Hydrogen generation by electrolysis of aqueous organic solutions

• US 7,056,428 B2
• Filed: 03/18/2003
• Issued: 06/06/2006
• Est. Priority Date: 09/10/1997
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Valdez, Thomas I., Narayanan, Sekharipuram R., Chun, William, Jeffries-Nakamura, Barbara
• Primary Examiner(s): King, Roy
• Assistant Examiner(s): Wilkins, III, Harry D.
• Application Number:
  US10/391,855
• Publication Number:
  US 20030226763A1
• Time in Patent Office: 1,176 Days
• Field of Search: 205/637, 205/638, 205/639, 204/252, 95/55, 95/56, 502/4
• US Class Current: 205/637
• CPC Class Codes: C25B 1/02 Hydrogen or oxygen
• CPC Class Codes: C25B 9/23 comprising ion-exchange membranes in or on which electrode material is embedded
• CPC Class Codes: H01M 8/0656 by electrochemical means H01M8/065 takes precedence
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 20/133 Renewable energy sources, e.g. sunlight

Abstract

A device for electrolysis of an aqueous solution of an organic fuel. The electrolyte is a solid-state polymer membrane with anode and cathode catalysts on both surfaces for electro-oxidization and electro-reduction. A low-cost and portable hydrogen generator can be made based on the device with organic fuels such as methanol.

Claims

1. A method, comprising:

using an electrolytic cell to electrolyze a fuel solution that includes at least a methanol compound and water, to form hydrogen gas output; and

purifying said hydrogen gas output to remove water and methanol compound from the hydrogen output.

2. A method as in claim 1, wherein said purifying comprises using a selective molecular material which traps said methanol compound.

3. A method as in claim 1, wherein said using comprises forming an electrode assembly including a anode and cathode, with the anode separated from the cathode, and with an electrolyte material, to electrolyze a methanol compound and water solution.

4. A method as in claim 3 further comprising reducing an amount of said methanol compound and water from the hydrogen output by reducing an amount of methanol compound and water solution that crosses between anode and cathode.

5. A method as in claim 4, wherein said reducing an amount of said methanol compound comprises selecting a fuel with a higher boiling point.

6. A method as in claim 4, wherein said reducing comprises selecting a fuel with a higher molecular size.

7. A method as in claim 4, wherein said electrolyte material has a low liquid content to carry out said reducing.

8. A method as in claim 4, further comprising wetting the anode to reduce said amount which crosses.

9. A method as in claim 4, wherein said reducing comprises changing a permeability of the electrode assembly.

10. A method as in claim 9, wherein said changing comprises processing a surface of the electrode assembly with a zeolite.

11. A method as in claim 10, wherein said the zeolite is mixed with catalyst on the electrode assembly.

12. A method as in claim 10, wherein said zeolite is mixed with electrolyte on the electrode assembly.

13. A method as in claim 10, wherein said zeolite is formed as a separate layer on the electrode assembly.

14. A method as in claim 3, further comprising adding a crossover inhibitor to said electrode assembly, to reduce an amount of fuel solution in the output hydrogen.

15. A method as in claim 1, wherein said using comprises using a proton conducting solid polymer membrane as the only electrolyte, without the need for free soluble acid in the fuel solution.

16. A method as in claim 4, wherein said electrode assembly includes a catalyst including Platinum.

17. A method, comprising:

forming an electrode assembly with an anode and separated cathode with electrolyte material therebetween;

electrolyzing a methanol containing fuel at said anode to produce a hydrogen output; and

reducing an amount of fuel in said hydrogen output.

18. A method as in claim 17, wherein said reducing comprises purifying said hydrogen output to remove fuel remnants therefrom.

19. A method as in claim 18, wherein said purifying comprises allowing certain molecules to pass and trapping other molecules to prevent them from passing.

20. A method as in claim 18, wherein said purifying comprises using a molecular sieve.

21. A method as in claim 17, wherein said reducing comprises reducing an amount of fuel that crosses from said anode to said cathode without electrolysis.

22. A method as in claim 21, wherein said reducing comprises processing a surface of the electrode assembly.

23. A method as in claim 21, wherein said reducing comprises changing a characteristic of the electrode assembly relative to a characteristic of the fuel.

24. A method as in claim 21, wherein said reducing comprises adding a crossover inhibitor to the electrode assembly.

25. A system comprising:

a source of methanol containing fuel an electrode assembly comprising an anode, a cathode, and an electrolyte, with said anode and cathode being separated from one another and configured to electrolyze the methanol containing fuel to produce a hydrogen output; and

means for reducing an amount of methanol containing fuel in the hydrogen output.

26. A system as in claim 25, wherein said reducing means comprises a molecular filter that reduces fuel in a hydrogen output.

27. A system as in claim 26, wherein said molecular filter is a molecular sieve.

28. A system as in claim 25, wherein said reducing means comprises a structure that reduces an amount of fuel that crosses from said anode to cathode without electrolysis.

29. A system as in claim 28, wherein said structure comprises a surface of the electrode assembly that has been processed in a specified way.

30. A system as in claim 28, wherein said structure comprises an additive which is added to the electrode assembly to reduce an amount of fuel crossover.