Exhaust gas treatment unit for the selective catalytic reduction of nitrogen oxides under lean exhaust gas conditions and a process for the treatment of exhaust gases
AssigneeUmicore AG & Co. KG
InventorsMarcus Pfeifer, Paul Spurk, Jurgen Gieshoff, Yvonne Demel, Egbert Lox, Thomas Kreuzer
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Abstract
An exhaust gas treatment unit for the selective catalytic reduction of nitrogen oxides under lean exhaust gas conditions which contains at least one catalyst with catalytically active components for selective catalytic reduction (SCR components). The exhaust gas treatment unit is characterised in that the catalyst also contains, in addition to SCR components, at least one storage component for nitrogen oxides (NOx components).
Claims28
An exhaust gas treatment unit for the selective catalytic reduction of nitrogen oxides under lean exhaust gas conditions comprising at least one catalyst with a catalytically active component for selective catalytic reduction and at least one storage component for nitrogen oxides.
A process for removing nitrogen oxides from lean exhaust gas from an internal combustion engine by selective catalytic reduction using ammonia, comprising passing the exhaust gas over a catalyst which contains a catalytically active component for selective catalytic reduction (SCR component) and a storage component for nitrogen oxides (NOx component), with at least the occasional supply of ammonia, wherein the NOx storage component absorbs the nitrogen oxides from the exhaust gas during operational phases of the engine with exhaust gas temperatures below the light-off temperature for the component for selective catalytic reduction and the nitrogen oxides are desorbed at exhaust gas temperatures above the light-off temperature for selective catalytic reduction by supplying ammonia and react with ammonia, together with the nitrogen oxides present in the exhaust gas, on the SCR component to give nitrogen and water.
Dependencies are inferred from the claim text.