WO2024101221A1 - Dispositif d'électroréduction, système d'électroréduction et procédé de fabrication de dispositif d'électroréduction - Google Patents

Dispositif d'électroréduction, système d'électroréduction et procédé de fabrication de dispositif d'électroréduction Download PDF

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WO2024101221A1
WO2024101221A1 PCT/JP2023/039237 JP2023039237W WO2024101221A1 WO 2024101221 A1 WO2024101221 A1 WO 2024101221A1 JP 2023039237 W JP2023039237 W JP 2023039237W WO 2024101221 A1 WO2024101221 A1 WO 2024101221A1
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cathode
electrolytic reduction
diffusion layer
reduction device
anode
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PCT/JP2023/039237
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English (en)
Japanese (ja)
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篤 深澤
香織 高野
孝司 松岡
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Ｅｎｅｏｓ株式会社
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Publication of WO2024101221A1 publication Critical patent/WO2024101221A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
    • C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
    • C25B11/031—Porous electrodes
    • C25B11/032—Gas diffusion electrodes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C25B15/021—Process control or regulation of heating or cooling
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C25B15/023—Measuring, analysing or testing during electrolytic production
    • C25B15/025—Measuring, analysing or testing during electrolytic production of electrolyte parameters
    • C25B15/029—Concentration
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/01—Products
    • C25B3/03—Acyclic or carbocyclic hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/25—Reduction
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded

Definitions

  • the present invention relates to an electrolytic reduction device, an electrolytic reduction system, and a method for manufacturing an electrolytic reduction device.
  • an organic hydride production device includes an anode that produces protons from water, a cathode that has a cathode catalyst layer that hydrogenates an organic compound (substance to be hydrogenated) that has unsaturated bonds, and an electrolyte membrane that separates the anode and the cathode (see, for example, Patent Document 1).
  • water is supplied to the anode, a substance to be hydrogenated is supplied to the cathode, and a voltage is applied between the anode and the cathode, whereby protons (H + ) generated by the oxidation reaction of water react with the substance to be hydrogenated to hydrogenate it, thereby producing an organic hydride in which hydrogen has been added to the substance to be hydrogenated.
  • an electrolytic reduction device such as the organic hydride production device of Patent Document 1
  • One aspect of the present invention aims to provide an electrolytic reduction device that can improve the efficiency of generating organic hydrides.
  • One aspect of the present invention is An electrolyte membrane; an anode electrode provided on one side of the electrolyte membrane; a cathode electrode provided on the other side of the electrolyte membrane; Equipped with the cathode electrode has a cathode diffusion layer that diffuses a cathode solution containing a substance to be hydrogenated on a surface opposite to the electrolyte membrane side,
  • the cathode diffusion layer of the electrolytic reduction device is a porous body having a porosity of 65% or more and a volume average pore size of 500 ⁇ m or more.
  • One aspect of the present invention provides an electrolytic reduction device that can improve the efficiency of generating organic hydrides.
  • FIG. 1 is a schematic diagram showing a schematic configuration of an electrolytic reduction system including an electrolytic reduction device according to an embodiment of the present invention. 1 is a flowchart showing an example of a method for manufacturing an electrolytic reduction device.
  • Fig. 1 is a schematic diagram showing a schematic configuration of an electrolytic reduction system including an electrolytic reduction device according to an embodiment of the present invention.
  • the electrolytic reduction system 1 includes a power supply unit 10 and an electrolytic reduction device 20, and generates an organic hydride in the electrolytic reduction device 20 using power supplied from the power supply unit 10.
  • electrolytic reduction devices such as the organic hydride production device of Patent Document 1
  • proton-accompanying water moving from the anode side to the cathode side and by-produced hydrogen gas can inhibit the diffusion of toluene into the catalyst layer.
  • the electrolytic reduction system 1 can increase the efficiency of organic hydride production by improving the Faraday conversion efficiency when hydrogenating the substance to be hydrogenated at the cathode electrode of the electrolytic cell of the electrolytic reduction device 20.
  • the power supply unit 10 has a first power supply unit 11 which is a renewable energy power supply unit, a second power supply unit 12, and a power conversion unit 13, and supplies direct current power to the electrolytic cell 21 of the electrolytic reduction device 20. Note that the power supply unit 10 may have only one of the first power supply unit 11 and the power conversion unit 13, and the second power supply unit 12.
  • the first power supply unit 11 generates electricity derived from renewable energy.
  • the first power supply unit 11 supplies the electricity derived from renewable energy to the anode electrode and cathode electrode of the electrolytic reduction device 20.
  • the first power supply unit 11 may be any power generation device that generates electricity using renewable energy, and may be, for example, a wind power generation device 111 that generates electricity using wind power, a solar power generation device 112 that generates electricity using sunlight, a hydroelectric power generation device that generates electricity using hydraulic power, or a geothermal power generation device that generates electricity using geothermal energy.
  • the second power supply unit 12 is a storage battery, a thermal power plant that burns fossil fuels such as natural gas or coal, or the like.
  • the second power supply unit 12 supplies electricity derived from fossil fuels to the anode electrode 312 and the cathode electrode 313 of the electrolytic reduction device 20.
  • the electricity of the second power supply unit 12 may be used as a secondary power when the electricity supplied from the first power supply unit 11 is insufficient. This allows the electrolytic reduction device 20 to operate stably by supplying electricity from the second power supply unit 12 to the electrolytic cell 21 in addition to the electricity from the first power supply unit 11.
  • the power conversion unit 13 converts the output voltage of the first power supply unit 11 to a predetermined voltage.
  • a DC/DC converter is used as the power conversion unit 13.
  • the power conversion unit 13 converts the voltage using a transformer, rectifies the voltage using a bridge-type diode, smooths the voltage using a smoothing electrolytic capacitor, and supplies the power from the output terminal to the electrolytic cell 21.
  • the power conversion unit 13 may also convert the output voltage of the second power supply unit 12 into a predetermined voltage.
  • the electrolytic reduction device 20 may operate when power from the first power supply unit 11, i.e., power generated by the first power supply unit 11, is supplied to the electrolytic cell 21 of the electrolytic reduction device 20, and may stop operating when power from the first power supply unit 11 is not supplied to the electrolytic cell 21.
  • operation refers to the time when the electrolytic reduction device 20 is generating organic hydrides, which is the main purpose of the electrolytic reduction device 20. Therefore, even if the electrolytic reduction device 20 is not operating, power may be supplied to the electrolytic reduction device 20 from the second power supply unit 12.
  • Power from the first power supply unit 11 is not supplied to the electrolytic cell 21 of the electrolytic reduction device 20 means, for example, that the voltage state of the electrolytic cell 21 obtained by power supplied only from the first power supply unit 11 is a voltage state lower than the theoretical electrolytic voltage. This state also includes the case where the power supplied from the first power supply unit 11 to the electrolytic cell 21 is zero.
  • the "theoretical electrolytic voltage” is a voltage calculated from the difference between the oxidation-reduction potential based on the Gibbs free energy ( ⁇ G) in the organic hydride production reaction (cathode reaction) generated by the hydrogenation of the substance to be hydrogenated and the oxidation-reduction potential based on the ⁇ G in the oxygen generation reaction (anode reaction) by the decomposition of water.
  • ⁇ G Gibbs free energy
  • cathode reaction the oxidation-reduction potential in the cathode reaction
  • the oxidation-reduction potential in the anode reaction is 1.23 V based on the ⁇ G. Therefore, the theoretical electrolytic voltage is 1.08 V. Therefore, a state in which the voltage applied to the electrolytic cell 21 by the power supply from the first power supply unit 11 is less than 1.08 V is a "no power supply" state.
  • the solubility of at least one of the material to be hydrogenated and the organic hydride in water at 25° C. is preferably 2 g/100 mL or less, the effect of improving the Faraday efficiency is more pronounced.
  • the solubility of at least one of the material to be hydrogenated and the organic hydride in water is greater than 2 g/100 mL, the material to be hydrogenated and the organic hydride are compatible with water, and the concentration of the material to be hydrogenated decreases, so the effect of improving the Faraday efficiency is not fully exhibited.
  • Examples of compounds to be hydrided and organic hydrides that are particularly expected to have an effect of improving the Faraday efficiency include benzene (0.18 g/100 mL H 2 O) and cyclohexane (0.36 g/100 mL H 2 O), toluene (0.05 g/100 mL H 2 O) and methylcyclohexane (1.6 g/100 mL H 2 O), naphthalene (0.003 g/100 mL H 2 O) and decahydronaphthalene (0.001 g/100 mL H 2 O), etc.
  • the Faraday efficiency is the amount of electricity used to hydrogenate the substances to be hydrogenated contained in the cathode liquid CL supplied to the electrolytic cell 21 relative to the total amount of electricity supplied to the electrolytic cell 21, as shown in the following formula (I).
  • Faraday efficiency [%] (amount of electricity used to hydrogenate the substance to be hydrogenated contained in the cathode fluid CL/total amount of electricity supplied to the electrolytic cell 21) ⁇ 100 (I)
  • the power from the first power supply unit 11 is not sufficiently supplied to the electrolytic cell 21, and either no positive current for generating electrolysis flows in the electrolytic cell 21 or a reverse current flows (except when power is supplied from the second power supply unit 12).
  • the electrical state of the electrolytic cell 21 when the electrolytic reduction system 1 is out of operation also includes a state in which a voltage is applied to the electrolytic cell 21 but no positive current flows.
  • the electrical state of the electrolytic cell 21 when the electrolytic reduction system 1 is out of operation also includes a state in which a slight positive current flows that is not able to suppress potential changes in the electrodes of the electrolytic cell 21.
  • the second power supply unit 12 may supply power to the power supply unit 22 independently of the first power supply unit 11.
  • the second power supply unit 12 may supply power to the power supply unit 22 while the operation of the electrolytic reduction system 1 is stopped based on the control of the control unit 28.
  • the second power supply unit 12 When the second power supply unit 12 is configured as a storage battery, the second power supply unit 12 may be charged by receiving power supply from the first power supply unit 11. This reduces CO2 emissions generated by the power supply unit 10.
  • the power supply unit 10 may include a storage battery, store the power generated by at least one of the first power supply unit 11 and the second power supply unit 12, and supply the power from the storage battery to the electrolytic reduction device 20 as needed.
  • the electrolytic reduction device 20 includes an electrolytic cell 21 , a power supply unit 22 , an anolyte supply unit 23 , a catholyte supply unit 24 , a heating unit 25 , a differential pressure detection unit 26 , a resistance measurement unit 27 , and a control unit 28 .
  • the electrolytic cell 21 is an electrolytic cell that hydrogenates the material to be hydrided, which is a dehydrogenated form of an organic hydride, by an electrochemical reduction reaction to produce an organic hydride.
  • the electrolytic cell 21 has a membrane electrode assembly 31, a plate member 32, and a gasket 33.
  • the membrane electrode assembly 31 has an electrolyte membrane 311, an anode electrode 312 which is an oxygen generating electrode (positive electrode), and a cathode electrode 313 which is a reduction electrode (positive electrode).
  • the electrolyte membrane 311 is disposed between the anode electrode 312 and the cathode electrode 313, and separates the anode electrode 312 from the cathode electrode 313.
  • the electrolyte membrane 311 transfers protons from the anode electrode 312 side to the cathode electrode layer 313A side.
  • the electrolyte membrane 311 is made of a material (ionomer) having proton conductivity and selectively conducts protons (H + ).
  • a solid polymer electrolyte membrane made of a material having proton conductivity can be used.
  • the thickness of the electrolyte membrane 311 is preferably 5 ⁇ m to 300 ⁇ m, more preferably 10 ⁇ m to 150 ⁇ m, and even more preferably 20 ⁇ m to 100 ⁇ m. If the thickness of the electrolyte membrane 311 is 5 ⁇ m or more, the barrier properties of the electrolyte membrane 311 can be maintained and the amount of cross leakage can be reduced. If the thickness of the electrolyte membrane 311 is 300 ⁇ m or less, excessive ion migration resistance is suppressed.
  • the area resistance of the electrolyte membrane 311, i.e., the ion transfer resistance per geometric area, is preferably 2000 m ⁇ cm 2 or less, more preferably 1000 m ⁇ cm 2 or less, and most preferably 500 m ⁇ cm 2 or less. If the contact resistance of the electrolyte membrane 311 is higher than 2000 m ⁇ cm 2 , the proton conductivity is insufficient.
  • a material having cation exchange type proton conductivity As a material having proton conductivity, a material having cation exchange type proton conductivity (cation exchange type ionomer) is used.
  • cation exchange type ionomers include perfluorosulfonic acid polymers such as Nafion (registered trademark) and Flemion (registered trademark).
  • the ion exchange capacity (IEC) of the cation exchange type ionomer is preferably 0.7 meq/g to 2 meq/g, and more preferably 1 meq/g to 1.2 meq/g. If the ion exchange capacity of the cation exchange type ionomer is 0.7 meq/g or more, the electrolyte membrane 311 has sufficient ion conductivity.
  • the electrolyte membrane 311 has a sufficiently high strength.
  • the anode electrode 312 is provided so as to be in contact with one of the main surfaces of the electrolyte membrane 311 (the main surface on the left side in FIG. 1).
  • the anode electrode 312 is an electrode (positive electrode) for oxidizing water to generate protons.
  • the anode electrode 312 contains an anode catalyst that oxidizes water.
  • anode catalyst for example, metals such as Ir, Ru, Pt, Pd, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, W, Re, Pb, Bi, etc., or oxides of these metals, etc. are used.
  • Ir, Ru, Pt, or oxides of these metals are preferred from the viewpoint of improving the electrode reaction of the anode electrode 312 and efficiently hydrogenating the material to be hydrogenated.
  • oxides of these metals for example, RuO2 , IrO2 , etc. are used.
  • the anode catalyst may be dispersed or coated on a substrate having electronic conductivity.
  • the substrate may be composed of, for example, a metal such as Ti, Zr, Nb, Mo, Hf, Ta, W, or an oxide thereof, or a material mainly composed of a metal such as stainless steel (SUS).
  • SUS stainless steel
  • Examples of the form of the substrate include wire, a woven or nonwoven sheet, a mesh, a porous body, and a foam.
  • RuO 2 or IrO 2 when RuO 2 or IrO 2 is used as the anode catalyst, since RuO 2 or IrO 2 is expensive, it is preferable to use RuO 2 or IrO 2 by dispersing and supporting it on a substrate or coating it, which reduces the manufacturing cost.
  • the anode electrode 312 is housed in the anode chamber 34 formed by the electrolyte membrane 311, the plate member 32, and the gasket 33.
  • the space in the anode chamber 34 excluding the anode electrode 312 constitutes a flow path through which water and oxygen (oxygen gas) generated by the electrode reaction pass.
  • Anode fluid AL is supplied to the anode chamber 34 from the anode fluid tank 231 by the anode pump 233.
  • the anode fluid AL is supplied from the anode chamber 34 to the anode electrode 312.
  • the plate member 32A may have one or more grooves on its main surface facing the anode electrode 312, and the space between the groove and the liquid diffusion layer 313B may be used as the anode chamber 34 to form a flow path through which the anode liquid AL flows.
  • the shape of the flow path is not particularly limited, and may be, for example, a linear flow path, a serpentine flow path, etc.
  • the cathode electrode 313 is provided so as to be in contact with the other main surface of the electrolyte membrane 311 (the main surface on the right side in FIG. 1). In other words, the cathode electrode 313 is provided on the main surface of the electrolyte membrane 311 opposite the anode electrode 312.
  • the cathode electrode 313 is an electrode (negative electrode) for hydrogenating the substance to be hydrided with protons to generate an organic hydride.
  • the cathode electrode 313 is housed in a cathode chamber 35 formed by an electrolyte membrane 311, a plate member 32, and a gasket 33.
  • the space in the cathode chamber 35 excluding the cathode electrode 313 constitutes a flow path through which the cathode liquid CL containing the substance to be hydrogenated and the hydrogen (hydrogen gas) generated by the electrode reaction pass.
  • the cathode chamber 35 is supplied with the cathode liquid CL from the cathode liquid tank 241 by the cathode pump 243.
  • the cathode chamber 35 supplies the cathode liquid CL to the cathode electrode layer 313A.
  • the plate member 32B may have one or more grooves on its main surface facing the cathode electrode layer 313A, and the space between this groove and the liquid diffusion layer 313B may be the cathode chamber 35 to form a flow path through which the cathode liquid CL flows.
  • the plate member 32B may be configured so that its main surface facing the cathode electrode layer 313A is in contact with the liquid diffusion layer 313B. In this case, the space between the groove and the liquid diffusion layer 313B becomes the cathode chamber 35 to form the flow path through which the cathode liquid CL flows.
  • the form of the flow path is not particularly limited, and a flow path similar to that described above may be formed.
  • the cathode electrode 313 has a cathode electrode layer 313A and a liquid diffusion layer 313B.
  • the cathode electrode layer 313A has a cathode catalyst that hydrogenates the substance to be hydrogenated.
  • the cathode catalyst contains, for example, platinum (Pt) or ruthenium (Ru).
  • the cathode electrode layer 313A may also contain other metals or metal compounds.
  • the cathode electrode layer 313A may contain a porous catalyst carrier that supports a cathode catalyst.
  • the catalyst carrier is made of an electronically conductive material, such as porous carbon, porous metal, or porous metal oxide.
  • the cathode electrode layer 313A may have an ionomer (cation exchange type ionomer) that covers the cathode catalyst.
  • the ionomer may cover the catalyst carrier that supports the cathode catalyst.
  • the ionomer include perfluorosulfonic acid polymers such as Nafion (registered trademark), Flemion (registered trademark), Fumion (registered trademark), and Aciplex (registered trademark). It is preferable that the ionomer partially covers the cathode catalyst. This allows the three elements (product to be hydrided, protons, and electrons) required for the electrochemical reaction in the cathode electrode layer 313A to be efficiently supplied to the reaction field of the cathode electrode layer 313A.
  • the liquid diffusion layer 313B is disposed on the main surface of the cathode electrode layer 313A opposite the electrolyte membrane 311 (the main surface on the right side in FIG. 1).
  • the liquid diffusion layer 313B has the function of uniformly diffusing the cathode liquid CL supplied from the outside to the cathode chamber 35 throughout the cathode electrode layer 313A.
  • the organic hydride generated in the cathode electrode layer 313A is discharged to the cathode chamber 35 via the liquid diffusion layer 313B.
  • the liquid diffusion layer 313B is a porous body having a porous structure, and has a porosity of 65% or more and a volume average pore diameter of 500 ⁇ m or more. If the porosity of the liquid diffusion layer 313B is 65% or more and the volume average pore diameter is 500 ⁇ m or more, the liquid diffusion layer 313B can have sufficient voids inside, making it easier for liquid (e.g., cathode solution CL) and gas (e.g., hydrogen gas) to pass through the liquid diffusion layer 313B. Therefore, the cathode solution CL can easily reach the cathode electrode layer 313A through the liquid diffusion layer 313B.
  • liquid e.g., cathode solution CL
  • gas e.g., hydrogen gas
  • the organic hydride generated in the cathode electrode layer 313A, the hydrogen gas by-produced in the cathode electrode layer 313A, and the proton-accompanying water moving from the anode side to the cathode electrode layer 313A can easily pass from the cathode electrode layer 313A to the liquid diffusion layer 313B and the cathode chamber 35.
  • the cathode chamber 35 is not necessarily required and may not be provided.
  • the liquid diffusion layer 313B allows the cathode solution CL, organic hydride, hydrogen gas, and proton-carrying water to pass through the liquid diffusion layer 313B easily, thereby reducing the internal pressure of the cathode chamber 35 when the organic hydride is produced from the cathode solution CL in the cathode electrode layer 313A.
  • the reduction in the internal pressure of the cathode chamber 35 reduces the load on the cathode pump 243.
  • liquid diffusion layer 313B has sufficient voids inside, which enhances heat dissipation and makes it difficult for heat to accumulate inside.
  • the liquid diffusion layer 313B has sufficient voids therein, so that even if foreign matter is mixed into the cathode solution CL, the liquid diffusion layer 313B can be prevented from becoming clogged with foreign matter.
  • the porosity refers to the ratio of the central space volume to the total volume of the liquid diffusion layer 313B.
  • the measurement method of the porosity is not particularly limited as long as the ratio of the central space volume to the total volume of the liquid diffusion layer 313B can be measured.
  • the porosity can be measured by the following measurement method. First, the thickness of the liquid diffusion layer 313B cut out to an area of a predetermined size (for example, 5 cm x 5 cm square) is measured, and the volume V 0 of the liquid diffusion layer 313B in a densely packed state is obtained.
  • the thickness of the liquid diffusion layer 313B may be measured using, for example, a digital micro stand MS11C (manufactured by Nikon Corporation).
  • the entire amount of the cut-out liquid diffusion layer 313B is finely ground in a mortar. 15 mL of hexane is placed in a graduated cylinder as a predetermined liquid, and the entire amount of the ground liquid diffusion layer 313B is added to the hexane to obtain the increase in volume V 1.
  • the porosity of the liquid diffusion layer 313B can be determined, for example, by disassembling a used electrolytic cell 21 and removing the gasket 33 and liquid diffusion layer 313B. Next, the gasket 33 and liquid diffusion layer 313B are pressed with two 0.5 mm thick resin plates at the same pressure as when the electrolytic cell 21 was assembled, compressing the liquid diffusion layer 313B. In this state, X-ray CT is performed to obtain three-dimensional data, and the porosity of the liquid diffusion layer 313B can be determined.
  • the volume average pore diameter indicates the size of the volume average pores present inside the liquid diffusion layer 313B.
  • the volume average pore diameter can be measured, for example, by the following measurement method. Note that the measurement of the volume average pore diameter is performed separately for cases where the size is 100 ⁇ m or less and cases where the size exceeds 100 ⁇ m.
  • a mercury porosimeter is used to determine the volume average pore diameter of the liquid diffusion layer 313B.
  • a general assumed device may be used as the measurement device, and an example of the measurement device that can be used is the Autopore IV 9510 model manufactured by Micromeritics. Specifically, the relationship between the mercury injection pressure and the amount of mercury injection is measured, and the mercury injection pressure is converted into the volume average pore diameter by the following Washburn formula, thereby determining the volume average pore diameter.
  • the volume average pore diameter that cannot be measured by a mercury porosimeter may be calculated using the value obtained by measuring the air permeability.
  • the air permeability is a value representing the pressure generated when a certain amount of air (for example, about 0.5 m/s per 5 cm2) is fed into a specified area per unit time.
  • the air permeability may be measured using a general air permeability tester (for example, FX3340MinAir (manufactured by Takayama Reed Co., Ltd.)).
  • the sample is placed in the air permeability tester, and the pressure is measured at room temperature when air is fed into a sample with an area of, for example, 5 cm2 at about 0.5 m/s.
  • the value of the tortuosity t may be set to 1.5.
  • the viscosity ⁇ of air is set to 1.833 ⁇ 10 ⁇ 5 Pa ⁇ s at 22.9° C.
  • the porosity of the liquid diffusion layer 313B is preferably 65% or more, more preferably 80% or more, and even more preferably 90% or more and 96% or less. If the porosity of the liquid diffusion layer 313B is 65% or more, the efficiency of generating organic hydride in the cathode electrode layer 313A can be further increased, and the Faraday efficiency can be further improved. In addition, since electronic conductivity is required for the liquid diffusion layer 313B, it is more preferable that the porosity be 96% or less from the viewpoint of electronic conductivity.
  • the volume average pore diameter of the liquid diffusion layer 313B is preferably 500 ⁇ m or more, more preferably 530 ⁇ m or more, and even more preferably 550 ⁇ m or more and 1000 ⁇ m or less. If the volume average pore diameter of the liquid diffusion layer 313B is 500 ⁇ m or more, the generation efficiency of the organic hydride in the cathode electrode layer 313A can be further improved, and the faradic efficiency can be further improved. If the volume average pore diameter is larger than 1000 ⁇ m, the electronic conductivity of the liquid diffusion layer 313B decreases, and the cell performance is significantly reduced.
  • the thickness of the liquid diffusion layer 313B is preferably approximately the same as or less than the thickness of the gasket 33.
  • the thickness of the gasket 33 is generally set between 0.2 mm and 0.6 mm. Therefore, the thickness of the liquid diffusion layer 313B is preferably 0.2 mm to 0.6 mm, more preferably 0.3 mm to 0.55 mm, and even more preferably 0.4 mm to 0.5 mm.
  • the thickness of the liquid diffusion layer 313B is 0.2 mm to 0.6 mm, the diffusion distance of the material to be hydrogenated to the cathode electrode layer 313A is prevented from becoming too large, and hydrogen gas and proton-accompanying water can easily escape from the liquid diffusion layer 313B when hydrogen gas is by-produced in the cathode electrode layer 313A.
  • the thickness of the liquid diffusion layer 313B refers to the length in the direction perpendicular to the main surface of the liquid diffusion layer 313B.
  • the thickness of the liquid diffusion layer 313B may be, for example, the thickness measured at any location on the cross section of the liquid diffusion layer 313B, or may be the average value of the measured values measured at several locations.
  • the definition of thickness is the same for other members.
  • the liquid diffusion layer 313B may be a porous body that has the function of diffusing the cathode liquid CL to the cathode electrode layer 313A.
  • the porous body may be formed using a porous material that is conductive and acid-resistant. If an ionomer that coats the cathode catalyst is present in the cathode electrode layer 313A, the ionomer is an acidic substance. Therefore, by including an acid-resistant porous material in the liquid diffusion layer 313B, an increase in resistance in the liquid diffusion layer 313B can be suppressed even when the electrolytic reduction device 20 is operated for a long period of time, and a good conductive path can be formed.
  • porous materials include carbon materials and acid-resistant metals. Even if the liquid diffusion layer 313B is placed in a reducing atmosphere during electrolysis, it can maintain a chemically stable state.
  • the carbon material it is preferable to use a pitch-based or polyacrylonitrile (PAN)-based carbon material or graphite. These may be used alone or in combination of two or more. Among these, pitch-based or PAN-based carbon materials are preferable.
  • PAN polyacrylonitrile
  • the carbon material is a pitch-based or PAN-based carbon material
  • the liquid diffusion layer 313B can maintain a chemically stable state even when placed in a reducing atmosphere during electrolysis.
  • the tensile modulus of the liquid diffusion layer 313B is further improved, and the mechanical strength during compression can be improved, making it easier to maintain the shape of the carbon material.
  • pitch-based carbon materials have a higher tensile modulus than PAN-based carbon materials, which increases the stability of the shape of the carbon material.
  • carbon materials that can be used include woven carbon fabric (carbon cloth), nonwoven carbon fabric, and carbon paper.
  • metals that are acid-resistant include Pt, Au, Ag, Cu, and Ti. These may be used alone or in combination of two or more.
  • a metal material in which the surface of a mesh formed of Pt or Au is coated with Ti may be used.
  • porous bodies examples include fibers, aggregates, and foams.
  • the fibrous body may be a fibrous body containing fibers made of the above-mentioned porous material.
  • the fibrous body may be manufactured by either a dry method or a wet method.
  • the fibrous body may be formed by a compression molding of fibers.
  • the fibers are preferably conductive fibers (conductive fibers).
  • the fibrous body may be formed into a woven fabric or a nonwoven fabric.
  • Conductive fibers include, for example, carbon fibers, metal fibers made by turning metal into fibers, conductive fibers in which metal or graphite is uniformly dispersed in synthetic fibers, conductive fibers in which the surface of synthetic fibers is coated with metal, and conductive fibers in which the surface of synthetic fibers is coated with resin containing a conductive material.
  • carbon fibers and metal fibers are preferred in terms of ease of production and production costs.
  • Synthetic fibers used for conductive fibers include inorganic fibers and organic fibers.
  • the inorganic fibers are not particularly limited, but examples include silica fibers, glass fibers, alumina fibers, silica-alumina fibers, silica-alumina-magnesia fibers, biosoluble inorganic fibers, glass fibers, zirconia fibers, alkaline earth silicate fibers, alkaline earth silicate (AES) wool, glass wool, rock wool, and basalt fibers. These may be used alone or in combination of two or more types.
  • the organic fibers are not particularly limited, but examples thereof include aramid fibers, polyester fibers, polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, fluorine resin fibers, nylon fibers, rayon fibers, acrylic fibers, and polyolefin fibers. These may be used alone or in combination of two or more types.
  • the conductive fibers are made of the above carbon materials, carbon fibers may be used.
  • pitch-based carbon fibers or polyacrylonitrile (PAN)-based carbon fibers can be used.
  • Pitch-based carbon fiber is a carbon fiber made from by-products (PITCH) of petroleum, coal, coal tar, etc.
  • PAN-based carbon fiber is a carbon fiber made from synthetic fibers whose main component is PAN.
  • the carbon fiber is pitch-based or PAN-based, for example, it is calcined at a high temperature of 2000°C or higher, which improves the tensile modulus of the carbon fiber and improves the mechanical strength during compression, thereby improving the self-supporting ability of the carbon fiber and making it easier to maintain the shape of the carbon fiber.
  • pitch-based carbon fibers have the characteristic of being stronger and less likely to break than PAN-based carbon fibers. Therefore, when fired at high temperatures of 2000°C or higher, pitch-based carbon fibers have a higher tensile modulus and higher self-supporting ability than PAN-based carbon fibers. Therefore, in order to maintain the shape of the porous body, it is preferable to use pitch-based carbon fibers rather than PAN-based carbon fibers.
  • the conductive fibers are made of the above-mentioned acid-resistant metals
  • metal fibers made by fiberizing Pt, Au, Ag, Cu, Ti, etc. may be used.
  • the average fiber diameter of the fibers is preferably 20 ⁇ m to 30 ⁇ m, more preferably 22 ⁇ m to 28 ⁇ m, and even more preferably 24 ⁇ m to 26 ⁇ m. If the average fiber diameter of the fibers is 20 ⁇ m to 30 ⁇ m, even if the liquid diffusion layer 313B is pressed at a high compression rate, each fiber can maintain its independence and deformation can be suppressed. In addition, the contact area between the fibers and the cathode liquid CL can be maintained.
  • the average fiber diameter refers to the diameter of the equivalent circle of the cross section along the direction perpendicular to the length of the fiber (fiber axis).
  • the number of fibers is not particularly limited and may be one or more.
  • the fibrous body may contain one or more types of metal particles that are used to form the aggregates.
  • the aggregate may be an aggregate having particles made of the above-mentioned porous material.
  • the particles are preferably conductive particles (conductive particles).
  • the aggregate may be formed by compression molding of an aggregate made of a plurality of conductive particles.
  • metal particles containing Pt, Au, Ag, Cu, Ti, etc. may be used.
  • foams examples include foams made of the acid-resistant porous materials mentioned above.
  • foams examples include urethane foam, phenol foam, polyethylene foam, polystyrene foam, and silicone foam.
  • the foam may contain fibers for use in the fibrous body or particles for use in the aggregates.
  • the plate member 32 is stacked on the membrane electrode assembly 31 so as to leave a predetermined space between the plate member 32 and the membrane electrode assembly 31.
  • the plate member 32 may be made of, for example, a metal such as stainless steel or titanium, a carbon material, or a corrosion-resistant alloy such as a Cr-Ni-Fe system, a Cr-Ni-Mo-Fe system, a Cr-Mo-Nb-Ni system, or a Cr-Mo-Fe-W-Ni system.
  • the plate member 32 has a pair of plate members 32A and 32B.
  • the plate member 32A is laminated on the surface of the membrane electrode assembly 31 facing the anode electrode 312.
  • the plate member 32B is laminated on the surface of the cathode electrode 313 opposite the membrane electrode assembly 31.
  • the pair of plate members 32 may be arranged to sandwich the membrane electrode assembly 31.
  • the gasket 33 is a sealing member that seals the gap between the membrane electrode assembly 31 and the plate member 32.
  • the gasket 33 has a gasket 33A that seals the gap between the plate member 32A and the membrane electrode assembly 31, and a gasket 33B that seals the gap between the plate member 32B and the membrane electrode assembly 31.
  • the pair of plate members 32 may correspond to so-called end plates.
  • the plate member 32 may correspond to so-called separators.
  • the power supply unit 22 is a DC power supply that supplies power to the electrolytic cell 21.
  • the power supply unit 22 receives power from the power supply unit 10 and supplies power to the electrolytic cell 21.
  • the positive output terminal of the power supply unit 22 is connected to the anode electrode 312 (positive electrode) of the electrolytic cell 21.
  • the negative output terminal of the power supply unit 22 is connected to the cathode electrode layer 313A (negative electrode) of the electrolytic cell 21. This applies a predetermined voltage between the anode electrode 312 and the cathode electrode layer 313A of the electrolytic cell 21.
  • the predetermined voltage applied by the power supply unit 22 can be set appropriately, and is preferably, for example, 1.2 V to 2.4 V.
  • the voltage required to proceed with the electrochemical reaction is the voltage obtained by adding to this potential difference the overvoltage required for the reaction, the overvoltage of mass transfer and diffusion, the ion transfer resistance of the electrolyte membrane 311, and the resistance loss (ohmic loss) caused by the contact resistance between the components of the electrolytic cell 21.
  • the voltage applied by the power supply unit 22 is 1.2 V to 2.4 V, the electrode reaction can proceed at both electrodes without applying excessive energy.
  • the potential on the cathode electrode layer 313A side is prevented from dropping too much, the progression of side reactions other than the hydrogenation of the material to be hydrogenated (for example, hydrogen generation) is suppressed.
  • the potential on the anode electrode 312 side is prevented from becoming too high, and the corrosion of the cathode catalyst used in the anode electrode 312 is suppressed.
  • the anode liquid supply unit 23 is a mechanism for circulating water in the anode chamber 34, and includes an anode liquid tank 231, an anode pipe 232, and an anode pump 233, which is a drive pump for the anode electrode.
  • the anode fluid tank 231 contains the anode fluid AL to be supplied to the anode chamber 34.
  • the anode fluid AL contains water to be supplied to the anode electrode 312.
  • Examples of the anode fluid AL include pure water, ion-exchanged water, and solutions having a predetermined ionic conductivity, such as an aqueous sulfuric acid solution, an aqueous nitric acid solution, and an aqueous hydrochloric acid solution.
  • the anode pipe 232 is a circulation path that flows between the anode fluid tank 231 and the anode chamber 34 of the electrolytic cell 21.
  • the anode pipe 232 has a first anode pipe 232-1 and a second anode pipe 232-2.
  • the first anode pipe 232-1 is a forward path for supplying the anode fluid AL from the anode fluid tank 231 to the anode chamber 34.
  • the first anode pipe 232-1 connects the anode fluid tank 231 and the anode chamber 34.
  • One end of the first anode pipe 232-1 is connected to the anode fluid tank 231, and the other end of the first anode pipe 232-1 is connected to the anode chamber 34.
  • the second anode pipe 232-2 is a return path for recovering the anode fluid from the anode chamber 34 to the anode fluid tank 231.
  • the second anode pipe 232-2 connects the anode chamber 34 to the anode fluid tank 231.
  • One end of the second anode pipe 232-2 is connected to the anode fluid tank 231, and the other end of the second anode pipe 232-2 is connected to the anode chamber 34.
  • the anode pump 233 is provided in the first anode pipe 232-1.
  • the anode fluid tank 231 is connected to the anode chamber 34 by the first anode pipe 232-1.
  • the anode fluid tank 231 is also connected to the anode chamber 34 by the second anode pipe 232-2.
  • the anode pump 233 can be composed of various pumps such as a gear pump or a cylinder pump, or a gravity flow device.
  • the anode liquid supply unit 23 may circulate the anode liquid AL using a liquid delivery device other than a pump.
  • the anode fluid AL stored in the anode fluid tank 231 flows through the anode pipe 232 by driving the anode pump 233, and circulates between the anode pump 233 and the anode chamber 34.
  • the anode fluid AL stored in the anode fluid tank 231 is supplied to the anode electrode 312 of the electrolytic cell 21 via the first anode pipe 232-1 by driving the anode pump 233.
  • the anode fluid AL that flows into the anode electrode 312 is subjected to an electrode reaction at the anode electrode 312.
  • the anode fluid AL in the anode electrode 312 is returned to the anode fluid tank 231 via the second anode pipe 232-2, and stored in the anode fluid tank 231.
  • the anode pump 233 may also function as a gas-liquid separator.
  • oxygen gas is generated by electrolysis of water, so the anode liquid AL recovered from the anode chamber 34 contains gaseous oxygen and dissolved oxygen.
  • the gaseous oxygen is separated from the anode liquid in the anode liquid tank 231 and taken out of the system.
  • the anode liquid from which the gaseous oxygen has been separated is supplied again to the electrolytic cell 21.
  • oxygen gas is generated by electrolysis of water.
  • the anode liquid tank 231 separates the oxygen gas in the anode liquid AL from the anode liquid AL and discharges it out of the system.
  • a gas-liquid separator (not shown) may be provided in the middle of the second anode pipe 232-2.
  • the oxygen gas generated by electrolysis of water in the anode electrode 312 is separated from the water and discharged out of the system.
  • the anode fluid supply unit 23 circulates the anode fluid AL between the anode electrode 312 and the anode fluid tank 231.
  • the anode fluid supply unit 23 may be configured to send the anode fluid AL from the anode electrode 312 to the outside of the system without returning it to the anode fluid tank 231.
  • the cathode liquid supply unit 24 is a mechanism for circulating the cathode liquid CL in the cathode chamber 35, and includes a cathode liquid tank 241, a cathode pipe 242, a cathode pump 243 which is a drive pump for the cathode electrode, a separation unit 244, and a branch discharge pipe 245.
  • the cathode fluid tank 241 contains the cathode fluid CL.
  • the cathode fluid CL contains the material to be hydrided (organic hydride raw material) to be supplied to the cathode electrode layer 313A.
  • the material to be hydrogenated is a compound that is hydrogenated by an electrochemical reduction reaction in the electrolytic cell 21 to become an organic hydride, in other words, a dehydrogenated organic hydride.
  • the material to be hydrogenated is preferably liquid at 20°C and 1 atmosphere.
  • the cathode liquid tank 241 collects not only the material to be hydrogenated but also the organic hydride generated at the cathode electrode 313.
  • the cathode liquid CL does not contain any organic hydride before the electrolytic reduction system 1 starts operating, but after operation starts, the cathode liquid CL becomes a mixture of the material to be hydrogenated and the organic hydride as the organic hydride produced by electrolysis is mixed in.
  • the material to be hydrogenated and the organic hydride are preferably liquid at 20°C and 1 atm.
  • the material to be hydrogenated and the organic hydride are not particularly limited as long as they are organic compounds that can add/desorb hydrogen gas by reversibly causing hydrogenation/dehydrogenation reactions.
  • the material to be hydrogenated and the organic hydride used in this embodiment can be a wide variety of materials such as acetone-isopropanol, benzoquinone-hydroquinone, and aromatic hydrocarbons. Of these, aromatic hydrocarbons are preferred from the standpoint of transportability during energy transport. In general, aromatic hydrocarbon-based materials to be hydrogenated and organic hydrides are hydrophobic.
  • the aromatic hydrocarbon compound used as the substance to be hydrogenated is a compound containing at least one aromatic ring.
  • aromatic hydrocarbon compounds include benzene, alkylbenzene, naphthalene, alkylnaphthalene, anthracene, diphenylethane, and the like.
  • Alkylbenzene includes compounds in which 1 to 4 hydrogen atoms of an aromatic ring are substituted with a linear or branched alkyl group having 1 to 6 carbon atoms. Examples of such compounds include toluene, xylene, mesitylene, ethylbenzene, diethylbenzene, and the like.
  • Alkylnaphthalene includes compounds in which 1 to 4 hydrogen atoms of an aromatic ring are substituted with a linear or branched alkyl group having 1 to 6 carbon atoms. Examples of such compounds include methylnaphthalene, and the like. These may be used alone or in combination.
  • the substance to be hydrogenated is preferably at least one of toluene and benzene.
  • Nitrogen-containing heterocyclic aromatic compounds such as quinoline, isoquinoline, N-alkylpyrrole, N-alkylindole, and N-alkyldibenzopyrrole may also be used as the material to be hydrogenated.
  • Organic hydrides are the above-mentioned materials to be hydrogenated, and examples of such compounds include cyclohexane, methylcyclohexane, dimethylcyclohexane, and decahydroquinoline.
  • the cathode fluid tank 241 is connected to the cathode electrode layer 313A by the cathode piping 242.
  • the cathode pipe 242 is a circulation path that flows between the cathode fluid tank 241 and the cathode electrode layer 313A of the electrolytic cell 21.
  • the cathode pipe 242 has a first cathode pipe 242-1, a second cathode pipe 242-2, and a third cathode pipe 242-3.
  • the first cathode pipe 242-1 is an outward path for supplying the cathode liquid CL from the cathode liquid tank 241 to the cathode chamber 35.
  • the first cathode pipe 242-1 connects the cathode liquid tank 241 and the cathode chamber 35.
  • One end of the first cathode pipe 242-1 is connected to the cathode liquid tank 241, and the other end of the first cathode pipe 242-1 is connected to the cathode chamber 35.
  • the second cathode pipe 242-2 is part of the return path for supplying the cathode liquid CL from the cathode chamber 35 to the cathode liquid tank 241.
  • the second cathode pipe 242-2 connects the cathode chamber 35 to the separation section 244.
  • One end of the second cathode pipe 242-2 is connected to the cathode chamber 35, and the other end of the second cathode pipe 242-2 is connected to the separation section 244.
  • the third cathode pipe 242-3 is the remaining part of the return path for supplying the cathode liquid CL from the cathode chamber 35 to the cathode liquid tank 241.
  • the third cathode pipe 242-3 connects the separation section 244 and the cathode liquid tank 241.
  • One end of the third cathode pipe 242-3 is connected to the separation section 244, and the other end of the third cathode pipe 242-3 is connected to the cathode liquid tank 241.
  • the cathode pump 243 is provided midway along the first cathode pipe 242-1. Like the anode pump 233, the cathode pump 243 can be configured with a known pump, such as a gear pump or a cylinder pump. Note that the cathode liquid supply unit 24 may circulate the cathode liquid CL using a liquid delivery device other than a pump.
  • the separation section 244 may be provided between the second cathode pipe 242-2 and the third cathode pipe 242-3.
  • a general gas-liquid separator, oil-water separator, or the like can be used as the separation section 244. Since hydrogen gas is generated by a side reaction at the cathode electrode 313, the cathode liquid CL recovered from the cathode chamber 35 contains gaseous hydrogen and dissolved hydrogen. The gaseous hydrogen is separated from the cathode liquid CL in the cathode liquid tank 241 and taken out of the system. The cathode liquid CL from which the gaseous hydrogen has been separated is supplied again to the electrolytic cell 21.
  • the branch discharge pipe 245 is provided in the separation section 244 and is a flow path for separating the water in the cathode liquid CL from the cathode liquid CL and discharging it outside the system. Water moves to the cathode electrode layer 313A together with protons from the anode electrode 312. Therefore, the cathode liquid CL discharged from the cathode electrode layer 313A may contain water.
  • the branch discharge pipe 245 discharges the water in the cathode liquid CL supplied to the separation section 244 outside the system.
  • the cathode fluid CL stored in the cathode fluid tank 241 flows through the cathode piping 242 by driving the cathode pump 243, and circulates between the cathode pump 243 and the cathode chamber 35.
  • the cathode fluid CL stored in the cathode fluid tank 241 is supplied to the cathode electrode layer 313A of the electrolytic cell 21 via the first cathode piping 242-1 by driving the cathode pump 243.
  • the cathode fluid CL that flows into the cathode electrode layer 313A is used for an electrode reaction in the cathode electrode layer 313A.
  • the cathode fluid CL in the cathode electrode layer 313A flows into the separation section 244 via the second cathode piping 242-2.
  • hydrogen gas is generated by a side reaction. Therefore, hydrogen gas is mixed into the cathode fluid CL discharged from the cathode electrode layer 313A.
  • the separation unit 244 separates the hydrogen gas in the cathode liquid CL from the cathode liquid CL and discharges it outside the system.
  • the separation unit 244 separates the water in the cathode fluid CL from the cathode fluid CL and discharges it outside the system.
  • the cathode fluid CL from which hydrogen gas and water have been separated is returned to the cathode fluid tank 241 via the third cathode piping 242-3.
  • the cathode fluid supply unit 24 circulates the cathode fluid CL between the cathode electrode layer 313A and the cathode fluid tank 241.
  • the cathode fluid supply unit 24 is not limited to this configuration, and may be configured to send the cathode fluid CL from the cathode electrode layer 313A to the outside of the system without returning it to the cathode fluid tank 241.
  • the heating unit 25 is provided on the outer periphery of the electrolytic cell 21.
  • the heating unit 25 may heat the electrolytic cell 21 to heat the anode fluid Al and cathode fluid CL flowing within the electrolytic cell 21.
  • the heating temperature is preferably 50°C to 80°C, more preferably 55°C to 75°C, and even more preferably 60°C to 70°C. If the temperature of the anode fluid Al or cathode fluid CL is 50°C to 80°C, the electrolytic reaction at both electrodes can proceed without delay, and the burden of removing the heat generated as the electrolytic reaction proceeds at both electrodes can be reduced.
  • the heating unit 25 may be a general heating device such as a heater or a capacitor. When a heater is used as the heating unit 25, the heater may be placed inside the electrolytic cell 21 and heated while measuring the temperature of the anode fluid Al and cathode fluid CL flowing inside the electrolytic cell 21 with a thermocouple or the like.
  • the heating unit 25 heats the electrolytic cell 21 using a heating device, but other methods may be used.
  • the heating unit 25 may have a configuration including a heat exchanger that heats a heat medium and a heat medium flow pipe that is arranged near the outer periphery of the electrolytic cell 21 and through which the heat medium flows.
  • the heating unit 25 may heat the electrolytic cell 21 by passing the heat medium heated in the heat exchange unit through the heat medium flow pipe and exchanging heat between the heat medium flowing in the heat medium flow pipe and the electrolytic cell 21.
  • the heat medium flow pipe may be arranged in the electrolytic cell 21 to exchange heat between the anode liquid Al and the cathode liquid CL and the heat medium flowing in the heat medium flow pipe.
  • the heating unit 25 may be a bathtub such as a jacket filled with warm water. The heating unit 25 may heat the electrolytic cell 21 by placing the electrolytic cell 21 in the bathtub and exchanging heat between the warm water and the electrolytic cell 21.
  • the differential pressure detection unit 26 measures the differential pressure between the cathode pump 243 and the electrolytic cell 21 in the first cathode piping 242-1.
  • the differential pressure detection unit 26 may detect the pressure inside the first cathode piping 242-1 downstream of the cathode pump 243 and inside the first cathode piping 242-1 near the inlet of the electrolytic cell 21.
  • a general differential pressure gauge or the like may be used as the differential pressure detection unit 26.
  • the pressure value measured by the differential pressure detection unit 26 is transmitted to the control unit 28.
  • the resistance measuring unit 27 measures the resistance of the electrolytic cell 21.
  • a general resistance measuring device may be used as the resistance measuring unit 27.
  • the resistance measuring unit 27 may have a first resistance measuring unit 27-1 connected to the anode electrode 312 and a second resistance measuring unit 27-2 connected to the cathode electrode layer 313A. The resistance value measured by the resistance measuring unit 27 is transmitted to the control unit 28.
  • the control unit 28 is connected to each component constituting the electrolytic reduction device 20 so as to be able to control these components.
  • the control unit 28 has a memory means for storing a control program and various memory information, and a calculation means for operating based on the control program.
  • the control unit 28 is realized by the calculation means reading and executing the control program etc. stored in the memory means.
  • the control unit 28 may control the output of the power supply unit 22 of the electrolytic reduction device 20 to control the potential of the anode electrode 312 and the cathode electrode 313 during operation of the electrolytic reduction system 1 based on the measurement results of the differential pressure detection unit 26, the resistance measurement unit 27, etc., and may control the driving of the anode pump 233 and the cathode pump 243, etc.
  • the control unit 28 may also control the discharge of oxygen from the anode liquid tank 231, the discharge of hydrogen from the separation unit 244, and the discharge of water from the branch discharge pipe 245, etc.
  • the control unit 28 may control the conversion of voltage in the power conversion unit 13 according to the operating status of the first power supply unit 11, the amount of power output, etc.
  • the control unit 28 may control the output of the power supply unit 22, the potential of the anode electrode 312 and the cathode electrode 313, the driving of the anode pump 233 and the cathode pump 243, etc. when or while the electrolytic reduction system 1 is stopped.
  • control unit 28 may control the drive of the cathode pump 243 according to the type and flow rate of the cathode liquid CL based on the measurement results of the differential pressure detection unit 26, thereby adjusting the flow rate of the cathode liquid CL and controlling the differential pressure between the inside and outside of the electrolytic cell 21.
  • the control unit 28 may control the pressure difference of the cathode liquid CL between the inside and outside of the cathode chamber 35 of the electrolytic cell 21 during non-electrolysis to, for example, 0.3 KPa to 6.0 KPa.
  • the pressure difference is the pressure of the cathode liquid CL at the inlet of the electrolytic cell 21.
  • the pressure difference of the cathode liquid CL between the inlet of the electrolytic cell 21 and the inside of the cathode chamber 35 of the electrolytic cell 21 indicates the ease of passage of toluene, which is the cathode liquid CL.
  • the liquid diffusion layer 313B is composed of a porous body having a porosity of 65% or more and a volume average pore size of 500 ⁇ m or more, even if the pressure difference of the cathode liquid CL between the inside and outside of the electrolytic cell 21 during non-electrolysis is low at 0.3 KPa to 6.0 KPa, the cathode liquid CL can be passed through the liquid diffusion layer 313B while suppressing the load on the cathode pump 243. This reduces the cost of operating the cathode pump 243.
  • the hydrogen gas by-produced in the cathode electrode layer 313A becomes fine bubbles and easily coalesces, so that it can be easily released from the cathode electrode layer 313A as bubbles.
  • the pressure difference of the cathode liquid CL is low, the flow rate can be increased even with the same pressure difference. This improves the diffusibility of toluene, and further improves the Faraday efficiency.
  • the pressure difference of the cathode liquid CL between the inside and outside of the electrolytic cell 21 to a low value of 0.3 KPa to 6.0 KPa, the pressure applied to the joint between the electrolytic cell 21 and the first cathode pipe 242-1 can be reduced. This allows the cost associated with sealing the joint to be significantly reduced.
  • the cathode liquid CL when electrolytic decomposition of the cathode liquid CL occurs in the electrolytic cell 21, especially in the latter half of the electrolysis of the cathode liquid CL, the cathode liquid CL contains water and MCH in addition to the substance to be hydrogenated.
  • the control unit 28 may control the differential pressure of the cathode liquid CL inside and outside the electrolytic cell 21 to be, for example, 0.5 KPa to 8.0 KPa.
  • the control unit 28 may control the operation of the cathode pump 243 so that the flow rate of the cathode liquid CL is made faster than during normal operation.
  • the cathode pump 243 can be used to increase the flow rate of the cathode liquid CL, thereby suppressing the decrease in the Faraday efficiency and enabling continuous operation.
  • by increasing the flow rate of the cathode liquid CL it becomes easier to remove heat generated by the electrolysis of water inside the electrolytic cell 21.
  • Normal operation refers to an operating state in which power generated by the first power supply unit 11 or the electrolytic reduction device 20 is supplied to the electrolytic cell 21 of the electrolytic reduction device 20, the operation of the electrolytic reduction device 20 is not hindered, and organic hydride is being generated in the electrolytic reduction device 20.
  • the threshold value is not particularly limited and may be set to any appropriate value depending on the amount of organic hydride generated, etc., set in the electrolytic reduction device 20.
  • the electrolytic reduction device 20 may have multiple electrolytic cells 21.
  • the electrolytic cells 21 are aligned, for example, so that the anode electrodes 312 and the cathode electrode layers 313A are arranged in the same order, and are stacked with a current-carrying plate between adjacent electrolytic cells 21.
  • the electrolytic cells 21 are electrically connected in series.
  • the current-carrying plate is made of a conductive material such as metal.
  • the electrolytic cells 21 may be connected in parallel, or a combination of series and parallel connections may be used.
  • the porous body constituting the liquid diffusion layer 313B is formed using a carbon material made of carbon fiber as an acid-resistant porous material.
  • FIG 2 is a flow chart showing an example of a method for manufacturing an electrolytic reduction device.
  • carbon fibers which are the raw material for the carbon material, are calcined at 2000°C to 3000°C and carbonized (carbonization process: step S11).
  • the tensile modulus of the carbon fiber can be improved by baking the carbon fiber at 2000°C to 3000°C, and the self-supporting properties of the carbon fiber can be enhanced.
  • the carbon fiber is a pitch-based carbon fiber
  • the tensile modulus of the carbon fiber can be improved more than when using PAN-based carbon fiber, so it is preferable to use pitch-based carbon fiber as the carbon fiber.
  • the carbon fibers are molded into any shape to produce a porous body, which is a fibrous body having a porosity of 90% or more and a volume average pore diameter of 500 ⁇ m or more (porous body production process: step S11).
  • the air permeability of the porous body is preferably 50 Pa or less, more preferably 40 Pa or less, and even more preferably 30 Pa or less. If the air permeability of the porous body is 50 Pa or less, the porous body can maintain a high porosity even if it is compressed and crushed, for example, to about 1/4 of its size.
  • the air permeability is a value representing the pressure generated when a certain amount of air (e.g., about 0.5 m/s per 5 cm2) is fed into a specified area per unit time.
  • the air permeability may be measured using a general air permeability tester (e.g., FX3340MinAir (manufactured by Takayama Reed Co., Ltd.)).
  • FX3340MinAir manufactured by Takayama Reed Co., Ltd.
  • the air permeability can be obtained by placing a sample in the air permeability tester and measuring the pressure when air is fed into a sample with an area of, for example, 5 cm2 at room temperature at about 0.5 m/s.
  • step S13 the porous body is layered on the cathode electrode layer 313A to form a laminate.
  • step S14 the porous body is compressed so that its thickness becomes 1/2 or less, forming the liquid diffusion layer 313B (liquid diffusion layer formation process: step S14).
  • cathode electrode 313 which is made up of the cathode electrode layer 313A and the liquid diffusion layer 313B stacked together.
  • the method for compressing the porous body is not particularly limited as long as it can reduce the thickness of the porous body.
  • a method may be used in which the porous body is compressed while being assembled to the cathode electrode layer 313A.
  • the electrolyte membrane 311, the anode electrode 312, and the cathode electrode 313 are stacked so that the electrolyte membrane 311 is sandwiched between the anode electrode 312 and the cathode electrode 313 to form the membrane electrode assembly 31 (membrane electrode assembly formation process: step S15).
  • step S16 the membrane electrode assembly 31, the plate member 32, and the gasket 33 are assembled so that the membrane electrode assembly 31 is sandwiched between the plate member 32 via the gasket 33, thereby forming the electrolytic cell 21 (electrolytic cell formation process: step S16).
  • electrolytic cell 21, power supply unit 22, anode fluid supply unit 23, cathode fluid supply unit 24, heating unit 25, differential pressure detection unit 26, resistance measurement unit 27, and control unit 28 are connected together to manufacture the electrolytic reduction device 20 (manufacturing process of electrolytic reduction device: step S17).
  • an electrode reaction at the anode electrode 312 and an electrode reaction at the cathode electrode layer 313A proceed in parallel as main reactions.
  • Water is electrolyzed by the electrode reaction at the anode electrode 312, and oxygen gas, protons (H + ), and electrons (e ⁇ ) are generated.
  • Oxygen gas generated by the electrolysis of water is discharged to the anode pipe 232 via the anode chamber 34.
  • Protons generated by the electrolysis of water pass through the electrolyte membrane 311 together with water molecules and move to the cathode electrode layer 313A.
  • Electrons generated by the electrolysis of water move to the positive output terminal of the power supply unit 22 and are supplied to the cathode electrode layer 313A via the negative output terminal of the power supply unit 22.
  • the protons and electrons supplied to the cathode electrode layer 313A are used for hydrogenating toluene in the electrode reaction at the cathode electrode layer 313A.
  • the toluene is hydrogenated by a reaction between the toluene, the electrons supplied from the negative output terminal of the power supply unit 22, and the protons that have passed through the electrolyte membrane 311.
  • methylcyclohexane is produced as an organic hydride.
  • the electrolysis of water and the hydrogenation reaction of toluene, the product to be hydrogenated can be carried out in a single step. This improves the efficiency of organic hydride production compared to conventional technologies that produce organic hydrides in a two-step process consisting of a process for producing hydrogen by water electrolysis or the like and a process for chemically hydrogenating the product to be hydrogenated in a reactor at a plant or the like.
  • a reactor for chemical hydrogenation or a high-pressure container for storing hydrogen produced by water electrolysis or the like since there is no need for a reactor for chemical hydrogenation or a high-pressure container for storing hydrogen produced by water electrolysis or the like, a significant reduction in equipment costs can be achieved.
  • a side reaction of generating hydrogen gas in addition to the main reaction of hydrogenation of the material to be hydrogenated, a side reaction of generating hydrogen gas, as shown in formula (3) below, may occur. Possible side reactions at the cathode electrode: 2H + +2e ⁇ ⁇ H 2 ... (3)
  • the electrolytic cell 21 is supplied with power from the power supply unit 10.
  • a predetermined electrolysis voltage is applied between the anode electrode 312 and the cathode electrode layer 313A of the electrolytic cell 21, causing an electrolysis current to flow.
  • the power supply sends the power supplied from the power supply unit 10 to the electrolytic cell 21.
  • the electrolytic reduction system 1 can generate hydrogen by desorbing hydrogen from an organic hydride produced in the electrolytic reduction device 20.
  • the generated hydrogen is supplied to, for example, a hydrogen station, a fuel cell, a hydrogen power generation device, etc.
  • the substances to be hydrogenated such as toluene, that are produced by desorption of hydrogen from the organic hydride may be recovered by known processes such as distillation separation, extraction separation, membrane separation, and adsorption separation, and may be stored in a storage tank, or may be used as a gasoline base material or a raw material for chemical products.
  • the substances to be hydrogenated stored in the storage tank may be reused.
  • the electrolytic reduction device 20 includes an electrolytic cell 21, and the liquid diffusion layer 313B of the electrolytic cell 21 is made of a porous material having a porosity of 65% or more and a volume average pore size of 500 ⁇ m or more.
  • the liquid diffusion layer 313B has sufficient voids therein, and is configured to easily pass the cathode solution CL, organic hydride, hydrogen gas, and proton-accompanying water through the liquid diffusion layer 313B.
  • the electrolytic reduction device 20 can easily allow the cathode solution CL to reach the cathode electrode layer 313A, and can easily allow the organic hydride and proton-accompanying water generated in the cathode electrode layer 313A to pass through the liquid diffusion layer 313B without being retained in the cathode electrode layer 313A.
  • the substance to be hydrided contained in the cathode solution CL can reach the interface with the liquid diffusion layer 313B of the cathode electrode layer 313A, a shortage of the substance to be hydrided at the interface can be avoided.
  • the electrolytic reduction device 20 can make it easier to hydrogenate the substance to be hydrogenated contained in the cathode solution CL2 in the cathode electrode layer 313A.
  • the electrolytic reduction device 20 can therefore improve the efficiency of the electrode reaction in the cathode electrode layer 313A, i.e., the faradaic efficiency, and therefore the efficiency of generating organic hydrides.
  • the electrolytic reduction device 20 can improve the hourly production efficiency of organic hydrides.
  • the liquid diffusion layer 313B has the above-mentioned porosity and volume average pore size, and is configured to allow liquid to easily drain, so that the proton-accompanying water can be quickly washed away from the liquid diffusion layer 313B together with the cathode liquid CL. Therefore, the electrolytic reduction device 20 can prevent water from remaining in the cathode electrode layer 313A and the liquid diffusion layer 313B, thereby preventing a decrease in the electrolytic performance of the electrolytic cell 21.
  • the electrolytic reduction device 20 uses the above-mentioned porous body for the liquid diffusion layer 313B, and can reduce the internal pressure of the cathode chamber 35 when the cathode electrode layer 313A produces organic hydride from the material to be hydrided in the cathode solution CL. This allows the electrolytic reduction device 20 to prevent the cathode solution CL from leaking from the joint between the electrolytic cell 21 and the cathode piping 242, etc. Furthermore, the electrolytic reduction device 20 can reduce the load on the cathode pump 243, thereby reducing the cost required to operate the cathode pump 243.
  • the electrolytic reduction device 20 uses the above-mentioned porous body for the liquid diffusion layer 313B, which makes it difficult for heat to accumulate inside, making it easier to manage heat inside the electrolytic cell 21.
  • the electrolytic reduction device 20 can reduce the costs required for measures against heat generation in the electrolytic cell 21.
  • the electrolytic reduction device 20 can prevent clogging of the liquid diffusion layer 313B due to foreign matter mixed in the cathode solution CL. Therefore, the electrolytic reduction device 20 can stably hydrogenate the material to be hydrided, and can stably generate organic hydrides.
  • the electrolytic reduction device 20 can set the thickness of the liquid diffusion layer 313B to 0.2 mm to 0.6 mm. This allows the electrolytic reduction device 20 to shorten the diffusion distance of the substance to be hydrided in the cathode liquid CL from the cathode chamber 35 to the cathode electrode layer 313A, thereby suppressing the decrease in the Faraday efficiency. In addition, the electrolytic reduction device 20 can suppress the contact resistance of the cathode liquid CL with the liquid diffusion layer 313B, thereby suppressing the increase in the cell voltage.
  • the electrolytic reduction device 20 can easily discharge the hydrogen gas from the liquid diffusion layer 313B, thereby suppressing the inhibition of the contact of the substance to be hydrided with the cathode electrode layer 313A by the hydrogen gas. Therefore, the electrolytic reduction device 20 can stably generate organic hydrides by hydrogenating the substance to be hydrided, and can more reliably suppress the decrease in the Faraday efficiency.
  • the porous body of the electrolytic reduction device 20 can be made of an acid-resistant porous material. This allows the liquid diffusion layer 313B to increase the contact area with the cathode liquid CL, making it possible to efficiently hydrogenate the substances to be hydrogenated in the cathode liquid CL and further improving the efficiency of generating organic hydrides.
  • the electrolytic reduction device 20 can include a carbon material or an acid-resistant metal in the acid-resistant porous material. This allows the liquid diffusion layer 313B to stably electrolyze the material to be hydrogenated contained in the cathode liquid CL, and therefore stably hydrogenate the material to be hydrogenated. Therefore, the electrolytic reduction device 20 can stably generate organic hydrides.
  • the electrolytic reduction device 20 can use pitch-based or PAN-based carbon materials as the carbon material.
  • the liquid diffusion layer 313B can more stably perform electrolysis of the material to be hydrogenated contained in the cathode liquid CL, and therefore can more stably perform hydrogenation of the material to be hydrogenated. Therefore, the electrolytic reduction device 20 can more stably generate organic hydrides.
  • the electrolytic reduction device 20 uses a fiber body as the porous body of the liquid diffusion layer 313B, and the average fiber diameter of the fibers contained in the fiber body can be set to 20 ⁇ m to 30 ⁇ m. As a result, the electrolytic reduction device 20 can maintain the shape of the liquid diffusion layer 313B even when it is pressed at a high compression rate, so that the contact area with the cathode liquid CL can be secured. Therefore, the electrolytic reduction device 20 can maintain the hydrogenation of the substance to be hydrogenated in the cathode liquid CL, and can reliably improve the production efficiency of organic hydrides.
  • the electrolytic reduction device 20 can press the liquid diffusion layer 313B at a high compression rate to maintain the contact area between the fiber and the cathode liquid CL, so that an increase in the resistance required for the cathode liquid CL to pass through the liquid diffusion layer 313B can be suppressed.
  • the electrolytic reduction device 20 can heat the material to be hydrided to 50°C to 80°C in the cathode chamber 35. This allows the electrolytic reduction device 20 to further improve the efficiency of generating organic hydrides.
  • the electrolytic reduction device 20 can include a cathode pump 243 and a control unit 28. This allows the electrolytic reduction device 20 to appropriately control the flow rate of the cathode liquid CL supplied to the cathode electrode 313 by controlling the cathode pump 243 with the control unit 28, thereby appropriately hydrogenating the material to be hydrogenated contained in the cathode liquid at the cathode electrode 313 and accurately producing an organic hydride.
  • the control unit 28 can increase the flow rate of the cathode liquid CL to increase the proportion of the substance to be hydrogenated at the cathode electrode 313.
  • the electrolytic reduction device 20 can increase the faradaic efficiency even when the faradaic efficiency decreases, and can therefore stably generate organic hydrides.
  • the electrolytic reduction system 1 can include a first power supply unit 11 and the electrolytic reduction device 20.
  • the electrolytic reduction system 1 can efficiently generate organic hydrides by generating organic hydrides in the electrolytic reduction device 20 using electricity derived from renewable energy supplied from the first power supply unit 11.
  • the electrolytic reduction system 1 can produce organic hydride using electricity derived from renewable energy generated by the first power supply unit 11, it is possible to reduce the consumption of fossil fuels and the amount of CO 2 emissions associated with the production of hydrogen.
  • the electrolytic reduction system 1 can include a second power supply unit 12. When the power supplied from the first power supply unit 11 to the electrolytic cell 21 of the electrolytic reduction device 20 is insufficient, the electrolytic reduction system 1 can stably operate the electrolytic reduction device 20 by supplying the power generated by the second power supply unit 12 to the electrolytic cell 21. This allows the electrolytic reduction system 1 to stably produce organic hydride in the electrolytic reduction device 20.
  • the electrolytic reduction system 1 can efficiently generate organic hydrides directly from energy such as renewable energy, without passing through hydrogen gas, using the material to be hydrided, as an energy carrier for transporting, storing, etc., hydrogen derived from the energy. Therefore, the electrolytic reduction system 1 can be effectively used as a device for producing energy carriers used for transporting, storing, etc., the electricity generated by the power supply unit 10.
  • renewable energy can be transported and stored via organic hydrides, allowing the renewable energy to be used efficiently without waste.
  • the electrolytic reduction system 1 can be suitably used for producing energy carriers for transporting and storing renewable energy.
  • Example 1 Preparation of electrolytic cell>
  • a polyfluorosulfonic acid-based cation exchange membrane Nafion (registered trademark) 117, manufactured by DuPont, membrane thickness: 183 ⁇ m
  • membrane thickness 183 ⁇ m
  • substantially rectangular shape length 200 mm, width 200 mm, thickness 183 ⁇ m
  • a dimensionally stable electrode (DSE) electrode manufactured by De Nora Permelec having IrO2 coated on a Ti substrate was prepared.
  • the catalyst loading density of the ink for forming a cathode electrode layer was 1 mg/cm 2 , and the ionomer/carbon ratio (I/C) was 0.5.
  • the prepared cathode catalyst ink for forming a cathode electrode layer was applied to the main surface of a substrate to form a cathode electrode layer.
  • a liquid diffusion layer material 1 was prepared using a fibrous body 1 (length 100 mm ⁇ width 100 mm ⁇ thickness 2 mm, average fiber diameter: 20 to 30 ⁇ m, porosity: 96%).
  • the prepared liquid diffusion layer material 1 was laminated on a cathode electrode layer, and then the liquid diffusion layer material 1 was compressed until the thickness of the liquid diffusion layer material 1 reached 0.5 mm, thereby producing a cathode electrode in which the liquid diffusion layer 1 was laminated on the cathode electrode layer.
  • the porosity and volume average pore diameter of the prepared liquid diffusion layer 1 were measured.
  • the thickness of the liquid diffusion layer 1 cut out to an area of 5 cm x 5 cm square was measured, and the volume V0 of the liquid diffusion layer 1 in a densely packed state was obtained.
  • the thickness of the liquid diffusion layer 1 was measured using a Digimicrostand MS11C (manufactured by Nikon Corporation).
  • the entire amount of the cut-out liquid diffusion layer 1 was finely ground in a mortar. 15 mL of hexane was placed in a graduated cylinder as a predetermined liquid, and the entire amount of the ground liquid diffusion layer 1 was added to the hexane, and the increase in volume V1 was obtained.
  • volume average Pore Diameter of Liquid Diffusion Layer 1 The volume average pore diameter of the liquid diffusion layer 1 was measured by the method described below, and was found to be 531 ⁇ m.
  • the volume average pore diameter was measured separately for sizes less than 100 ⁇ m and for sizes greater than 100 ⁇ m.
  • the volume average pore diameter that cannot be measured by a mercury porosimeter was calculated using the value obtained by measuring the air permeability.
  • the air permeability is a value that represents the pressure generated when a certain amount of air (for example, about 0.5 m/s per 5 cm2) is sent per unit time to a specified area.
  • the air permeability was measured using a breathability tester (FX3340MinAir, manufactured by Takayama Reed Co., Ltd.). The sample was placed in the breathability tester, and the pressure was measured at room temperature when air was sent at about 0.5 m/s to a sample with an area of 5 cm2 .
  • the volume average pore diameter that cannot be measured by a mercury porosimeter was calculated using the value obtained by measuring the air permeability according to the following formula (III).
  • D (32t ⁇ Lu ⁇ P ⁇ 1 ⁇ ⁇ 1 ) 0.5 ...
  • III (In the formula, d is the volume average pore diameter, t is the tortuosity, ⁇ is the viscosity of air, L is the thickness of the diffusion layer, u is the flow velocity of air, ⁇ P is the pressure loss when air is sent into the liquid diffusion layer 313B, and ⁇ is the porosity.)
  • the calculation was performed using the value obtained by measuring the air permeability.
  • the tortuosity t was set to 1.5.
  • the viscosity of air at 22.9° C. was set to 1.833 ⁇ 10 ⁇ 5 Pa ⁇ s.
  • An electrolytic cell was produced by stacking an anode electrode and a cathode electrode sandwiched between an electrolyte membrane, with the anode electrode disposed on one main surface of the electrolyte membrane and the cathode electrode disposed on the other main surface of the electrolyte membrane.
  • Examples 2 and 3 An electrolytic cell was produced in the same manner as in Example 1, except that the liquid diffusion layer 1 was formed so that the porosity thereof was as shown in Table 1, and the liquid was supplied so that the flow rate thereof was as shown in Table 1.
  • the porosity and volume average pore diameter of the liquid diffusion layer 1 in Example 2 were the same as in Example 1.
  • the porosity and volume average pore diameter of the liquid diffusion layer 1 in Example 3 were 68% and the same as in Example 1.
  • Example 1 An electrolytic cell was prepared in the same manner as in Example 1, except that a cathode electrode was prepared in which a liquid diffusion layer 2 was formed instead of the liquid diffusion layer 1 in Example 1.
  • the cathode electrode formed with the liquid diffusion layer 2 was prepared by the method described below. (Preparation of cathode electrode)
  • a liquid diffusion layer material 2 was prepared using a fibrous body 2 (length 100 mm ⁇ width 100 mm ⁇ thickness 0.2 mm, average fiber diameter: 6 to 8 ⁇ m, porosity: 79%).
  • the prepared liquid diffusion layer material 2 was laminated on a cathode electrode layer, and then compressed until the thickness of the liquid diffusion layer material 2 reached 0.5 mm, to produce a cathode electrode in which the liquid diffusion layer 2 was laminated on the cathode electrode layer.
  • the porosity of the liquid diffusion layer 2 was 78%, and the volume average pore diameter was 35 ⁇ m.
  • Example 2 An electrolytic cell was produced in the same manner as in Example 1, except that a cathode electrode was produced using the following liquid diffusion layer 3 instead of the liquid diffusion layer 1 in Example 1.
  • the cathode electrode formed with the liquid diffusion layer 3 was produced by the method described below. (Preparation of cathode electrode)
  • a liquid diffusion layer material 3 was prepared using a fibrous body 3 (length 100 mm, width 100 mm, thickness 290 ⁇ m, average fiber diameter: 12 to 15 ⁇ m, porosity: 66%).
  • the prepared liquid diffusion layer material 3 was laminated on a cathode electrode layer, and then compressed until the thickness of the liquid diffusion layer material 3 became 0.5 mm, to produce a cathode electrode in which the liquid diffusion layer 3 was laminated on the cathode electrode layer.
  • the porosity of the liquid diffusion layer 3 was 62%, and the volume average pore diameter was 32 ⁇ m.
  • a heating device was installed around the electrolytic cells of each of the examples and comparative examples prepared, and the anode solution and cathode solution in the electrolytic cells were heated to 60°C to 65°C.
  • a DC power supply was connected to the anode electrode and the cathode electrode. Water was supplied to the anode chamber of the electrolytic cell, and toluene was supplied to the cathode chamber at the ratio shown in Table 1.
  • An electrolysis test was performed by passing a DC power supply of 1 A/ cm2 through the anode electrode and the cathode electrode, and the Faraday efficiency was measured.
  • Table 1 shows the type of liquid diffusion layer, the amount of toluene supplied, and the Faraday efficiency for each example and comparative example.
  • the Faraday efficiency of the electrolytic cell was 95.1% or more. In contrast, in each comparative example, the Faraday efficiency of the electrolytic cell was 94.2% or less.
  • the electrolytic cells of the above examples can improve the Faraday efficiency if the porosity of the liquid diffusion layer is 68% or more and the volume average pore diameter is 531 ⁇ m. Therefore, the electrolytic reduction device of this embodiment can improve the production efficiency of organic hydrides by using an electrolytic cell equipped with a liquid diffusion layer having a porosity and volume average pore diameter of a predetermined size. Therefore, it can be said that the electrolytic reduction device of this embodiment can be effectively used as a means for converting electricity obtained from energy such as renewable energy into a hydrogen carrier and transporting it.
  • the cathode diffusion layer is a porous body having a porosity of 65% or more and a volume average pore size of 500 ⁇ m or more.
  • ⁇ 2> The electrolytic reduction apparatus according to ⁇ 1>, wherein the cathode diffusion layer has a thickness of 0.2 mm to 0.6 mm.
  • the porous body includes a porous material having acid resistance.
  • the porous material contains at least one of a carbon material and an acid-resistant metal.
  • the carbon material contains at least one of pitch-based and PAN-based carbon fibers.
  • the porous body is a fibrous body containing fibers
  • a drive pump that causes the cathode fluid to flow through the cathode electrode; a control unit for controlling a flow rate of the cathode fluid flowing from the drive pump;
  • the electrolytic reduction device according to any one of ⁇ 1> to ⁇ 7>, ⁇ 9>
  • a renewable energy power supply unit that supplies electricity derived from renewable energy
  • an electrolytic reduction device that hydrogenates a substance to be hydrogenated using the electric power supplied from the renewable energy electric power supply unit; Equipped with The electrolytic reduction device is An electrolyte membrane; an anode electrode provided on one side of the electrolyte membrane; a cathode electrode provided on the other side of the electrolyte membrane; Equipped with the cathode electrode has a cathode diffusion layer that diffuses a cathode fluid containing the substance to be hydrogenated on a surface opposite to the electrolyte membrane side,
  • the cathode diffusion layer is a porous body having a porosity of 65% or more and a volume average pore size of 500 ⁇ m or more.
  • the electrolytic reduction system according to ⁇ 10>, further comprising a second power supply unit that supplies electric power derived from a fossil fuel to the anode electrode and the cathode electrode of the electrolytic reduction device.
  • ⁇ 12> A step of preparing a porous body having a porosity of 90% or more and a volume average pore diameter of 500 ⁇ m or more; laminating the porous body on a cathode electrode layer; compressing the porous body by at least two times to form a cathode diffusion layer;
  • a method for producing an electrolytic reduction device comprising the steps of: ⁇ 13> The method for producing an electrolytic reduction apparatus according to ⁇ 12>, wherein the porous body has an air permeability of 50 Pa or less.
  • Electrolytic reduction system 10 Power supply unit 11 First power supply unit 12 Second power supply unit 20 Electrolytic reduction device 21 Electrolytic cell 22 Power supply unit 23 Anode fluid supply unit 231 Anode fluid tank 232 Anode piping 233 Anode pump 24 Cathode fluid supply unit 241 Cathode fluid tank 242 Cathode piping 243 Cathode pump 244 Separation unit 25 Heating unit 26 Differential pressure detection unit 27 Resistance measurement unit 28 Control unit 31 Membrane electrode assembly 311 Electrolyte membrane 312 Anode electrode 313 Cathode electrode 313A Cathode electrode layer 313B Liquid diffusion layer 34 Anode chamber 35 Cathode chamber AL Anode fluid CL Cathode fluid

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Abstract

Le dispositif d'électroréduction selon la présente invention comprend : un film d'électrolyte ; une électrode d'anode se situant sur une face du film d'électrolyte ; et une électrode de cathode se situant sur l'autre face du film d'électrolyte. L'électrode de cathode comprend une couche de diffusion de cathode qui diffuse un catholyte contenant une substance à hydrogéner sur une surface différente de la surface côté film d'électrolyte. La couche de diffusion de cathode est un corps poreux présentant une porosité supérieure ou égale à 65 %, et un diamètre de pore moyen en volume supérieur ou égal à 500 µm.
PCT/JP2023/039237 2022-11-10 2023-10-31 Dispositif d'électroréduction, système d'électroréduction et procédé de fabrication de dispositif d'électroréduction WO2024101221A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014156126A1 (fr) * 2013-03-29 2014-10-02 Ｊｘ日鉱日石エネルギー株式会社 Dispositif de réduction électrochimique et procédé de production d'un produit hydrogéné de composé aromatique
JP2018018665A (ja) * 2016-07-27 2018-02-01 アイシン化工株式会社 ガス拡散層基材及びその製造方法
WO2018037774A1 (fr) * 2016-08-23 2018-03-01 国立大学法人横浜国立大学 Cathode, cellule d'électrolyse pour produire un hydrure organique, et procédé de production d'hydrure organique
WO2018092496A1 (fr) * 2016-11-15 2018-05-24 国立大学法人横浜国立大学 Appareil de production d'hydrure organique et procédé de production d'hydrure organique
WO2021131416A1 (fr) * 2019-12-26 2021-07-01 Ｅｎｅｏｓ株式会社 Système de génération d'hydrure organique, dispositif de commande pour système de génération d'hydrure organique, et procédé de commande pour système de génération d'hydrure organique

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014156126A1 (fr) * 2013-03-29 2014-10-02 Ｊｘ日鉱日石エネルギー株式会社 Dispositif de réduction électrochimique et procédé de production d'un produit hydrogéné de composé aromatique
JP2018018665A (ja) * 2016-07-27 2018-02-01 アイシン化工株式会社 ガス拡散層基材及びその製造方法
WO2018037774A1 (fr) * 2016-08-23 2018-03-01 国立大学法人横浜国立大学 Cathode, cellule d'électrolyse pour produire un hydrure organique, et procédé de production d'hydrure organique
WO2018092496A1 (fr) * 2016-11-15 2018-05-24 国立大学法人横浜国立大学 Appareil de production d'hydrure organique et procédé de production d'hydrure organique
WO2021131416A1 (fr) * 2019-12-26 2021-07-01 Ｅｎｅｏｓ株式会社 Système de génération d'hydrure organique, dispositif de commande pour système de génération d'hydrure organique, et procédé de commande pour système de génération d'hydrure organique

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