Oxidation catalyst with low CO and HC light-off and systems and methods
AssigneeBASF SE
InventorMichel Deeba
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Abstract
An oxidation catalyst for the treatment of exhaust gas emissions, such as the oxidation of unburned hydrocarbons (HC), and carbon monoxide (CO) and the reduction of nitrogen oxides (NOx) from a diesel engine and methods of exhaust gas treatment are disclosed. More particularly, a washcoat composition is disclosed comprising at least two washcoat layers, a first washcoat comprising palladium supported on ceria-zirconia and ceria-zirconia-alumina and a second washcoat containing one or more of platinum and palladium and one or more hydrocarbon storage components. An undercoat may also be included in the catalyst. Also disclosed are method of exhaust gas treatment and diesel exhaust gas treatment systems that include the oxidation catalyst and a downstream soot filter.
Claims26
An oxidation catalyst for abatement of exhaust gas emissions from an engine comprising:
- a carrier substrate;
- an undercoat coated on the carrier substrate, the undercoat comprising a refractory metal oxide support;
- and
- a first washcoat layer comprising a support material selected from ceria-zirconia and ceria-zirconia-alumina and a precious metal catalyst containing palladium (Pd), wherein said first washcoat layer does not contain a zeolite.
A method for treating a diesel exhaust gas stream comprising:
- contacting the exhaust gas stream with a top layer catalyst coated over a first catalyst layer, the top layer catalyst comprising a support material, one or more hydrocarbon storage components, and a precious metal catalyst containing one or more of platinum (Pt) and palladium (Pd);
- and
- after contacting the exhaust gas stream with the top layer catalyst, contacting the exhaust gas stream with a first catalyst layer comprising a support material selected from ceria-zirconia and ceria-zirconia-alumina and a precious metal catalyst containing palladium (Pd) and substantially no platinum, wherein said first catalyst layer does not contain a zeolite.
Dependencies are inferred from the claim text.