METHOD AND APPARATUS FOR REDUCING HARMFUL EMISSIONS FROM A DIESEL ENGINE BY POST COMBUSTION CATALYST INJECTION

摘要

Emissions of pollutants from diesel engines (10) are reduced by a regimen for catalytically treating engine exhaust and, preferably, also the combustion of the fuel. The balance point of a diesel trap (30) is reduced to permit more efficient regeneration, preferably self-regeneration, while also reducing emissions of carbon monoxide and hydrocarbons by a combination of mechanical devices and fuel additives. The regimen requires the introduction of from 0.05 to 1 ppm of a platinum group metal catalyst (based on the volume of fuel combusted) into the particulates, by introducing at least half of the platinum group metal catalyst (50) directly into the hot exhaust gases (52, 20). Preferably, the platinum group metal catalyst is employed with a combustible organic liquid to aid in either progressively loading the trap (30) with the combustible organics or to combust in the hot combustion gases to facilitate burning of the particulates on the trap (30) for more effective regeneration. The judicious selection and use of an auxiliary catalyst metal (e.g., copper), preferably adding at least half of its total to the fuel as a fuel additive, is a preferred part of the regimen to achieve the lowest trap balance point.