Impact of Higher Alcohols Blended in Gasoline on Light-Duty Vehicle Exhaust Emissions

Matthew A. Ratcliff, Jon Luecke, Aaron Williams, Earl Christensen, Janet Yanowitz, Aaron Reek, Robert L. McCormick

Research output: Contribution to journalArticlepeer-review

40 Scopus Citations


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.

Original languageAmerican English
Pages (from-to)13865-13872
Number of pages8
JournalEnvironmental Science and Technology
Issue number23
StatePublished - 3 Dec 2013
Externally publishedYes

NREL Publication Number

  • NREL/JA-5400-58466


  • CO reduction
  • gasoline blend
  • light-duty vehicles
  • vehicles


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