Renewable Oxygenate Blending Effects on Gasoline Properties

Abstract

The oxygenates ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol (isobutanol), 1-pentanol, 3-methyl-1-butanol (isopentanol), methyl levulinate, ethyl levulinate, butyl levulinate, 2-methyltetrahydrofuran (MTHF), 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) were blended in three gasoline blendstocks for oxygenate blending (BOBs) at levels up to 3.7 wt % oxygen. Chemical and physical properties of the blends were compared to the requirements of ASTM specification D4814 for spark-ignited engine fuels to determine their utility as gasoline extenders. Vapor pressure, vapor lock protection, distillation, density, octane rating, viscosity, and potential for extraction into water were measured. Blending of ethanol at 3.7% oxygen increased vapor pressure by 5–7 kPa as expected. 2-Propanol slightly increased vapor pressure in the lowest-volatility BOB, while all other oxygenates caused a reduction in vapor pressure of up to 10 kPa. Coefficients for the Wilson equation were fitted to the measured vapor pressure data and were shown to adequately predict the vapor pressure of oxygenate–gasoline blends for five individual alcohols and MTHF in different gasolines. Higher alcohols and other oxygenates generally improved vapor lock protection. Butyl levulinate blended at 2.7% oxygen caused the distillation end point to exceed 225 °C, thus failing the specification. Distillation parameters were within specification limits for the other oxygenates tested. Other than ethanol, MF, and DMF, the oxygenates examined will not produce blends with satisfactory octane ratings at these blend levels when blended into lower-octane blendstocks designed for ethanol blending. However, all oxygenates tested except 1-pentanol and MTHF produced an increase in octane rating. For ethanol, the propanol isomers, and methyl levulinate, 20 wt % or more of the oxygenate could be extracted into water in a room-temperature water tolerance experiment. For the butanol isomers and ethyl levulinate, the percent extracted ranged from about 4% to 8%. Extraction for other oxygenates was 2% or lower. Methyl levulinate separates from gasoline as a separate liquid phase at temperatures below 0 °C.

Investigation of biofuels from microorganism metabolism for use as anti-knock additives

“…Thus, the blending octane number can be closely approximated by the octane number of the pure fuel when calculated as a function of the molar composition. However, this effect is less pronounced for fuels with a similar molar mass to gasoline [32], as is seen when calculated the BRON on a molar basis for 3-methyl-2-buten-1-ol, 3-methyl-3-buten-1-ol, and limonene. As expected, the BRON for 2-methylpropan-1-ol (isobutanol) based on a molar basis does approach the RON of pure 2-methyl-1-proponal (isobutanol) due to its lower molar mass in comparison with gasoline.…”

Recent Trends in the Production, Combustion and Modeling of Furan-Based Fuels

“…Other studies have focused on the comparative engine performance of pure furans, as well as their blends with gasoline and diesel [16,191]. Christensen et al [16] tested the effect of blending oxygenates, including 2-MF, 2,5-DMF and 2-MTHF with gasoline at oxygen levels up to 3.7%.…”

“…Christensen et al [16] tested the effect of blending oxygenates, including 2-MF, 2,5-DMF and 2-MTHF with gasoline at oxygen levels up to 3.7%. Physical and chemical properties of the blends, including octane rating, were compared to the American Society for Testing and Materials (ASTM) specifications for SI engine fuels to evaluate the possibility to use them as gasoline additives.…”

Oxidation of 2-methylfuran and 2-methylfuran/n-heptane blends: An experimental and modeling study

“…However, the ethanol blending with conventional fuels also increases the formation of other toxic pollutants like formaldehyde and acetaldehyde [8,9]. Other drawbacks associated with the use of ethanol are its lower vapor pressure and miscibility in water [10]. Compared to ethanol, 2-methylfuran (2-MF) has been identified as a new potential lignocellulosicderived biofuel [11].…”