PROCESS FOR PREPARING PYROCHLORE OXIDE, AND POLYMER ELECTROLYTE MEMBRANE FUEL CELL, FUEL CELL SYSTEM, AND PROCESS FOR PRODUCING ELECTRODE CATALYST FOR FUEL CELL

摘要

A process for preparing a pyrochlore oxide having a larger specific surface area, a polymer electrolyte membrane fuel cell and a fuel cell system which have an improved power generation efficiency and can be produced at a lower cost, and a process for producing an electrode catalyst for fuel cells which has a larger specific surface area, is relatively inexpensive, and has a high electrode activity per unit mass. The preparation process is a process for preparing a pyrochlore oxide represented by A2B2O7-z (wherein A and B each is a metallic element; Z is a number of 0-1; A comprises at least one element selected from a group consisting of Pb, Sn, and Zn; and B comprises at least one element selected from a group consisting of Ru, W, Mo, Ir, Rh, Mn, Cr, and Re), and comprises reacting a halide or nitrate of A with an alkali metalate of B to yield the pyrochlore oxide. The process for producing an electrode catalyst for fuel cells involves the step of yielding the oxide in such a manner. The polymer electrolyte membrane fuel cell and the fuel cell system each includes the oxide.