Patent ID: 8216521

Claim:
An exhaust gas aftertreatment system for treating an engine-out exhaust gas feedstream of a spark-ignition direct-injection engine, comprising: a multi-stage catalytic converter comprising a converter inlet, a converter outlet, and a substrate having a first end associated with the converter inlet and a second end associated with the converter outlet, the substrate further comprising a multiplicity of flow passages between the first and second ends of the substrate, a first surface location corresponding to the first end of the substrate, and a second surface location corresponding to the second end of the substrate; a first washcoat stage applied to the substrate at the first surface location corresponding to the first end of the substrate; a second washcoat stage applied to the substrate at the second surface location corresponding to the second end of the substrate; wherein the first and second washcoat stages comprising washcoats formulated to generate hydrogen and ammonia from the engine-out exhaust gas feedstream; and an ammonia-selective catalytic reduction device downstream of the first and second washcoat stages.