| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a catalyst system for exhaust emission control capable of sufficiently matching the timing of starting of exhaust emission control by delaying the separation of the HC from a HC adsorbent material layer, and improving exhaust emission efficiency of the cold HC. <P>SOLUTION: The catalyst system has multiple HC adsorbing type three-way catalysts arranged, comprising the HC adsorbing material layer containing a three way catalyst on the upstream side and a zeolite on the downstream side of an exhaust gas flow passage, and a purifying catalyst component layer containing catalytic metals laminated inside a polygonal carrier cell. The multiple HC adsorbing type three-way catalysts are arranged so that the number of sides of the carrier cell (the number of corners) increases toward the downstream side of the exhaust gas flow passage. <P>COPYRIGHT: (C)2004,JPO |
