Catalytic filter having a soot catalyst and an SCR catalyst
AssigneeJohnson Matthey Public Limited Company
InventorsGuy Richard Chandler, Paul Richard Phillips
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Abstract
A catalytic filter is provided having a mixture of an SCR catalyst and soot oxidation catalyst where the soot oxidation catalyst is a copper doped ceria, iron doped ceria or manganese doped ceria. The mixture of an SCR catalyst and soot oxidation catalyst provides for a lowering of the peak oxidation temperature for soot removal from the filter. The use of the filter allows for improved soot combustion and reduces the susceptibility of an SCR catalyst contained on a filter to deterioration. The soot oxidation catalyst also improves the resistance of the SCR catalyst to poisoning and subsequent deterioration of SCR performance.
Claims28
A composition comprising a mixture of an SCR catalyst and a soot catalyst comprising copper doped ceria, iron doped ceria or manganese doped ceria, wherein the composition is formulated for application to a filter.
A filter comprising an SCR catalyst and a soot catalyst comprising copper doped ceria, iron doped ceria or manganese doped ceria, where the SCR catalyst and the soot catalyst are present on the filter as a mixture.
A system for treating a lean burn exhaust gas comprising:
- (a) a nitrogenous reducing agent injector;
- and (b) a catalytic filter comprising (i) an SCR catalyst and (ii) a soot catalyst comprising copper doped ceria, iron doped ceria or manganese doped ceria, where the SCR catalyst and the soot catalyst are present on the filter as a mixture and the injector is disposed upstream of, and is in fluid communication with, the catalytic filter.
A method for treating a lean burn exhaust gas comprising (a) flowing a lean burn exhaust gas stream comprising soot, NOx, and a nitrogenous reducing agent through a catalytic filter comprising (i) an SCR catalyst and (ii) a soot catalyst comprising copper doped ceria, iron doped ceria or manganese doped ceria, where the SCR catalyst and the soot catalyst are present on the filter as a mixture, (b) oxidizing at least a portion of the soot on the catalytic filter;
- and (c) reducing at least a portion of the NOx.
A method for trapping particulate matter from exhaust gas emitted from an engine, the method comprising:
- contacting the exhaust gas containing the particulate matter with a filter comprising a mixture of an SCR catalyst and a soot oxidation catalyst comprising copper doped ceria, iron doped ceria or a manganese doped ceria.
Dependencies are inferred from the claim text.