| abstract |
PURPOSE: To selectively purify NOx even in the lean atmosphere by allowing zeolite to carry one or more kinds of metal selected from among Pt, Pd, Rh and Ir by ion exchange and forming a catalyst for purifying exhaust gas. n CONSTITUTION: Synthetic zeolite is treated with a soln. incorporating one or more kinds of metallic ion selected from the group of Pt, Pd, Rh and Ir and allowed to carry the metallic ion by ion exchange. Then this synthetic zeolite is kneaded with a binder consisting of alumina sol and silica sol and the carrier is provided with a wash coat by the obtained slurry and thereafter calcined to produce a catalyst for purifying exhaust gas. When using this catalyst, NOx incorporated in exhaust gas is selectively taken into the narrow pores of the catalytic zeolite and allowed to react with active metal in the narrow pores and decomposed. n COPYRIGHT: (C)1989,JPO&Japio |