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

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.