Abstract: A double-layer three-way catalyst for purification of the exhaust gases from internal combustion engines which has excellent activity and thermal stability is described. The catalyst contains active aluminium oxide and a first cerium/zirconium mixed oxide which are both catalytically activated with palladium in the first layer applied to a catalyst support. In the second layer which is in direct contact with the exhaust gas, the catalyst likewise contains an active aluminium oxide and a second cerium/zirconium mixed oxide which are both catalytically activated with rhodium. The second cerium/zirconium mixed oxide has a higher zirconium oxide content than the first mixed oxide.

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.

Abstract: A one-layer three-way catalyst is described for the cleaning of the exhaust gases of internal combustion engines with outstanding activity and thermal stability. The catalyst comprises an active aluminum oxide, a first cerium/zirconium mixed oxide and a second cerium/zirconium mixed oxide. The first cerium/zirconium mixed oxide has a higher zirconium oxide content than the second mixed oxide. The first cerium/zirconium mixed oxide is catalytically activated with rhodium and the second cerium/zirconium mixed oxide with palladium.

Abstract: The exhaust gas of internal combustion engines operated with a predominantly stoichiometric air/fuel mixture contains, as well as the gaseous hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOx) pollutants, also ultrafine particulates. The introduction of the EU-5 exhaust gas standard in Europe in 2010 will for the first time impose a legal limit to these particulate emissions for gasoline vehicles. Future exhaust gas cleaning concepts for these vehicles must include devices for removing these particulates. A catalytically active particulate filter, an exhaust gas cleaning system and a process for cleaning the exhaust gases of predominantly stoichiometrically operated internal combustion engines are presented, which are suitable, as well as the gaseous CO, HC and NOx pollutants, also for removing particulates from the exhaust gas. The particulate filter comprises a filter body and a catalytically active coating consisting of two layers. Both layers contain alumina.