Patent ID: 8006485

Claim:
A process for operating an apparatus comprising a compression ignition engine configured to operate in a first, normal running mode to produce exhaust gas and in a second mode, wherein when operating in the second mode, the engine produces an exhaust gas comprising an increased level of carbon monoxide (CO) relative to the exhaust gas of the first mode, means when in use to switch engine operation between the two modes and an exhaust system comprising a catalysed component of an oxidation catalyst or a NO oxidation catalyst, wherein when the catalysed component is the NO oxidation catalyst, a filter is located downstream of a catalyst component, and wherein the catalysed component comprises a flow through, non-filtered substrate monolith comprising a palladium (Pd) catalyst supported on a first support material associated with at least one base metal promoter and a platinum (Pt) catalyst associated with the supported Pd catalyst, which process comprising running the engine in the first, normal running mode and switching the engine to the second running mode producing a value of at least one measurable parameter indicative of a condition of the engine is outside a pre-determined range, and wherein the substrate monolith comprises an arrangement of the Pd catalyst and Pt catalyst components selected from the group consisting of: (a) a first layer comprising the Pt catalyst and a second layer overlying the first layer, which second layer comprising the supported Pd catalyst and the associated at least one base metal promoter; and (b) a Pt catalyst located downstream of the supported Pd catalyst and the associated at least one base metal promoter.