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.

Bifunctional fixed-bed catalysts improve CFP performance.

The properties of ethyl (EL) and n-butyl levulinate (BL), two potential cellulose-derived diesel blend components, were assessed as both neat oxygenates and blends with diesel fuel. The samples tested were produced commercially from cellulose and alcohols but were not reagent-grade samples. They were relatively free of impurities, although EL contained some acidic compounds and both contained parts-per-million levels of calcium. Both esters exhibited a very low cetane number. The melting points of both esters were less than −60 °C. The water solubility of EL was 15.2 wt %, while that of BL was only 1.3 wt %. Blends of diesel fuel with EL were found to have an elevated cloud point, despite the extremely low melting point of this compound, because EL separates from diesel fuel as a separate liquid phase at low temperatures. This can be mitigated to some extent by including biodiesel in the blend. BL remained in solution and raised the diesel cloud point only when blended into −45 °C cloud point/15% aromatic no. 1 diesel fuel. Both esters were found to significantly increase diesel lubricity and conductivity. The esters were treated with the cetane-enhancing compound 2-ethyl hexyl nitrate and were tested as blends with diesel fuel in a 2008 model year Cummins ISB engine with the measurement of regulated pollutant emissions over the federal heavy duty diesel transient cycle. Fuel chemistry had no effect on tailpipe total hydrocarbons, carbon monoxide, or particulate matter for this diesel oxidation catalyst and particle filter equipped engine. The engine-out smoke number was reduced by 41.3% with a 10% blend of EL (EL10) and reduced by 55% with a blend of 20% BL (BL20). EL10 had no effect on emissions of nitrogen oxides (NO x ), while BL20 increased NO x by 4.6%. Because of the poor solubility of EL in diesel fuel at low temperatures, its use as a diesel blend component will be technically challenging. The low cetane number of both esters can be addressed with cetane improver additives.

Three hydrotreated bio-oils with different oxygen contents (8.2, 4.9, and 0.4 w/w) were distilled to produce light, naphtha, jet, diesel, and gas oil boiling range fractions that were characterized for oxygen-containing species by a variety of analytical methods. The bio-oils were originally generated from lignocellulosic biomass in an entrained-flow fast pyrolysis reactor. Analyses included elemental composition, carbon type distribution by 13C nuclear magnetic resonance, acid number, gas chromatography/mass spectroscopy, volatile organic acids by liquid chromatography, and carbonyl compounds by 2,4-dinitrophenylhydrazine derivatization and liquid chromatography. Acid number titrations employed an improved titrant–electrode combination with faster response that allowed the detection of multiple end points in many samples and allowed for acid values attributable to carboxylic acids and to phenols to be distinguished. The results of these analyses showed that the highest oxygen content bio-oil fractions contained oxygen as carboxylic acids, carbonyls, aryl ethers, phenols, and alcohols. Carboxylic acids and carbonyl compounds detected in this sample were concentrated in the light, naphtha, and jet fractions (<260 °C boiling point). The carboxylic acid content of all of the high oxygen content fractions was likely too high for these materials to be considered as fuel blendstocks, although the potential for blending with crude oil or refinery intermediate streams may exist for the diesel and gas oil fractions. The 4.9% oxygen sample contained, almost exclusively, phenolic compounds found to be present throughout the boiling range fractions, which imparted measurable acidity primarily in the light, naphtha, and jet fractions. Additional study is required to understand what levels of the weakly acidic phenols could be tolerated in a refinery feedstock. The diesel and gas oil fractions from this upgraded oil had low acidity but still contained 3–4 wt % oxygen present as phenols that could not be specifically identified. These materials appear to have excellent potential as refinery feedstocks and some potential for blending into finished fuels. Fractions from the lowest oxygen-content oil exhibited some phenolic acidity but generally contained very low levels of oxygen functional groups. These materials would likely be suitable as refinery feedstocks and potentially as fuel blend components. Paraffins, isoparaffins, olefins, naphthenes, and aromatics (PIONA) analysis of the light and naphtha fractions showed benzene contents of 0.5 and 0.4 vol % and predicted (research octane number (RON) + motor octane number (MON))/2 of 63 and 70, respectively.

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Biomass and bioproduct composition critical improvements are a priority for the nascent algae-based bioeconomy.

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