Impact of Sulfur in Gasoline on Nitrous Oxide and Other Exhaust Gas Components 2000-01-0857

Sulfur content in gasoline is known to reduce the efficiency of the catalytic converters that are used to reduce pollutants in the exhaust gas of cars. There is some concern that nitrous oxide emissions (N₂O) increase when fuel with a high sulfur content is used. The engine out and tailpipe mass emissions of two cars conforming to the California LEV-standard were analyzed. The influence of the fuel sulfur content on the emissions of the regulated and some unregulated pollutants during FTP test cycles was determined. Four fuels covering the range from less than 1 to 330 ppm sulfur content were used. Over that range of fuel sulfur concentration the engine out emissions of sulfur dioxide (SO₂ ) of both cars increased. Tailpipe emissions of SO₂ were only found at fuel sulfur concentrations of 150 and 330 ppm. For both vehicles a correlation between the N₂O emissions and the fuel sulfur content was found. For vehicle B increasing the fuel sulfur content resulted in a decrease in converter efficiency for methane (CH₄), carbon monoxide (CO) and nitric oxides (NO_x) and an increase in NH₃ and N₂O emissions. In the case of vehicle A an increase in N₂O emission was found as well. For the other compounds we found less influence compared to vehicle B.