Process for producing catalyst carrier, process for producing composite catalyst, composite catalyst, and fuel cell using same

1. A process for producing a composite catalyst comprising:

a step (a) of mixing a transition metal compound (1), a nitrogen-containing organic compound (2) and a solvent to provide a thermally treated product precursor solution;

a step (b) of removing the solvent from the thermally treated product precursor solution;

a step (c) of thermally treating a solid residue obtained in the step (b) at a temperature of 500 to 1100° C. to provide a thermally treated product; and

a step (d) of providing a composite catalyst comprising the thermally treated product and a catalyst metal supported on the thermally treated product;

wherein

the transition metal compound (1) is partly or wholly a compound comprising a transition metal element (M1) selected from the group 4 and 5 elements of the periodic table as a transition metal element;

one or both of the transition metal compound (1) and the nitrogen-containing organic compound (2) comprises an oxygen atom; and

the step (d) is carried out by any one of the following methods (1) to (3):

(1) a method comprising a step of dispersing the thermally treated product in a catalyst metal precursor solution and evaporating the resultant dispersion to dryness; and thereafter a step of thermally treating the resultant solid;

(2) a method comprising a step of dispersing the thermally treated product in a catalyst metal precursor colloidal solution to adsorb the catalyst metal precursor colloid on the thermally treated product, thereby making the thermally treated product carry the catalyst metal; and

(3) a method comprising a step of adjusting the pH of a mixed solution of a solution containing one or more metal compound serving as a material of the thermally treated precursor and a catalyst precursor colloidal solution to provide a precursor of the thermally treated product and simultaneously to adsorb the catalyst precursor colloid; and a step of thermally treating the resultant product.

2. The process for producing a composite catalyst according to claim 1 , wherein the transition metal element (M1) is at least one selected from the group consisting of titanium, zirconium, niobium and tantalum.

3. The process for producing a composite catalyst according to claim 1 , wherein the transition metal compound (1) further comprises a second transition metal compound containing at least one transition metal element (M2) selected from iron, nickel, chromium, cobalt, vanadium and manganese.

4. The process for producing a composite catalyst according to claim 1 , wherein the transition metal compound (1) is at least one selected from the group consisting of a metal phosphate, a metal sulfate, a metal nitrate, a metal organic acid salt, a metal oxyhalide, a metal alkoxide, a metal halide, a metal halogen oxoate, a metal hypohalogenite and a metal complex.

5. The process for producing a composite catalyst according to claim 1 , wherein in the step (a), a precipitation suppressant comprising a compound having a diketone structure is further mixed.

6. The process for producing a composite catalyst according to claim 5 , wherein in the step (a), a solution of the transition metal compound (1) is mixed with the precipitation suppressant, and then the resultant solution is mixed with the nitrogen-containing organic compound (2).

7. The process for producing a composite catalyst according to claim 1 , wherein the nitrogen-containing organic compound (2) has, in its molecule, at least one selected from

functional groups such as an amino group, a nitrile group, an imide group, an imine group, a nitro group, an amide group, an azide group, an aziridine group, an azo group, an isocyanate group, an isothiocyanate group, an oxime group, a diazo group, a nitroso group; and a pyrrole ring, porphyrin ring, an imidazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring.

8. The process for producing a composite catalyst according to claim 1 , wherein the nitrogen-containing organic compound (2) further has, in its molecule, at least one group selected from a hydroxyl group, a carboxyl group, an aldehyde group, an acid halide group, a sulfo group, a phosphoric acid group, a ketone group, an ether group and an ester group.

9. The process for producing a composite catalyst according to claim 1 , wherein the catalyst metal is at least one selected from the group consisting of platinum, gold, silver, copper, palladium, rhodium, ruthenium, iridium, osmium, rhenium and an alloy made of two or more thereof.

10. The process for producing a composite catalyst according to claim 1 , wherein the content of the catalyst metal is 0.01 to 50% by weight based on the total weight of the composite catalyst.