Cloud point and crystallization in fatty acid ethyl ester biodiesel mixtures with and without additives

• Published in: Fuel (Guildford) Vol. 222; pp. 243 - 249
• Main Authors: Leggieri, Patrick A., Senra, Michael, Soh, Lindsay
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-06-2018; Elsevier BV
• Subjects: Additives; Biodiesel; Biodiesel fuels; Biofuels; Cloud point; Cocrystallization; Cold flow; Cold-flow properties; Crystallization; Data processing; Diesel; Differential scanning calorimetry; Esters; Ethyl esters; Fatty acid ethyl ester; Fatty acid methyl esters; Fatty acids; Mental depression; Triacetin; Cloud point; Fatty acid ethyl ester; Biodiesel; Cold-flow properties; Crystallization
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2018.02.100

•FAEE showed consistently lower cloud points than the analogous FAME.•Cocrystallization occurs in saturated FAEE mixtures with and without additives.•Triacetin and Dimethyl azelate depress FAEE and FAME CP.•Thermodynamic modeling reasonably predicts the CP of FAEE mixtures.
Biodiesels, composed of saturated fatty acid alkyl esters (FAAE), have relatively high cloud points (CP), which limit their commercial application. However, fatty acid ethyl esters (FAEE) have potentially advantageous properties, including those related to cold flow, compared to their methyl analogs. This work systematically evaluates FAEE cloud point and crystallization data to aid in the development of FAEE biodiesel blends with practical cold flow properties. Neat FAEE CP increases with alkyl-chain length and decreases with greater degree of unsaturation. Mixtures of saturated/saturated FAEE show partial cocrystallization, which impact the mixture’s CP. The effects of cold-flow improving additives dimethyl azelate (DMAz) and triacetin on fatty acid methyl esters (FAME) and FAEE are also analyzed. Additives lowered the overall CP, however the degree of depression for each additive varied indicating different crystallization mechanisms. Thermodynamic ideal solution modeling predicts binary FAEE CP with and without additives within 2% of experimental values.