Effects of blending ethanol with gasoline on the performance of motorcycle catalysts and airborne pollutant emissions

This study investigated the effects of blending ethanol with gasoline on the exhaust emissions of fuel-injected motorcycles. Regulated gasoline (RF), and 15 (E15) and 30 (E30) vol% ethanol fuel were used as test fuels. Measurements of several air pollutants (CO, HC, and NO_x) and organic air pollutant groups were conducted for two new fuel-injected four-stroke motorcycles. In addition, various catalysts were inserted into the motorcycles’ tailpipes to determine the characteristics and performance of the catalysts in treating the exhaust. Compared to using RF, we found that using blended fuel potentially reduced the CO and HC emissions by 30–37% and 19–28%, respectively. New catalytic systems, in conjunction with using different fuels, reduced CO, HC, and NO_x emissions in the tailpipe exhaust by 12–61%, 32–39%, and 81–85%, respectively. The CO and HC emissions were directly proportional in quantity to the running mileage of the catalyst, but the NO_x emissions were unaffected by this mileage, although they increased as the catalyst aged. We also discovered that at identical running mileages for a catalyst, the fuel consumption increased by –1.7–6.5% and 4.1–15% when using E15 and E30 fuel instead of RF. Furthermore, the specific surface area and pore volume of the catalyst decreased; the phosphorus and sulfur content in the catalyst increased with the catalyst’s running mileage; adding ethanol to the fuel decreased emissions of paraffins, olefins, and aromatics but increased those of carbonyls; and the ozone formation potential of volatile organic compounds (VOCs) in the tailpipe exhaust was 16.7–17.2% for paraffins, 22–33% for olefins, 26–45% for aromatics, and 4.9–25% for carbonyls.