PROCESS FOR CATALYTIC REDUCTION OF NITROGEN OXIDES

摘要

A process which comprises combusting a fuel while oscillating the combustion atmosphere cyclically and alternately between rich and lean conditions, leading the formed exhaust gas to a catalytic converter, and bringing the exhaust gas into contact with a catalyst in the converter to conduct the catalytic reduction of nitrogen oxides contained in the gas, wherein the catalyst contains as the catalyst components (A) an oxide catalyst component consisting of (a) ceria, (b) praseodymium oxide, or (c) a mixture of oxides of at least two elements selected from among cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium, and lanthanum and/or a double oxid e of at least two elements selected from among the same and (B) a noble metal catalyst component consisting of (d) at least one member selected from among platinum, rhodium, palladium, and oxides of them and the oxygen concentratio n at the exit of the converter under rich condition is adjusted to 0.1 to 1.0 %.