| 摘要 |
<p>A catalyst which is used for purifying exhaust gas of an internal-combustion engine of an automobile or the like and can exhibit an excellent performance of purification even after a prolonged, high-temperature service. The catalyst is composed of at least two catalytic component layers carried on a monolithic support, wherein the inner layer contains a catalytic component comprising at least one platinum group element, activated alumina and cerium oxide, while the outer layer at least one platinum group element, activated alumina and optionally a zirconium compound, and at least one of the inner and outer layers also contains a coprecipitated oxide of zirconium stabilized by cerium. This catalyst is produced by preparing activated alumina containing at least one platinum group element, adding other catalytic components thereto to prepare a slurry for each of the inner and outer layers, applying the slurry for the inner layer to a monolithic support followed by firing, and further applying the slurry for the outer layer to the inner layer, followed by firing.</p> |
