Unregulated Emissions from Gasoline Engine Using Ethanol-Blended Gasoline as Fuels

Referring to the oxygen concentrations in the mixture of gasoline with 5%, 10% ,15% and 20% methyl tertiary butyl ether(MTBE) respectively, ethanol anhydrous(EA) was mixed into 90# unleaded gasoline. Using gas chromatography, the effects of ethanol blended gasoline on unregulated emissions from an electronic fuel in-jection(EFI) gasoline engine without modification and the catalytic conversion efficiencies were investigated. The experimental results indicated that with the increase of ethanol concentration in the blended fuels, the benzene emission was drastically reduced ( the max reduction level is 50 % when the ethanol concentration is 9.826%) , and formaldehyde emission was also reduced. Contrastively, engine-out acetaldehyde and unburned ethanol emissions were increased due to ethanol addition to gasoline. Three-way catalyst was effective to reduce benzene and formaldehyde emissions, while acetaldehyde and ethanol were the most resistant compounds to oxidation. The average catalytic conversion efficiency of benzene exceeded 87%, and there was no formaldehyde detected in the tailpipe after the catalyst operation.