(254e) Determination of Lipid Hydrolysis Kinetics in Soybean Oil and Algal Systems

Joshua C. Wissinger, Amber L. Bosley, Constance A. Schall

The third generation of biofuels, algae, is of growing interest as a renewable feedstock due to its high yield of energy per unit area, use of carbon dioxide and other available resources for growth, and minimal competition with the food industry.  Biodiesel and jet fuel can be produced from lipid-rich algae.  However, extracting lipids from algae is complicated due to the high water content of harvested and mechanically dewatered algae (60 to 90% water). Thus, there is a need for processes that convert wet algal biomass into fuels or fuel precursors directly in the aqueous phase.  Such a process alternative is to use the water in the harvested and partially dewatered algae for hydrolysis of lipids to free fatty acids (FFA), forming aqueous and oil rich phases for ease of extraction and separation of the lipid component. Lipid processing techniques include refining FFA by catalytic cracking and hydrotreating for jet fuel production, or the UOP/Eni Ecofining™ process to obtain clean green diesel. In our first step, subcritical water is reacted with lipids producing FFA by lipid hydrolysis eliminating the need for expensive and water sensitive catalysts.  In the initial development of an empirical kinetic model, soybean oil, a system much less complex than alga, was used in hydrolysis studies at subcritical water (SCW) conditions. This model was applied to algal lipid hydrolysis. The robustness of our model has been tested by verifying both the autocatalytic behavior of lipid hydrolysis reactions, as well as hydrolysis reactions over a range of temperatures.