Patent ID: 8734743

Claim:
A nitrogen oxide storage catalyst comprising: a substrate; a first washcoat layer provided on the substrate, the first washcoat layer comprising a nitrogen oxide storage material, wherein the nitrogen oxide storage material comprises at least one metal compound selected from the group consisting of alkali metal compounds, alkaline earth metal compounds, rare earth metal compounds, and mixtures thereof, a second washcoat layer provided on the first washcoat layer, the second washcoat layer comprising a hydrocarbon trap material, wherein the hydrocarbon trap material comprises a zeolite, wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing selective catalytic reduction, said catalyst further comprising a nitrogen oxide conversion material which is either comprised in the second washcoat layer and/or in an optional washcoat layer provided between the first washcoat layer and the second washcoat layer.