling with the chiller. The temperature detector may measure the temperature of the electrolytic cell 101 and output a detection signal to the computing device 601.

[0052] The cathode gas supply source 201 is connected to the inlet of the cathode flow channel 111 via the cathode supply flow channel 116. The cathode gas supply source 201 supplies a cathode gas containing a substance to be reduced. The cathode gas supply source 201 has, for example, a cylinder cabinet capable of accommodating the cathode gas.

[0053] The flow rate controller 202 is provided in the cathode supply flow path 116, downstream of the cathode gas supply source 201. The flow rate controller 202 has, for example, a mass flow controller that controls the flow rate of the cathode gas supplied from the cathode gas supply source 201 to the cathode flow path 111 via the cathode supply flow path 116.

[0054] The humidifier 203 is provided in the cathode supply flow path 116 and downstream of the flow rate controller 202. The humidifier 203 can humidify the cathode gas. The humidifier 203 has a tank that stores, for example, hot water. The humidifier 203 is not necessarily provided.

[0055] The pressure detector 204 measures the pressure in the cathode supply flow path 116 and outputs a detection signal to the arithmetic unit 601. The pressure detector 204 is connected to the cathode supply flow path 116, for example, at a stage subsequent to the flow rate controller 202 and the humidifier 203.

[0056] The pressure controller 301 is provided midway through the cathode exhaust flow path 118. The pressure controller 301 has a back pressure valve that controls the pressure of the cathode exhaust flow path 118 (primary side pressure) in response to a control signal input from the computing device 601, thereby controlling the pressure of the cathode flow path 111.

[0057] The gas-liquid separator 302 is provided, for example, midway through the cathode discharge flow path 118, downstream of the pressure controller 301. The gas-liquid separator 302 separates the gas-liquid two-phase second cathode fluid discharged from the cathode flow path 111 of the electrolytic cell 101 into a cathode effluent and a cathode exhaust. The cathode exhaust contains reduction products. The gas-liquid separator 302 has, for example, a gas-liquid separation membrane. The cathode effluent may be discarded at regular intervals, or may be returned to the anode solution supply source 401 and reused as an electrolytic solution.

[0058] The flow rate detector 303 can measure the flow rate of the reduction product flowing through the cathode discharge flow path 118 .

[0059] The pressure detector 304 measures the pressure in the cathode exhaust flow path 118 and outputs a detection signal to the arithmetic unit 601. The pressure detector 304 is connected to the cathode exhaust flow path 118 at the subsequent stage of the flow rate detector 303, for example.

[0060] The gas detector 305 measures the concentration of the reduction products flowing through the cathode exhaust flow path 118 and outputs a detection signal to the computing device 601. The gas detector 305 includes, for example, a gas sensor using gas chromatography, a controlled potential electrolysis gas sensor, a thermal conduction gas sensor, a gas sensor using a catalyst whose temperature increases in response to the reduction products, and a gas sensor using a color reagent.

[0061] The anolyte solution supply source 401 is connected to the inlet of the anode flow channel 112 via the anode supply flow channel 119. The anolyte solution supply source 401 supplies an anolyte solution containing a substance to be oxidized. The anolyte solution supply source 401 has a tank capable of containing the anolyte solution.

[0062] Flow rate controller 402 is provided midway through anode supply flow path 119. Flow rate controller 402 has, for example, a pump that controls the flow rate of the anode solution supplied from anode solution supply source 401 to anode flow path 112 via anode supply flow path 119.

[0063] Pressure detector 403 measures the pressure in anode supply flow path 119 and outputs a detection signal to arithmetic device 601. Pressure detector 403 is connected to anode supply flow path 119, for example, at the subsequent stage of flow rate controller 402.

[0064] The pressure controller 501 is provided midway along the anode exhaust flow path 120. The pressure controller 501 has a back pressure valve that controls the pressure in the anode exhaust flow path 120 (primary pressure) in response to a control signal input from the computing device 601, thereby controlling the pressure in the anode flow path 112.

[0065] The gas-liquid separator 502 is provided midway through the anode discharge flow path 120, downstream of the pressure controller 501. The gas-liquid separator 502 separates the gas-liquid two-phase flow of the second anode fluid discharged from the anode flow path 112 of the electrolysis cell 101 into an anode exhaust gas and an anode effluent. The anode exhaust gas contains oxidation products. The anode exhaust gas is sent to a flow rate detector 503. The anode effluent may be discarded at regular intervals or returned to the anode solution supply source 401 and reused as the electrolyte. The gas-liquid separator 502 has, for example, a gas-liquid separation membrane.

[0066] The flow rate detector 503 measures the flow rate of the anode exhaust flowing through the anode exhaust flow path 120 and outputs a detection signal to the computing device 601 .

[0067] The gas detector 504 can measure the concentration of each component contained in the anode exhaust and includes sensors such as gas chromatography, a controlled potential electrolysis gas sensor, a thermal conduction gas sensor, a catalyst temperature rise measurement sensor, and a color reagent sensor.

[0068] The arithmetic device 601 receives detection signals including data on the measurement values ​​of the pressure detector 204, the pressure detector 304, the gas detector 305, the pressure detector 403, the flow rate detector 503, and the gas detector 504. The arithmetic device 601 performs arithmetic processing using the data on the measurement values ​​of the pressure detector 204, the pressure detector 304, the gas detector 305, the pressure detector 403, the flow rate detector 503, and the gas detector 504, and determines the pressure in the cathode flow channel 111, the pressure in the anode flow channel 112, and the temperature of the electrolysis cell 101.

[0069] Examples of arithmetic processing by the arithmetic device 601 to determine the pressure in the cathode flow channel 111, the pressure in the anode flow channel 112, and the temperature of the electrolytic cell 101 include arithmetic processing based on feedback control in which changes in the amount of crossover in response to changes in the pressure in the cathode flow channel 111, the pressure in the anode flow channel 112, and the temperature of the electrolytic cell 101 are measured in advance, and based on this change, the pressure in the cathode flow channel 111, the pressure in the anode flow channel 112, and the temperature of the electrolytic cell 101 are determined so as to minimize the amount of crossover; arithmetic processing in which optimal pressure in the cathode flow channel 111, the pressure in the anode flow channel 112, and the temperature of the electrolytic cell 101 are determined based on empirical values; and arithmetic processing based on optimal values ​​using time-series data including machine learning.

[0070] Furthermore, the calculation device 601 sends control signals to the pressure controller 501, the pressure controller 301, and the temperature controller 103, respectively, and controls the pressure controller 501, the pressure controller 301, and the temperature controller 103 to adjust the pressure of the cathode flow path 111, the pressure of the anode flow path 112, and the temperature of the electrolytic cell 101 to the set values ​​calculated by the calculation processing of the calculation device 601.

[0071] The arithmetic device 601 may be configured using hardware that uses, for example, a processor, etc. Note that 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 the hardware by appropriately reading out the operation program stored in the recording medium.

[0072] The pressure loss due to the cathode flow channel 111 can be calculated from the difference (differential pressure) between the pressures measured by the pressure detector 204 and the pressure detector 304, and the pressure on both sides of the diaphragm 113 can be calculated from the difference (differential pressure) between the pressures measured by the pressure detector 204 and the pressure detector 403. The pressure loss due to the cathode flow channel 111 has a value equal to or greater than a certain value depending on the cross-sectional area of ​​the cathode flow channel 111 and the flow rate of the cathode gas.

[0073] Foreign matter such as precipitated salt and metal rust peeled off by corrosion accumulates in the cathode flow channel 111 and blocks the cathode flow channel 111, reducing the cross-sectional area of ​​the cathode flow channel 111 and increasing its impact, but conversely, reducing the foreign matter can increase the cross-sectional area of ​​the cathode flow channel 111, or reduce the impact of reduction products leaking from the cathode flow channel 111 to the outside due to damage to the storage section or diaphragm 113. Therefore, measuring the change in pressure drop through the cathode flow channel 111 can serve as an indicator for predicting changes in the cross-sectional area of ​​the cathode flow channel 111 and leakage of reduction products without observing the internal state of the electrolysis cell 101, and it is possible to detect the movement (crossover) of reduction products by a decrease in pressure drop through the cathode flow channel 111.

[0074] The pressure on both sides of the diaphragm 113 is preferably 1 MPa or less because an excessively high pressure can lead to damage to the diaphragm 113. The pressure on both sides of the diaphragm 113 is determined, for example, by the bubble point, which is the pressure at which gas begins to permeate when gas is pressurized on one side of the diaphragm 113, or the liquid permeation pressure, which is the pressure at which water begins to permeate when water is pressurized on one side of the diaphragm 113, and is set to a value that prevents the reduction products from migrating from the cathode channel 111 to the anode channel 112 through the diaphragm 113 and prevents the second electrolytic solution from migrating from the anode channel to the cathode channel 111. When the bubble point or liquid permeation pressure changes due to deterioration of the diaphragm 113, it is possible to set pressure conditions that prevent the reduction products and the anode solution from migrating through the diaphragm 113 by adjusting the pressure on both sides of the diaphragm 113. The pressure on both sides of the diaphragm 113 is the pressure applied to each of the two sides of the diaphragm 113, and is calculated from the difference between the pressures measured by the pressure detector 204 and the pressure detector 403, respectively.

[0075] The increase or decrease in the flow rate of the reduction product relative to the flow rate of the cathode gas is determined depending on the type of reduction reaction. For example, in the reaction of reducing carbon dioxide (CO2) to carbon monoxide (CO) (Equation (1)), the generated hydroxide ions (OH - ) and carbon dioxide in the cathode gas dissolve in the electrolyte according to formula (2) and move to the anode flow channel 112 side, so the flow rate of the reduction products decreases compared to the flow rate of the cathode gas. On the other hand, if the reaction is one in which nitrogen (N2) is reduced to produce ammonia (NH3) (formula (3)) or one in which water (H2O) is reduced to produce hydrogen (H2) (formula (4)), the flow rate of the reduction products increases compared to the flow rate of the cathode gas. When some of the reduction products move to the anode flow channel 112 side through the diaphragm 113, the flow rate of the reduction products in the cathode exhaust measured by flow detector 303 decreases, and the flow rate of the reduction products in the anode exhaust measured by flow detector 503 increases. Therefore, if the type and amount of the oxidation-reduction reaction do not change, it is possible to detect the movement (crossover) of the reduction products from the value of the flow rate of the reduction products measured by flow detector 303. CO2+H2O+2e - →CO+2OH- ···(1) CO2+OH - →HCO3 - ···(2) N2+6H + +6e - →2NH3···(3) 2H2O+2e - →H2+2OH - ···(4)

[0076] One possible adjustment mechanism is to adjust the cathode gas concentration in the reduction products to an optimal value by changing the flow rate of the cathode gas supplied to the cathode flow channel 111 according to the concentration of the reduction products measured by the gas detector 305. This simplifies or eliminates the need for mechanisms and processes for adjusting the concentration of the reduction products in the cathode exhaust gas discharged from the cathode flow channel 111, thereby reducing the cost of the entire system. Furthermore, by measuring the flow rate and concentration of the reduction products, the total amount of the reduction products can be calculated, and by comparing this with a theoretical value, it is possible to detect the movement (crossover) of the reduction products to the outside or to the anode flow channel 112. Furthermore, if reduction products are detected in the anode exhaust gas, crossover can be detected in the same way.

[0077] Hereinafter, a method (method of controlling the electrolysis device) for detecting crossover and suppressing it by controlling the pressure in the cathode flow channel 111, the pressure in the anode flow channel 112, and the temperature of the electrolysis cell 101 in this embodiment will be described.

[0078] 3 is a diagram showing the pressure difference measured by the pressure detector 204, the pressure detector 304, and the pressure detector 403, i.e., the required pressure range of the pressure on both sides of the diaphragm 113, used to determine the pressure to be applied to the electrolytic cell 101. At the start of operation of the electrolytic cell 101, the pressure to be applied to the electrolytic cell 101 is determined based on the bubble points and liquid permeation pressures of the cathode 114, the anode 115, and the diaphragm 113, the cathode gas pressure (the pressure of the cathode gas supply source 201) supplied to the electrolytic cell 101, and the reduction product pressure supplied to a storage container for collecting the reduction product or a reduction product purifier connected downstream of the flow rate detector 303. The pressures measured by the pressure detector 204 and the pressure detector 403 are controlled by the pressure controllers 301 and 501. The reduction product pressure is the pressure in the cathode discharge flow path 118 and is measured by the pressure detector 304. Specifically, the pressure measured by the pressure detector 204 must be lower than the cathode gas pressure, and the pressure on both sides of the diaphragm 113 must be lower than the bubble point of the diaphragm 113 to suppress crossover and higher than the liquid permeation pressure. The pressure value measured by the pressure detector 403, in particular, fluctuates during operation due to the influence of pulsation of the liquid feed pump and a two-phase gas-liquid flow caused by gas generated in the anode flow path 112. Therefore, when the current supplied to the electrolytic cell 101 is about 100 A or less, it is preferable to have a margin of at least about ±50 kPa. Because the amount of gas generated by the anode 115 increases in proportion to the current value, it is preferable to have a larger pressure margin as the current value increases. The required pressure range for the pressure on both sides of the diaphragm 113 is preferably within a range of about 300 kPaG to −50 kPaG when a membrane with a low porosity, such as an ion exchange membrane, is used, and preferably within a range of about 200 kPaG to 50 kPaG when a membrane with a high porosity, such as a porous membrane, is used. Within this range, depending on the supply gas specifications required in the downstream stage of the electrolysis device 1, it may be preferable to set the pressure as high as possible in order to increase the pressure of the reduction product.

[0079] When the electrolysis cell 101 is operated for a long period of time, the diaphragm 113 may be crushed or dissolved, or may deteriorate due to the adhesion of impurities or the flow-off of water-repellent or hydrophilic materials, resulting in changes in the bubble point and liquid permeation pressure. As a result, when the set pressure is within a set margin above the bubble point of the diaphragm 113 or within a set margin above the liquid permeation pressure of the diaphragm 113, the reduction product or the electrolyte moves between the cathode channel 111 and the anode channel 112. The timing at which the bubble point and liquid permeation pressure change varies depending on the type of diaphragm 113, operation time, applied current density, cell temperature, etc., and the longer the operation time, the higher the applied current density, and the higher the cell temperature, the greater the deterioration. For example, when a hydrophilic porous diaphragm is used, at an applied current density of 200 mA / cm 2 If the cell temperature is about 60° C., the diaphragm 113 may deteriorate after about 1600 hours of operation.

[0080] If crossover occurs due to deterioration of the diaphragm 113, the pressure measured by the pressure detector 204 or the pressure measured by the pressure detector 403 is controlled to control the pressure in the cathode channel 111 and the pressure in the anode channel 112 so that the pressure on both sides of the diaphragm 113 is within an optimal pressure range. One example of a process for determining the optimal pressure is to measure the total Faraday efficiency (recovery rate of reduction products), which is the sum of the Faraday efficiencies of all gases generated in the cathode channel 111 when the pressure is changed, and determine the pressure at which the total Faraday efficiency is maximized as the optimal pressure. This may be control to maximize the flow rate measured by the flow detector 303 when the pressure is changed, or control to minimize the pressure loss in the cathode channel 111, which is the difference (differential pressure) between the pressure measured by the pressure detector 204 and the pressure measured by the pressure detector 403. Alternatively, a combination of these may be used for optimization.

[0081] As described above, the electrolysis device of this embodiment can suppress crossover by controlling the pressure in the cathode flow channel 111 and the pressure in the anode flow channel 112 in accordance with the detected amount of reduction products. Suppressing the crossover of reduction products can suppress a decrease in electrolysis efficiency.

[0082] (Second embodiment) The electrolysis device of the second embodiment differs from the electrolysis device of the first embodiment in the structure of the electrolysis cell 101.

[0083] Fig. 4 is a schematic diagram showing an example configuration of an electrolytic cell 101 according to the second embodiment. The electrolytic cell 101 shown in Fig. 4 has a solid polymer structure and includes a flow path plate 131, a flow path plate 132, a diaphragm 113, a cathode 114, an anode 115, a cathode supply flow path 116, a cathode discharge flow path 118, an anode supply flow path 119, an anode discharge flow path 120, a current collector 135, and a current collector 136, but does not include a cathode supply flow path 117.

[0084] The flow channel plate 131 forms a cathode flow channel 133 including a groove facing the cathode 114. The cathode flow channel 133 is connected to the cathode supply flow channel 116 and the cathode discharge flow channel 118. The description of the cathode flow channel 111 can be used as appropriate for the description of the cathode flow channel 133.

[0085] The flow path plate 132 forms an anode flow path 134 including a groove facing the anode 115. The anode flow path 134 is connected to the anode supply flow path 119 and the anode discharge flow path 120. The description of the anode flow path 112 can be used as appropriate for the description of the anode flow path 134.

[0086] The current collector 135 is electrically connected to the flow path plate 131 and the cathode 114. The current collector 136 is electrically connected to the flow path plate 132 and the anode 115. The current collectors 135 and 136 are connected to the power source 102 via wiring. By disposing gaskets around the cathode 114 and the anode 115 that have a thickness equivalent to that of these electrodes, leakage of gas and liquid to the outside of the electrolysis cell 101 can be suppressed.

[0087] The flow path plate 131, the flow path plate 132, the diaphragm 113, the cathode 114, and the anode 115 are integrated together under a certain pressure.

[0088] Other explanations are the same as those for the electrolysis cell 101 of the first embodiment, and therefore the explanations of the first embodiment can be used as appropriate.

[0089] FIG. 5 is a schematic diagram illustrating another configuration example of the electrolytic cell 101 according to the second embodiment. The electrolytic cell 101 illustrated in FIG. 5 includes a stacked structural unit A having, in order, the cathode flow path 133, the cathode 114, the diaphragm 113, the anode 115, the anode flow path 134, the cathode flow path 133, the cathode 114, the diaphragm 113, the anode 115, and the anode flow path 134 of the electrolytic cell 101 illustrated in FIG. 4. The description of the cathode flow path 111 may be used as appropriate for the description of the cathode flow path 133. The description of the anode flow path 112 may be used as appropriate for the description of the anode flow path 134. As illustrated in FIG. 5, the structural unit A may include a flow path plate 137 having the cathode flow path 133 and the anode flow path 134, and may include a cooling plate that forms a flow path through which cooling water flows between the structural units A. Furthermore, the clamping plate 140 and the clamping plate 141 may each have a flow path through which cooling water flows. The number of the multiple structural units A is not particularly limited.

[0090] In the multiple structural units A, the multiple cathode supply flow paths 116, the multiple anode supply flow paths 119, the multiple cathode discharge flow paths 118, and the multiple anode discharge flow paths 120 are connected in parallel. The connection point (junction point) of the multiple cathode supply flow paths 116 is connected to a humidifier 203 and a pressure detector 204. The connection point (junction point) of the multiple cathode discharge flow paths 118 is connected to a pressure controller 301 and a pressure detector 304. The connection point (junction point) of the multiple anode supply flow paths 119 is connected to a flow rate controller 402 and a pressure detector 403. The connection point (junction point) of the multiple anode discharge flow paths 120 is connected to a pressure controller 501. This is not a limitation, and it is more preferable to connect each structural unit A to a different pressure detector 204, pressure detector 304, pressure detector 403, pressure controller 301, and pressure controller 501.

[0091] During operation of the electrolytic cell 101, reduction products and components of the anode solution moving toward the cathode 114 may solidify and precipitate in the cathode flow channel 133, causing the cathode flow channel 133 to become clogged and the supply of cathode gas to stop. For this reason, it is preferable to humidify the cathode gas so that moisture is present in the cathode gas in order to suppress the formation of precipitates.

[0092] On the other hand, if the moisture content of the cathode gas is too high, it is not preferable because too much moisture is supplied to the catalyst surface in the cathode 114, which makes it easier for hydrogen to be generated. Therefore, the moisture content in the cathode gas is preferably 20% or more and 90% or less in relative humidity, and more preferably 30% or more and 70% or less.

[0093] Humidified cathode gas is supplied to the cathode flow channel 133 via the cathode supply flow channel 116, and reduction products produced by the cathode 114 are discharged via the cathode discharge flow channel 118. As described above, it is preferable for the cathode gas containing the substance to be reduced to contain a certain amount of moisture, and therefore it is preferable to connect a humidifier 203 to the cathode supply flow channel 116 to control the humidity of the supply gas. Anode solution is supplied to the anode flow channel 134 via the anode supply flow channel 119, and oxidation products produced by the anode 115 and the substance to be reduced that migrates from the cathode 114 are discharged via the anode discharge flow channel 120 together with the anode solution.

[0094] As in the first embodiment, the electrolysis device of this embodiment can suppress crossover by controlling the pressure in the cathode flow channel 111 and the pressure in the anode flow channel 112 in accordance with the detected amount of reduction products. By suppressing crossover of reduction products, it is possible to suppress a decrease in electrolysis efficiency.

[0095] This embodiment can be combined with other embodiments as appropriate. [Example]

[0096] Next, examples and their evaluation results will be described. Figure 6 is a schematic diagram showing an example of the configuration of an electrolysis device of an example. The electrolysis device 1 shown in Figure 6 differs from the electrolysis device 1 shown in Figure 1 in that it does not include a gas-liquid separator 502, a flow rate detector 503, and a computing device 601. The electrolysis cell 101 used had the configuration shown in Figure 5 and included five structural units A, each with a total of 10 cell stacks.

[0097] Carbon dioxide in the cathode gas was reduced to produce carbon monoxide using the electrolysis device 1 shown in FIG. 6. The flow rate controller 202 had a mass flow controller. The gas detector 305 and the gas detector 504 each had a gas sensor using gas chromatography. The power supply 102 had a galvanostat and supplied a constant current to the electrolysis cell 101. The cathode 114 was connected to a 100 cm 2 The anode 115 is an electrode made of carbon-supported gold nanoparticles coated on a square piece of carbon paper. 2 The electrode is made of Ti nonwoven fabric with cut corners coated with IrO2 nanoparticles. The diaphragm 113 is a hydrophilic porous membrane.

[0098] The electrolytic cell 101 was connected to the cathode supply unit 200 and the anode supply unit 400 and operated under the following conditions. The flow rate of carbon dioxide gas with a purity of over 99.9% was controlled by the mass flow controller of the flow rate controller 202 so that the flow rate was 5 SLM into the cathode flow path 111, and the carbon dioxide gas humidified by the humidifier 203 so that the dew point was 50°C was supplied to the electrolytic cell 101. The reduction product discharged from the cathode flow path 111 passed through the pressure controller 301 and then merged with 20 SLM of Ar gas downstream of the gas-liquid separator 302, where it was diluted and supplied to the gas chromatograph of the gas detector 305. Five liters of a 0.1 M KHCO3 aqueous solution was supplied to the electrolyte tank of the anode solution supply source 401 as the anode solution, and the electrolyte was supplied to the anode flow path 112 at a flow rate of 100 mL / min using the liquid pump of the flow rate controller 402. The second anode fluid in the gas-liquid two-phase flow discharged from the anode flow channel 112 passed through a pressure controller 501, where it was separated into gas and liquid. The anode waste liquid was returned to the electrolyte tank, and the anode exhaust was discharged through a waste line provided in the electrolyte tank. The temperature of the electrolytic cell 101 was controlled to be about 60°C, and the initial pressure was set so that the pressure measured by the pressure detector 204 was about 50 kPaG and the pressure measured by the pressure detector 403 was about 0 kPaG. At this time, the pressure measured by the pressure detector 304 was about 48 kPaG, the pressure loss in the cathode flow channel 111 was about 2 kPaG, and the pressure on both sides of the diaphragm 113 was about 50 kPaG. A current of 20 A and a current density of 200 mA / cm were applied between the cathode 114 and anode 115 of the electrolytic cell 101 using a galvanostat of a power source 102. 2 A current of 1000 kJ / s was supplied, and the components of the reduction products were measured at regular intervals.

[0099] Figure 7 shows the change over time in the total faradaic efficiency (the sum of the CO faradaic efficiency and the H2 faradaic efficiency) from 1600 hours to 2000 hours after the start of measurement. Despite the electrolysis current flowing through the cathode flow channel 111, the total amount of reduction products discharged from the cathode flow channel 111 was smaller than the total amount of reduction products predicted from the applied current value, and therefore the total faradaic efficiency decreased over time. A gas sensor that reacts to CO and H2 was installed outside the electrolysis cell 101, but no CO or H2 was detected. Therefore, it is expected that the reduction products not detected in the cathode discharge flow channel 118 migrated to the anode flow channel 112 through the diaphragm 113.

[0100] FIG. 8 is a diagram showing the change over time in the flow rate of the reduction products measured in the cathode discharge flow path 118. FIG. 9 is a diagram showing the change over time in the difference between the pressure in the cathode supply flow path 116 and the pressure in the cathode discharge flow path 118 (pressure loss through the cathode flow path 111). FIGS. 8 and 9 show that the flow rate of the reduction products in the cathode discharge flow path 118 decreases because the reduction products move to the anode flow path 112, and that the pressure loss through the cathode flow path 111 decreases because the number of paths through which gas escapes to the anode flow path 112 increases. Therefore, it can be seen that crossover can be detected by evaluating the flow rate of the reduction products using not only gas detector 305 but also flow rate detector 303 and the change in pressure loss through the cathode flow path 111 using pressure detector 204, pressure detector 304, and pressure detector 403.

[0101] The above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the inventions and their equivalents as set forth in the claims.

[0102] The above embodiments can be summarized in the following technical solutions. (Technical proposal 1) an electrolysis cell having a cathode flow channel through which a first cathode fluid containing a first substance flows, an anode flow channel through which a first anode fluid containing a second substance flows, a cathode facing the cathode flow channel and reducing the first substance to produce a reduction product, an anode facing the anode flow channel and oxidizing the second substance to produce an oxidation product, and a diaphragm disposed between the cathode flow channel and the anode flow channel; an anode supply flow path connected to an inlet of the anode flow path, through which the anode solution containing the second substance flows; an anode discharge flow path connected to an outlet of the anode flow path, through which a second anode fluid containing the oxidation product flows; a cathode supply flow path connected to an inlet of the cathode flow path and through which a cathode gas containing the first substance flows; a cathode discharge flow path connected to an outlet of the anode flow path and through which a second cathode fluid containing the reduction product flows; a first pressure detector that measures the pressure in the cathode supply flow path; a second pressure detector that measures the pressure in the cathode exhaust flow path; a third pressure detector that measures the pressure in the anode supply channel; a first pressure controller that controls the pressure in the cathode flow channel; a second pressure controller that controls the pressure in the anode flow path; a first gas-liquid separator for separating the reduction product from the second cathode fluid; a gas detector for measuring the concentration of the separated reduction product; a computing device that performs a calculation process to calculate the pressure of the anode flow channel and the pressure of the cathode flow channel based on the measured concentration, the measured pressure of the cathode supply flow channel, the measured pressure of the cathode discharge flow channel, and the measured pressure of the anode supply flow channel, and controls the first pressure controller and the second pressure controller to adjust the pressure of the anode flow channel and the pressure of the cathode flow channel to the values ​​calculated by the calculation process; An electrolysis device comprising: (Technical proposal 2) the first substance comprises carbon dioxide; the second substance comprises water; the reduction product comprises a carbon compound; The electrolysis device according to Technical Solution 1, wherein the oxidation product comprises oxygen. (Technical proposal 3) the first substance comprises nitrogen; the second substance comprises water; the reduction products include ammonia; The electrolysis device according to Technical Solution 1, wherein the oxidation product comprises oxygen. (Technical proposal 4) The electrolysis device according to any one of Technical Schemes 1 to 3, wherein the gas detector comprises a gas sensor using gas chromatography, a controlled potential electrolysis gas sensor, a thermal conduction gas sensor, a gas sensor using a catalyst, or a gas sensor using a color reagent. (Technical proposal 5) The electrolysis device according to any one of Technical Schemes 1 to 4, further comprising a flow rate detector for measuring the flow rate of the separated reduction product. (Technical proposal 6) The electrolysis apparatus according to any one of Technical Schemes 1 to 5, wherein the arithmetic device controls the first pressure controller and the second pressure controller to adjust the pressure in the anode flow path and the pressure in the cathode flow path to the values ​​calculated by the arithmetic processing, thereby reducing the amount of the reduction product that moves from the cathode flow path to the anode flow path. (Technical proposal 7) a temperature controller for adjusting the temperature of the electrolysis cell; The electrolysis apparatus according to any one of Technical Schemes 1 to 6, wherein the calculation device calculates a temperature value of the electrolytic cell by the calculation process, and controls the temperature controller to adjust the temperature of the electrolytic cell to the value calculated by the calculation process, thereby reducing the amount of the reduction product moving from the cathode flow path to the anode flow path. (Technical proposal 8) 1. A method for controlling an electrolysis device, comprising: The electrolysis device comprises: an electrolysis cell having a cathode flow channel through which a first cathode fluid containing a first substance flows, an anode flow channel through which a first anode fluid containing a second substance flows, a cathode facing the cathode flow channel and reducing the first substance to produce a reduction product, an anode facing the anode flow channel and oxidizing the second substance to produce an oxidation product, and a diaphragm disposed between the anode flow channel and the cathode flow channel; an anode supply flow path connected to an inlet of the anode flow path, through which the anode solution containing the second substance flows; an anode discharge flow path connected to an outlet of the anode flow path, through which a second anode fluid containing the oxidation product flows; a cathode supply flow path connected to an inlet of the cathode flow path and through which a cathode gas containing the reduction product flows; a cathode discharge flow path connected to an outlet of the anode flow path and through which a second cathode fluid containing the reduction product flows; Equipped with The method comprises: a first step of measuring the pressure of the cathode supply flow path, the pressure of the cathode exhaust flow path, and the pressure of the anode supply flow path, and separating the reduction product from the second cathode fluid to measure the concentration of the reduction product; a second step of performing a calculation process to calculate the pressure of the anode flow path and the pressure of the cathode flow path based on the measured concentration, the measured pressure of the cathode supply flow path, the measured pressure of the cathode exhaust flow path, and the measured pressure of the anode supply flow path; a third step of adjusting the pressure in the anode flow channel and the pressure in the cathode flow channel to the values ​​calculated by the arithmetic processing; A method for controlling an electrolysis device, comprising: (Technical proposal 9) the first substance comprises carbon dioxide; the second substance comprises water; the reduction product comprises a carbon compound; The method according to Technical Scheme 8, wherein the oxidation product comprises oxygen. (Technical proposal 10) the first substance comprises nitrogen; the second substance comprises water; the reduction products include ammonia; The method according to Technical Scheme 8, wherein the oxidation product comprises oxygen. (Technical proposal 11) The method according to any one of technical proposals 8 to 10, wherein the flow rate of the reduction product is measured in the first step. (Technical proposal 12) The method according to any one of Technical Schemes 8 to 11, wherein the third step adjusts the pressure in the anode flow channel and the pressure in the cathode flow channel to the values ​​calculated by the arithmetic processing, thereby reducing the amount of the reduction product moving from the cathode flow channel to the anode flow channel. (Technical proposal 13) The method according to any one of Technical Schemes 8 to 12, wherein in the third step, the temperature value of the electrolytic cell is calculated by the calculation process, and the temperature of the electrolytic cell is adjusted to the value calculated by the calculation process to reduce the amount of the reduction product moving from the cathode flow path to the anode flow path. (Technical proposal 14) The method according to any one of Technical Schemes 8 to 13, wherein the calculation process is a first calculation process based on feedback control, a second calculation process based on experience, or a third calculation process based on optimization using time-series data including machine learning. [Explanation of symbols]

[0103] 1...electrolysis device, 1a...drive unit, 1b...drive control unit, 100...electrolysis unit, 101...electrolysis cell, 102...power supply, 103...temperature controller, 111...cathode flow path, 112...anode flow path, 113...diaphragm, 114...cathode, 115...anode, 116...cathode supply flow path, 117...cathode supply flow path, 118...cathode discharge flow path, 119...anode supply flow path, 120...anode discharge flow path, 131...flow path plate, 132...flow path plate, 133...cathode flow path, 134...anode flow path, 135...current collector, 136...current collector, 137...flow path plate, 140...clamping plate, 141... clamping plate, 200... cathode supply unit, 201... cathode gas supply source, 202... flow rate controller, 203... humidifier, 204... pressure detector, 300... cathode exhaust unit, 301... pressure controller, 302... gas-liquid separator, 303... flow rate detector, 304... pressure detector, 305... gas detector, 400... anode supply unit, 401... anode solution supply source, 402... flow rate controller, 403... pressure detector, 500... anode exhaust unit, 501... pressure controller, 502... gas-liquid separator, 503... flow rate detector, 504... gas detector, 600... control unit, 601... computing device.

Claims

1. an electrolysis cell having a cathode flow channel through which a first cathode fluid containing a first substance flows, an anode flow channel through which a first anode fluid containing a second substance flows, a cathode facing the cathode flow channel and reducing the first substance to produce a reduction product, an anode facing the anode flow channel and oxidizing the second substance to produce an oxidation product, and a diaphragm disposed between the cathode flow channel and the anode flow channel; an anode supply flow path connected to an inlet of the anode flow path, through which the anode solution containing the second substance flows; an anode discharge flow path connected to an outlet of the anode flow path, through which a second anode fluid containing the oxidation product flows; a cathode supply flow path connected to an inlet of the cathode flow path and through which a cathode gas containing the first substance flows; a cathode discharge flow path connected to an outlet of the anode flow path and through which a second cathode fluid containing the reduction product flows; a first pressure detector that measures the pressure in the cathode supply flow path; a second pressure detector that measures the pressure in the cathode exhaust flow path; a third pressure detector that measures the pressure in the anode supply flow path; a first pressure controller that controls the pressure in the cathode flow path; a second pressure controller that controls the pressure in the anode flow path; a first gas-liquid separator for separating the reduction product from the second cathode fluid; a gas detector for measuring the concentration of the separated reduction product; a computing device that performs a calculation process to calculate values ​​of the pressure in the anode flow channel and the pressure in the cathode flow channel based on the measured concentration, the measured pressure in the cathode supply flow channel, the measured pressure in the cathode discharge flow channel, and the measured pressure in the anode supply flow channel, and that adjusts the pressure in the anode flow channel and the pressure in the cathode flow channel to the values ​​calculated by the calculation process by controlling the first pressure controller and the second pressure controller so as to reduce the amount of the reduction products that move from the cathode flow channel to the anode flow channel; An electrolysis device comprising:

2. An electrolytic cell having a cathode flow path through which a first cathode fluid containing a first substance flows, an anode flow path through which a first anode fluid containing a second substance flows, a cathode facing the cathode flow path and reducing the first substance to produce a reduction product, an anode facing the anode flow path and oxidizing the second substance to produce an oxidation product, and a diaphragm provided between the cathode flow path and the anode flow path; an anode supply flow path connected to an inlet of the anode flow path, through which the anode solution containing the second substance flows; an anode discharge flow path connected to an outlet of the anode flow path, through which a second anode fluid containing the oxidation product flows; a cathode supply flow path connected to an inlet of the cathode flow path and through which a cathode gas containing the first substance flows; a cathode discharge flow path connected to an outlet of the anode flow path and through which a second cathode fluid containing the reduction product flows; a first pressure detector that measures the pressure in the cathode supply flow path; a second pressure detector that measures the pressure in the cathode exhaust flow path; a third pressure detector that measures the pressure in the anode supply flow path; a first pressure controller that controls the pressure in the cathode flow path; a second pressure controller that controls the pressure in the anode flow path; a first gas-liquid separator for separating the reduction product from the second cathode fluid; a gas detector for measuring the concentration of the separated reduction product; a computing device that performs a calculation process to calculate values ​​of the pressure in the anode flow channel and the pressure in the cathode flow channel based on the measured concentration, the measured pressure in the cathode supply flow channel, the measured pressure in the cathode discharge flow channel, and the measured pressure in the anode supply flow channel, and that adjusts the pressure in the anode flow channel and the pressure in the cathode flow channel to the values ​​calculated by the calculation process by controlling the first pressure controller and the second pressure controller so as to reduce the amount of the reduction products that move from the cathode flow channel to the anode flow channel; Equipped with a temperature controller for adjusting the temperature of the electrolysis cell; the calculation device calculates a temperature value of the electrolytic cell by the calculation processing, and controls the temperature controller so as to reduce the amount of the reduction product moving from the cathode flow path to the anode flow path, thereby adjusting the temperature of the electrolytic cell to the value calculated by the calculation processing.

3. the first substance comprises carbon dioxide; the second substance comprises water; the reduction product comprises a carbon compound; 3. The electrolysis device according to claim 1, wherein the oxidation product comprises oxygen.

4. the first substance comprises nitrogen; the second substance comprises water; the reduction products include ammonia; 3. The electrolysis device according to claim 1, wherein the oxidation product comprises oxygen.

5. 3. The electrolysis apparatus according to claim 1, wherein the gas detector comprises a gas sensor using gas chromatography, a controlled potential electrolysis gas sensor, a thermal conduction gas sensor, a gas sensor using a catalyst, or a gas sensor using a color reagent.

6. 3. The electrolysis apparatus according to claim 1, further comprising a flow rate detector that measures the flow rate of the separated reduction product.

7. 1. A method for controlling an electrolysis device, comprising: The electrolysis device comprises: an electrolysis cell including: a cathode flow channel through which a first cathode fluid containing a first substance flows; an anode flow channel through which a first anode fluid containing a second substance flows; a cathode facing the cathode flow channel and reducing the first substance to produce a reduction product; an anode facing the anode flow channel and oxidizing the second substance to produce an oxidation product; and a diaphragm disposed between the anode flow channel and the cathode flow channel; an anode supply flow path connected to an inlet of the anode flow path, through which the anode solution containing the second substance flows; an anode discharge flow path connected to an outlet of the anode flow path, through which a second anode fluid containing the oxidation product flows; a cathode supply flow path connected to an inlet of the cathode flow path and through which a cathode gas containing the reduction product flows; a cathode discharge flow path connected to an outlet of the anode flow path and through which a second cathode fluid containing the reduction product flows; Equipped with The method comprises: a first step of measuring a pressure in the cathode supply flow path, a pressure in the cathode exhaust flow path, and a pressure in the anode supply flow path, and separating the reduction product from the second cathode fluid to measure a concentration of the reduction product; a second step of performing a calculation process to calculate the pressure of the anode flow path and the pressure of the cathode flow path based on the measured concentration, the measured pressure of the cathode supply flow path, the measured pressure of the cathode exhaust flow path, and the measured pressure of the anode supply flow path; a third step of adjusting the pressure in the anode flow channel and the pressure in the cathode flow channel to the values ​​calculated by the arithmetic processing; Equipped with the third step adjusts each of the pressure in the anode flow channel and the pressure in the cathode flow channel to the value calculated by the arithmetic processing so as to reduce the amount of the reduction product moving from the cathode flow channel to the anode flow channel.

8. A method for controlling an electrolysis device, comprising: The electrolysis device comprises: an electrolysis cell including: a cathode flow channel through which a first cathode fluid containing a first substance flows; an anode flow channel through which a first anode fluid containing a second substance flows; a cathode facing the cathode flow channel and reducing the first substance to produce a reduction product; an anode facing the anode flow channel and oxidizing the second substance to produce an oxidation product; and a diaphragm disposed between the anode flow channel and the cathode flow channel; an anode supply flow path connected to an inlet of the anode flow path, through which the anode solution containing the second substance flows; an anode discharge flow path connected to an outlet of the anode flow path, through which a second anode fluid containing the oxidation product flows; a cathode supply flow path connected to an inlet of the cathode flow path and through which a cathode gas containing the reduction product flows; a cathode discharge flow path connected to an outlet of the anode flow path and through which a second cathode fluid containing the reduction product flows; Equipped with The method comprises: a first step of measuring a pressure in the cathode supply flow path, a pressure in the cathode exhaust flow path, and a pressure in the anode supply flow path, and separating the reduction product from the second cathode fluid to measure a concentration of the reduction product; a second step of performing a calculation process to calculate the pressure of the anode flow path and the pressure of the cathode flow path based on the measured concentration, the measured pressure of the cathode supply flow path, the measured pressure of the cathode exhaust flow path, and the measured pressure of the anode supply flow path; a third step of adjusting the pressure in the anode flow channel and the pressure in the cathode flow channel to the values ​​calculated by the arithmetic processing; Equipped with the third step calculates a temperature value of the electrolytic cell by the arithmetic processing, and adjusts the temperature of the electrolytic cell to the value calculated by the arithmetic processing so as to reduce the amount of the reduction product moving from the cathode flow path to the anode flow path.

9. the first substance comprises carbon dioxide; the second substance comprises water; the reduction product comprises a carbon compound; 9. The method of claim 7 or claim 8, wherein the oxidation product comprises oxygen.

10. the first substance comprises nitrogen; the second substance comprises water; the reduction products include ammonia; 9. The method of claim 7 or claim 8, wherein the oxidation product comprises oxygen.

11. 9. The method according to claim 7 or claim 8, wherein the first step measures the flow rate of the reduction product.

12. 9. The method according to claim 7, wherein the calculation process is a first calculation process based on feedback control, a second calculation process based on empirical values, or a third calculation process based on optimization using time-series data including machine learning.

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