摘要 |
Three-way catalysts containing rhodium, rare earth oxide and platinum and/or palladium of improved durability, when subjected to exhaust gases containing excess oxygen, are formed when the rhodium is segregated from the rare earth oxide, thereby preventing undersirable interactions between the rhodium and rare earth oxide. The efficiency of the catalyst is optimized when the rhodium has an initial average particle size ranging from about 35 to about 80 ANGSTROM in diameter. P-type oxides in intimate contact with ceria are found to enhance the catalytic efficiency of platinum containing catalysts. |