| 摘要 |
PROBLEM TO BE SOLVED: To provide a method which burns a fuel supplied in a periodical rich/lean fuel feeding system in the presence of oxygen, sulfur oxides or water, or at a high temperature, and performs a catalytic decomposition of NOx with high durability in an exhaust gas generated by the combustion. SOLUTION: In the method for performing the catalytic reduction of nitrogen oxides in the exhaust gas by burning the fuel by supplying the fuel under the periodical rich/lean condition and containing the generated exhaust gas with the catalyst, the catalyst comprises (A) a surface catalyst layer having as a surface catalyst ingredient a mixture of oxides of at least two elements selected from (a) cerium oxide (b) praseodymium oxide or (c) oxides of cerium, ziruconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum, and at least one selected from complex oxides of at least two these elements and (B) an inner catalyst layer having as inner catalyst ingredients (a) at least one selected from platinum, rhodium, palladium, platinum oxide, rhodium oxide and palladium oxide, (b) an NOx absorbent/adsorbent and (c) a carrier. |
