CATALYST AND METHOD FOR CONTACT DECOMPOSITION OF NITROGEN OXIDE

摘要

A catalyst for the direct reductional decomposition of nitrogen oxides contained in an exhaust gas generated by feeding and burning a fuel under periodic rich/lean conditions, by contacting the gas with the catalyst, characterized by comprising: (A) a first catalyst ingredient which comprises a zeolite and, supported thereon, at least one metal selected between rhodium and palladium; (B) a second catalyst ingredient which comprises at least one member selected among (a) ceria, (b) praseodymium oxide, and (c) a mixture of oxides of at least two elements selected among cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium, and lanthanum and/or a composite oxide of the at least two elements; and (C) a third catalyst ingredient which comprises (a) at least one member selected among platinum, rhodium, palladium, and oxides of these and (b) a support.