Mitigating crystallization of saturated FAMEs (fatty acid methyl esters) in biodiesel: 2. The phase behavior of 2-stearoyl diolein–methyl stearate binary system. (1st April 2015)

• Record Type: Journal Article
• Authors: Baker, Mark; Bouzidi, Laziz; Narine, Suresh S.
• Is Part Of: Energy. Volume 83(2015)
• Page Start: 647
• Page End: 657
• Publication Date: 2015-04-01
• Subjects: Biodiesel -- FAME (fatty acid methyl ester) -- TAG (triacylglycerol) -- Phase behavior -- Polymorphism -- Binary phase diagram; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2015.02.076
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The phase behavior of a model binary system made of OSO (2-stearoyl diolein) and MeS (methyl stearate) was investigated with differential scanning calorimetry and X-ray diffraction. The study is part of a series of investigations of unconventional additives such as TAGs (triacylglycerols) and dimers of TAGs with a demonstrated potential to significantly alter the crystallization of biodiesel. The TAG (triacylglycerol) was found to be effective in depressing the crystallization onset of the FAME (fatty acid methyl ester) significantly even at low concentration. OSO was shown to affect the crystallization of the mixtures strongly, and to dramatically alter their polymorphism. The system's phase diagram involved marked transformation lines including eutectics and solid–solid transitions. The molecular interactions were evaluated using a simple thermodynamic model. A mechanism for disruption of crystallization was proposed to be dependent on the peculiar geometry of OSO: the "straight" stearic acid participates easily in the lamellar packing of the equally "straight" FAME, whilst its kinked oleic acids effectively halt additional saturated FAMEs from participating due to steric hindrances. The findings of the study indicate that judicious loadings of TAGs which would target biodiesel's saturated FAMEs will have a substantial beneficial effect on the low temperature performance of the fuel. Highlights: 2-Steroyl diolein/methyl stearate (OSO/MeS) binary system investigated comprehensively. OSO/MeS mixtures presented very complex phase trajectories and behavior. OSO alters crystallization at both nucleation and growth stages profoundly. Mechanism for disruption of crystallization proposed and verified. OSO and homologues formulations can be effectives cold flow additives for biodiesel.