| 摘要 |
PROBLEM TO BE SOLVED: To suppress the grain growth of a carried noble metal by suppressing the movement of the grain even in the case of being acted at >=800 deg.C for a long time under an oxygen excess lean atmosphere. SOLUTION: The noble metal is supported at least in the internal defect of a carrier consisting of the crystal grain of an oxide having a nucleus and the internal defect extending nearly radially around the nucleus. Many functional groups such as OH group are present in the internal defect and the noble metal is easily carried in the functional group by the ion exchange. Since the internal defect is a narrow space, it is considered that the movement of the carried noble metal grain is restricted. Then the movement of the noble metal grain is suppressed even under the high temperature leans atmosphere to suppress the growth of the grain. |
