Catalyst for exhaust gas purification
AssigneeMazda Motor Corporation
InventorsHiroshi Murakami, Yasuto Watanabe, Naoko Sakatani, Masayuki Koishi
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Abstract
A three-way catalyst is generally used in an automotive exhaust system. This catalyst has a sufficient total content of noble metal active species and is prevented from heat deterioration so that the activity of the noble metal active species can be well utilized at low temperatures to enable the catalyst to exhibit improved purification performance at the low temperatures. The catalyst comprises a first catalyst layer formed on the surface of a honeycomb-shaped carrier and containing Pd (palladium) and alumina (.gamma.-Al.sub.2 O.sub.3), and a second catalyst layer formed on the outer surface of the first catalyst layer and containing Pd and ceria (CeO.sub.2).
Claims7
An exhaust gas purifying catalyst comprising:
- a catalyst carrier;
- a first catalyst layer formed on said catalyst carrier and consisting essentially of palladium and alumina;
- and
- a second catalyst layer formed on said first catalyst layer and containing palladium and ceria;
- wherein the weight ratio of Pd content in said second catalyst layer to Pd content in said first catalyst layer is from 3/7 to 9/1.
Dependencies are inferred from the claim text.