초록 ▼

Emissions of pollutants from diesel engines are reduced by a combination of mechanical devices and fuel additives. In one series of embodiments, diesel emissions of NO.sub.x and particulates are reduced, simultaneously with gaseous hydrocarbons and carbon monoxide, by the combined use of exhaust gas

Emissions of pollutants from diesel engines are reduced by a combination of mechanical devices and fuel additives. In one series of embodiments, diesel emissions of NO.sub.x and particulates are reduced, simultaneously with gaseous hydrocarbons and carbon monoxide, by the combined use of exhaust gas recirculation or engine timing modification, with a particulate trap and a platinum group metal catalyst composition. In another embodiment, a multi-metal catalyst composition, comprising a combination of a platinum metal catalyst composition and at least one auxiliary catalyst metal composition, especially cerium or copper, is employed to provide catalyst metal to the exhaust system including a diesel trap to lower the balance point of the particulate trap (the temperature at which the rate of trap loading equals the rate of regeneration) while also lowering the emissions of carbon monoxide and unburned hydrocarbons. Data for platinum, copper and cerium catalysts establishes effective amounts. Tests also show selective maintenance of low oxidation of SO.sub.2 to SO.sub.3.

대표청구항 ▼

[ We claim:] [1.] A method for improving the operation of a diesel engine equipped with a diesel trap, comprising:adding a platinum group metal composition and a cerium compound to a diesel fuel in an effective amount to lower the emissions of unburned hydrocarbons and carbon monoxide and to lower t

[ We claim:] [1.] A method for improving the operation of a diesel engine equipped with a diesel trap, comprising:adding a platinum group metal composition and a cerium compound to a diesel fuel in an effective amount to lower the emissions of unburned hydrocarbons and carbon monoxide and to lower the temperature at which particulates are burned from the trap;operating the diesel engine by burning the fuel over a sufficient period of time to produce exhaust gases and achieve a sustained reduction in unburned hydrocarbons and carbon monoxide; andpassing the exhaust gases from the operation of the engine through the diesel trap whereby particulates are collected in the trap and burned therein at a temperature lower than could be achieved in the absence of the platinum group metal and the cerium.