High efficiency metal removal from hexane-extracted algae oil using super and subcritical propane

Abstract

As a renewable energy source, oil-producing algae have received much attention in recent years. Raw oil, which is normally extracted from algae using solvents such as hexane or ethyl acetate, includes trace metal compounds that rapidly deactivate the hydrogenation catalyst. In this study, metal removal from hexane-extracted algae oil with supercritical and subcritical propane extraction was examined at temperatures from 40°C to 130°C and at 6MPa pressure. The results showed that the metal concentration became decreasing with temperature increasing and metals were not detectable at 114°C. Using these results, an energy saving process was proposed. Simulation results showed that the metal removal required a mere 3–4% energy consumption compared to a lower heating value of raw oil.