EXHAUST GAS PURIFYING CATALYST

文件类型：PDF文档
文件大小：677K
An exhaust gas purifying catalyst includes a substrate (1) that defines an exhaust gas passage; a lower catalyst layer (2) formed over the substrate, and an upper catalyst layer (3) formed over the lower catalyst layer (2). The lower catalyst layer (2) has a lower catalytic precious metal that contains at least one of Pt and Pd, and a lower-layer carrier that supports the lower catalytic precious metal. The upper catalyst layer (3) has an upper catalytic precious metal that contains Rh, and an upper-layer carrier that supports the upper catalytic precious metal. The upper-layer carrier comprises an inorganic mixed oxide that contains Ce, Zr, Al, Nd, and at least one element selected from the group consisting of rare earth elements other than Ce. The inorganic mixed oxide has interior regions containing a mixed aggregate composed of first particles comprising Ce and Zr in a form of a composite oxide, and second particles comprising Al in a form of alumina, and has cover layers containing Nd that cover surfaces of the respective interior regions. The Nd is unevenly present in the cover layers or the Nd is concentrated in the cover layers.