Water electrolysis-integrated methanation cell, and laminate methanation cell and electrolysis methanation device using the same

Abstract

To provide a water electrolysis-integrated methanation cell that enables water electrolysis and methanation, allowing for relatively easy temperature management.SOLUTION: A water electrolysis-integrated methanation cell includes: an anode part that electrolyzes water or water vapor to produce oxygen and hydrogen ions; a cathode part that reduces hydrogen ions to produce hydrogen; a methanation part that reduces carbon dioxide to produce a carbon compound; and a heat removal part that removes heat by coming into contact with at least one of the anode part and the methanation part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an integrated water electrolysis methanation cell, and a stacked methanation cell and an electrolytic methanation device using the same. [Background technology]

[0002] From the perspective of carbon neutrality, there is also a demand to replace part of the gas supply with e-methane, and studies are underway to introduce e-methane gas into the gas supply.

[0003] To date, there have been reports of renewable energy utilization systems that include a water electrolysis device that produces hydrogen and oxygen using surplus electricity from a renewable energy power generation device, and a methanation facility that synthesizes the hydrogen produced in the water electrolysis device with carbon dioxide generated within the system to produce hydrocarbon fuels such as methane (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-45430 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, water electrolysis and methanation are performed in separate devices (facilities), which requires large-scale facilities. Therefore, the present inventors have investigated performing water electrolysis and methanation in a single device rather than in separate devices.

[0006] One issue to be addressed in this regard is that if overvoltage occurs during the methanation reaction or water electrolysis, both of these reactions will become exothermic, making temperature control difficult.

[0007] Therefore, a main object of the present disclosure is to provide a water electrolysis integrated methanation cell that can perform water electrolysis and methanation and that allows relatively easy temperature control. [Means for solving the problem]

[0008] One aspect of the present disclosure is to provide a method for producing An anode portion that electrolyzes water to generate oxygen and hydrogen ions; a cathode portion that reduces hydrogen ions to generate hydrogen; a methanation unit that reduces carbon dioxide to produce carbon compounds; The present invention relates to a water electrolysis integrated methanation cell comprising: a heat removal section that is in contact with at least one of the anode section and the methanation section and removes heat.

[0009] A stacked methanation cell according to another aspect of the present disclosure is characterized in that it includes two or more of the above-mentioned integrated water electrolysis methanation cells.

[0010] An electrolytic methanation device according to yet another aspect of the present disclosure includes the above-described integrated water electrolysis methanation cell, and a power source that applies a current between the anode portion and the cathode portion. Effect of the Invention

[0011] According to the present disclosure, it is possible to provide an integrated water electrolysis methanation cell that is capable of performing water electrolysis and methanation and in which temperature control is relatively easy, and to provide a stacked methanation cell and an electrolytic methanation device using the same. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an example (first embodiment) of a water electrolysis integrated methanation cell according to the present embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of a heat removal section that can be used in the integrated water electrolysis methanation cell of this embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing another example (second embodiment) of the integrated water electrolysis methanation cell of the present embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of a stacked methanation cell in which the integrated water electrolysis methanation cells of the first embodiment are stacked. [Diagram 5] FIG. 5 is a schematic diagram showing an example of a bipolar plate that can be used in the stacked methanation cell of this embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an example of a stacked methanation cell in which the integrated water electrolysis methanation cells according to the second embodiment are stacked. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be specifically described with reference to the drawings, but the present disclosure is not limited thereto. In addition, all drawings used in this specification are schematic diagrams (schematic diagrams).

[0014] [Water electrolysis integrated methanation cell] The integrated water electrolysis methanation cell of this embodiment is a methanation cell in which water electrolysis and methanation are integrated, and is used in a methanation device. The integrated water electrolysis methanation cell of this embodiment can perform water electrolysis and methanation using carbon dioxide and water as raw materials to obtain desired carbon compounds. Examples of carbon compounds that can be obtained by the methanation cell of this embodiment include methane (CH4), carbon monoxide (CO), and methanol.

[0015] The integrated water electrolysis methanation cell of this embodiment includes an anode part, a cathode part, a methanation part, and a heat removal part. The heat removal part is in contact with at least one of the anode part and the methanation part to remove heat. With this configuration, first, water electrolysis and methanation can be performed in one facility. In other words, the gases that need to be supplied are carbon dioxide and water (water vapor), so there is an advantage that hydrogen gas does not leave the system and handling is simplified. Furthermore, since the heat removal part is provided, heat generation (temperature rise) due to the electrolysis reaction and / or the methanation reaction can be controlled, and temperature management is also facilitated.

[0016] First embodiment FIG. 1 is a schematic diagram showing an example of the configuration of a water electrolysis integrated methanation cell (hereinafter, simply referred to as a "methanation cell") according to a first embodiment of the present disclosure. The water electrolysis integrated methanation cell 1 of this embodiment includes at least an anode section 11, a cathode section 12, a methanation section 13, and a heat removal section 14. The methanation cell 1 may be fixed by a pair of support plates (not shown) or may be covered by a case (not shown) or the like, without being particularly limited thereto. The support plate and the case are preferably made of a material having low chemical reactivity and high conductivity. Examples of such materials include metal materials such as SUS, carbon, and the like. The shape of the methanation cell 1 is not particularly limited, and may be a box shape or a cylindrical shape.

[0017] In the anode section 11, water or water vapor is electrolyzed to generate oxygen and hydrogen ions. In the cathode section, hydrogen is generated by reducing the hydrogen ions generated in the anode section 11. In the methanation section 13, carbon dioxide is reduced to generate carbon compounds. In the first embodiment, the heat removal section 14, as shown in FIG. 1, is in contact with both the anode section and the methanation section to remove heat. By providing the heat removal section 14, excessive temperature rise in the methanation section 13 can be suppressed, and the methanation reaction rate is also excellent. In addition, the methanation cell of the first embodiment is structured so that hydrogen generated in the cathode section and carbon dioxide supplied to the cathode section are premixed before the methanation section 13, and this structure is also considered to provide an excellent methanation reaction rate.

[0018] The anode unit 11 typically includes an anode, a first flow path for supplying water or water vapor to the anode, and an electrolyte having hydrogen ion conductivity. The anode causes an oxidation reaction of water (HO) to produce oxygen (O) and hydrogen ions (H + ) is an electrode (oxidation electrode).

[0019] The anode is preferably made of a catalyst material (anode catalyst material) capable of electrolyzing water to generate oxygen and hydrogen ions. Specific examples of the catalyst material include metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys and intermetallic compounds containing these metals, binary metal oxides such as manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), ruthenium oxide (Ru-O), lithium oxide (Li-O), and lanthanum oxide (La-O), ternary metal oxides such as Ni-Co-O, Ni-Fe-O, La-Co-O, Ni-La-O, and Sr-Fe-O, quaternary metal oxides such as Pb-Ru-Ir-O and La-Sr-Co-O, and metal complexes such as Ru complexes and Fe complexes. Among these, it is preferable to use Pt or iridium oxide, etc., from the viewpoint of reducing the overvoltage.

[0020] The anode may be composed of only the above-mentioned anode catalyst material, but may further include a substrate. As the substrate for the anode, a substrate having a structure capable of diffusing water and generated oxygen, such as a porous structure such as a mesh material, a punching material, a porous body, or a sintered metal fiber body, is suitable. In addition, the substrate is preferably composed of a metal material such as titanium (Ti), nickel (Ni), iron (Fe), or an alloy containing at least one of these metals (e.g., SUS).

[0021] When an oxide as described above is used as the anode catalyst material of the anode, it is preferable to form the anode by adhering or laminating the anode catalyst material on the surface of a substrate made of the above-mentioned metal material.

[0022] The anode section 11 is usually provided with a first flow path for supplying water to the anode. The water supplied to the first flow path may be used as it is, or may be in the form of water vapor. The first flow path is connected to a water or water vapor supply section, and is not particularly limited as long as it is a flow path that can supply water or water vapor from the supply section to the anode. The first flow path is preferably made of a material that has low chemical reactivity and high conductivity. Examples of such materials include metal materials such as SUS, carbon, and the like. Furthermore, the first flow path may be provided with a flow controller that adjusts the amount of water or water vapor supplied to the anode, a measuring device that measures the amount of water or water vapor, and the like.

[0023] The anode section 11 may also be provided with an outlet for discharging unused excess water (water vapor) and oxygen generated together with hydrogen ions in the electrolysis reaction. This outlet may be the outlet of the first flow path.

[0024] An electrolyte is usually provided between the anode and the cathode described later. The electrolyte to be used is not particularly limited as long as it has hydrogen ion conductivity, and polymer electrolytes such as polyvinylidene fluoride, polyacrylic acid, polyethylene oxide, polyacrylonitrile, and polymethyl methacrylate, as well as cesium hydrogen phosphate, an aqueous potassium chloride solution, and an aqueous sodium chloride solution can be used. The form of the electrolyte is also not particularly limited, and for example, the electrolyte may be a sheet-like membrane type, in which case an electrolyte membrane may be provided.

[0025] The cathode section 12 usually has a cathode that reduces hydrogen ions to generate hydrogen, a second flow path that supplies carbon dioxide to the methanation section 13, and the like. A hydrogen ion reduction reaction mainly occurs at the cathode in the cathode section 12. The cathode is preferably composed of a catalyst material (cathode catalyst material) capable of the reduction reaction. Specific examples of the catalyst material include palladium-silver, platinum, iridium, platinum-coated titanium, platinum-supported carbon, palladium-supported carbon, cobalt glyoxime, nickel glyoxime, and the like. An ionomer may be mixed into the cathode catalyst material.

[0026] The cathode may be composed of only the above-mentioned cathode catalyst material, or may further include a substrate such as carbon paper, carbon cloth, carbon nonwoven fabric, or titanium nonwoven fabric.

[0027] The cathode can be obtained, for example, by applying a mixture of the above-mentioned cathode catalyst material and an ionomer to the above-mentioned substrate.

[0028] The second flow path for supplying carbon dioxide in the cathode section 12 is not limited as long as it can supply carbon dioxide to the methanation section 13, but is preferably made of a material with low chemical reactivity and high conductivity. Examples of such materials include metal materials such as SUS, and carbon.

[0029] The anode and the cathode can be connected to a power source, for example, by using a terminal plate, etc. The power source can supply a current between the anode and the cathode to carry out an electrolytic reaction.

[0030] Next, the methanation unit 13 included in the methanation cell 1 of this embodiment will be described. The methanation unit 13 uses hydrogen generated at the cathode to reduce carbon dioxide (CO2) supplied from the second flow path to generate carbon compounds. In this methanation unit 13, methane (CH4) is generated from carbon dioxide (CO2) (methanation reaction). Depending on the catalyst used, carbon compounds such as carbon monoxide (CO) and methanol are also generated.

[0031] The methanation unit 13 is usually provided with a catalyst that reduces carbon dioxide to generate carbon compounds, and a third flow path that discharges the generated carbon compounds. There are no particular limitations on this third flow path as long as it can discharge the carbon compounds.

[0032] The catalyst is in contact with the cathode to receive hydrogen, and is made of a catalyst material. Specific examples of catalyst materials that can be used in this embodiment include metals such as zirconium (Zr), gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), and tin (Sn), metal materials such as alloys and intermetallic compounds containing at least one of the metals, oxides of the metals, carbon materials such as carbon (C), graphene, CNT (carbon nanotube), fullerene, and Ketjen Black, and metal complexes such as Ru complexes and Re complexes.

[0033] The shape of the catalyst in the methanation section 13 is not particularly limited, and various shapes such as powder, plate, mesh, wire, particle, porous, thin film, and island shapes can be used.

[0034] Carbon dioxide is supplied to the catalyst through the second flow path of the cathode section 12. Specifically, for example, a gas containing carbon dioxide is introduced by a flow controller. The second flow path may further be provided with a measuring device for measuring the amount of gas. The carbon dioxide introduced from the second flow path is reduced by contacting with the catalyst in the methanation section 13, and carbon compounds such as methane are generated. The generated gas containing the carbon compounds (for example, methane gas) is discharged from the third flow path.

[0035] The methanation cell 1 of this embodiment further includes a heat removal section 14. The heat removal section 14 is in contact with at least one of the anode section 11 and the methanation section 13, and removes heat generated from an exothermic reaction carried out therein (an electrolytic reaction in the anode section 11 and / or a carbon dioxide reduction reaction in the methanation section 13).

[0036] In the methanation cell 1 of the first embodiment, as shown in FIG. 1, the heat removal section 14 is in contact with both the anode section 11 and the methanation section 13, and therefore can remove the heat generated in the electrolytic reaction in the anode section 11 and the methanation reaction in the methanation section 13.

[0037] The heat removal means in the heat removal section 14 is not particularly limited, and for example, heat removal can be performed using a cooling solvent such as water. As a specific example, the heat removal section 14 of the methanation cell 1 of the first embodiment may be provided with two cooling water inlets 31 and 32, a cooling water outlet 33, and a partition plate 34, as shown in FIG. 2. When removing heat, the temperatures in the anode section 11 and the methanation section 13 are measured, and cooling water is supplied to the inlet closer to the one with the higher temperature. In other words, when it is desired to remove heat from the anode section 11, cooling water is supplied from the cooling water inlet 32, and when it is desired to remove heat from the methanation section 13, cooling water is supplied from the cooling water inlet 31, so that the desired one can be removed.

[0038] By providing such a heat removal section 14, it becomes relatively easy to control the temperature in the methanation cell 1, and the reaction efficiency of methanation (carbon dioxide reduction) can also be improved.

[0039] In the methanation cell 1 of the first embodiment, as shown in FIG. 1, a heat removal section 14 and a methanation section 13 are laminated on an anode section 11 and a cathode section 12. This configuration has the advantage that the thickness of the methanation cell 1 can be made thin. As described above, the heat removal section 14 can remove heat from both the anode section 11 and the methanation section 13, so it is considered that the amount of heat removal can be easily controlled. In the methanation cell 1 of the first embodiment, it is preferable in terms of configuration that the total thickness of the methanation section 13 and the heat removal section 14 is equal to the total thickness of the anode section 11 and the cathode section 12.

[0040] A dispersion plate 16 may be provided between the cathode section 12 and the methanation section 13. The use of the dispersion plate 16 can prevent a shortcut of hydrogen generated in the cathode section 12 and improve the mixed state with carbon dioxide, which is considered to improve the methanation reaction rate. In addition, the dispersion plate 16 can also suppress the catalyst from falling from the methanation section 13.

[0041] The dispersion plate 16 is not particularly limited as long as it can prevent hydrogen from being short-circuited, and for example, a perforated plate of a predetermined size, sintered metal, etc. can be used. The size of the holes in the perforated plate can be about several μm to several mm. Furthermore, the dispersion plate 16 preferably has a heat removal function in order to remove heat generated by the methanation reaction in the methanation section 13. The dispersion plate 16 having a heat removal function is not particularly limited, and for example, a perforated plate type heat exchanger or the like can be used.

[0042] Second Embodiment Next, a methanation cell of a second embodiment will be described. The methanation cell of the present disclosure is not limited to the first embodiment described above, and may be such that the heat removal section 14 is in contact with the anode section 11, and the cathode section 12 and the methanation section 13 are integrated, as in the methanation cell 1' shown in Fig. 3. This configuration has the advantage of increasing the heat transfer area with the heat removal section.

[0043] The anode part 11 in the methanation cell 1' of the second embodiment may have the same configuration as that of the first embodiment.

[0044] In the methanation cell 1' of the second embodiment, the cathode section 12 and the methanation section 13 are integrated. That is, the cathode section 12 also serves as the methanation section 13 described in the first embodiment. That is, in this embodiment, the methanation section is located within the cathode section, and more specifically, the cathode section includes a cathode frame, a cathode electrode, and a methanation catalyst. Thus, the cathode section 12 of the second embodiment includes a cathode that reduces hydrogen ions to produce hydrogen, a catalyst that reduces carbon dioxide to produce carbon compounds, and a second flow path that supplies carbon dioxide to the catalyst. The specific configuration of these components can be the same as that of the methanation cell 1 of the first embodiment.

[0045] The heat removal section 14 in the methanation cell 1' of the second embodiment is in contact with the anode section 11, and can remove heat generated by the electrolytic reaction in the anode section 11. The heat removal means of the heat removal section 14 can be the same as that of the first embodiment. That is, the heat removal section 14 in the second embodiment may also be provided with a cooling water inlet and a cooling water outlet. However, the positions of the inlet and outlet are not particularly limited,

[0046] In the second embodiment, the carbon compounds produced in the methanation unit 13 integrated with the cathode unit 12 are discharged through a flow path 17 for carbon compounds adjacent to the methanation unit 13. The flow path 17 includes a third flow path for discharging the carbon compounds.

[0047] A dispersion plate 16 may be provided on the side of the methanation unit 13 integrated with the cathode unit 12 from which the generated carbon compounds are discharged. That is, the dispersion plate 16 may be provided between the methanation unit 13 and the flow path 17. The dispersion plate 16 is provided to prevent the dispersion of the hydrogen generated in the cathode unit 12 while dispersing the carbon compounds generated in the methanation unit 13 to the flow path 17. By using such a dispersion plate 16, it is possible to prevent a shortcut of the hydrogen generated in the cathode unit 12 and improve the mixed state with carbon dioxide, which is thought to improve the methanation reaction rate.

[0048] The dispersion plate 16 is not particularly limited as long as it can prevent hydrogen from being short-circuited. For example, the same dispersion plate as described in the first embodiment can be used.

[0049] [Stacked methanation cell] The methanation cell of the present disclosure can also be used as a stacked methanation cell by stacking two or more of the methanation cells. In other words, the present disclosure also includes a stacked methanation cell including two or more of the above-mentioned integrated water electrolysis methanation cells.

[0050] For example, in the stacked methanation cell 20 shown in Figure 4, five methanation cells 1 of the first embodiment are stacked, but the number of methanation cells 1 constituting the stacked methanation cell 20 is not particularly limited as long as it is two or more, and can be appropriately determined depending on the desired amount of carbon compounds produced, the size of the equipment, etc.

[0051] It is believed that including two or more methanation cells 1 in this manner can further increase the efficiency of the methanation reaction in the stacked methanation cell 20. In addition, the heat removal section 14 in one methanation cell can remove heat not only from the anode section 11 and methanation section 13 of the methanation cell, but also from the methanation section 13 of another adjacent methanation cell, further improving the efficiency of heat removal.

[0052] For convenience, in Fig. 4, the cooling water inlet, outlet, and partition plate are shown for only one heat removal section 14, but it goes without saying that the heat removal sections 14 of all the methanation cells may be provided with a similar configuration. Also, a stacked methanation cell consisting of a stack of two or more methanation cells may be fixed with a pair of support plates (not shown) or may be covered with a case (not shown) or the like.

[0053] A bipolar plate 15 can also be used in the stacked methanation cell. The bipolar plate 15 is provided between the anode section 11 and the cathode section 12. The bipolar plate 15 plays a role in blocking air and the like between the anode section 11 and the cathode section 12. The bipolar plate 15 also has a flow path, and can send water (water vapor) and carbon dioxide to the anode section 11 and the cathode section 12.

[0054] Providing such bipolar plates 15 has the advantage that the size of the stacked methanation cell can be reduced in addition to the above-mentioned effects.

[0055] 5 shows an example of the bipolar plate 15. A bipolar plate used in technical fields such as fuel cells can be used as the bipolar plate 15. The material may be metal or carbon.

[0056] 5 shows flow path A on one side, but a similar flow path B is formed on the other side. Flow path A on the bipolar plate 15 can be used as the first flow path of the anode section 11 described above, and flow path B can be used as the second flow path of the cathode section 12.

[0057] In the case of a stacked methanation cell including a plurality of methanation cells 1 of the first embodiment, the bipolar plates 15 can be used as substitutes for the anode section 11 and the cathode section 12 of the methanation cell. For example, in the case of the stacked methanation cell shown in FIG. 4, all sections except the anode section 11 at the left end and the cathode section 12 at the right end may be bipolar plates 15. That is, in FIG. 4, four bipolar plates 15 are provided between the anode section 11 at the left end and the cathode section 12 at the right end. In this case, the flow path A of each bipolar plate 15 functions as the anode section, and the flow path B functions as the cathode section.

[0058] When the bipolar plate 15 is used as a substitute for the anode section 11 and the cathode section 12, the heat removal section 13 and the methanation section 14 are disposed on the bipolar plate 15. In this case, it is preferable that the thickness of one bipolar plate is equal to the total thickness of the anode section 11 and the cathode section 12.

[0059] 6 shows a stacked methanation cell 20' in which four methanation cells 1' of the second embodiment are stacked as another embodiment of the stacked methanation cell. In this stacked methanation cell 20', the heat removal section 14 in one methanation cell can remove heat not only from the anode section 11 of the methanation cell, but also from the cathode section 12 and the methanation section 13 via the flow passage 17 of another adjacent methanation cell, improving the efficiency of heat removal. In order to increase the heat removal efficiency, it is preferable to make the flow passage 17 as thin as possible.

[0060] In the case of a stacked methanation cell 20 or a stacked methanation cell 20', it is preferable that the first flow path for supplying water (steam) to each of the methanation cells 1 and 1' is not provided to each individual methanation cell, but is a flow path capable of supplying water to all of the methanation cells constituting the stacked methanation cell 20 or stacked methanation cell 20', as shown in Fig. 4 or 6. In this case, the outlet of the first flow path may also serve as an outlet for discharging unused excess water (steam) in the anode section 11 and oxygen generated together with hydrogen ions in the electrolysis reaction.

[0061] [Electrolytic methanation device] Next, an electrolytic methanation device including the above-mentioned water electrolysis integrated methanation cell or stacked methanation cell will be described.

[0062] The electrolytic methanation device of the present embodiment is an electrolytic methanation device including the above-mentioned water electrolysis integrated methanation cell or stacked methanation cell, and a power source that applies a current between the anode portion and the cathode portion.

[0063] Examples of power sources that can be used in the present embodiment include, but are not limited to, ordinary commercially available power sources, batteries, etc. In addition, a device that can supply renewable energy such as a solar cell as power can be used as the power source.

[0064] The electrolytic methanation device of this embodiment is not particularly limited in other configuration as long as it is an electrolytic device equipped with the above-mentioned water electrolysis integrated methanation cell or stacked methanation cell and a power source. A configuration of a known carbon dioxide electrolysis device or the like can be appropriately adopted as necessary. An insulating plate may be provided to prevent electricity from flowing to the outside.

[0065] The electrolytic methanation device of the present embodiment can produce carbon compounds from carbon dioxide, but as a specific example, the synthesis of methane will be described.

[0066] First, in a water electrolysis integrated methanation cell, when a current is supplied from a power source between the anode and cathode and water vapor (HO) is supplied from the first flow path, an oxidation reaction of HO occurs at the anode in contact with the HO. Specifically, HO is oxidized to oxygen (O2) and hydrogen ions (H + ) is produced. Hydrogen ions (H + The first flow channel is connected to the cathode of the cathode section, and the second flow channel is connected to the cathode of the cathode section. The second ...

[0067] Then, the carbon dioxide supplied from the second flow path is reduced by the catalyst in the cathode section with the electrons derived from the current supplied from the power source to the cathode and the hydrogen ions that have moved from the anode to the cathode. Through this reduction reaction, methane and water are synthesized from the carbon dioxide and hydrogen.

[0068] That is, in the case of methane synthesis, the following oxidation reaction and reduction reaction occur in the electrolytic methanation device of this embodiment. Anode section: H2O→2H + +1 / 2O2+2e- Cathode: CO2+4H2→CH4+2H2O 2H + +2e - →H2

[0069] In the electrolytic methanation device of this embodiment, the water electrolysis reaction and the methanation reaction can be carried out in one device. In other words, the gases that need to be supplied are carbon dioxide and water (water vapor), so there is an advantage that hydrogen gas does not leave the device, making handling easier. Furthermore, because the methanation cell is equipped with a heat removal section, heat generation (temperature rise) due to the electrolytic reaction and / or the methanation reaction can be controlled, making it easier to manage the temperature of the device.

[0070] As described above, this specification discloses various aspects of the technology, the main technologies of which are summarized below.

[0071] The integrated water electrolysis methanation cell in a first aspect comprises an anode unit that electrolyzes water or water vapor to produce oxygen and hydrogen ions, a cathode unit that reduces the hydrogen ions to produce hydrogen, a methanation unit that reduces carbon dioxide to produce a carbon compound, and a heat removal unit that is in contact with at least one of the anode unit and the methanation unit and removes heat.

[0072] With such a configuration, it is possible to provide a water electrolysis integrated methanation cell which is capable of performing water electrolysis and methanation and in which temperature control is relatively easy.

[0073] The integrated water electrolysis methanation cell in the second aspect is characterized in that, in the methanation cell in the first aspect, the heat removal part is in contact with the anode part and the methanation part. With this configuration, heat can be removed from both the anode part and the methanation part, which is thought to facilitate control of the amount of heat removal.

[0074] The integrated water electrolysis methanation cell in the third aspect is the methanation cell in the first aspect, further comprising a dispersion plate between the cathode section and the methanation section. This configuration is believed to prevent a shortcut of hydrogen generated in the cathode section, improve the mixed state with carbon dioxide, and increase the methanation reaction rate.

[0075] The integrated water electrolysis methanation cell in a fourth aspect is the methanation cell in the first aspect, characterized in that the heat removal part is in contact with the anode part, and the cathode part and the methanation part are integrated together. This configuration has the advantage of increasing the heat transfer area with the heat removal part.

[0076] In addition, the integrated water electrolysis methanation cell in a fifth aspect is the methanation cell in the fourth aspect, characterized in that a dispersion plate is provided on the side of the methanation unit integrated with the cathode unit from which the generated carbon compounds are discharged. It is believed that such a configuration can prevent a shortcut of hydrogen generated in the cathode unit, improve the mixed state with carbon dioxide, and increase the methanation reaction rate.

[0077] The integrated water electrolysis methanation cell in a sixth aspect is characterized in that, in the methanation cell in the third or fifth aspect, the dispersion plate has a heat removal effect. This makes it possible to remove heat generated by the methanation reaction in not only the anode section but also the methanation section in the methanation cell in the third or fifth aspect.

[0078] The stacked methanation cell in the seventh aspect includes two or more of the integrated water electrolysis methanation cells in the first to sixth aspects. Since the integrated water electrolysis methanation cells have a heat removal section, by using two or more of them to form a stacked methanation cell, further improvement in heat removal efficiency can be expected.

[0079] The integrated water electrolysis methanation cell in an eighth aspect is characterized in that, in the stacked methanation cell in the seventh aspect, a bipolar plate having flow paths on both sides is provided between the anode part and the cathode part. This configuration has the advantage that the size of the stacked methanation cell can be made relatively small.

[0080] The electrolytic methanation device in a ninth aspect includes the integrated water electrolysis methanation cell in any one of the first to sixth aspects, and a power source that applies a current between the anode portion and the cathode portion.

[0081] The electrolytic methanation device in a tenth aspect comprises the stacked methanation cell of the seventh or eighth aspect, and a power source that applies a current between the anode portion and the cathode portion. [Explanation of symbols]

[0082] 1.1' Integrated water electrolysis methanation cell 11 Anode part 12 Cathode section 13 Methanation Department 14 Heat removal section 15 Bipolar Plate 16 Dispersion plate 17 Carbon Compounds Flow Path 20, 20' stacked methanation cells 31, 32 Cooling water inlet 33 Cooling water outlet 34 Partition

Claims

1. an anode portion that electrolyzes water or water vapor to generate oxygen and hydrogen ions; a cathode portion that reduces hydrogen ions to generate hydrogen; a methanation unit that reduces carbon dioxide to produce carbon compounds; a heat removal section that is in contact with at least one of the anode section and the methanation section and removes heat.

2. The integrated water electrolysis methanation cell according to claim 1 , wherein the heat removal section is in contact with the anode section and the methanation section.

3. 2. The integrated water electrolysis methanation cell according to claim 1, further comprising a dispersion plate provided between the cathode section and the methanation section.

4. the heat removal portion is in contact with the anode portion, The integrated water electrolysis methanation cell according to claim 1 , wherein the cathode section and the methanation section are integrated together.

5. 5. The integrated water electrolysis methanation cell according to claim 4, wherein a dispersion plate is provided on a side of the methanation unit integrated with the cathode unit from which the produced carbon compounds are discharged.

6. The integrated water electrolysis methanation cell according to claim 3 or 5, wherein the dispersion plate has a heat removal function.

7. A stacked methanation cell comprising two or more water electrolysis integrated methanation cells according to any one of claims 1 to 6.

8. 8. The stacked methanation cell according to claim 7, wherein a bipolar plate having flow channels on both sides is provided between the anode section and the cathode section.

9. An electrolytic methanation device comprising the water electrolysis integrated methanation cell according to any one of claims 1 to 6, and a power source that passes an electric current between the anode part and the cathode part.

10. An electrolytic methanation device comprising the stacked methanation cell according to claim 7 and a power source that applies a current between the anode portion and the cathode portion.

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