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AssigneeJohnson Matthey Public Limited Company
InventorsLouise Clare Arnold, Robert James Brisley, Neil Robert Collins, David Robert Greenwell, Christopher Gough Morgan
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An exhaust system for a vehicular positive ignition internal combustion engine comprises a filter for filtering particulate matter from exhaust gas emitted from the engine, which filter comprising a porous substrate having inlet and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores of a first mean pore size, wherein the porous substrate is coated with a three-way catalyst washcoat comprising a plurality of solid particles wherein the porous structure of the washcoated porous substrate contains pores of a second mean pore size, which is less than the first mean pore size, and a three-way catalyst washcoat disposed on a separate substrate monolith located upstream of the filter, wherein a mass of three-way catalyst washcoat on the upstream substrate monolith is ≦75% of the total mass of three-way catalyst washcoat in the exhaust system.
An exhaust system for a vehicular positive ignition internal combustion engine which system comprising a filter for filtering particulate matter from exhaust gas emitted from the engine, which filter comprising a porous substrate having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores of a first mean pore size, wherein the porous substrate is coated with a three-way catalyst washcoat comprising a plurality of solid particles wherein the porous structure of the washcoated porous substrate contains pores of a second mean pore size, and wherein the second mean pore size is less than the first mean pore size and a three-way catalyst washcoat disposed on a separate substrate monolith located upstream of the filter, wherein a mass of three-way catalyst washcoat on the upstream substrate monolith is ≦75% of the total mass of three-way catalyst washcoat in the exhaust system.
A method of trapping and combusting particulate matter (PM) from exhaust gas emitted from a positive ignition engine by depth filtration, which method comprising directing the exhaust gas containing the PM into an exhaust system, contacting the exhaust gas containing the PM with a three-way catalyst washcoat disposed on a substrate monolith within the exhaust system, contacting exhaust gas containing the PM with a filter in the exhaust system downstream of the three-way catalyst substrate monolith, which filter comprising a porous substrate having inlet and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores of a first mean pore size, wherein the porous substrate is coated with a three-way catalyst washcoat comprising a plurality of solid particles wherein the porous structure of the washcoated porous substrate contains pores of a second mean pore size, and wherein the second mean pore size is less than the first mean pore size, wherein a mass of three-way catalyst washcoat on the substrate monolith is ≦75% of the total mass of three-way catalyst washcoat in the exhaust system.
Dependencies are inferred from the claim text.