| 摘要 |
PURPOSE:To prevent decrease of catalytic purifying capacity for exhaust gas caused by the fluctuation of air/fuel ratio by supporting a specified amt. of CeO2 on a base material of a carrier at an upstream side of exhaust gas, and a smaller amt. of CeO2 on the base material of the carrier at a downstream side of the exhaust gas and allowing the carrier to support catalyst metal only at the downstream part. CONSTITUTION:A monolithic catalyst for purifying exhaust gas is constituted of a cylindrical base material 1 for a monolithic carrier made of cordierite, a layer 2 for supporting activated gamma-alumina formed on the surface of the base material 1, CeO2 and noble metal (Pt, Rh) catalyst component contained in the supporting-layer 2. 0.3-1.0mol./l CeO2 is supported by the base material 1 contained in the upstream part basing on the direction of the flow of the exhaust gas. Further, <=0.3mol./l CeO2 is supported by the base material at the downstream part 4, and the catalyst ingredients are supported by the base material at the same part. By this constitution, decrease of catalytic purifying capacity is kept at lower lever than conventional catalysts. |
