| 摘要 |
PROBLEM TO BE SOLVED: To provide a composite catalyst with high NOx removing efficiency by employing a first catalyst comprising a Pt-carrying zeolite and CeO2 having a specified average crystal diameter and a second catalyst comprising H-type zeolite or a Pt- or Au-carrying zeolite. SOLUTION: In a composite catalyst for exhaust gas purification comprising a first and a second catalysts, the first catalyst is produced from Pt-carrying zeolite and CeO2 having average crystal diameter D>=13.0 nm. The amount of the Pt-carrying zeolite of the first catalyst is controlled to 19-100 wt.% and the amount of deposited Pt is controlled to be 3.5-11 wt.%. On the other hand, the second catalyst is produced from an least one of a H-type zeolite, a Pt- carrying zeolite, and an Au-carrying zeolite. The SiO2 /Al2 O3 mole ratio of the H-type zeolite is controlled to be SiO2 /Al2 O3 <=300 and the amount of deposited Pt of the Pt-carrying zeolite is controlled to be 0.1-5 wt.%. |
