(289a) Synthesis of Biodiesel with Fat Based Feed of High Content of Free Fatty Acids

Authors: 
Kofler, I., VTU Engineering
Glasl, W., VTU Engineering
Siebenhofer, M., Graz University of Technology


The conversion of triglycerides with alkaline catalysts and methanol is a state of the art process in biodiesel production in industrial scale, preferably applied for processing raw material with low content of free fatty acids. Several feedstock for methylester-production may contain up to 100% of free fatty acids. Alkali catalysis would lead to saponification instead of esterification. Therefore acidic catalysts are used instead. In this project the kinetics of esterification of feedstock with a high content of free fatty acids with methanol is investigated. To avoid demand of excessive catalyst, reaction the temperature of reaction was raised. To study the influence of different reaction conditions on the rate and yield runs were made in a lab scale batch vessel. The amount of FFA was reduced from 90% to less than 10% after one hour of reaction time. The experimentally obtained data indicate kinetics of second order reversible reaction. The rate of esterification increases with temperature. Even high excess of alcohol can not decrease FFA to less than 5% in single step operation. After removing the byproduct water, the amount of FFA can be reduced to 2% in a second esterification step. Conversion was also investigated with heterogeneous catalysts.