Crossflow PNA-SCR aftertreatment device

An exhaust aftertreatment system, comprising:

• a cross-flow selective catalytic reduction catalyst, comprising:
• a housing defining a first inlet in exhaust gas receiving communication with an engine, and
• a substrate assembly positioned within the housing, the substrate assembly comprising:
• a plurality of first substrate layers defining a plurality of first flow channels, the plurality of first substrate layers being uncoated, and
• a plurality of second substrate layers defining a plurality of second flow channels, the plurality of second substrate layers comprising a selective catalytic reduction washcoat;
• and
• a passive NOx adsorber, comprising:
• a housing, comprising:
• an inlet in exhaust gas receiving communication with the plurality of first flow channels of the cross-flow selective catalytic reduction catalyst, and
• an outlet in exhaust gas providing communication with the plurality of second flow channels of the cross-flow selective catalytic reduction catalyst, and
• a substrate positioned in the housing, the substrate comprising a passive NOx adsorber washcoat.