CO2 electrolysis device

Abstract

The invention provides a CO2 electrolysis device capable of improving the recovery efficiency of CO2. A CO2 electrolysis device is provided with: a CO2 electrolysis laminate including a plurality of CO2 electrolysis cells stacked on each other; end plates provided at both ends of the CO2 electrolysis laminate in the lamination direction; and collars provided at both ends of the CO2 electrolysis laminate in a first direction perpendicular to the lamination direction, the collars being sandwiched by the end plates, the collars being longer in the lamination direction than the CO2 electrolysis laminate, and the collars being provided at both ends of the CO2 electrolysis laminate in the first direction perpendicular to the lamination direction. The end plate has a shape that is bent inward in the lamination direction at a central portion of the CO2 electrolysis laminate in the first direction.

Description

[0001] Cross-references between related applications

[0002] This application claims priority based on Japanese Patent Application No. 2024-046463 filed on March 22, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to an invention related to a CO2 electrolysis device. Background Art

[0004] Efforts to mitigate or reduce the impact of climate change have been ongoing, and research and development related to reducing CO2 emissions is being carried out towards achieving this goal.

[0005] The technology of recovering CO2 from waste gas and the atmosphere and reducing it to valuable products through electrochemical reduction is a promising technology for achieving carbon neutrality, but economic efficiency is the biggest challenge. To improve economic efficiency, it is important to improve energy efficiency and minimize CO2 losses in CO2 recovery and reduction.

[0006] As a technology for recovering CO2, for example, Japanese Patent Publication No. 2022-151886 discloses that by making the pH of the cathode-side electrolyte used in the electrochemical reaction device higher than the pH of the anode-side electrolyte, the generation of hydrogen at the cathode is suppressed, so that CO2 is adsorbed on the adsorbent. Compared with the case where CO2 is desorbed and reduced under the action of heating, the energy required for desorption of CO2 is reduced, the energy efficiency can be improved, and the loss of CO2 can also be reduced. Summary of the Invention

[0007] In addition, in order to further improve the CO 2 recovery efficiency while reducing the amount of CO 2 emitted, the further enlargement of the CO 2 recovery device is a problem.

[0008] like Figure 3A 、 Figure 3B As shown, the electrochemical reaction device (CO2 electrolysis stack 11) described in Japanese Patent Application Laid-Open No. 2022-151886 comprises end plates 20 disposed at both ends in the stacking direction, bolts 3 inserted through a plurality of bolt holes 20a, and nuts 4, forming a CO2 electrolysis device 100. The bolts 3 and nuts 4 are tightened together, bringing the end plates 20 into contact with the CO2 electrolysis stack 11, applying pressure to the CO2 electrolysis stack 11.

[0009] When pressure is applied to the CO2 electrolysis stack 11, current flows in the CO2 electrolysis cells 1, which can promote chemical reactions. However, when the CO2 electrolysis device 100 is enlarged, only the ends of the end plates 20 are fastened by the bolts 3 and nuts 4. Figure 3BAs emphasized by the two-dot chain line in the figure, the central portion of the end plate 20 may bend outward in the stacking direction, and insufficient pressure may not be applied to the CO2 electrolysis stack 11. When there is a portion where insufficient pressure is applied to the CO2 electrolysis stack 11, insufficient current does not flow in that portion, and the reaction efficiency in the CO2 electrolysis cell 1 decreases.

[0010] One method for solving this problem is to use thicker end plates 20 to increase rigidity and suppress deflection in the center. However, this raises the issue of increased cost due to the increased amount of end plate 20 and increased weight of the CO2 electrolysis device 100, including the CO2 electrolysis stack 11.

[0011] The present invention provides a CO2 electrolysis device that improves CO2 recovery efficiency. The present invention contributes to mitigating climate change or alleviating its impact.

[0012] The gist of the present invention is as follows.

[0013] [1] A CO2 electrolysis device, characterized in that:

[0014] The CO2 electrolysis device comprises:

[0015] A CO2 electrolysis stack comprising a plurality of stacked CO2 electrolysis cells;

[0016] end plates, which are provided at both ends of the CO2 electrolysis stack in the stacking direction; and

[0017] Axle rings are provided at both ends of the CO2 electrolysis stack in a first direction perpendicular to the stacking direction and are sandwiched by the end plates.

[0018] The collar is longer in the stacking direction than the CO2 electrolysis stack.

[0019] The end plate has a shape bent inward in the stacking direction at the center portion of the CO 2 electrolysis stack in the first direction.

[0020] [2] The CO2 electrolysis device according to [1], characterized in that:

[0021] The end plate has a plurality of bolt holes,

[0022] The end plates are fastened together by bolts inserted through the bolt holes and nuts, so that the end plates have a shape that is bent inward in the stacking direction.

[0023] [3] The CO2 electrolysis device according to [1] or [2], characterized in that:

[0024] The electrolyte inlet of the CO 2 electrolysis stack is arranged at a position closer to the center of the second direction perpendicular to the stacking direction and the first direction than the electrolyte outlet.

[0025] According to the above-mentioned aspects of the present invention, a CO 2 electrolysis device that improves the CO 2 recovery efficiency can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A This is a schematic diagram showing an example of a CO2 electrolysis device according to the present invention.

[0027] Figure 1B This is a schematic diagram showing an example of a CO2 electrolysis device according to the present invention.

[0028] Figure 2 This is a schematic diagram showing another example of the CO2 electrolysis device of the present invention.

[0029] Figure 3A This is a schematic diagram showing an example of a CO2 electrolysis device according to the conventional technology.

[0030] Figure 3B This is a schematic diagram showing an example of a conventional CO2 electrolysis device. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the dimensions and the like in the drawings shown in the following description are merely examples, and the present invention is not necessarily limited thereto and can be implemented with appropriate modifications without departing from the spirit of the present invention.

[0032] like Figure 1A 、 Figure 1B As shown, the CO2 electrolysis device 10 of this embodiment includes: a CO2 electrolysis stack 11, which includes a plurality of stacked CO2 electrolysis cells 1; end plates 2, which are arranged at both ends of the stacking direction of the CO2 electrolysis stack 11; and an axial ring 5, which is arranged at both ends of the CO2 electrolysis stack 11 in a first direction perpendicular to the stacking direction and is clamped by the end plates 2.

[0033] Here, in this embodiment, the stacking direction is Figure 1A as well as Figure 2 The direction is perpendicular to the paper surface. Figure 1B In the vertical direction, the first direction is parallel to the paper surface. Figure 1A as well as Figure 2 The middle is the left-right direction parallel to the paper surface. Figure 1A to Figure 2 In the example shown, the first direction coincides with the longitudinal direction of the CO 2 electrolysis stack 11 .

[0034] The collar 5 is longer in the stacking direction than the CO2 electrolysis stack 11. Figure 1A When the bolts 3 and nuts 4 are fastened together in the order shown, the end plate 2 is Figure 1B As emphasized by the double-dashed line, the CO2 electrolysis stack 11 is bent inward in the stacking direction at the center portion in the first direction. This allows a stronger pressure to be applied to the CO2 electrolysis stack 11 than at the two end portions in the first direction. In this case, it is preferable to use an end plate 2 with relatively low rigidity so that the CO2 electrolysis stack 11 can be bent inward in the stacking direction at the center portion in the first direction.

[0035] With the structure described above, in the CO2 electrolysis device 10 of this embodiment, even when the device is larger, it is possible to prevent the central portion of the end plate 2 from deflecting outward in the stacking direction and to apply sufficient pressure to the CO2 electrolysis stack 11. Therefore, a decrease in the reaction efficiency in the CO2 electrolysis cells 1 can be prevented.

[0036] Furthermore, since it is not necessary to use thicker end plates 2 to improve rigidity, it is possible to prevent an increase in the amount of straight material in the end plates 2. Furthermore, when using end plates 2 with lower rigidity, the amount of straight material and the weight of the end plates 2 can be reduced.

[0037] It should be noted that the collar 5 is preferably several μm longer than the CO2 electrolysis stack 11 so that sufficient pressure can be applied to both ends of the CO2 electrolysis stack 11 in the first direction. By making the collar 5 not excessively longer but several μm longer, it is possible to prevent pressure from being applied to the CO2 electrolysis stack 11 at both ends in the first direction.

[0038] The CO2 electrolysis device 10 may be as follows Figure 1A 、 Figure 1B The rectangular parallelepiped having a long side as shown may also be a cube. When the CO2 electrolysis device 10 is a rectangular parallelepiped, for example, the size may be about 300 mm in the long side direction and about 100 mm in the short side direction.

[0039] In the CO2 electrolysis device 10 of this embodiment, it is also possible to Figure 1A 、 Figure 1B As shown, the end plate 2 includes a plurality of bolt holes 2 a , and is fastened together by bolts 3 inserted through the bolt holes 2 a and nuts 4 , so that the end plate 2 has a shape that is bent inward in the stacking direction.

[0040] As mentioned above, by connecting the bolt 3 and the nut 4 Figure 1A By fastening and fastening in the order shown, the end plate 2 can be bent well inward in the stacking direction.

[0041] It should be noted that in Figure 1A In FIG, the bolt hole 2b without the collar 5 is distinguished from the bolt hole 2a with the collar 5. Figure 1B Only a portion of the bolts 3 and nuts 4 are shown in the figure.

[0042] In addition, in the CO2 electrolysis device 10 of this embodiment, it is preferable that Figure 2 As shown, the electrolyte inlet 6 of the CO 2 electrolysis stack 11 is arranged closer to the center of the electrolyte outlet 7 in the second direction perpendicular to the stacking direction and the first direction.

[0043] It should be noted that in this embodiment, the second direction perpendicular to the stacking direction and the first direction is Figure 2 The vertical direction is parallel to the paper surface. Figure 2 In the embodiment, the second direction coincides with the short side direction of the CO 2 electrolysis stack 11 .

[0044] In the CO2 electrolysis stack 11, the raw material for at least one of the cathode and anode is typically a solution, and the product is a gas. Therefore, in order to discharge the product and utilize the buoyancy of the gas, the CO2 electrolysis stack 11 has a structure where the raw material inlet is located at the bottom of the stack and the outlet is located at the top. Furthermore, in the CO2 electrolysis stack 11, chemical reactions are more likely to occur near the electrolyte inlet 6 (cathode inlet 6a, anode inlet 6b), where the raw material concentration is higher, while hydrogen is more likely to be produced as a byproduct near the electrolyte outlet 7 (cathode outlet 7a, anode outlet 7b), where the raw material concentration is lower.

[0045] In the CO2 electrolysis device 10 of this embodiment, Figure 2 The area indicated by the double-dashed line in FIG. 3 gives the highest pressure. Figure 2 By positioning the electrolyte inlet 6 of the CO2 electrolysis stack 11 near the center in the second direction (the short side direction), as shown, a higher pressure can be applied near the electrolyte inlet 6. This allows for better current flow near the electrolyte inlet 6, further promoting the chemical reaction. Furthermore, since the pressure near the electrolyte outlet 7 is lower than near the electrolyte inlet 6, current flow is less likely to occur, suppressing the generation of hydrogen as a byproduct. These effects further improve the CO2 recovery efficiency of the CO2 electrolysis device 10.

[0046] In addition, the CO2 electrolytic stack 11 is preferably as follows Figure 2 As shown in FIG, the distance between the flow path 8 (cathode flow path 8a, anode flow path 8b) is shortened. Figure 2Compared with the case where the CO2 electrolysis stack 11 is arranged in the left-right direction (longitudinal direction of the CO2 electrolysis stack 11) parallel to the paper surface, the pressure loss at the longitudinal end can be suppressed, and the CO2 recovery efficiency can be further improved.

Claims

1. A CO2 electrolysis device, characterized in that: The CO2 electrolysis device comprises: A CO2 electrolysis stack comprising a plurality of stacked CO2 electrolysis cells; End plates, which are arranged at both ends of the CO2 electrolysis stack in the stacking direction; as well as Axle rings are provided at both ends of the CO2 electrolysis stack in a first direction perpendicular to the stacking direction and are sandwiched by the end plates. The collar is longer in the stacking direction than the CO2 electrolysis stack. The end plate has a shape bent inward in the stacking direction at the center portion of the CO 2 electrolysis stack in the first direction.

2. The CO2 electrolysis device according to claim 1, characterized in that The end plate has a plurality of bolt holes, The end plates are fastened together by bolts inserted through the bolt holes and nuts, so that the end plates have a shape that is bent inward in the stacking direction.

3. The CO2 electrolysis device according to claim 1 or 2, characterized in that: The electrolyte inlet of the CO 2 electrolysis stack is arranged at a position closer to the center of the second direction perpendicular to the stacking direction and the first direction than the electrolyte outlet.

Images