Exhaust system for a lean-burn IC engine comprising a PGM component and a SCR catalyst

摘要

Methods are disclosed for reducing or preventing a selective catalytic reduction (SCR) catalyst disposed on a first substrate monolith in an exhaust system of a lean-burn internal combustion engine from becoming poisoned with platinum group metal (PGM) which may volatilize from a catalyst composition comprising PGM disposed on at least one second substrate monolith upstream of the SCR catalyst. The methods comprise adsorbing volatilized PGM in at least one PGM trapping material, which is disposed on a third substrate monolith disposed between the first substrate monolith and the second substrate monolith.

主权项

1. A method of reducing or preventing a selective catalytic reduction (SCR) catalyst disposed on a first substrate monolith in an exhaust system of a lean-burn internal combustion engine from becoming poisoned with platinum group metal (PGM) which may volatilise from a catalyst composition comprising PGM disposed on at least one second substrate monolith upstream of the SCR catalyst when the catalyst composition comprising PGM is exposed to relatively extreme conditions including relatively high temperatures, which method comprising adsorbing volatilised PGM in at least one PGM trapping material, where the at least one PGM trapping material is disposed on a third substrate monolith, and wherein the third substrate monolith is disposed between the first substrate monolith and the or each second substrate monolith, 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.