Reducing NO.sub.x emissions from an engine by selective catalytic reduction utilizing solid reagents
AssigneeClean Diesel Technologies, Inc.
InventorsTheodore J. Tarabulski, Jeremy D. Peter-Hoblyn, James M. Valentine
Life of this patent
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Abstract
Urea or other solid NO.sub.x -reducing reagent is employed in a selective catalytic reduction process on emissions from diesel and lean-burn gasoline engines. The solid reagent is fed to a gas generator that produces a reactant gas by heating. In one embodiment the reactant gas is maintained at elevated temperatures to prevent condensation products from forming. The reactant gas contains ammonia and is fed to the exhaust on an as-needed basis.
Claims16
A method for reducing the emissions of NO.sub.x from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NO.sub.x reduction, comprising:
- supplying solid NO.sub.x -reducing reagent capable of generating ammonia-containing reactant gas upon heating, into a vessel having an outlet;
- heating the solid NO.sub.x -reducing reagent in the vessel at a temperature above the pyrolysis temperature for the reagent, to produce a reactant gas containing ammonia;
- introducing the reactant gas into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction;
- and
- passing the exhaust gas containing the reactant gas through an SCR reactor.
An apparatus for reducing the emissions of NO.sub.x from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NO.sub.x reduction, comprising:
- means for supplying solid NO.sub.x -reducing reagent to a vessel having an outlet;
- means for heating the solid NO.sub.x -reducing reagent in the vessel at a temperature above the pyrolysis temperature for the reagent, to produce a reactant gas containing ammonia;
- means for introducing the reactant gas into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction;
- and means for passing the exhaust gas containing the reactant gas through an SCR reactor.
Dependencies are inferred from the claim text.