title: Impact of higher alcohols blended in gasoline on light-duty vehicle exhaust emissions.
abstract: Certification gasoline was splash blended with alcohols to produce four blends: ethanol (16 vol%), n-butanol (17 vol%), i-butanol (21 vol%), and an i-butanol (12 vol%)/ethanol (7 vol%) mixture; these fuels were tested in a 2009 Honda Odyssey (a Tier 2 Bin 5 vehicle) over triplicate LA92 cycles. Emissions of oxides of nitrogen, carbon monoxide, non-methane organic gases (NMOG), unburned alcohols, carbonyls, and C1-C8 hydrocarbons (particularly 1,3-butadiene and benzene) were determined. Large, statistically significant fuel effects on regulated emissions were a 29% reduction in CO from E16 and a 60% increase in formaldehyde emissions from i-butanol, compared to certification gasoline. Ethanol produced the highest unburned alcohol emissions of 1.38 mg/mile ethanol, while butanols produced much lower unburned alcohol emissions (0.17 mg/mile n-butanol, and 0.30 mg/mile i-butanol); these reductions were offset by higher emissions of carbonyls. Formaldehyde, acetaldehyde, and butyraldehyde were the most significant carbonyls from the n-butanol blend, while formaldehyde, acetone, and 2-methylpropanal were the most significant from the i-butanol blend. The 12% i-butanol/7% ethanol blend was designed to produce no increase in gasoline vapor pressure. This fuel's exhaust emissions contained the lowest total oxygenates among the alcohol blends and the lowest NMOG of all fuels tested.
authors.affiliation: National Renewable Energy Laboratory/U.S. Department of Energy, Golden, Colorado 80401, United States.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Ratcliff
authors.forename: Jon
authors.initials: J
authors.lastname: Luecke
authors.forename: Aaron
authors.initials: A
authors.lastname: Williams
authors.forename: Earl
authors.initials: E
authors.lastname: Christensen
authors.forename: Janet
authors.initials: J
authors.lastname: Yanowitz
authors.forename: Aaron
authors.initials: A
authors.lastname: Reek
authors.forename: Robert L
authors.initials: RL
authors.lastname: McCormick
mesh_terms: D020001:1-Butanol / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis; D000438:Alcohols / Q000032:analysis*; D016001:Confidence Intervals; D000431:Ethanol / Q000032:analysis; D005742:Gasoline / Q000032:analysis*; D006838:Hydrocarbons / Q000032:analysis; D055548:Vapor Pressure; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D000438:Alcohols; D005742:Gasoline; D006838:Hydrocarbons; D001335:Vehicle Emissions; D000431:Ethanol; D020001:1-Butanol