Patent ID: 8668891

Claim:
An exhaust system for a vehicular lean-burn internal combustion engine, which system comprising: (a) a first substrate monolith comprising a SCR catalyst; (b) at least one second substrate monolith comprising a catalytic washcoat coating comprising at least one platinum group metal (PGM), which at least one second substrate monolith is disposed upstream of the first substrate monolith; and (c) a third substrate monolith disposed between the first substrate monolith and the or each second substrate monolith, wherein at least one PGM on the or each second substrate monolith is liable to volatilise when the or each second substrate monolith is exposed to relatively extreme conditions including relatively high temperatures, and wherein the third substrate monolith comprises at least one material for trapping volatilised PGM, and wherein: (i) the first substrate monolith is a filtering substrate monolith having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure; or (ii) the second substrate monolith or each second substrate monolith is a filtering substrate monolith having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure.