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US 6,546,717 B1Granted
Combatting air pollution
AssigneeJohnson Matthey Public Limited Company
InventorsGuy Richard Chandler, Alan Francis Diwell, Raj Rao Rajaram
Life of this patent
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Abstract
In the control of pollutants such as NOx in the exhaust gases from internal combustion engines, ozone is reacted with NO to form NO2, which is then reduced catalytically to N2, by reacting NO2 with ammonia. The NO2 produced can react with the particulates of Diesel engine to exhaust gas to regenerate a particulate filter.
Claims16
A method of combatting air pollution from a lean-burn engine whose exhaust gas comprises NO and SO2, comprising the steps of:
- oxidizing NO to NO2 selectively over oxidizing SO2 to SO3 by contacting the exhaust gas with ozone at a temperature of from 50° C. to 250° C. and in the absence of material catalytic for oxidizing SO2 to SO3, wherein NO2 produced is adsorbed by an adsorbent which adsorbs the NO2 when the exhaust gas is lean and releases the adsorbed NO2 when the exhaust gas is rich, and the exhaust gas is periodically made rich to release the adsorbed NO2;
- reducing NO2 to nitrogen;
- and
- discharging unreacted SO2 to atmosphere.
1 more element
A method of combatting air pollution from a diesel engine whose exhaust gas comprises NO and SO2, comprising the steps of:
- oxidizing NO to NO2 selectively over oxidizing SO, to SO3 by contacting the exhaust gas with ozone at a temperature of from 50° C. to 250° C. and in the absence of material catalytic for oxidizing SO2 to SO3;
- reducing NO2 to nitrogen by reacting NO2 produced from the oxidizing step with particulates from the exhaust gas which have been deposited on a particulate filter to oxidize and remove the deposited particulates from the filter;
- and
- discharging unreacted SO2 to atmosphere.
1 more element
Dependencies are inferred from the claim text.