An exhaust system for a lean-burn internal combustion engine comprising a PGM component and an SCR catalyst

摘要

Described is an exhaust system 10 for a lean-burn vehicle internal combustion engine comprising the following components: (a) a first substrate monolith 6 comprising an SCR catalyst; (b) at least one second substrate monolith 4 comprising a catalytic washcoat coating comprising at least one platinum group metal (PGM), wherein the at least one second substrate monolith is disposed upstream of the first substrate monolith, and (c) a third substrate monolith 2 interposed between the at least one PGM on the or each second substrate monolith 4 is susceptible to volatilization when the or each second substrate monolith 4 is exposed to relatively extreme conditions including relatively high temperatures, and wherein the third substrate monolith 2 comprises a washcoat coating comprising at least one metal oxide for capturing volatilized PGM.