EXHAUST GAS PURIFYING APPARATUS AND PRODUCTION THEREOF

摘要

PROBLEM TO BE SOLVED: To enhance the purifying capacity of an NOx catalyst in an exhaust gas purifying apparatus equipped with the NOx catalyst containing zeolite having a noble metal supported thereon and purifying NOx in exhaust gas even within an oxygen excessive atmosphere. SOLUTION: A powder of MFI type zeolite and water are charged in an autoclave and an aq. soln. of platinum Pt is added to the mixture of the zeolite powder and water to perform stirring. The resulting slurry is held to about 120 deg.C for 6 hr to perform ion exchange and allowed to stand to cool and filtered to obtain a solid which is, in turn, washed with water and further dried and baked to obtain a Pt+-MFI catalyst powder. This catalyst powder is applied to a carrier 2 by wash coating to form a catalyst layer 3.