Patent ID: 7422731

Claim:
A catalyst for catalytic direct decomposition of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, which catalyst comprises: (A) a first catalyst component comprising at least one metal selected from the group consisting of rhodium and palladium supported on zeolite; (B) a second catalyst component comprising at least one selected from the group consisting of (a) ceria, (b) praseodymium oxide, and (c) a mixture and/or a composite oxide of oxides of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and (C) a third catalyst component comprising (a) at least one selected from the group consisting of platinum, rhodium, palladium and oxides thereof, and (b) a carrier.