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DE-102025127935-A1 - CARBON DIOXIDE SEPARATION SYSTEM WITH pH CONTROL FUNCTION

DE102025127935A1DE 102025127935 A1DE102025127935 A1DE 102025127935A1DE-102025127935-A1

Abstract

The disclosure relates to a carbon dioxide separation system with a pH control function that enables the recycling of an electrolyte solution.

Inventors

  • Se Won Pyo
  • Ji Hoon Jang
  • Yun Su Lee

Assignees

  • HYUNDAI MOTOR COMPANY
  • KIA MOTORS CORPORATION

Dates

Publication Date
20260513
Application Date
20250716
Priority Date
20241111

Claims (20)

  1. Carbon dioxide capture system comprising: an electrolyte storage unit configured to store, retain, or contain a first electrolyte solution containing an aqueous alkaline carbonate solution; an inlet unit in liquid connection with the electrolyte storage unit and a gas supply, the inlet unit being configured to (i) receive the first electrolyte solution from the electrolyte storage unit, (ii) receive a carbon dioxide-containing gas mixture from the gas supply, and (iii) produce a concentrated liquid by dissolving the carbon dioxide from the gas mixture in the first electrolyte solution; a degassing unit in liquid connection with the inlet unit and a discharge, the degassing unit being configured to (i) degasse carbon dioxide from the concentrated liquid supplied by the inlet unit, thus providing a degassed concentrated liquid, and (ii) discharge the carbon dioxide; A distribution unit in liquid connection with the degassing unit and with at least one distribution line, wherein the distribution unit is configured to (i) receive the degassed concentrated liquid from the degassing unit and distribute the degassed concentrated liquid via the at least one distribution line; a first reaction unit in liquid connection with the distribution unit and configured to react at least a portion of the degassed concentrated liquid from the distribution unit with a hydroxide under conditions to produce a carbonate and an aqueous alkaline solution; and a second reaction unit in liquid connection with (a) the electrolyte storage unit, (b) the distribution unit, and (c) the first reaction unit, configured to (i) react the remaining portion of the degassed concentrated liquid from the distribution unit with an amount of the aqueous alkaline solution from the first reaction unit to produce a second electrolyte solution, and (ii) supply the second electrolyte solution to the electrolyte storage unit.
  2. System according Claim 1 , wherein the aqueous alkaline carbonate solution comprises one or more solutions selected from the group consisting of an aqueous sodium carbonate solution (Na 2 CO 3 ), an aqueous potassium carbonate solution (K 2 CO 3 ) and combinations thereof.
  3. System according Claim 1 , wherein the aqueous alkaline carbonate solution has a concentration of 0.0001 M to 0.5 M.
  4. System according Claim 1 , where the first electrolyte solution has a pH value of 9 to 12.5.
  5. System according Claim 1 , wherein the inlet unit comprises an inlet separating membrane which divides its interior into an electrolyte flow space and a gas mixture flow space, and wherein the inlet separating membrane is permeable to the carbon dioxide contained in the gas mixture which flows in the gas mixture flow space, and allows the carbon dioxide to diffuse into the first electrolyte solution in the electrolyte flow space.
  6. System according to Claim 1 , wherein the gas mixture comprises one or more gases selected from by-product gas of steel production, exhaust gas and combinations thereof.
  7. System according Claim 1 , wherein the gas mixture flow chamber has a pressure of 0.1 bar to 10 bar.
  8. System according Claim 1 , wherein the pressure in the gas mixture flow space is lower than the pressure in the electrolyte flow space, wherein the pressure difference between the gas mixture flow space and the electrolyte flow space is in the range of 3 bar or less.
  9. System according Claim 1 , wherein the ratio between the flow rate of the gas mixture and the flow rate of the first electrolyte solution supplied to the inlet unit is in a range of 0.1 to 15.
  10. System according Claim 1 , where the concentrated liquid has a pH value of 6 to 9.
  11. System according Claim 1 , wherein the degassing unit comprises a degassing separation membrane which divides its interior into a flow space for concentrated liquid and a carbon dioxide flow space, and wherein the degassing separation membrane is permeable to the carbon dioxide contained in the concentrated liquid which flows in the flow space for concentrated liquid and allows the carbon dioxide to pass through the degassing separation membrane to be released into the carbon dioxide flow space.
  12. System according to Claim 1 , wherein the draining fluid comprises one or more fluids selected from an aqueous sodium bicarbonate (NaHCO 3 ) solution, an aqueous potassium bicarbonate (KHCO 3 ) solution and combinations thereof.
  13. System according to Claim 1 , where the draining fluid has a pH value of 7 to 9.
  14. System according Claim 1 , wherein the hydroxide comprises a hydroxide of one or more metal ions of calcium (Ca), magnesium (Mg), strontium (Sr), copper (Cu), lithium (Li), barium (Ba), iron (Fe) and combinations thereof.
  15. System according Claim 1 , wherein the molar ratio of the portion of the draining liquid and the hydroxide reacted with each other in the first reaction unit is in the range of 1:0.5 to 1:2.
  16. System according Claim 1 , wherein the carbonate comprises a carbonate of one or more metal ions of calcium (Ca), magnesium (Mg), strontium (Sr), copper (Cu), lithium (Li), barium (Ba), iron (Fe) and combinations thereof, and the first reaction unit further comprises a filter unit configured to separate and recover the carbonate.
  17. System according Claim 1 , wherein the aqueous alkaline solution comprises one or more solutions of an aqueous sodium hydroxide (NaOH) solution, an aqueous potassium hydroxide (KOH) solution and combinations thereof.
  18. System according Claim 1 , where the aqueous alkaline solution has a pH value of 12 to 14.
  19. System according Claim 1 , wherein the molar ratio between the remaining part of the draining liquid and the aqueous alkaline solution, which are reacted together in the second reaction unit, is in the range of 1:0.5 to 1:1.2.
  20. System according Claim 1 , wherein the second electrolyte solution drained from the second reaction unit has a pH of 9 to 12.5.

Description

TECHNICAL AREA The present disclosure relates to a carbon dioxide separation system with a pH control function that enables the recycling of an electrolyte solution. BACKGROUND Recently, research in the field of electrochemical water electrolysis has been actively promoted in line with the development of renewable energies to address climate change. Furthermore, technologies for capturing, storing, and converting carbon dioxide ( CO2 ) to reduce greenhouse gases have gained importance. Representative methods for carbon dioxide removal include methods based on amine compounds, methods using solid absorbents, and methods using membrane contactors. The carbon dioxide capture process based on amine compounds requires a lot of energy to regenerate the amine compounds and impairs the durability of the equipment due to its highly corrosive properties. The process, which uses solid absorbents to capture carbon dioxide, requires regular replacement due to the decreasing efficiency of the absorbents and has a slow absorption rate of carbon dioxide. In processes that utilize membrane contactors for carbon dioxide removal, differences in solubility depending on the type of gas are exploited. Specifically, in this process, a carbon dioxide-containing gas mixture is brought into contact with an aqueous solution to dissolve the carbon dioxide contained in the gas mixture and separate it into the aqueous solution. The process using membrane contactors for carbon dioxide removal offers the advantage of high removal efficiency, as the reaction between the aqueous solution and the carbon dioxide occurs rapidly, and provides relatively low costs and energy consumption. When the aqueous solution is mixed with water, the carbon dioxide removal efficiency is typically around 85%. When propylene carbonate is added to the water, the carbon dioxide removal efficiency is typically around 91%. However, regardless of the current state of the art, new techniques with higher removal efficiencies are needed to approach or achieve carbon neutrality. SUMMARY OF THE REVELATION In one aspect, the present disclosure provides a system with very high carbon dioxide capture efficiency. In another aspect, the present disclosure provides a system capable of continuously separating carbon dioxide. In another aspect, the present disclosure provides a system capable of selectively separating carbon dioxide contained in a gas mixture. In yet another aspect, the present revelation provides a system that can easily be scaled up. The various aspects of this disclosure are not limited to those mentioned above. Other aspects and embodiments of this disclosure will become clearer from the following description and can be realized by means and combinations thereof, as set forth in the claims. According to one embodiment of the present disclosure, the carbon dioxide separation system may comprise: an electrolyte storage unit for storing a first electrolyte solution containing an aqueous alkaline carbonate solution; an inlet unit for producing a concentrated Liquid by dissolving carbon dioxide contained in a gas mixture in the first electrolyte solution supplied by the electrolyte storage unit; a degassing unit for degassing carbon dioxide from the concentrated liquid supplied by the inlet unit and for releasing the carbon dioxide; a distribution unit for receiving a discharge liquid discharged by the degassing unit and for distributing the discharge liquid; a first reaction unit for producing a carbonate and an aqueous alkaline solution by receiving a portion of the discharge liquid from the distribution unit and reacting that portion with hydroxide; and a second reaction unit for producing a second electrolyte solution and supplying the second electrolyte solution to the electrolyte storage unit, wherein the production is carried out by receiving the remaining portion of the discharge liquid from the distribution unit and an aqueous alkaline solution from the first reaction unit and reacting the remaining portion of the discharge liquid with the aqueous alkaline solution. The aqueous alkaline carbonate solution may comprise one or more solutions selected from the group consisting of an aqueous sodium carbonate solution (Na 2 CO 3 ), an aqueous potassium carbonate solution (K 2 CO 3 ), and combinations thereof. The aqueous alkaline carbonate solution can have a concentration of 0.0001 M to 0.5 M. The first electrolyte solution can have a pH value of 9 to 12.5. The inlet unit can include an inlet divider membrane installed within it to separate its space into an electrolyte flow chamber and a gas mixture flow chamber. The carbon dioxide contained in the gas mixture and flowing in the gas mixture flow chamber can pass through the inlet divider membrane and dissolve in the first electrolyte solution flowing in the electrolyte flow chamber. The gas mixture may include one or more gases selected from the group consisting of by-product gas from steel production, exh