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

摘要

The sulfur content of diesel fuel is a health concern because sulfur promotesformation 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% to0.05% (2000 ppm to 500 ppm). Recognizing the role of sulfur in DPM formation, theEPA 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 andDPM extracts were examined. The effects of engine load and fuel sulfur on the DPMcomposition 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 weremore abundant in the DPM extracts. Diesel fuels having higher sulfur contentsconsisted mostly of lighter sulfur compounds. The sulfur content of DPM extractsincreased with increasing fuel sulfur, but the conversion rate of fuel sulfur to DPMsulfur decreased with increasing fuel sulfur, possibly because higher sulfur fuelscontain more of lighter components that remain in the gas phase. As engine loadincreased, the concentration of the lighter compounds in DPM decreased, and themost abundant sulfur components shifted to heavier compounds.