Emission treatment system for treating an exhaust stream from an engine, and methods of treating an exhaust stream from a diesel engine and treating an exhaust gas stream from a diesel engine

摘要

An emission treatment system and method for remediating the nitrogen oxides (NOx), particulate matter, and gaseous hydrocarbons present in diesel engine exhaust streams are described. The emission treatment system has an oxidation catalyst upstream of a soot filter upstream from a NOx reducing catalyst. The diesel oxidation catalyst contains a catalyst effective to produce substantially no additional NO 2 and the catalyzed soot filter is effective to optimize the ratio of NO to NO 2 exiting the filter.