Biodiesel is an oxygenated diesel fuel made from vegetable oils and animal fats by conversion of the triglyceride fats to esters via transesterification. In this study we examined biodiesels produced from a variety of real-world feedstocks as well as pure (technical grade) fatty acid methyl and ethyl esters for emissions performance in a heavy-duty truck engine. The objective was to understand the impact of biodiesel chemical structure, specifically fatty acid chain length and number of double bonds, on emissions of NOx and particulate matter (PM). A group of seven biodiesels produced from real-world feedstocks and 14 produced from pure fatty acids were tested in a heavy-duty truck engine using the U.S. heavy-duty federal test procedure (transient test). It was found that the molecular structure of biodiesel can have a substantial impact on emissions. The properties of density, cetane number, and iodine number were found to be highly correlated with one another. For neat biodiesels, PM emissions were essentially constant at about 0.07 g/bhp-h for all biodiesels as long as density was less than 0.89 g/cm3 or cetane number was greater than about 45. NOx emissions increased with increasing fuel density or decreasing fuel cetane number. Increasing the number of double bonds, quantified as iodine number, correlated with increasing emissions of NOx. Thus the increased NOx observed for some fuels cannot be explained by the NOx/PM tradeoff and is therefore not driven by thermal NO formation. For fully saturated fatty acid chains the NOx emission increased with decreasing chain length for tests using 18, 16, and 12 carbon chain molecules. Additionally, there was no significant difference in NOx or PM emissions for the methyl and ethyl esters of identical fatty acids.

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.

online ordering: http://www.ntis.gov/ordering.htm Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste i AcknowledgementsThe authors of this report wish to acknowledge the assistance of CIFER staff members Jim Macomber, Bruce Sater, and Greg Korthius in completion of the test work described here. The biodiesel prepared from soapstock was supplied . Thanks are also due to AG Environmental Products for donation of a drum of Soyagold soybean-oil methyl ester. Constructive criticism from Shaine Tyson of the National Renewable Energy Laboratory, as well as funding from NREL is gratefully acknowledged. SummaryThe National Renewable Energy Laboratory (NREL) is conducting an investigation of various biodiesel fuels produced from waste oils. As a part of this study, data on emissions on the Environmental Protection Agency (EPA) heavy-duty transient cycle have been measured to demonstrate the sensitivity of engine emissions to biodiesel ester composition. The objective of the investigation was to determine the effect of biodiesel source material and ester molecular structure (number of double bonds and chain length) on particulate matter (PM), nitrogen oxides (NO x ), and certain unregulated pollutants. Testing included a series of fuels consisting of nearly pure fatty acid esters with different chain lengths and numbers of double bonds, as well as a number of fuels from practical feedstocks. A detailed analysis of the data was performed in an effort to determine how fuel chemistry and fuel properties correlate with the increase in NO x emissions observed for many biodiesels here, and in most previous studies.In total, 28 neat biodiesels and four B-20 blends (with EPA certification diesel) were tested. Seven fuels prepared from various natural feedstocks were obtained from the Institute of Gas Technology (IGT), and three of these were tested as B-20 blends. A methyl ester biodiesel prepared from soapstock was supplied by the Agricultural Research Service (ARS) and tested neat and as a B-20 blend. Twenty fuels were prepared at the Colorado School of Mines (CSM), primarily from nearly pure (or technical grade) fatty acids. Nevertheless, many of these fuels were not as pure as was originally intended because of high levels of impurities in the feedstocks. These fuels covered a very wide range of realistic feedstocks as well as systematically varying chemical properties such as fatty acid chain length and number of double bonds in the fatty acid chain. Fuels were analyzed for a wide range of properties including water and sediment, free and total glycerine, iodine number, peroxide value, acid number, cetane number, density, kinematic viscosity, gross heating value, and carbon, hydrogen, and oxygen content. The specific fatty acid esters present in the fuels were also determined by GC/MS analysis. Regulated pollutant emissions, along with certain non-regulated pollutants, were measured on a 1991 DDC Series 60 engine via the heavy-duty transient test (40 CFR Part 86 Subpart N). Emissions from bio...

A previously developed bench-scale method for the production of fatty acid methyl esters (biodiesel) from soybean soapstock (Haas, M. J.; Bloomer, S.; Scott, K. J. Am. Oil Chem. Soc. 2000, 77, 373-379) was taken to the small pilot scale, producing approximately 2.5 L of material per run. By multiple successive reactions, 25 L of product was accumulated. The fatty acid composition of the ester product (wt %) was palmitic: 16.2, stearic: 4.7, oleic: 16.2, linoleic: 54.4, and linolenic: 6.9. This mirrors the fatty acid composition of soy soapstock and is quite similar to that of commercial biodiesel produced from refined soybean oil. The ester product met the provisional biodiesel specifications of the American Society for Testing and Materials with regard to all variables examined: flash point, water and sediment, carbon residue, sulfated ash, density, kinematic viscosity, sulfur, cetane number, cloud point, copper corrosion, acid number, free glycerin, and total glycerin, and had density and iodine number values comparable to those of commercial soy-based biodiesel. Emissions data for both the neat fuel and a 20 vol % blend in low-sulfur petroleum diesel were collected according to the Environmental Protection Agency heavy-duty transient cycle protocol using a DDC Series 60 engine on an engine test stand. The emissions profile of biodiesel from soapstock was quite similar to that of biodiesel produced from refined soy oil. Compared with petroleum diesel fuel, emissions of total hydrocarbons, particulates, and carbon monoxide were reduced 55%, 53%, and 48%, respectively, with neat soapstock biodiesel. Total nitrogen oxides increased 9%. Operation on a 20 vol % blend of soapstock biodiesel in petroleum diesel gave reductions of 27.7%, 19.7%, and 2.4%, respectively, in total hydrocarbons, particulate matter, and carbon monoxide, relative to petroleum diesel. Nitrogen oxide emissions increased 1.3%. In the context of engine emissions, these data suggest the suitability of the methyl esters of soy soapstock as a diesel fuel.

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Regulated emissions from 21 in-use heavy-duty diesel vehicles were measured on a heavy-duty chassis dynamometer via three driving cycles using a low-sulfur diesel fuel. Emissions of particulate matter (PM), nitrogen oxides (NO x ), carbon monoxide (CO), total hydrocarbon (THC), and PM sulfate fraction were measured. For hot start tests, emissions ranged from 0.30 to 7.43 g/mi (mean 1.96) for PM; 4.15−54.0 g/mi (mean 23.3) for NO x ; 2.09−86.2 g/mi (mean 19.5) for CO; and 0.25−8.25 g/mi (mean 1.70) for THC. When emissions are converted to a g/gal basis, the effect of driving cycle is eliminated for NO x and largely eliminated for PM. Sulfate comprised less than 1% of the emitted PM for all vehicles and test cycles. A strong correlation is observed between emissions of CO and PM. Cold starting at 77 °F produced an 11% increase in PM emissions. Multivariate regression analyses indicate that in-use PM emissions have decreased at a slower rate than anticipated based on the stricter engine certification test standards put into effect since 1985. NO x emissions do not decrease with model year for the vehicles tested here. Smoke opacity measurements are not well correlated with mass emissions of regulated pollutants.

The introduction of more stringent standards for fuel economy as well as greenhouse gas emissions [1] is driving research to increase the efficiency of spark ignition (SI) engines. Approaches for increasing SI engine efficiency include increased compression ratio, direct injection (DI), turbocharging, downsizing, and down-speeding. Higher octane number (more highly knock resistant) fuels allow improved combustion phasing and operation at higher loads at the same engine speed, while also allowing the higher in-cylinder temperature and pressure generated by increased compression ratio and turbocharging which are critical for downsizing and down-speeding [2,3,4]. At the same time, renewable fuel usage is mandated to increase in the United States under the Renewable Fuel Standard [5], and globally under laws enacted in other countries. Ethanol, the most commonly used renewable fuel, has a research octane number (RON) of approximately 110 [6] compared to typical U.S. regular gasoline at 91-93 [2]. Accordingly, high octane number ethanol blends containing from 20 volume percent (vol%) to 40 vol% ethanol are being extensively studied [3,7,8,9,10]. A unique property of ethanol is its high heat of vaporization (HOV), which significantly increases charge cooling for DI engines, providing additional knock resistance.The tendency of a spark-ignited engine fuel to autoignite and cause knock is measured as the octane number, a critical performance parameter for SI engines. In the United States, octane number at the retail pump is given as the anti-knock index, the average of two octane number measurements: research octane number (RON) (ASTM D2699-13b) and motor octane number (MON) (ASTM D2700-13b). The primary differences between the RON and MON measurements are fuel-air charge temperature and engine speed, with the RON test using a comparatively low fuel-air charge temperature (that is dependent on the fuel's latent heat of evaporation) and slower engine speed while the MON test is conducted at a significantly higher fuel-air charge temperature (149°C) and faster engine speed. Recent studies have demonstrated that MON is correlated with different effects in modern engines than was the case when these tests were introduced in 1932, and in fact increasing MON at constant RON may actually lower the fuel knock resistance [11]. The ABSTRACTThe objective of this work was to measure knock resistance metrics for ethanol-hydrocarbon blends with a primary focus on development of methods to measure the heat of vaporization (HOV). Blends of ethanol at 10 to 50 volume percent were prepared with three gasoline blendstocks and a natural gasoline. Performance properties and composition of the blendstocks and blends were measured, including research octane number (RON), motor octane number (MON), net heating value, density, distillation curve, and vapor pressure. RON increases upon blending ethanol but with diminishing returns above about 30 vol%. Above 30% to 40% ethanol the curves flatten and converge at a RON of about 103 to 105, even for...

Biodiesel is most commonly used as a blend with petroleum diesel. At concentrations of up to 5 vol% (B5) in conventional diesel fuel, the mixture will meet ASTM D975 diesel fuel specification and can be used in any application as if it were neat petroleum diesel; for home 1. The ASTM standard for B100 to be used as a blend stock is D6751. Diesel fuel is defined in ASTM D975. ASTM D396 defines heating oils.A-A-59693A defines B20 for military use.