Process for producing oxygen reducing catalyst and uses thereof

Patent metadata

Field	Value
Publication number	US-9780385-B2
Application number	US-201214237277-A
Country	US
Kind code	B2
Filing date	May 10, 2012
Priority date	Aug 8, 2011
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A process for producing an oxygen reducing catalyst including a step of heat-treating, in a non-oxidizing atmosphere, a catalyst precursor including a compound (i) supplying a carbon element and a nitrogen element by heating in a non-oxidizing atmosphere, and a compound (ii) containing at least one element of iron and cobalt. Also disclosed is an oxygen reducing catalyst, a fuel cell catalyst layer including the oxygen reducing catalyst, an electrode including the fuel cell catalyst layer, a membrane-electrode assembly including the electrode and a fuel cell including the membrane-electrode assembly.

First claim

The invention claimed is:

1. An oxygen reducing catalyst obtained by:
a step (A) of mixing a compound (i) supplying a carbon element and a nitrogen element by heating in a non-oxidizing atmosphere, a compound (ii) comprising at least one element of iron and cobalt, a solvent, and an acid to prepare a catalyst precursor solution having pH of not more than 3.5;
a step (B) of removing the solvent from the catalyst precursor solution, and
a step (C) of heat-treating, in a non-oxidizing atmosphere, a catalyst precursor obtained from the step (B), wherein the catalyst precursor comprises a uniform mixture of the compound (i) and the compound (ii).

2. The oxygen reducing catalyst according to claim 1 , wherein the proportion of atomic numbers of iron, cobalt, carbon, nitrogen and oxygen in elements contained in the oxygen reducing catalyst is (total atomic number of iron and cobalt): atomic number of carbon: atomic number of nitrogen: atomic number of oxygen=1: x:y:z wherein 10≦x≦65, 0<y≦2 and 0<z≦20.

3. The oxygen reducing catalyst according to claim 1 , which is a fuel cell electrode catalyst.

4. A fuel cell catalyst layer comprising the oxygen reducing catalyst according to claim 3 .

5. An electrode comprising the fuel cell catalyst layer according to claim 4 , and a gas diffusion layer.

6. A membrane-electrode assembly comprising a cathode, an anode and an electrolyte membrane interposed between the cathode and the anode, wherein the cathode and/or the anode is the electrode according to claim 5 .

7. A fuel cell comprising the membrane-electrode assembly according to claim 6 .

8. A polymer electrolyte fuel cell comprising the membrane-electrode assembly according to claim 6 .

9. The oxygen reducing catalyst according to claim 1 , wherein the acid is an organic acid.

10. A process for producing the oxygen reducing catalyst according to claim 1 , comprising:
(A) mixing the compound (i), the compound (ii), the solvent and the acid to prepare the catalyst precursor solution having a pH of not more then 3.5;
(B) removing the solvent from the catalyst precursor solution; and
(C) heat-treating, in a non-oxidizing atmosphere, a catalyst precursor obtained from step (B), wherein the catalyst precursor comprises a uniform mixture of the compound (i) and the compound (ii).

11. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the compound (ii) is a compound not containing titanium.

12. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the ratio of the atomic number of carbon contained in the oxygen reducing catalyst to the total atomic number of iron and cobalt contained in the oxygen reducing catalyst is 10 to 65, provided that the total atomic number of the metal elements is 1.

13. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the compound (ii) is at least one selected from organic acid salts, inorganic acid salts, organic complexes, inorganic complexes, alkoxides and other organometallic compounds.

14. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the compound (i) is an α-nitrogen carboxylic acid.

15. The process for producing an oxygen reducing catalyst according to claim 14 , wherein the α-nitrogen carboxylic acid is at least one selected from glycine, glycylglycine, alanine, alanylalanine and norvaline.

16. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the pH of the catalyst precursor solution is controlled using an organic acid.

17. The process for producing an oxygen reducing catalyst according to claim 16 , wherein the organic acid is acetic acid.

18. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the catalyst precursor solution contains 1 to 20% by mass of a ketone, an alcohol or an ether.

19. The process for producing an oxygen reducing catalyst according to claim 18 , wherein the catalyst precursor solution comprises a ketone, and the ketone is 1,3-diketone.

20. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the non-oxidizing atmosphere is:
at least one gas atmosphere selected from nitrogen, argon, ammonia and hydrogen cyanide, or
a mixed gas atmosphere of at least one gas selected from nitrogen, argon, ammonia and hydrogen cyanide and at least one gas selected from hydrogen, methane, propane, butane and carbon monoxide.

21. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the heat treatment temperature is 800 to 1100° C.

22. The process for producing an oxygen reducing catalyst according to claim 10 , wherein the heating rate in the heat treatment is 10 to 40° C./min.

Assignees

• Ichioka Kazunori
• Imai Takuya
• Yu Chunfu
• Showa Denko Kk

Inventors

• Ichioka Kazunori
• Imai Takuya
• Yu Chunfu

Classifications

• H01M4/9091 Primary

  Unsupported catalytic particles; loose particulate catalytic materials, e.g. in fluidised state · CPC title

• H01M8/1007

  with both reactants being gaseous or vaporised (H01M8/12 takes precedence) · CPC title

• H01M4/9041 Primary

  Metals or alloys (H01M4/92 takes precedence) · CPC title

• Y02E60/50

  Fuel cells · CPC title