Exhaust System
AssigneeJohnson Matthey Public Limited Company
InventorsGavin BROWN, Andrew CHIFFEY, Jonathan RADCLIFFE
Life of this patent
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Abstract
An exhaust system for an internal combustion engine, the exhaust system comprising, a lean NOx trap (LNT), a wall flow monolithic substrate having a NOx storage and reduction zone thereon, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater, the NOx storage and reduction zone comprising a platinum group metal loaded on a first support, the first support comprising one or more alkaline earth metal compounds, a mixed magnesium/aluminium oxide, cerium oxide, and at least one base metal oxide selected the group consisting of copper oxide, manganese oxide, iron oxide and zinc oxide.
Claims23
An exhaust system for an internal combustion engine, the exhaust system comprising,
- a) a lean NOx trap,
- b) a wall flow monolithic substrate having a NOx storage and reduction zone thereon, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater, the NOx storage and reduction zone comprising a platinum group metal loaded on a first support, the first support comprising one or more alkaline earth metal compounds, a mixed magnesium/aluminium oxide, cerium oxide, and at least one base metal oxide selected the group consisting of copper oxide, manganese oxide, iron oxide and zinc oxide.
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The exhaust system according to clam 1, wherein the wall flow monolithic substrate comprises pores having a diameter, the pores of the wall flow monolithic substrate have a pre-coated mean pore diameter in the range 9 μm to 25 μm.
A catalytic wall flow monolithic substrate, the wall flow monolithic substrate having a NOx storage and reduction zone thereon, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater , the NOx storage and reduction zone comprising a platinum group metal loaded on a first support, the first support comprising an alkaline earth metal compound a mixed magnesium/aluminium oxide, cerium oxide, and a base metal oxide selected from copper oxide, manganese oxide, iron oxide or zinc oxide.
A method of making a catalysed monolithic substrate, the method comprising
- a) providing a wall flow monolithic substrate, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater preparing a NOx storage and reduction zone washcoat comprising a source of a platinum group metal, a source of an alkaline earth metal compound and a mixed magnesium/aluminium oxide, cerium oxide, and at least one base metal oxide selected from the group consisting of copper oxide, manganese oxide, iron oxide and zinc oxide, and
- b) applying the NOx storage and reduction zone washcoat to at least a first portion of the monolithic substrate.
Dependencies are inferred from the claim text.