| 摘要 |
PROBLEM TO BE SOLVED: To provide suppress grain growth by suppressing the migration of carried and supported noble metal particles even when a high temperature of >=800 deg.C acts for a long time under a lean atmosphere of oxygen excess. SOLUTION: The noble metal 3 is carried and supported near the surface of a carrier 1 consisting of silica in an embedded state. After the noble metal is carried and supported on the silica carrier, the silica carrier is impregnated with an alkoxy silane, is hydrolyzed and is fired, by which a silica layer is formed and the noble metal is coated. The noble metal particles are coated with the silica layer 2 and the silica layer 2 is integrally bonded to the silica carrier 1 and therefore the migration of the noble metal particles is suppressed. |
