Provided is an emission treatment system and method for simultaneously
remediating the nitrogen oxides (NOx), particulate matter, and gaseous
hydrocarbons present in diesel engine exhaust streams. The emission
treatment system has an oxidation catalyst upstream of a soot filter
coated with a material effective in the Selective Catalytic Reduction
(SCR) of NOx by a reductant, e.g., ammonia. Also provided is a method for
disposing an SCR catalyst composition on a wall flow monolith that
provides adequate catalyst loading, but does not result in unsuitable
back pressures in the exhaust.