CATALYST FOR CLEANING EXHAUST GAS

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PROBLEM TO BE SOLVED : To provide a catalyst for cleaning exhaust gas which achieves high performance of removing NOx under a high temperature condition by using a small amount of a noble metal. SOLUTION : The catalyst 1 for cleaning exhaust gas is provided with : a base material 2; a lower layer 3 which is formed on the base material 2 and comprises palladium, platinum and a first compound oxide, which comprises cerium, zirconium and elements selected from the group consisting of rare earth elements other than cerium and alkaline earth elements, and in which the mass ratio of the platinum to the palladium is within 1/50 to 1/20; and an upper layer 4 which is formed on the lower layer 3 and comprises rhodium and a second compound oxide, which comprises zirconium and elements selected from the group consisting of rare earth elements other than cerium and alkaline earth elements, and in which the atomic ratio of the cerium to the zirconium is made smaller than that of the cerium to the zirconium in the first compound oxide. COPYRIGHT : (C)2009, JPO&INPIT