Exhaust gas purification catalyst

Abstract

In an exhaust gas purification catalyst in which Rh-doped CeZr-based mixed oxide powder and precious-metal (at least one of Pt and Pd)-supporting heat-resistant powder are included in a catalyst layer 2 provided on a support 1, Rh-doped CeZr-based mixed oxide particles either contain at least one of Pr, La, and Y, or are complexed with Al 2 O 3 , and support none of Pt and Pd, and heat-resistant particles supporting the precious metal are one of at least one of activated Al 2 O 3 particles containing La, BaSO 4 particles, and complex particles made of CeZr-based mixed oxide and Al 2 O 3 .

1 . An exhaust gas purification catalyst, comprising a support and a catalyst layer provided on the support, wherein
 the catalyst layer includes Rh-doped CeZr-based mixed oxide powder in which Rh is dissolved in CeZr-based mixed oxide particles containing Ce and Zr, and also includes precious-metal-supporting heat-resistant powder in which a precious metal of at least one of Pt and Pd is supported on heat-resistant particles,   the CeZr-based mixed oxide particles in which Rh is dissolved either contain at least a material selected from the group consisting of Pr, La, and Y, or are complexed with Al 2 O 3 , and support none of Pt and Pd, and   the heat-resistant particles supporting the precious metal are at least one type of particles selected from the group consisting of activated Al 2 O 3  particles containing La, BaSO 4  particles, and complex particles made of CeZr-based mixed oxide and Al 2 O 3 .   
     
     
         2 . The exhaust gas purification catalyst of  claim 1 , wherein the catalyst layer includes a layer containing the Rh-doped CeZr-based mixed oxide powder and a layer containing the precious-metal-supporting heat-resistant powder, and
 the layer containing the Rh-doped CeZr-based mixed oxide powder is located above the layer containing the precious-metal-supporting heat-resistant powder.   
     
     
         3 . The exhaust gas purification catalyst of  claim 1 , including, as the precious-metal-supporting heat-resistant powder, Pt-supporting heat-resistant powder in which Pt is supported on the heat-resistant particles, and Pd-supporting heat-resistant powder in which Pd is supported on the heat-resistant particles,
 the catalyst layer includes a layer containing the Rh-doped CeZr-based mixed oxide powder and a layer containing the Pd-supporting heat-resistant powder,   the layer containing the Rh-doped CeZr-based mixed oxide powder is located above the layer containing the Pd-supporting heat-resistant powder, and   the Pt-supporting heat-resistant powder is included in at least one of the layer containing the Rh-doped CeZr-based mixed oxide powder and the layer containing the Pd-supporting heat-resistant powder.