JP-2026074591-A - Electrodialysis machine

Abstract

[Problem] To provide an electrodialysis apparatus capable of suppressing the increase in applied voltage that occurs as the electrodialysis reaction progresses. [Solution] The electrodialysis apparatus 10 comprises a first cation exchange membrane 32, a second cation exchange membrane 34, a second chamber 26 which is an acidification chamber defined by the first cation exchange membrane 32 and the second cation exchange membrane 34, and an electrolyte supplied to the second chamber 26. The electrolyte contains an alkali metal salt and a carbonate ion species, and the alkali metal salt contains at least one of a salt of a strong acid and a strong base containing an alkali metal ion, and a salt of a weak acid other than carbonic acid and a strong base containing an alkali metal ion. The second chamber 26 is characterized in that, by electrodialysis, protons that have moved from the first cation exchange membrane 32 react with the carbonate ion species to produce carbon dioxide (gas). [Selection Diagram] Figure 1

Inventors

• 西村 友作
• 猪飼 正道
• 加藤 千和
• 岡村 和政

Assignees

• 株式会社豊田中央研究所
• トヨタ自動車株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (4)

1. An electrodialysis apparatus comprising a first cation exchange membrane, a second cation exchange membrane, an acidification chamber defined by the first cation exchange membrane and the second cation exchange membrane, and an electrolyte supplied to the acidification chamber, The electrolyte comprises an alkali metal salt and a carbonate ion species, wherein the alkali metal salt comprises at least one of the following: a salt of a strong acid and a strong base containing an alkali metal ion, and a salt of a weak acid other than carbonate and a strong base containing an alkali metal ion. The acidification chamber is characterized in that, by electrodialysis, protons that have moved from the first cation exchange membrane react with the carbonate ion species to produce carbon dioxide (gas).
2. The electrodialysis apparatus according to claim 1, characterized in that the sum of the products of the limiting molar ionic conductivity and concentration of the alkali metal salt, for both the cation and anion, is 0.01 S/cm or greater.
3. The electrodialysis apparatus according to claim 1 or 2, characterized in that the concentration of the alkali metal salt in the electrolyte is less than or equal to the saturation concentration at the operating temperature.
4. The electrodialysis apparatus according to claim 1 or 2, characterized in that the electrolyte contains a salt of the carbonate ion species and alkali metal ions.

Description

This invention relates to the technology of an electrodialysis apparatus. As technologies that can contribute to carbon neutralization, there is interest in electrolytic devices that utilize electrolysis technology to obtain CO2 reduction valuable products from carbonate ion species or carbon dioxide, and electrodialysis technology that recovers carbon dioxide using an alkaline aqueous solution containing carbonate ion species ( at least one of carbonate ions ( CO3 2- ) and bicarbonate ions ( HCO3- )), and separates and concentrates carbon dioxide from the recovered solution containing carbon dioxide. For example, Patent Documents 1-6 and Non-Patent Document 1 disclose an electrodialysis apparatus that separates and concentrates carbon dioxide by applying voltage to an anode electrode and a cathode electrode. Patent Publication No. 5848964Japanese Patent Publication No. 2012-096975Patent Publication No. 5750220Japanese Patent Publication No. 2008-100211International Publication No. 2022/235708Patent Publication No. 5952104 A. Iizuka et al., “Carbon dioxide recovery from carbonate solutions using bipolar membrane electrodialysis”, Separation and Purification Technology, 101, 49(2012) This is a schematic diagram showing an example of an electrolytic system according to this embodiment.This is a schematic diagram showing another example of the electrodialysis apparatus of this embodiment.This figure shows the change in applied voltage relative to the dialysis progress index in Comparative Examples 1 and 2.This figure shows the changes in applied voltage relative to the dialysis progress index in Examples 1-1 to 1-3 and Comparative Example 1.This figure shows the changes in current efficiency with respect to the dialysis progress index in Examples 1-1 to 1-3 and Comparative Example 1.This figure shows the changes in the applied voltage relative to the dialysis progress index in Example 2 and Comparative Example 3.This figure shows the changes in current efficiency against the dialysis progress index in Example 2 and Comparative Example 3. Embodiments of the present invention will be described below. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment. Figure 1 is a schematic diagram showing an example of an electrolytic system according to this embodiment. The electrolytic system 1 shown in Figure 1 comprises an electrodialysis machine 10, a gas-liquid separation device 12, an H2 supply mechanism 14, an aqueous medium supply device 15, and an electrolyte supply device 17. The electrodialysis apparatus 10 shown in Figure 1 includes an anode electrode 22, a first chamber 24, a second chamber 26 which is an acidification chamber, a cathode electrode 28, a third chamber 30, a first cation exchange membrane 32, a second cation exchange membrane 34, and frame members 36a and 36b. The first chamber 24 is provided between the frame member 36a and the first cation exchange membrane 32, and the anode electrode 22 is positioned there. The anode electrode 22 is adjacent to the first cation exchange membrane 32. In the first chamber 24, the space between the anode electrode 22 and the frame member 36a is a flow path 23 through which a gas containing H2 flows. The third chamber 30 is provided between the frame member 36b and the second cation exchange membrane 34, and the cathode electrode 28 is positioned there. The cathode electrode 28 is adjacent to the second cation exchange membrane 34. In the third chamber 30, the space between the cathode electrode 28 and the frame member 36b is a flow path 29 through which an aqueous medium flows. The second chamber 26 is located between the first cation exchange membrane 32 and the second cation exchange membrane 34. That is, the second chamber 26 is defined by these membranes. The first cation exchange membrane 32 is positioned between the first chamber 24 and the second chamber 26, and the second cation exchange membrane 34 is positioned between the second chamber 26 and the third chamber 30. The second chamber 26 serves as a flow path for the electrolyte solution, which will be described later. In the electrodialysis apparatus 10 shown in Figure 1, the anode electrode 22, cathode electrode 28, cation exchange membrane, etc., are structurally supported by frame materials 36a and 36b. The frame materials 36a and 36b can be made of metal, plastic, glass, etc. The anode electrode 22 includes an anode catalyst and is an electrode that generates protons, for example, by applying a voltage. The cathode electrode 28 includes a cathode catalyst and is an electrode that generates H₂ and hydroxide ions ( OH⁻ ) by the reductive electrolysis of H₂O , for example. The gas-liquid separation device 12 comprises, for example, a gas-liquid separator 16 and discharge lines 18a and 18b. One end of discharge line 18a is connected to the flow path 29 of the third chamber 30, and the other end is connected to the gas-liquid se