Hydrogen-assisted electrolysis processes

• US 7,108,777 B2
• Filed: 03/13/2003
• Issued: 09/19/2006
• Est. Priority Date: 03/15/2002
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc), Millennium Cell Inc.
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc), Millennium Cell Inc.
• Inventors: Wu, Ying, Kelly, Michael, Xu, Jianguo, Pez, Guido, Sharp-Goldman, Stefanie
• Primary Examiner(s): King, Roy
• Assistant Examiner(s): Alexander, Michael P.
• Application Number:
  US10/388,197
• Publication Number:
  US 20040011662A1
• Time in Patent Office: 1,286 Days
• Field of Search: 205406-409, 205/546, 205/358, 423286-288
• US Class Current: 205/408
• 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. A process for reducing in an electrolytic cell an ionic alkali metal compound, said cell containing anode and cathode compartments, comprising:

supplying said alkali metal compound in molten form to at least the cathodic compartment 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 an electric voltage to said cell to reduce said alkali metal compound at said cathode; and

electro-oxidizing hydrogen or a hydrogen containing gas at the anode while said compound is reduced at the cathode

2. The process of claim 1 wherein said alkali metal is sodium.

3. The process of claim 1, further comprising passing hydrogen into the cathode compartment so as to react with said reduced compound.

4. The process of claim 2 wherein said compound is sodium hydroxide.

5. The process of claim 1 wherein the alkali metal compound is supplied in the molten state by dissolving said compound in a molten solvent.

6. A process of electrolyzing alkali metal hydroxide in an electrolytic cell containing anodic and cathodic compartments to produce an alkali metal 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; and

electro-oxidizing hydrogen or a hydrogen containing gas at said anode while said electric voltage is applied to form the metallic alkali metal in said cathodic compartment.

7. The process of claim 6 wherein the alkali metal formed in the cathodic compartment is continuously removed from the cell and alkali metal hydroxide is continuously supplied to the anodic compartment.

8. The process of claim 7 wherein the cell is maintained at a temperature during the formation of alkali metal sufficient to keep the alkali metal hydroxide in its molten state.

9. The process of claim 6 wherein said alkali metal is sodium.

10. A process for reducing in an electrolytic cell a sodium borate compound, said cell containing anode and cathode compartments, comprising:

supplying said sodium borate compound in molten form to at least the cathodic compartment 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 an electric voltage to said cell to reduce said sodium borate compound at said cathode; and

passing hydrogen or a hydrogen containing gas in the anode compartment while said sodium borate compound is reduced at the cathode.