CERAMIC CATALYST FOR NOX OXIDATION AND NOX CONVERSION IN EMISSION CONTROL SYSTEMS

摘要

Ceramic catalytic compositions, systems, and methods for oxidizing, converting and/or removing NO_Xgas species present in gas streams such as exhaust gases are provided. The catalysts of the invention oxidize the nitrogen monoxide (NO) in gas streams to nitrogen dioxide (NO₂), which may be adsorbed by a metal oxide or other NO₂ adsorber. Catalysts suitable for use in systems of the present invention include ceramic oxides, mixtures of ceramic oxides, complex ceramic oxides, and mixtures of complex ceramic oxides. Such catalysts are shown herein to successfully achieve an NO-NO₂ equilibrium gas composition at temperatures as low as 275°C. In addition, by using the catalyst with an NO₂ adsorber, greater than 95% removal of combined NO and NO₂ from the gas stream has been successfully demonstrated. Further, specific strategies have been identified to regenerate the catalyst system and restore performance after prolonged exposure to species such as sulfur dioxide (SO₂).