Patent ID: 8038951

Claim:
An exhaust system effective to substantially simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides, the system comprising a combination of a first composite and a second composite, wherein the first composite comprises a precious metal that is a palladium component and an oxygen storage component that comprises at least a first ceria-zirconia composite and a second ceria-zirconia composite, the oxygen storage component being present in an amount of at least 10% by weight, wherein substantially all of the oxygen storage component is in intimate contact with the palladium component; wherein the first composite is substantially free of other precious metal components; and the second composite comprises a catalytic material having a rhodium component present in a low amount; wherein the first composite comprises a first catalytic material on a carrier, the first catalytic material comprising at least two layers, the first catalytic material comprising: an inner layer above the carrier comprising the palladium component in an amount in the range of 30 to 70% by weight of palladium in the catalytic material, a first high surface area refractory metal oxide support, the first ceria-zirconia composite, and one or more of a promoter, stabilizer, or binder; and an outer layer deposited on the inner layer comprising the palladium component in an amount in the range of 30 to 70% by weight of palladium in the catalytic material, a second high surface area refractory metal oxide support different from the first high surface area refractory metal oxide support, the second ceria-zirconia composite, and one or more of a promoter, stabilizer, or binder.