| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent the generation of sulfate and to reduce the discharge of particulates. SOLUTION: The quantity of noble metal supported on the surface layer of the secondary particles of a porous material on the incoming gas side located upstream in an exhaust gas flow is made greater than that on the outgoing gas side located downstream. Since HC is oxidized easily as compared with SO2 , HC is oxidized preferentially on the incoming gas side, while the oxidation of SO2 is controlled on the outgoing gas side because of poor Pt on the surface layer. Therefore, the oxidation of SO2 is prevented by the catalyst as a whole. |
