Patent ID: 7722845

Claim:
A method for treating emissions produced in the exhaust gas stream of a diesel or lean-burn vehicle, the method comprising: passing a vehicle's engine exhaust stream through at least a NO x abatement catalyst composition; and passing the exhaust stream exiting the NO x abatement catalyst composition and possibly containing ammonia through a bifunctional oxidation catalyst composition effective for oxidizing ammonia, the bifunctional oxidation catalyst composition comprising a first catalyst for catalyzing the oxidation of ammonia, the first catalyst consisting essentially of platinum supported on a refractory metal oxide selected from alumina, silica, zirconia, titania, and physical mixtures or chemical combinations thereof, including atomically doped combinations, and a second catalyst for improving N 2 selectivity, the second catalyst comprising a second metal from one of the groups VB, VIB, VIIB, VIIIB, IB, or IIB of the periodic table supported on a zeolite.