Abstract: An exhaust gas purification catalyst includes an alumina support, a silica layer, and active metal particles. The silica layer is formed on a surface of the alumina support. The active metal particles are formed of platinum and palladium, the platinum and the palladium being supported on the silica layer. A ratio of fine particles having a particle size of 2.0 nm or less to all the active metal particles is 50% or higher in terms of the number of particles, the fine particles being included in the active metal particles. A ratio of fine alloy particles having a palladium content ratio of 10 at % to 90 at % to all the fine particles is 50% or higher in terms of the number of particles, the fine alloy particles being included in the fine particles.

Abstract: An exhaust gas purification catalyst includes an alumina support, a silica layer, and active metal particles. The silica layer is formed on a surface of the alumina support. The active metal particles are formed of platinum and palladium, the platinum and the palladium being supported on the silica layer. A ratio of fine particles having a particle size of 2.0 nm or less to all the active metal particles is 50% or higher in terms of the number of particles, the fine particles being included in the active metal particles. A ratio of fine alloy particles having a palladium content ratio of 10 at % to 90 at % to all the fine particles is 50% or higher in terms of the number of particles, the fine alloy particles being included in the fine particles.

Abstract: An exhaust gas purification catalyst includes: a support formed of alumina and yttria; and platinum and palladium that are supported on the support. An yttria content in the support is 2 mass % to 15 mass %. A content ratio of the platinum to the palladium is in a range of 1 to 10 by mass ratio. At least a portion of the platinum and at least a portion of the palladium constitute a solid solution. A diffraction peak of a (311) plane of a crystal including the platinum, the palladium and the solid solution is present at 81.5° or higher in a range of 81.2° to 82.1°, the diffraction peak being identified by an X-ray diffraction method using CuK? rays.

Abstract: The present invention provides an exhaust gas purification catalyst which has a structure which prevents competitive adsorption of HC, CO, and NOx and enables effective utilization of an NOx storage reduction type catalyst. The exhaust gas purification catalyst of the present invention is characterized by having an NOx storage reduction type catalyst layer which contains at least one type of NOx storage material which is selected from an alkali metal or an alkali earth metal and Pt and/or Rh on a substrate and having an oxidation catalyst layer which carries Pt and/or Pd on the NOx storage reduction type catalyst layer.