| abstract |
An exhaust gas containing a large amount of pentane and CO discharged from HCCI combustion from a gasoline engine is efficiently purified. A first catalyst 27 on the upstream side and a second catalyst 28 on the downstream side each contain Pt and Rh as catalytic metals. In each of the catalysts 27 and 28, Pt is supported only on activated alumina, and Rh is Supported or doped on at least one of Ce-containing oxide and Ce-free oxide, and the Pt / Rh mass ratio of the first catalyst 27 is not less than 4 times and not more than 10 times the Pt / Rh mass ratio of the second catalyst 28. It is. [Selection] Figure 1 |