| abstract |
An exhaust system ( 10 ) for a lean-burn internal combustion engine ( 12 ) comprises a first substrate monolith ( 16 ) comprising a catalyst for oxidising nitric oxide (NO) comprising a catalytic oxidation component followed downstream by a second substrate monolith ( 18 ) which is a wall-flow filter having inlet channels and outlet channels, wherein the inlet channels comprise a NO x absorber catalyst ( 20 ) and the outlet channels comprise a catalyst for selective catalytic reduction ( 22 ) of nitrogen oxides with nitrogenous reductant. |