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AssigneeJohnson Matthey Public Limited Company
InventorsKIERAN COLE, COLIN NEWMAN, ISABEL TINGAY, OLIVIER SONNTAG, GUDMUND SMEDLER, RUTH SAVAGE
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A catalytic aftertreatment system for a diesel engine exhaust gas is described. The system comprises a diesel oxidation catalyst (DOC) and an aftertreatment device located downstream of the diesel oxidation catalyst (DOC), which aftertreatment device requires periodic heat treatment, and means to generate a temperature increase within the aftertreatment device, said diesel oxidation catalyst (DOC) comprising an upstream zone of length from 0.5 to 2 inches (12.7-50.81 mm) of higher oxidation activity for hydrocarbons (HC) than the remainder of the diesel oxidation catalyst (DOC).
A catalytic aftertreatment system for a diesel engine exhaust gas, said system comprising a diesel oxidation catalyst (DOC) and an aftertreatment device located downstream of the diesel oxidation catalyst (DOC), which aftertreatment device requires periodic heat treatment, and means to generate a temperature increase within the aftertreatment device, said diesel oxidation catalyst (DOC) comprising an upstream zone of length from 0.5 to 2 inches (12.7-50.81 mm) of higher oxidation activity for hydrocarbons (HC) than the remainder of the diesel oxidation catalyst (DOC).
A method of maintaining diesel oxidation catalyst (DOC) activity during active heat treatment of an aftertreatment device located downstream of the diesel oxidation catalyst (DOC) in a diesel engine exhaust gas aftertreatment system, at exhaust gas temperatures of 200 to 375° C., by passing the exhaust gas over a diesel oxidation catalyst (DOC) comprising an upstream zone of length from 0.5 to 2 inches (12.7 to 50.81 mm) of higher oxidation activity for hydrocarbons (HC) than the remainder of the diesel oxidation catalyst (DOC).
A method of avoiding extinction of a diesel oxidation catalyst (DOC) during an active heat treatment event for an aftertreatment device located downstream of the diesel oxidation catalyst (DOC), at an exhaust gas temperature of 200 to 375° C., by passing exhaust gas enriched with hydrocarbons (HC) over a diesel oxidation catalyst (DOC) comprising an upstream zone of length from 0.5 to 2 inches (12.7 to 50.81 mm) of higher oxidation activity for hydrocarbons (HC) than the remainder of the DOC.
Dependencies are inferred from the claim text.