Hydrogen-assisted electrolysis processes

• US 20060169593A1
• Filed: 03/29/2006
• Published: 08/03/2006
• Est. Priority Date: 03/15/2002
• Status: Abandoned Application

• Current Assignee: Guido Pez, Jianguo Xu, Michael Kelly, Stefanie Sharp-Goldman, Ying Wu
• Original Assignee: Guido Pez, Jianguo Xu, Michael Kelly, Stefanie Sharp-Goldman, Ying Wu
• Inventors: Wu, Ying, Kelly, Michael, Xu, Jianguo, Pez, Guido, Sharp-Goldman, Stefanie
• Application Number:
  US11/391,315
• Publication Number:
  US 20060169593A1
• Time in Patent Office: Days
• US Class Current: 205/406
• CPC Class Codes: C25B 1/14 Alkali metal compounds
• CPC Class Codes: C25C 1/04 in mercury cathode cells
• CPC Class Codes: C25C 3/02 of alkali or alkaline earth metals

Abstract

A process and electrolytic cell for reducing in an ionic alkali metal compound, the cell containing anode and cathode electrodes, by supplying an electrolyte containing the alkali metal compound to the cell, applying an electric voltage to the cell to reduce said alkali metal compound at the cathode, and passing hydrogen or a hydrogen containing gas to at least one electrode while the compound is reduced at the cathode.

Claims

1-6. -6. (canceled)

7. An electrolytic cell for reducing an ionic alkali metal compound said cell comprising:

a) an anode and a cathode compartment,

b) the anode compartment containing an anode electrode and the cathode compartment containing a cathode electrode,

c) at least said cathodic compartment being substantially free of water,

d) both of said compartments being separated by a membrane which is permeable to alkali metal ions but is not permeable to water and water vapor,

e) said cathodic compartment containing as an electrolyte said molten alkali metal compound, and

f) means for supplying hydrogen or hydrogen containing gas from an external source to said electrolytic cell to said anode compartment

8. The electrolytic cell of claim 7 wherein said membrane is a ceramic cation exchange membrane.

9. The electrolytic cell of claim 8 wherein said membrane is sodium β

″

-alumina.

10. A process for electrolyzing an alkali metal borate in an electrolytic cell having anodic and cathodic compartments to produce an alkali metal borohydride, comprising providing a molten alkali metal borate salt in said cathodic compartment and a molten alkali metal hydroxide in said anodic compartment, at least said cathodic compartment being substantially free of water and said anodic and cathodic compartments being separated by a membrane permeable to alkali metal ions but non-permeable to water and water vapor, applying a voltage in the said electrolytic cell, and supplying a gas comprising hydrogen to both said anodic and cathodic compartments while said electrolytic voltage is being applied, electro-oxidizing hydrogen at the anode, and forming said borohydride in said cathodic compartment.

11. The process of claim 10 wherein the alkali metal borate salt is provided in its molten state by dissolving the alkali metal borate salt in molten alkali metal hydroxide.

12. The process of claim 11 wherein the alkali metal is sodium.

13. The process of claim 11 wherein the alkali metal borohydride formed in the cathodic compartment is continuously removed from the cell while the alkali metal borate is continuously supplied to the cell during the formation of molten alkali metal borohydride.

14. An electrolytic cell comprising an anodic and a cathodic compartment, said cathodic compartment containing an alkali metal borate and said anodic compartment containing an alkali metal hydroxide, both said alkali metal hydroxide and said alkali metal borate being in their molten state and being substantially free of water, both said anodic and cathodic compartments containing a means for supplying hydrogen or a hydrogen containing gas from an external source into each of these respective compartments, wherein the hydrogen supplied to the anodic compartment is electro-oxidized, and both of said compartments being separated by a membrane, which is permeable to alkali metal ions but non-permeable to water and water vapor.

15. The electrolytic cell of claim 14 wherein said alkali metal is sodium.

16. The electrolytic cell of claim 15 wherein said membrane is a ceramic cation exchange membrane.

17. The electrolytic cell of claim 16 wherein said membrane is sodium β

″

-alumina.

18-21. -21. (canceled)

22. An electrolytic cell for producing an alkali metal, comprising anodic and cathodic compartments, said compartments containing molten alkali metal hydroxide, at least said cathodic compartment being substantially free of water, said anodic and cathodic compartments being separated by a membrane which is permeable to alkali metal ions, and impermeable to water or water vapor, said anodic compartment containing a means for passing hydrogen or a hydrogen containing gas from an external source into said anodic compartment.

23. The electrolytic cell of claim 22 wherein said membrane is a ceramic cation exchange membrane.

24. The electrolytic cell of claim 23 wherein said membrane is sodium β

″

-alumina.

25. A process for electrolytically producing alkali metal amalgam in an electrolytic cell from aqueous alkali metal hydroxide, said cell having cathode and anode electrodes, comprising providing to said cell an aqueous alkali metal hydroxide solution which contacts said cathode and anode electrodes, providing an electric voltage and passing hydrogen or a hydrogen containing gas onto the surface of the anode in said cell, so as to form alkali metal at said cathode which reacts with said cathode to form said alkali metal containing amalgam, and electro-oxidizing hydrogen at the anode.

26. The process of claim 25 wherein said alkali metal amalgam is formed while said cell is maintained at a temperature which is as least as great as the temperature at which said cathode is in its liquid state.

27. An electrolytic cell for producing alkali metal amalgam comprising an anode and a cathode, containing aqueous alkali metal hydroxide solution, which solution contacts both the cathode and anode electrodes, said cathode electrode being formed from a material which is either a metal or metal alloy capable of forming an amalgam with an alkali metal, and a means for supplying hydrogen or hydrogen containing gas from an external source to the surface of the anode.

28. The electrolytic cell of claim 27 wherein said cathode electrode is in its liquid state.

29. The electrolytic cell of claim 27 wherein said cathode electrode is Rose'"'"'s metal, lead, mercury, bismuth, tin, indium and alloys thereof.

30. A process for electrolyzing alkali metal hydroxide in an electrolytic cell containing anodic and cathodic compartments to produce alkali metal hydride, comprising providing molten alkali metal hydroxide to both the cathodic and anodic compartments in the electrolytic cell, at least said cathodic compartment being substantially free of water, said anodic and cathodic compartments being separated by a membrane which is permeable to alkali metal ions but is not permeable to water and water vapor, applying a voltage to the cell to form alkali metal at said cathode, and supplying hydrogen or a hydrogen containing gas to said cathodic compartment while said electric voltage is applied to react with said alkali metal and form alkali metal hydride in said cathodic compartment.

31. The process of claim 30 wherein the alkali metal hydride formed in the cathodic compartment is continuously removed from the cell and alkali metal hydroxide is continuously supplied to the anodic compartment.

32. The process of claim 31 wherein the cell is maintained at a temperature during the formation of alkali metal hydride sufficient to keep the alkali metal hydroxide in its molten state.

33. The process of claim 30 wherein said alkali metal is sodium.

40. The electrolytic cell of claim 31 wherein said alkali metal is sodium.

34. An electrolytic cell for producing alkali metal hydride comprising anodic and cathodic compartments, said compartments containing molten alkali metal hydroxide, said cathodic compartment being substantially free of water, said anodic and cathodic compartments being separated by a membrane which is permeable to alkali metal ions but is impermeable water or water vapor, and a means for passing hydrogen or a hydrogen containing gas from an external source into said cathodic compartment.

35. The electrolytic cell of claim 34 wherein said membrane is sodium β

″

-alumina.

36. A process for electrolyzing an alkali metal hydroxide in an electrolytic cell having anodic and cathodic compartments to produce an alkali metal hydride, comprising providing a molten alkali metal hydroxide in said cathodic compartment and in said anodic compartment, at least said cathodic compartment being substantially free of water and, said anodic and cathodic compartments being separated by a membrane permeable to alkali metal ions but non-permeable to water and water vapor, applying a voltage in the said electrolytic cell to form alkali metal at said cathode, supplying hydrogen or hydrogen containing gas to both said anodic and cathodic compartments while said voltage is being applied to react with the alkali metal and form said hydride in said cathodic compartment, and electro-oxidizing hydrogen at the anode.

37. The process of claim 36 wherein the alkali metal is sodium.

38. The process of claim 37 wherein the alkali metal hydride formed in the cathodic compartment is continuously removed from the cell while the alkali metal hydroxide is continuously supplied to the cell during the formation of alkali metal hydride.

39. An electrolytic cell having an anodic and a cathodic compartment, said cathodic compartment containing an alkali metal hydroxide and said anodic compartment containing an alkali metal hydroxide, said alkali metal hydroxide being in its molten state and being substantially free of water, both said anodic and cathodic compartments containing a means for supplying hydrogen or a hydrogen containing gas from an external source into each of these respective compartments, wherein the hydrogen supplied to the cathodic compartment reacts with alkali metal in the cathodic compartment, and both of said compartments being separated by a membrane, which is permeable to alkali metal ions and non-permeable to water and water vapor.

41. The electrolytic cell of claim 39 wherein said membrane is a ceramic cationic exchange membrane.

42. The electrolytic cell of claim 41 wherein said membrane is sodium β

″

-alumina.