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

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.