Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: February 10, 2009
Publication Date: May 3, 2009
Citation: Dunn, R.O. 2009. Modeling the Crystallization Behavior of Biodiesel at Low Temperatures [abstract]. Annual Meeting and Expo of the American Oil Chemists' Society. p. 73.
The most common form of biodiesel is made by transesterification of vegetable oil or animal fat fatty acids with methanol (FAME). Biodiesel from feedstocks such as palm oil (PME), rapeseed oil (RME), soybean oil (SME) or used cooking oil (UCOME) is susceptible to performance issues during cold weather. The temperature where solid crystals begin to form (onset temperature) depends on composition and melting properties of the individual FAME components in the biodiesel. For example, SME is composed of long-chain esters that are 14-18 wt% saturated (melting point [MP] > 27ºC) mixed with unsaturated esters (MP < -20ºC). As a result, SME has a cloud point (CP) near 0.5ºC. In contrast, PME may contain 32-47.5 % methyl palmitate (MP = 27.79ºC) and has CP = 11.7ºC. This work utilizes sub-ambient differential scanning calorimetry (DSC) analysis to accurately determine MP and enthalpy of fusion of pure FAME components found in SME, RME, PME and UCOME. DSC data were applied to develop thermodynamic models for calculating onset temperature of FAME mixtures based on composition of the four types of biodiesel (determined by GC analyses). Predicted onset temperatures were comparable to corresponding results from direct measurement of CP.