Abstract: Disclosed is an exhaust gas purifying catalyst, which comprises a catalyst layer formed on a honeycomb-shaped support. The catalyst layer is formed by mixing a catalyst powder (A) consisting of a composite oxide (RhZrCeNdO) which contains at least Ce, Zr, and a catalytic noble metal composition, and a catalyst powder (B) consisting of a Zr-based oxide (RhZrXO) which contains at least Zr and has Rh existing on a surface thereof. A ratio (RhZrXO/RhZrCeNdO) of a mass of the catalyst powder (B) to a total mass of the catalyst powder (A) and the catalyst powder (B) may be set in the range of 1 to 50%. Further, the catalyst powder (B) may consist of a composite oxide which contains Zr as a primary component, a rare-earth metal except Ce, and Rh. The exhaust gas purifying catalyst of the present invention can provide enhanced exhaust gas conversion efficiency.

Abstract: An upstream catalyst and a downstream catalyst are disposed in an exhaust passage of an engine. The downstream catalyst contains in the same catalyst layer thereof. Rh-doped CeZrNd mixed oxide particles on which Rh is supported and active alumina particles on which Pt is supported. The upstream catalyst is a three-way catalyst containing an oxygen storage component having a lower oxygen storage capacity than the Rh-doped CeZrNd mixed oxide.

Abstract: An exhaust gas purification catalyst comprises: an oxygen storage component constituted by a mixed oxide containing cerium and zirconium; and a catalytic metal carried on the oxygen storage component. The oxygen storage component is in the form of hollow secondary particles each formed so that primary particles of an average particle size of less than 10 nm cohere into a shell.

Abstract: 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.

Abstract: Disclosed is an exhaust gas purifying catalyst system, which comprises an upstream catalyst disposed in an exhaust gas passage of an engine at a position on an upstream side with respect to a direction of an exhaust gas stream, and a downstream catalyst disposed in the exhaust gas passage at a position on a downstream side with respect to the direction of the exhaust gas stream. In the exhaust gas purifying catalyst system, the downstream catalyst includes a cerium (Ce)-containing rhodium-doped composite oxide and an Ni component, and the upstream catalyst includes a cerium (Ce)-containing composite oxide other than the rhodium-doped composite oxide, and a Ni component. A ratio of Ni to CeO2 in the upstream catalyst is in the range of 15 to 20 mass %, and a ratio of Ni to CeO2 in the downstream catalyst is in the range of 10 to 60 mass %. The exhaust gas purifying catalyst system of the present invention can reduce an amount of H2S emission while achieving high purification performance.

Abstract: In an exhaust gas purification catalyst that contains an oxygen storage component containing Ce and Zr, alumina and a catalytic metal, a plurality of primary particles of the oxygen storage component and a plurality of primary particles of the alumina agglomerate to form each of mixed oxide particles and the catalytic metal includes Pd doped in the oxygen storage component particles to constitute each of the oxygen storage component particles with Ce and Zr and exposed at the surfaces of the oxygen storage component particles and Pd adhered to the surfaces of the oxygen storage component particles and the surfaces of the alumina particles.

Abstract: An upstream catalyst and a downstream catalyst are disposed in an exhaust passage of an engine. The downstream catalyst contains in the same catalyst layer thereof. Rh-doped CeZrNd mixed oxide particles on which Rh is supported and active alumina particles on which Pt is supported. The upstream catalyst is a three-way catalyst containing an oxygen storage component having a lower oxygen storage capacity than the Rh-doped CeZrNd mixed oxide.

Abstract: Disclosed is an exhaust gas purifying catalyst, which comprises a catalyst layer formed on a honeycomb-shaped support. The catalyst layer is formed by mixing a catalyst powder (A) consisting of a composite oxide (RhZrCeNdO) which contains at least Ce, Zr, and a catalytic noble metal composition, and a catalyst powder (B) consisting of a Zr-based oxide (RhZrXO) which contains at least Zr and has Rh existing on a surface thereof. A ratio (RhZrXO/RhZrCeNdO) of a mass of the catalyst powder (B) to a total mass of the catalyst powder (A) and the catalyst powder (B) may be set in the range of 1 to 50%. Further, the catalyst powder (B) may consist of a composite oxide which contains Zr as a primary component, a rare-earth metal except Ce, and Rh. The exhaust gas purifying catalyst of the present invention can provide enhanced exhaust gas conversion efficiency.

Abstract: Disclosed is an exhaust gas purifying catalyst, which comprises an oxygen absorbing material having a catalytic noble metal arranged at a lattice position or an interlattice position of a crystal structure of a composite oxide containing Ce and Zr, which is capable of sufficiently exhibiting a catalytic function even if a ZrO2 mass ratio is out of the range of 20 to 30 mass % or 65 to 90 mass %. Specifically, in an exhaust gas purifying catalyst formed with a catalyst layer including a cerium-zirconium (CeZr) composite oxide, the composite oxide contains ceria (CeO2) and zirconia (ZrO2) in such a manner that a mass ratio of ceria to a total mass of ceria and zirconia falls within the range of 36 to 64 mass %. Further, the composite oxide contains, in the form of an oxide, a rare-earth metal other than cerium (Ce), in the range of 3 to 20 mass % with respect to a total mass of the composite oxide.

Abstract: An exhaust gas purification catalyst comprises: an oxygen storage component constituted by a mixed oxide containing cerium and zirconium; and a catalytic metal carried on the oxygen storage component. The oxygen storage component is in the form of hollow secondary particles each formed so that primary particles of an average particle size of less than 10 nm cohere into a shell.

Abstract: An exhaust gas purification catalyst comprises an oxygen storage component constituted by a mixed oxide containing cerium and zirconium, and a catalytic metal and a NOx storage component are carried on the oxygen storage component. The oxygen storage component is in the form of porous secondary particles in each of which primary particles of an average particle size of less than 10 nm cohere to form fine pores inside each said secondary particle.

Abstract: 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.