Correlating the Cloud Point of Biodiesel to the Concentration and Melting Properties of the Component Fatty Acid Methyl Esters

Dunn, Robert O.

doi:10.1021/acs.energyfuels.7b02935

Cited by 15 publications

(43 citation statements)

References 44 publications

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“…An earlier work (Dunn, ) reported that the CP of biodiesel is correlated with the solid–liquid equilibrium temperature ( T SLE ) of a given FAME mixture. T SLE may be determined from the molar concentrations and melting properties of individual species in the mixture.…”

Section: Resultsmentioning

confidence: 99%

“…In the case of CP, the highest temperature where solid crystals are detected optically occurs at a temperature below the SLE phase transition temperature ( T SLE ) of the mixture. It was reported for binary L‐FAME admixtures that CP and T SLE are linearly correlated (CP = 0.82[ T SLE ] – 5.0; R 2 = 0.95) (Dunn, ). Thus, the CP of a biodiesel admixture may be measured at ~ 5.0 °C below the T SLE .…”

Section: Resultsmentioning

confidence: 99%

“…Biodiesel made from FOG is composed of saturated and unsaturated FAME mixed together. Therefore, biodiesel with higher concentrations of long‐chain (16+) saturated FAME will exhibit less desirable cold flow properties than biodiesel with lower concentrations of saturated FAME (Dunn, ; Dunn and Moser, ).…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Branched‐Chain Fatty Acid Alkyl Esters on the Cold‐Flow Properties of Biodiesel

Dunn

Wyatt

Wagner

et al. 2019

J Americ Oil Chem Soc

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Biodiesel (fatty acid methyl esters [FAME]) is produced from various fats, oils, and greases (FOG) using catalytic transesterification with methanol. These fuels have poor cold-flow properties depending on the fatty acid (FA) composition of the parent FOG. Improving the coldflow properties of biodiesel will enhance its prospects for use during cooler months in moderate temperature climates. This work is a study on the use of skeletally branchedchain alkyl esters (BCAE) composed of the isopropyl, nbutyl, and 2-ethylhexyl esters of iso-oleic acid isomers (iPr-iOL, nBu-iOL, and 2EH-iOL). These BCAE additives were tested in blends with linear-FAME (L-FAME) derived from soybean oil (SME), lard (LME), tallow (TME), and sewage scum grease (SGME). Binary L-FAME/SME admixtures were also studied. Admixtures were tested for the effects of the additives on cloud point (CP), pour point (PP), and kinematic viscosities at standard (ν 40 = 40 C) and low temperatures (T L ) = CP + 5 C (ν L ). Although the BCAE additives were more effective than SME, relatively large additive concentrations (y Add ) were needed to depress CP and PP by more than 2 C. Admixtures with high concentrations of BCAE additive had ν 40 > 6.0 mm 2 s −1 , the maximum limit in ASTM fuel specification D 6751. While the iPr-iOL and nBu-iOL additives may be blended at concentrations up to y Add = 0.50, 2EH-iOL should not exceed y Add = 0.28 in LME, 0.31 in SGME, 0.35 in TME, or 0.41 in SME to avoid driving the admixture out of specification. Some anomalies observed in the results at low y Add for SGME/BCAE admixtures were speculated to have been affected by the low-temperature rheology of SGME. KeywordsAdmixture Á Branched-chain alkyl esters Á Cloud point Á Kinematic viscosity Á Additive mass fraction Á Pour point J Am Oil Chem Soc (2019) 96: 805-823. Scheme 1 Molecular structures of linear-fatty acid methyl ester (L-FAME), skeletally branched-chain-fatty acid methyl ester (BC-FAME) and skeletally branched-chain alkyl esters (BCAE) 807 J Am Oil Chem Soc J Am Oil Chem Soc (2019) 96: 805-823

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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The Effect of Branched‐Chain Fatty Acid Alkyl Esters on the Cold‐Flow Properties of Biodiesel

Dunn

Wyatt

Wagner

et al. 2019

J Americ Oil Chem Soc

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“…The cold flow properties of biodiesel are highly affected by the fatty acid composition. Saturated fatty acids, such as palmitic (FAME16:0) and stearic acid (FAME18:0) methyl esters, were considered to have an important effect on the cloud point [7,14]. Meanwhile, unsaturated fatty acids, such as oleic (FAME18:1) and linoleic (FAME18:2) methyl esters, have only negligible effects on the cold flow properties due to their low melting points [8,9].…”

Section: Resultsmentioning

confidence: 99%

“…Empirical models were formulated by a linear correlation between the cold flow properties and chemical composition in biodiesel, as reported by Sarin et al, [5,6]. Although such models are straightforward and relatively easy to use, they are sensitive to the fatty acid composition of biodiesel and thus error-prone [7].…”

Section: Introductionmentioning

confidence: 99%

Development and Evaluation of Thermodynamic Models for Predicting Cold Flow Properties of Biodiesel

Seniorita

Minami

Kawamoto

2020

ARFMTS

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Biodiesel, especially palm oil-based methyl esters (PME), is steadily increasing in consumption in Indonesia and Malaysia as a petroleum diesel substitute. PME has poor cold flow properties due to the presence of saturated bound glycerols. Bound glycerols, such as monoglycerides (MAGs), diglycerides (DAGs), and triglycerides (TAGs), are impurities in biodiesel as a result of incomplete transesterification, and have high melting points. These minor components often solidify even at temperatures higher than the cloud point and thus cause clogging in fuel filters. It is, therefore, essential to predict the solidification temperature for the application of biodiesel, particularly in high blending levels. This study developed and evaluated thermodynamic models for predicting the solidification of biodiesel. Binary and multicomponent mixtures of fatty acid methyl esters (FAMEs) and bound glycerols were prepared as biodiesel models. The solidification temperature was measured by differential scanning calorimetry and the results were compared with the predicted values. It was discovered that most of the binary mixtures of a FAME and a bound glycerol (MAG, DAG, or TAG) behaved as eutectic systems, in which a solid phase consists of a single component. In the case of the eutectic system, the solidification temperature could be estimated by assuming non-ideal liquid solutions, and the modified UNIFAC (Dortmund) model helped calculate the activity coefficient. However, the mixtures of MAG/MAG differed from the eutectic system, suggesting that the solid compounds of different types of MAGs were formed. Thus, the compound formation model was developed, which was successful in predicting the solidification temperatures of biodiesel model fuels that consist of several kinds of FAMEs and MAGs.

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Solubility limitations of residual steryl glucosides, saturated monoglycerides and glycerol in commercial biodiesel fuels as determinants of filter blockages

Heiden¹,

Schober

Mittelbach

2021

J Americ Oil Chem Soc

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Newer, improved high pressure common rail diesel engines require increased protection from damaging particles in fuel, resulting in tighter, low-micron filtration requirements. The unobstructed flow of fuel through filters underlies the well-known efficiencies and reduced exhaust emissions of diesel engines, and when flows are hindered, these efficiencies become severely compromised. Biodiesel fuels frequently contain saturated monoglycerides, glycerol (GLY) and/or steryl glucosides, systemic impurities that become problematic when low concentrations exceed ill-defined solubility limits, usually unexpectedly at low temperatures. Here, filters and blended fuels from seven flow obstruction incidents were subjected to detailed compositional analyses. With one exception the fuels contain estimated levels within international specifications, yet exhibit heterophase (HP) formation in the laboratory at 2 C, well above measured cloud points. Feedstock composition, pretreatment and/or purification processes are found to modulate insolubility risks. Interferences in standard gas chromatography methods used without modification can hide or complicate estimates of residual levels of GLY. The data show that classical variables controlling solubility, such as concentrations and temperatures, play important roles in setting the risks associated with in situ formation of HPs from these common impurities. Further, such risks are likely attenuated considerably by reductions in critical impurities beyond currently specified limits.

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Correlating the Cloud Point of Biodiesel to the Concentration and Melting Properties of the Component Fatty Acid Methyl Esters

Cited by 15 publications

References 44 publications

The Effect of Branched‐Chain Fatty Acid Alkyl Esters on the Cold‐Flow Properties of Biodiesel

The Effect of Branched‐Chain Fatty Acid Alkyl Esters on the Cold‐Flow Properties of Biodiesel

Development and Evaluation of Thermodynamic Models for Predicting Cold Flow Properties of Biodiesel

Solubility limitations of residual steryl glucosides, saturated monoglycerides and glycerol in commercial biodiesel fuels as determinants of filter blockages

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