NON-STOICHIOMETRIC PEROVSKITE OXIDE OXIDATION CATALYST FOR OXIDIZING NO TO NO2

摘要

A non-stoichiometric perovskite oxide having the general chemical formula La_XMnO_Y, in which the molar ratio of lanthanum to manganese (“X”) ranges from 0.85 to 0.95, can be used in particle form as an oxidation catalyst to oxidize NO to NO₂ in an exhaust aftertreatment system for a hydrocarbon-fueled engine. The oxygen content (“Y”) fluctuates with variations in the molar ratio of lanthanum to manganese but generally falls somewhere in the range of 3.0 to 3.30. The crystal lattice adjustments spurred by the non-stoichiometric molar ratio of lanthanum to manganese are believed responsible for an enhanced NO oxidative activity relative to similar perovskite oxides with a higher molar ratio of lanthanum and manganese.