US Patent 7608561 Exhaust gas purifying catalyst

An exhaust gas purifying catalyst comprising: a honeycomb-like substrate disposed in an exhaust passage for an engine; and a catalytic layer formed on a cell wall of said substrate, said catalytic layer including a mixed oxide which contains Ce (cerium) and Zr (zirconium), and retains a catalytic noble metal in such a manner that said noble metal atoms are located at crystal lattice points or between the lattice points of the mixed oxide, wherein said mixed oxide includes a first mixed oxide containing CeO2 in a mass greater than that of ZrO2, and a second mixed oxide containing ZrO2 in a mass greater than that of CeO2.