Patent attributes
The oxidation of nitrogen oxide (NO) in an oxygen-containing exhaust gas flow from a diesel or other lean-burn engine may be catalyzed using particles of co-precipitated and calcined manganese (Mn), cerium (Ce) and zirconium (Zr) mixed oxides. In preferred embodiments, the molar ratios of Mn, Ce and Zr to the total amount of base metals in the ternary mixed oxide catalyst are in the range of 0.25-0.35, 0.40-0.50 and 0.20-0.25, respectively. Further, this ternary mixed oxide catalyst is less susceptible to sulfur poisoning than previously-disclosed binary mixed oxide catalysts. The ternary mixed oxide catalyst may also be regenerated—and the inhibiting effect of SO2 reversed—by briefly exposing the catalyst to a reducing exhaust gas environment.
