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Process Development to Reduce Minor Component Content In Biodiesel

Haiying Tang, Rhet Joseph De Guzman, Steven O. Salley, and K. Y. Simon Ng. Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, MI 48202

Biodiesel is a renewable and environmentally friendly alternative fuel, which is comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats. However, filter plugging and engine failure have taken place in vehicles using biodiesel blends due to precipitate formation at low-temperature. The majority of these precipitates can be attributed to either steryl glucosides or monoglycerides found in biodiesel. These dispersed particles increase the filtration time, and also promote the crystallization of other compounds. Up until now, no ASTM standard analytical methods to determine steryl glucosides in biodiesel exist. The objective of this work is to evaluate and develop processing strategies to reduce steryl glucosides, and monoglycerides content in biodiesel, as well as to develop a robust analytical method to determine their content in biodiesel.

A number of processing techniques were evaluated: 1. ambient filtering; 2. cold filtering; 3. water degumming; 4. absorbent treatment; and 5. vacuum distillation. In each processing technique, the amount of sterol glucosides and glycerin in biodiesel before and after the processing treatment was determined by gas chromatography - flame ionization detector (GC-FID). Moreover, cold flow proprieties, viscosity, acid number, and oxidative stability, flash point, and Cetane number of biodiesel were evaluated.

Developing a cost-effective processing technique to reduce sterol glucosides and glycerin can result in reduced precipitate formation, and minimize filter plugging problems for the automotive fuel delivery system. By improving its quality, biodiesel will become more competitive on the market, and its acceptance to the public will be enhanced.