Patent ID: 8545779

Claim:
A method of promoting the oxidation of NO to NO 2 in an exhaust stream of an operating diesel engine, the exhaust stream being at a temperature of up to 900° C. and also comprising sulfur-containing gases, the method comprising: bringing the exhaust stream into reactive contact with a sulfur-tolerant perovskite of general chemical formula ABO 3 , where ‘A’ and ‘B’ are each distinguishable elemental cations, the perovskite comprising; one ‘A’ cation selected from the group consisting of Tm, Hg, Na, Yb, Pr, Nd, Pm, Sm, Ag, Tb, Ho, Y, Er, Lu, Pd, Ti, Cr, In, Pt, V, Li, Sb, Sc, Sc, Cu, Mg, Nb, Ta, Mo, Ru and Mn; and one ‘B’ cation selected from the group consisting of Ge, Se, Tm, Ga and I.