Exhaust gas treatment catalyst for internal combustion engines with two catalytically active layers on a carrier structure

摘要

A catalyst for treating the exhaust gas from internal combustion engines is provided, wherein the catalyst contains two catalytically active layers supported on a support. The first catalytically active layer contains a platinum group metal in close contact with all of the constituents of the first catalytically active layer, wherein the constituents of the first catalytically active layer include particulate aluminum oxide; particulate oxygen storage material, such as cerium oxide, cerium/zirconium and zirconium/cerium mixed oxides, and alkaline earth metal oxides. The second catalytically active layer, which is in direct contact with the exhaust gas, contains particulate aluminum oxide and at least one particulate oxygen storage material, such as cerium oxide, cerium/zirconium and zirconium/cerium mixed oxides. Rhodium is supported on part of the aluminum oxides in the second catalytically active layer or on the particulate oxygen storage material in the second catalytically active layer. By providing the platinum group metal in close contact with all of the constituents of the first catalytically active layer, improved conversion efficiency of the impurities in the exhaust gas can be achieved.