Co2 electrolytic apparatus

Abstract

To provide a CO2 electrolytic apparatus with enhanced CO2 recovery efficiency.SOLUTION: A CO2 electrolytic apparatus has a CO2 electrolytic laminate comprising multiple CO2 electrolytic cells stacked together, end plates provided at both ends of the CO2 electrolytic laminate in the stacking direction, and collars provided at both ends of the CO2 electrolytic laminate in a first direction perpendicular to the stacking direction and sandwiched between the end plates, where the collars extend longer in the stacking direction than the CO2 electrolytic stack, and the end plates have a shape that bends inward in the stacking direction at the central portion of the CO2 electrolytic stack in the first direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a CO2 electrolysis device. [Background technology]

[0002] Efforts aimed at mitigating or reducing the impact of climate change have been ongoing for some time, and research and development into reducing CO2 emissions is being carried out to achieve this.

[0003] The technology of capturing CO2 from exhaust gases and the atmosphere and electrochemically reducing it to obtain valuable materials is a promising technology with the potential to achieve carbon neutrality, but economic viability is the biggest challenge. To improve economic viability, it is important to increase energy efficiency and minimize CO2 loss in the CO2 capture and reduction processes.

[0004] As a technology for recovering CO2, for example, Patent Document 1 discloses that by making the pH of the cathode-side electrolyte used in an electrochemical reaction device higher than the pH of the anode-side electrolyte and suppressing hydrogen generation at the cathode, the energy required to desorb CO2 can be reduced compared to when CO2 is adsorbed onto an adsorbent and then desorbed and reduced by heating, thereby improving energy efficiency and reducing CO2 loss. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-1518866 Summary of the Invention [Problem to be solved by the invention]

[0006] Meanwhile, in reducing CO2 emissions, a challenge is to further increase the size of CO2 capture equipment in order to further increase the efficiency of CO2 capture.

[0007] 3, the electrochemical reaction device (CO electrolysis stack 11) described in Patent Document 1 comprises end plates 20 provided at both ends in the stacking direction, bolts 3 inserted into multiple bolt holes 20a, and nuts 4, constituting a CO electrolysis device 100. Tightening the bolts 3 and nuts 4 brings the end plates 20 into contact with the CO electrolysis stack 11, applying pressure to the CO electrolysis stack 11.

[0008] When pressure is applied to the CO2 electrolysis stack 11, a current flows in the CO2 electrolysis cell 1, accelerating the chemical reaction. 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. This can cause the central portions of the end plates 20 to bend outward in the stacking direction, as highlighted by the two-dot chain line in Figure 3(b), making it difficult to apply sufficient pressure to the CO2 electrolysis stack 11. If there are portions of the CO2 electrolysis stack 11 to which insufficient pressure is applied, an insufficient current will flow in those portions, resulting in a decrease in the reaction efficiency in the CO2 electrolysis cell 1.

[0009] One way to solve this problem is to use thicker end plates 20 to increase rigidity and thereby suppress deflection in the central portion. However, this method results in problems such as increased costs due to the increased amount of direct material used for the end plates 20 and an increase in the weight of the CO electrolysis device 100 including the CO electrolysis stack 11.

[0010] The present invention has been made in view of the above-mentioned problems, and aims to provide a CO2 electrolysis device with improved CO2 recovery efficiency, which will ultimately contribute to mitigating or reducing the impact of climate change. [Means for solving the problem]

[0011] The gist of the present invention is as follows. [1] A CO2 electrolysis stack comprising a plurality of stacked CO2 electrolysis cells; end plates provided at both ends of the CO electrolysis stack in the stacking direction; a collar provided at each end of the CO electrolysis stack in a first direction perpendicular to the stacking direction and sandwiched between the end plates; The collar is longer in the stacking direction than the CO electrolysis stack, a CO2 electrolysis device, wherein the end plate has a shape that is bent inward in the stacking direction at a central portion in the first direction of the CO2 electrolysis stack. [2] The end plate has a plurality of bolt holes; The CO electrolysis device according to [1], characterized in that the end plates have a shape that is bent inward in the stacking direction by fastening bolts inserted into the bolt holes and nuts. [3] The CO electrolysis device according to [1] or [2], wherein the electrolyte inlet of the CO electrolysis stack is positioned closer to the center in a second direction perpendicular to the stacking direction and the first direction than the electrolyte outlet of the CO electrolysis stack. [Effects of the Invention]

[0012] According to the above aspect of the present invention, it is possible to provide a CO2 electrolysis device with improved CO2 recovery efficiency. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing an example of a CO2 electrolysis device according to the present invention. [Figure 2] FIG. 2 is a schematic diagram showing another example of a CO2 electrolysis device according to the present invention. [Figure 3] FIG. 1 is a schematic diagram showing an example of a CO2 electrolysis device according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensions of the drawings shown in the following description are merely examples, and the present invention is not necessarily limited thereto. Appropriate changes can be made within the scope of the present invention.

[0015] As shown in FIG. 1, a CO electrolysis device 10 according to this embodiment includes a CO electrolysis stack 11 consisting of a plurality of stacked CO electrolysis cells 1, end plates 2 provided at both ends of the CO electrolysis stack 11 in the stacking direction, and collars 5 provided at both ends of the CO electrolysis stack 11 in a first direction perpendicular to the stacking direction and sandwiched between the end plates 2.

[0016] In this embodiment, the stacking direction is the direction perpendicular to the paper surface in Fig. 1(a) and Fig. 2, and is the up-down direction parallel to the paper surface in Fig. 1(b). Furthermore, the first direction perpendicular to the stacking direction is the left-right direction parallel to the paper surface in Fig. 1(a) and Fig. 2. In the example shown in Fig. 1(a) to Fig. 2, the first direction coincides with the longitudinal direction of the CO electrolytic laminate 11.

[0017] The collar 5 is longer in the stacking direction than the CO2 electrolytic laminate 11. Therefore, when the bolts 3 and nuts 4 are fastened in the order shown in FIG. 1(a), for example, the end plate 2 bends inward in the stacking direction at the center of the CO2 electrolytic laminate 11 in the first direction, as highlighted by the two-dot chain line in FIG. 1(b). This allows a stronger pressure to be applied to the CO2 electrolytic laminate 11 than at both ends in the first direction. In this case, it is preferable to use an end plate 2 with low rigidity so that the center of the CO2 electrolytic laminate 11 in the first direction bends inward in the stacking direction.

[0018] With the above-described configuration, even when the CO electrolysis device 10 according to this embodiment is enlarged, the central portions of the end plates 2 are prevented from bending outward in the stacking direction, and sufficient pressure can be applied to the CO electrolysis stack 11. This prevents a decrease in the reaction efficiency of the CO electrolysis cell 1.

[0019] In addition, since there is no need to use thick end plates 2 to increase rigidity, it is possible to prevent an increase in the amount of direct material for the end plates 2. Furthermore, when end plates 2 with low rigidity are used, the amount of direct material and weight of the end plates 2 can be reduced.

[0020] The collar 5 is preferably several micrometers longer than the CO2 electrolytic laminate 11 so that sufficient pressure is applied to both ends of the CO2 electrolytic laminate 11 in the first direction. By making the length of the collar 5 not too long but several micrometers longer, it is possible to prevent pressure from being insufficiently applied to the CO2 electrolytic laminate 11 at both ends in the first direction.

[0021] The CO2 electrolysis device 10 may be a rectangular parallelepiped having a longitudinal direction as shown in Figure 1, or may be a cube. When the CO2 electrolysis device 10 is a rectangular parallelepiped, it may have dimensions of, for example, approximately 300 mm in the longitudinal direction and approximately 100 mm in the lateral direction.

[0022] In the CO electrolysis device 10 according to this embodiment, as shown in FIGS. 1(a) and 1(b), the end plate 2 may have a plurality of bolt holes 2a, and bolts 3 inserted into the bolt holes 2a may be fastened to nuts 4, so that the end plate 2 is bent inward in the stacking direction. As described above, by fastening the bolts 3 and nuts 4 in the order shown in FIG. 1(a), the end plates 2 can be desirably deflected inward in the stacking direction. In Fig. 1(a), bolt holes 2b without collars 5 are shown to be distinct from bolt holes 2a with collars 5. In Fig. 1(b), only some of the bolts 3 and nuts 4 are shown.

[0023] In the CO electrolysis device 10 according to this embodiment, as shown in FIG. 2, the electrolyte inlet 6 of the CO electrolysis stack 11 is preferably positioned closer to the center in the stacking direction and in a second direction perpendicular to the first direction than the electrolyte outlet 7. In this embodiment, the second direction perpendicular to the stacking direction and the first direction is the up-down direction parallel to the paper surface in Fig. 2. In Fig. 2, the second direction coincides with the short-side direction of the CO electrolysis stack 11.

[0024] 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, the CO2 electrolysis stack 11 is configured with the raw material inlet on the lower side of the stacking direction and the outlet on the upper side of the stacking direction, with the aim of utilizing the buoyancy of the gas to expel the product. Furthermore, in the CO2 electrolysis stack 11, chemical reactions are likely to occur near the electrolyte inlets 6 (cathode inlet 6a, anode inlet 6b) where the raw material concentration is high, while hydrogen, a by-product, is likely to be generated near the electrolyte outlets 7 (cathode outlet 7a, anode outlet 7b) where the raw material concentration is low.

[0025] In the CO2 electrolysis device 10 according to this embodiment, the highest pressure is applied to the region indicated by the two-dot chain line in FIG. 2. Therefore, by positioning the electrolyte inlet 6 of the CO2 electrolysis stack 11 closer to the center in the second direction (the transverse direction) as shown in FIG. 2, a higher pressure can be applied near the electrolyte inlet 6. This allows a current to flow favorably 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 does not flow easily, suppressing the generation of hydrogen as a by-product. These effects further improve the CO2 capture efficiency of the CO2 electrolysis device 10.

[0026] Furthermore, the CO2 electrolysis stack 11 is preferably arranged so that the distance between the flow paths 8 (cathode flow path 8a and anode flow path 8b) is short, as shown in Fig. 2. This arrangement can reduce pressure loss at the longitudinal ends and further improve CO2 capture efficiency, compared to when the CO2 electrolysis stack 11 is arranged so that the flow paths 8 are aligned in the left-right direction (the longitudinal direction of the CO2 electrolysis stack 11) parallel to the paper surface of Fig. 2. [Explanation of symbols]

[0027] 1...CO2 electrolysis cell 2, 20...End plate 2a, 20a...Bolt holes 3...Bolt 4...Nut 5...Color 6...Electrolyte inlet 7…Electrolyte outlet 8...Flow path 10…CO2 electrolyzer 11...CO2 electrolytic laminate

Claims

1. Stacked multiple CO ２ CO electrolysis cell ２ an electrolytic laminate; The CO ２ end plates provided at both ends of the electrolytic laminate in the lamination direction; The CO ２ a collar provided at each end of the electrolytic laminate in a first direction perpendicular to the lamination direction and sandwiched between the end plates; The color is ２ It is longer in the stacking direction than the electrolytic laminate, The end plate is ２ a CO 3000 having a shape that is bent inward in the stacking direction at a central portion of the electrolytic laminate in the first direction; ２ Electrolyzer.

2. the end plate includes a plurality of bolt holes; 2. The CO assembly according to claim 1, wherein the end plates are bent inward in the stacking direction by fastening bolts inserted through the bolt holes and nuts. ２ Electrolyzer.

3. The CO ２ 3. The CO evaporator according to claim 1, wherein the electrolytic solution inlet of the electrolytic laminate is disposed closer to the center in the stacking direction and a second direction perpendicular to the first direction than the electrolytic solution outlet. ２ Electrolyzer.

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