CATALYST FOR CLEANING EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To improve an HC cleaning capacity in a low temperature area by decreasing the amount of HC to be released until a noble metal supported on a catalyst layer is activated and activating the noble metal supported on the catalyst layer early in a catalyst for cleaning exhaust gas having the double layer structure of an HC adsorbing material layer and the catalyst layer. SOLUTION: The heat capacity of an HC adsorbing material layer is decreased on the upstream side of an exhaust gas flow and increased on the downstream side. Since the heat capacity of the HC adsorbing material layer 1 is large on the downstream side, the increase of temperature is difficult so that the HC desorbed on the upstream side can be re-adsorbed on the downstream side, and the amount of the HC to be released until the noble metal supported on the catalyst layer 2 is activated can be decreased.