Cold Flow Properties of Fatty Acid Methyl Ester Blends with and without Triacetin

Optimizing the cold flow properties of biodiesel is pertinent to its applicability as an alternative to conventional petrodiesel products. This work provides a systematic study of specific cold flow properties of binary blends of fatty acid methyl esters (FAME) and a cold flow improver, triacetin. The cloud point, melting point, and heat of crystallization of various blends of FAME and triacetin were analyzed to further understand the molecular interactions affecting crystallization. Cloud point analysis revealed trends based on FAME and additive composition. Generally, the cloud point of pure FAME decreased with decreasing carbon number and increasing degree of unsaturation. The use of triacetin, which is a potential fuel component, as a cloud point depressant was also investigated for pure component and binary FAME fuel blends. The addition of triacetin depressed the cloud point up to 2.7 K in proportions of up to 20 wt %. Thermodynamic analysis and predictive modeling revealed the effect of component co-crystallization on the cloud point of a mixture. The role of triacetin in reducing a mixture's cloud point appears to be caused by its function as a diluent rather than as a crystal modifier. As such, the presence of triacetin can moderately improve the cold flow behavior of biodiesel blends, indicating that triacetin may be a promising biodiesel component.