METHODS FOR REDUCING HARMFUL EMISSIONS FROM A DIESEL ENGINE

摘要

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 NOx 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 SO2 to SO3.