Patent ID: 8071038
Filing Date: 2011-12-06
Classification: B01D,F01N,Y02T

Abstract:
1. An emission control system comprising: an exhaust passage for transporting the exhaust from the combustion engine; and a particulate filter and selective catalytic reduction (SCR/PF) unit disposed within the passage, the unit having a plurality of spaced filter walls extending axially along the passage and selective catalytic reduction catalyst variably loaded on the unit to provide a more uniform pressure drop relative to a unit having uniformly loaded catalyst, wherein the unit has more catalyst loading at least one of the axial ends of the unit and the unit has a washcoat loading concentration from 0.2 to 0.4 grams per cubic inch of filter at its axial center and a catalyst loading concentration from 0.7 to 1.25 grams per cubic inch of filter at least one of its axial ends.