| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas cleaning device which cleans an exhaust gas from an engine, has a simple structure and an improved heat resistance, and can efficiently remove HC from the exhaust gas at cold start of the engine. <P>SOLUTION: This cleaning device is placed at the upstream section 31a of an exhaust line 31 of an engine 30 and has a three way catalyst layer 1 composed mainly of a Pd-Rh catalyst component and a HC adsorption layer containing β-zeolite comprising Si and Al. While the adsorbent capability of the HC adsorption layer increases with the increase in the content of Al in the β-zeolite, the increase in temperature of the β-zeolite causes the composition of the β-zeolite to collapse in proportion to the Al content, thus decreasing the adsorption capacity. Therefore, the composition ratio of Si/Al is set in such a range that even when the temperature is raised, the composition of β-zeolite hardly collapses and the adsorption capacity of the HC adsorbent layer is kept high. <P>COPYRIGHT: (C)2004,JPO |
