| 摘要 |
PROBLEM TO BE SOLVED: To lower the ignition temp. of soot, to enable a combustion of PM at an exhaust gas temp. and to simplify a DPF system by using a perovskite type composite oxide having a specified chemical composition as a catalyst for purifying the exhaust gas. SOLUTION: The perovskite type composite oxide is produced by a method in which an aq. soln. of lanthanum nitrate, strontium nitrate, iron nitrate, zinc nitrate and citric acid is stirred and concentrated to obtain a citric acid complex, and after drying the complex, the complex is heated to decompose the complex. This perovskite type composite oxide has a chemical composition of a general formula, Ax A'1-x By B'1-y O3 (where, A is La; A' is Sr and/or Ca; B is Fe and/or Y; B' is Fe, Zn or Mg; 0.5<x<=1 and 0.5<y<=1). The soot contained in the exhaust gas from a diesel engine is burned at low temp. with this catalyst for purifying the exhaust gas. |
