| abstract |
A substrate monolith 6 has a length L and comprises a first zone 11 comprising a selective catalytic reduction (SCR) catalyst for reducing oxides of nitrogen with a nitrogenous reductant in exhaust gas emitted from an internal combustion engine. A second zone 8 has a length less than L, and comprises means for trapping a gas phase platinum group metal (PGM). The trapping means may be either (a) at least one particulate metal oxide, or a mixture of any two or more thereof, which does not act as a support for any other catalytic component, or (b) a component capable of trapping and/or alloying with gas phase PGM. The substrate monolith may be used an internal combustion engine of a vehicle, and reduces contamination of the SCR by trapping gas phase platinum group metals before they reach the SCR. |