Effects of Engine Load and Fuel Sulfur on the Organosulfur Content of Diesel Particulate Matter

摘要

The sulfur content of diesel fuel is a health concern because sulfur promotes formation of diesel particulate matter (DPM). Studies have shown that a 7-12% decrease in DPM emissions can be obtained by reduction of fuel sulfur from 0.2% to 0.05% (2000 ppm to 500 ppm). Recognizing the role of sulfur in DPM formation, the EPA has established more stringent regulations for the sulfur content of diesel fuels. In this study, the types and amounts of organosulfur compounds in diesel fuels and DPM extracts were examined. The effects of engine load and fuel sulfur on the DPM composition also were investigated. In the fuels tested, dibenzothiophene (DBT), 4- methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6- DMDBT) were the most abundant sulfur compounds, while heavier components were more abundant in the DPM extracts. Diesel fuels having higher sulfur contents consisted mostly of lighter sulfur compounds. The sulfur content of DPM extracts increased with increasing fuel sulfur, but the conversion rate of fuel sulfur to DPM sulfur decreased with increasing fuel sulfur, possibly because higher sulfur fuels contain more of lighter components that remain in the gas phase. As engine load increased, the concentration of the lighter compounds in DPM decreased, and the most abundant sulfur components shifted to heavier compounds.