Low energy electrochemical hydroxide system and method

• US 7,790,012 B2
• Filed: 12/23/2008
• Issued: 09/07/2010
• Est. Priority Date: 12/23/2008
• Status: Active Grant

• Current Assignee: Eleryc Incorporated
• Original Assignee: Calera Corporation
• Inventors: Kirk, Donald W., Way, J. Douglas, Farsad, Kasra, Decker, Valentin, Bard, Allen J., Gilliam, Ryan J.
• Primary Examiner(s): Phasge; Arun S
• Application Number:
  US12/375,632
• Publication Number:
  US 20100155258A1
• Time in Patent Office: 623 Days
• Field of Search: 205/510, 205/514, 205/555, 204/263, 204/265
• US Class Current: 205/510
• CPC Class Codes: B01D 2251/402 of magnesium
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/326 in electrochemical cells
• CPC Class Codes: C25B 1/02 Hydrogen or oxygen
• CPC Class Codes: C25B 1/26 Chlorine; Compounds thereof by simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine C25B1/34
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

A low-energy method and system of forming hydroxide ions in an electrochemical cell. On applying a low voltage across the anode and cathode, hydroxide ions form in the electrolyte containing the cathode, protons form at the anode but a gas e.g. chlorine or oxygen does not form at the anode.

Claims

1. A system comprising:

an anode electrolyte in contact with an anode;

a cathode electrolyte comprising in contact with a cathode, wherein the system is configured to introduce carbon dioxide into the cathode electrolyte;

a third electrolyte disposed between an anion exchange membrane and a cation exchange membrane such that the anion exchange membrane contacts the anode electrolyte and the cation exchange membrane contacts the cathode electrolyte,

a gas delivery system configured to deliver hydrogen gas to the anode, wherein the system is configured to produce hydrogen gas at the cathode and absorb hydrogen gas and produce protons at the anode, without producing a gas at the anode, on applying a voltage across the anode and cathode; and

wherein the system is further configured to add magnesium and calcium to the cathode electrolyte to precipitate magnesium and calcium carbonates, bicarbonates or hydroxides from the cathode electrolyte.

2. The system of claim 1, wherein the system is configured to produce hydroxide ions in the cathode electrolyte without forming a gas at the anode on applying a voltage of less than 0.05 V across the anode and cathode.

3. The system of claim 1, wherein the system is configured to form hydroxide ions in the cathode electrolyte without forming a gas at the anode on applying a voltage of less than 0.05 V across the anode and cathode.

4. The system of claim 1, wherein the gas delivery system is configured to direct hydrogen gas from the cathode to the anode.

5. The system of claim 1, wherein the cathode electrolyte comprises seawater, freshwater, brine, or brackish water.

6. The system of claim 1, wherein the cathode electrolyte comprises calcium or magnesium ions or a combination thereof.

7. The system of claim 1, wherein the cathode electrolyte comprises carbonate ions, bicarbonate ions, or a combination thereof.

8. The system of claim 1, wherein the third electrolyte comprises sodium chloride.

9. The system of claim 1, wherein the anode electrolyte comprises hydrochloric acid.

10. The system of claim 1, wherein the anode electrolyte comprises hydrochloric acid and the cathode electrolyte comprises sodium hydroxide and/or carbonate and/or bicarbonate.

11. The system of claim 1 or 2, wherein the system is configured to produce a pH difference of at least 4 pH units between the anode electrolyte and the cathode electrolyte.

12. The system of claim 11, wherein the system is configured to produce the pH difference of 4 pH units when a voltage of less than 0.6 V is applied between the anode and the cathode.

13. The system of claim 12, wherein the system is configured to produce said pH difference in less 30 minutes.

14. The system of claim 11, wherein the system is configured to produce the pH difference of 4 pH units when a voltage of less than 0.4V is applied between the anode and the cathode.

15. The system of claim 1 or 2, configured to produce a pH difference of at least 8 pH units between the cathode electrolyte and the anode electrolyte.

16. The system of claim 15, wherein the system is configured to produce the pH difference of at least 8 pH units when a voltage of less than 0.6V is applied between the anode and the cathode.

17. The system of claim 1, configured to produce a change of at least 12.0 pH units in the cathode electrolyte or the anode electrolyte.

18. The system of claim 17, wherein the system is configured to produce the pH difference of at least 12 pH units between the cathode electrolyte and anode electrolyte when a voltage of less than 1.0 V is applied between the anode and the cathode.

19. The system of claim 1, that is configured for continuous flow operation.

39. The system of claim 1 or 27, configured to produce a pH difference of at least 8 pH units between the cathode electrolyte and the anode electrolyte.

40. The system of claim 39, wherein the system is configured to produce the pH difference of at least 8 pH units when a voltage of less than 0.6 V is applied between the anode and the cathode.

20. A method comprising:

contacting an anode with an anode electrolyte and a cathode with a cathode electrolyte;

placing a third electrolyte between a cation exchange membrane and an anion exchange membrane such that the third electrolyte is separated from the cathode electrolyte by the cation exchange membrane, and is separated from the anode electrolyte by the anion exchange membrane;

dissolving carbon dioxide in the cathode electrolyte;

forming hydroxide ions in the cathode electrolyte and hydrogen at the cathode while absorbing hydrogen at the anode to form protons, by applying a voltage across the anode and cathode without forming a gas at the anode; and

adding calcium and magnesium to the cathode electrolyte and precipitating magnesium and calcium carbonates, bicarbonates or hydroxides from the cathode electrolyte.

21. The method of claim 20, wherein said voltage is less than 0.1 V.

22. The method of claim 20, wherein said voltage is less than 0.05 V.

23. The method of claim 20, further comprising directing hydrogen gas from the cathode to the anode.

24. The method of claim 20, wherein the cathode electrolyte comprises freshwater, brine, or brackish water.

25. The method of claim 20, further comprising forming sodium hydroxide in the cathode electrolyte.

26. The method of claim 20, further comprising forming hydrochloric acid in the anode electrolyte.

27. A system comprising:

an anode electrolyte contacting an anode;

a cathode electrolyte contacting a cathode, wherein the system is configured to introduce carbon dioxide into the cathode electrolyte, and

an ion-exchange membrane disposed between the anode electrolyte and the cathode electrolyte;

wherein

the system is configured to produce hydroxide ions in the cathode electrolyte and hydrogen gas at the cathode while absorbing hydrogen gas at the anode to form protons without forming a gas at the anode, on applying a voltage across the anode and cathode; and

the system is further configured to add magnesium and calcium to the cathode electrolyte to precipitate magnesium and calcium carbonates, bicarbonates or hydroxides from the cathode electrolyte.

28. The system of claim 27, wherein the system is configured to produce hydroxide ions without forming a gas at the anode on applying a voltage of 0.05 V or less across the anode and cathode.

29. The system of claim 27, further comprising a gas delivery system configured for directing hydrogen gas from the cathode to the anode.

30. The system of claim 27, wherein the cathode electrolyte comprises carbon dioxide, bicarbonate ions, carbonate ions, or a combination thereof.

31. The system of claim 30, wherein the cathode electrolyte comprises calcium ions, magnesium ions, or a combination thereof.

32. The system of claim 27, wherein the cathode electrolyte comprises seawater, freshwater, brine, or brackish water.

33. The system of claim 27, wherein the cathode electrolyte comprises sodium hydroxide.

34. The system of claim 27, wherein the anode electrolyte comprises hydrochloric acid.

35. The system of claim 27, wherein the system is configured to produce a pH difference of at least 4 pH units between the anode electrolyte and the cathode electrolyte.

36. The system of claim 27, wherein the system is configured to produce the pH difference of 4 pH units when a voltage of less than 0.6 V is applied between the anode and the cathode.

37. The system of claim 36, wherein the system is configured to produce said pH difference in less 30 minutes.

38. The system of claim 27, wherein the system is configured to produce the pH difference of 4 pH units when a voltage of less than 0.4V is applied between the anode and the cathode.

41. The system of claim 27, configured to produce a change of at least 12.0 pH units in the cathode electrolyte or the anode electrolyte.

42. The system of claim 41, wherein the system is configured to produce a pH difference of at least 12 pH units when a voltage of less than 1.0 V is applied between the anode and the cathode.

43. A method comprising:

contacting an anode with an anode electrolyte, and a cathode with a cathode electrolyte, wherein the anode electrolyte and the cathode electrolyte are separated by an ion exchange membrane;

dissolving carbon dioxide in the cathode electrolyte;

forming hydroxide ions in the cathode electrolyte and hydrogen gas at the cathode while absorbing hydrogen at the anode to form protons, by applying a voltage across the anode and cathode without forming a gas at the anode; and

adding calcium and magnesium to the cathode electrolyte and precipitating magnesium and calcium carbonates, bicarbonates or hydroxides from the cathode electrolyte.

44. The method of claim 43, comprising forming hydroxide ions by applying a voltage of 0.05 V or less across the anode and cathode.

45. The method of claim 43, further comprising directing hydrogen gas from the cathode to the anode.

46. The method of claim 43, wherein the cathode electrolyte comprises freshwater, brine, or brackish water.

47. The method of claim 43, comprising forming sodium hydroxide in the cathode electrolyte and hydrochloric acid in the anode electrolyte.