To recover the activity of catalyst by pulverizing permanently deteriorated precious metal again by grain growth.
Catalyst comprising a carrier including basic oxides of 10 m2/g or more in specific surface and precious metal carried on the carrier and having a catalyst performance lowered by the exposure thereof to exhaust gas is treated in hot oxidizing atmosphere of 600°C or higher, and then treated in stoic atmosphere or reducing atmosphere of 800°C lower. In the oxidizing treatment, the grown precious metal is oxidized to produce a solid phase reaction in the clearance thereof from the carrier, and precious metal components are put on the surface of the carrier in wet state. In the reducing treatment, a reducing reaction is gradually advanced from the surface of the precious metal components in wet state placed on the surface of the carrier to deposit the metal-like precious metal as particulate.
HATANAKA YOSHIO
SUDA AKIHIKO
SOFUGAWA HIDEO
SUGIURA MASAHIRO
| JPH09253491A | 1997-09-30 | |||
| JPS59154141A | 1984-09-03 |