Nox reduction system utilizing pulsed hydrocarbon injection
AssigneeThe Regents of the University of California
InventorsRaymond M. Brusasco, Bernardino M. Penetrante, George E. Vogtlin, Bernard T. Merritt
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Abstract
Hydrocarbon co-reductants, such as diesel fuel, are added by pulsed injection to internal combustion engine exhaust to reduce exhaust NOx to N2 in the presence of a catalyst. Exhaust NOx reduction of at least 50% in the emissions is achieved with the addition of less than 5% fuel as a source of the hydrocarbon co-reductants. By means of pulsing the hydrocarbon flow, the amount of pulsed hydrocarbon vapor (itself a pollutant) can be minimized relative to the amount of NOx species removed.
Claims22
A method for reducing nitrogen oxides (NOx) in oxygen-rich exhausts from high-temperature combustion, the method comprising the steps of:
- intermittently adding hydrocarbons to an engine exhaust comprising NOx to produce a hydrocarbon-added engine exhaust;
- and
- converting NOx in the hydrocarbon-added engine exhaust with a selective catalytic reduction (SCR) catalyst, to a gas flow including N2 and O2.
An apparatus comprising a catalytic converter and a diesel fuel inlet flow controller, said apparatus comprising:
- an engine-exhaust gas inlet;
- a diesel fuel inlet;
- a diesel fuel pulse controller connected to said diesel fuel inlet;
- and
- a reductive stage convert of NOx connected to receive a mixture of NOx from the engine-exhaust gas inlet and diesel fuel from the diesel fuel inlet, the convert comprising an amphoteric catalyst support that further serves to convert NOx to gases that include N2, CO2, and H2O.
A method for reducing NOx contained in an oxygen-rich diesel engine exhaust, said method comprising:
- injecting a diesel fuel into said diesel engine exhaust for a predetermined time interval to produce a mixture containing said diesel engine exhaust and said diesel fuel, said diesel fuel in a concentration from about 500 ppm to about 3500 ppm;
- contacting a selective catalytic reduction (SCR) catalyst with said mixture at a temperature less than about 450 degrees C. to reduce said NOx contained in said diesel engine exhaust;
- and
- stopping said injecting and continually contacting said diesel engine exhaust with said catalyst to reduce said NOx contained in said diesel engine exhaust.
A vehicle with reduced NOx engine exhaust emissions, comprising:
- a fuel supply of diesel fuel;
- an internal combustion engine connected to receive a major portion of said fuel supply of diesel fuel and to propel a vehicle, and having an oxygen-rich exhaust comprising NOx;
- a first reactor comprising a catalyst for NOx reduction gas treatment connected to receive pulsed inletted minor portions of said fuel supply of diesel fuel and further connected to receive said oxygen-rich exhaust comprising NOx, and connected to output therefrom a product comprising N2 that has been converted from said NOx and noncombusted hydrocarbons from said diesel fuel, and
- a second reactor for collection and combustion of said noncombusted hydrocarbons connected to receive said product of the first reactor with said NOx and connected to receive said noncombusted hydrocarbons, and operably connected to output a second exhaust with reduced NOx emissions.
A method for reducing nitrogen oxides (NOx) in oxygen-rich exhausts from high-temperature combustion, the method comprising the steps of:
- intermittently adding diesel fuel boiling in the range from about 150 degrees C. to about 450 degrees C. to an engine exhaust comprising NOx to produce a diesel fuel-added engine exhaust;
- converting NOx in the diesel fuel-added engine exhaust at a temperature less than about 450 degrees C., with a selective catalytic reduction (SCR) catalyst, to a gas flow including N2 and O2;
- and
- converting NOx in the engine exhaust in the absence of added diesel fuel at a temperature less than about 450 degrees C., with a selective catalytic reduction (SCR) catalyst, to a gas flow including N2 and O2.
Dependencies are inferred from the claim text.