| 摘要 |
PROBLEM TO BE SOLVED: To improve NOx cleaning performance in a lean atmosphere by preparing such a catalyst that contains alumina or zeolite which carries one or more kinds of noble metals selected from platinum, palladium, rhodium and iridium and contains a multiple oxide expressed by the formula, and by depositing platinum, on zeolite. SOLUTION: As for the noble metal in the catalyst for cleaning of exhaust gas, at least one kind selected from platinum, palladium, rhodium and iridium is used. As for the base body to carry the noble metal, a heat-resistant inorg. material having a large specific surface area is preferable, especially so as to maintain the dispersibility of the noble metal after the catalyst is used for a long time, and alumina or zeolite is preferably used. The multiple oxide included in the catalyst is expressed by (La1-x Ax )1-αBO1-δ , wherein x, α and δsatisfy 0<x<1, 0<α<0.2, 0ηδ<1, and A is barium and/or potassium, B is least one element selected from iron, cobalt, nickel and manganese, and this multiple oxide contains lanthanum, potassium, barium, iron etc. |
