WALL-FLOW FILTER COMPRISING CATALYTIC WASHCOAT
First Claim
1. A catalysed honeycomb wall-flow filter for treating exhaust gas comprising particulate matter emitted from an internal combustion engine, which filter comprising a honeycomb substrate having a first end and a second end and comprising an array of interconnecting porous walls defining an array of longitudinally extending first channels and second channels, wherein the first channels are bordered on their sides by the second channels and have a larger hydraulic diameter than the second channels, wherein the first channels are end-plugged at a first end of the honeycomb substrate and the second channels are end-plugged at a second end of the honeycomb substrate, wherein channel wall surfaces of the first channels comprise an on-wall-type catalytic washcoat.
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Accused Products
Abstract
A catalysed honeycomb wall-flow filter for treating exhaust gas comprising particulate matter emitted from an internal combustion engine, which filter comprising a honeycomb substrate having a first end and a second end and comprising an array of interconnecting porous walls defining an array of longitudinally extending first channels and second channels, wherein the first channels are bordered on their sides by the second channels and have a larger hydraulic diameter than the second channels, wherein the first channels are end-plugged at a first end of the honeycomb substrate and the second channels are end-plugged at a second end of the honeycomb substrate, wherein channel wall surfaces of the first channels comprise an on-wall-type catalytic washcoat. The invention also relates to an exhaust system comprising the catalysed filter and to methods of making it.
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Citations
21 Claims
- 1. A catalysed honeycomb wall-flow filter for treating exhaust gas comprising particulate matter emitted from an internal combustion engine, which filter comprising a honeycomb substrate having a first end and a second end and comprising an array of interconnecting porous walls defining an array of longitudinally extending first channels and second channels, wherein the first channels are bordered on their sides by the second channels and have a larger hydraulic diameter than the second channels, wherein the first channels are end-plugged at a first end of the honeycomb substrate and the second channels are end-plugged at a second end of the honeycomb substrate, wherein channel wall surfaces of the first channels comprise an on-wall-type catalytic washcoat.
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4. A catalysed honeycomb substrate having a first end and a second end and comprising an array of interconnecting porous walls defining an array of longitudinally extending first channels and second channels, wherein the first channels are bordered on their sides by the second channels, wherein the first channels of the honeycomb substrate are open at both the first end and the second end of the honeycomb substrate and wherein the second channels are open at the first end of the honeycomb substrate but are blocked with end plugs at the second end of the honeycomb substrate;
- and a first catalytic washcoat is disposed on surfaces of the porous channel walls of the first channels, permeates the porous channel walls of the first channels or is both disposed on a surface of the porous channel walls and permeates the porous channel walls of the first channels, which first catalytic washcoat being defined at one end by the second end of the honeycomb substrate.
- View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of making a catalysed wall-flow filter substrate for treating exhaust gas comprising particulate matter emitted from an internal combustion engine, which method comprising providing a honeycomb flow-through substrate monolith having a first end and a second end, having physical properties and parameters pre-selected for use in a honeycomb wall-flow filter substrate and comprising an array of interconnecting porous walls defining an array of longitudinally extending first and second channels which are open at both the first end and the second end of the honeycomb flow-through substrate monolith, wherein the first channels are bordered on their sides by the second channels and have a larger hydraulic diameter than the second channels, contacting at least porous channel wall surfaces which define the first channels of the honeycomb flow-through substrate monolith with a liquid catalytic washcoat, wherein at least one of:
- a liquid catalytic washcoat solids content;
a liquid catalytic washcoat rheology;
a porosity of the flow-through substrate monolith;
a mean pore size of the flow-through substrate monolith;
a liquid catalytic washcoat volumetric mean particle size; and
a liquid catalytic washcoat D90 (by volume), is pre-selected so that the liquid catalytic washcoat remains on a surface of the porous channel walls of the first channels or both remains on the surface of the porous channel walls and permeates the porous channel walls of the first channels;
drying and calcining the coated honeycomb flow-through substrate monolith; and
inserting end plugs into open ends of the first channels at the first end of the honeycomb flow-through substrate monolith and into open ends of the second channels at a second end of the honeycomb flow-through substrate monolith to form the catalysed wall-flow filter substrate. - View Dependent Claims (18, 19, 20, 21)
- a liquid catalytic washcoat solids content;
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15. A method of making a catalysed wall-flow filter substrate for treating exhaust gas comprising particulate matter emitted from an internal combustion engine, which method comprising providing a honeycomb substrate monolith having a first end and a second end, having physical properties and parameters pre-selected for use in a honeycomb wall-flow filter substrate and comprising an array of interconnecting porous walls defining an array of longitudinally extending first and second channels, wherein the first channels are bordered on their sides by the second channels, wherein the first channels are open at both the first and the second end of the honeycomb substrate monolith and the second channels are open at the first end of the honeycomb substrate monolith but are blocked with end plugs at the second end thereof, contacting porous channel wall surfaces which define the first channels of the honeycomb substrate monolith with a liquid catalytic washcoat to produce a coated honeycomb substrate monolith, wherein at least one of:
- a liquid catalytic washcoat solids content;
a liquid catalytic washcoat rheology;
a porosity of the honeycomb substrate monolith;
a mean pore size of the honeycomb substrate monolith;
a liquid catalytic washcoat volumetric mean particle size; and
a liquid catalytic washcoat D90 (by volume), is pre-selected so that at least some of the liquid catalytic washcoat remains on a surface of the porous channel walls of the first channels, permeates the porous channel walls of the first channels or both remains on the surface of the porous channel walls and permeates the porous channel walls of the first channels;
drying and calcining the coated honeycomb substrate monolith; and
inserting end plugs into open ends of the first channels at the first end of the honeycomb substrate monolith to form the catalysed wall-flow filter substrate. - View Dependent Claims (16, 17)
- a liquid catalytic washcoat solids content;
Specification