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AssigneeJohnson Matthey Public Limited Company
InventorsRobert James Brisley, Martyn Vincent Twigg, Anthony John Joseph Wilkins
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A wall-flow filter (10) for an exhaust system of a combustion engine comprises: a plurality of channels (4,6,8) in honeycomb arrangement, wherein at least some of the channels (6) are plugged (12) at an upstream end and at least some of the channels (4,8) not plugged at the upstream end are plugged (14) at a downstream end; an oxidation catalyst (16) on a substantially gas impermeable zone at an upstream end of the channels (4,8) plugged at the downstream end; and a gas permeable filter zone (22) downstream of the oxidation catalyst for trapping soot, characterised in that in an exhaust system, preferably a diesel exhaust system, the oxidation catalyst is capable of generating sufficient NO2 from NO to combust the trapped soot continuously at a temperature less than 400° C.
A method for treating soot-containing exhaust gas with a wall-flow filter comprising the steps of:
A process for treating soot-containing exhaust gas comprising the steps of first passing the soot-containing exhaust gas over an oxidation catalyst to convert NO in the exhaust gas to NO2, then filtering the gas to deposit soot on a filter disposed in an exhaust system of a combustion engine wherein the exhaust gas containing NO2 is used to combust the soot trapped on the filter, the amount of NO converted to NO2 being sufficient to enable combustion of soot trapped on the filter to proceed at a temperature less than 400° C., wherein the filter is a wall-flow filter comprising:
Dependencies are inferred from the claim text.