| 摘要 |
PROBLEM TO BE SOLVED: To exhibit high NOx purifying performance even in a low temp. region by forming an exhaust gas purifying catalyst used for reducing and purifying nitrogen oxide in an excess oxygen containing exhaust gas from a 1st and a 2nd catalyst each obtained by carrying a catalyst noble metal on a porous carrier, and heat treating. SOLUTION: As the exhaust gas purifying catalyst purifying the exhaust gas, the 1st and the 2nd catalyst each obtained by carrying the catalyst noble metal on the porous carrier and heat treating are used. The 1st porous carrier of the 1st catalyst is composed of one kind selected from alumina and silica based porous body and, as the 1st catalyst carried thereon, one kind of platinum, palladium, rhodium is used. On the other hand, as the 2nd porous carrier of the 2nd catalyst, zirconium oxide, titanium oxide or the like is used and, as the 2nd catalyst carried thereon, the same one as the 1st catalyst is used. The 1st catalyst is heat treated in a oxidizing atmosphere and the 2nd catalyst is heat treated in a non-oxidizing atmosphere. |
