Patent ID: 7407911

Claim:
A method of preparing a double layered, palladium-only three-way catalyst comprising the steps of: preparing a first catalyst slurry and a second catalyst slurry using palladium, alumina, cerium oxide and a mixing solution; first coating of the first catalyst slurry on a ceramic monolith substrate; drying the substrate; calcining the substrate; and second coating of the second catalyst slurry: wherein said first catalyst slurry is prepared by adding 15 to 25 g/L of a mixture of cerium oxide, cerium—zirconium composite oxide [(Ce.Zr)O 2 ] and cerium—zirconium—yttrium composite oxide [(Ce.Zr.Y)O 2 ], proportions of which ranging from 25:60:15 to 20:60:20 by weight, with respect to the total apparent volume of the substrate to alumina; adding 2 to 5 g/L of praseodymium oxide with respect to the total apparent volume of the substrate; and adding 15 to 25 g/L of metal oxide (perovskite) selected from (LaCe)(FeCo)O 3 and (LaSr)(FeCo)O 3 with respect to the total apparent volume of the substrate.