| abstract |
Exhaust gas treatment substrates, and systems and methods including the same are provided. Catalyst substrates having flow properties where in configuring an outer, peripheral zone, more exhaust gas flows through a central zone as compared to the outer, peripheral zone. The outer, peripheral zone can have a trapping or adsorbing material on surfaces of its passages, or it can have a longer axial length as compared to the inner zone, or its passages can have smaller openings as compared to the inner zone. In one embodiment, an overcoat containing a trapping material such as a hydrocarbon trap is applied to an inlet end. In another embodiment, catalyst having an oxygen storage component is applied to an outlet end. |