Two-layer-three-way catalyst

Abstract

A double-layer three-way catalyst is presented, which is formed from a catalytic coating applied directly to an inert honeycomb and a catalytically active coating thereon, and is suitable especially for cleaning of exhaust gases of motor vehicles with gasoline-operated internal combustion engines. The catalyst contains, in each layer, an active aluminum oxide and a cerium/zirconium mixed oxide, both of which are catalytically activated by palladium. The second layer on the gas side contains not only palladium but also rhodium, which is applied to the active aluminum oxide and the cerium/zirconium mixed oxide of the second layer in addition to the palladium. The cerium/zirconium mixed oxide of the second layer has a higher zirconium oxide content than the cerium/zirconium mixed oxide of the first layer. The catalyst is notable for exceptional activity coupled with outstanding aging stability.

Dependencies are inferred from the claim text.