Engine exhaust catalysts containing palladium-gold

摘要

An engine exhaust catalyst exhibits improved CO oxidation performance relative to conventional engine exhaust catalysts and includes a first supported catalyst comprising platinum and a second supported catalyst comprising palladium and gold species. The first supported catalyst may be a platinum catalyst, a platinum-palladium catalyst, or a platinum catalyst promoted with bismuth, and the second supported catalyst preferably has a palladium to gold weight ratio of about 0.85:1.0. To improve aged catalyst performance, the first and second supported catalysts are coated onto different layers, zones, or monoliths of the substrate for the engine exhaust catalyst.