Evaluation of Different Operational Strategies for Biodiesel Production by Direct Transesterification of Microalgal Biomass

In this study, different operational strategies for biodiesel production by direct transesterification of microalgal biomass (Botryococcus braunii) were evaluated. These operational strategies include the use of different acyl acceptors and the application of different catalysts and solvent mixtures. All these strategies were performed in two reaction systems: a conventional batch reactor (CBR) and a reflux extraction reactor (RER). The highest biodiesel production yields (80.6 wt %) were obtained in the RER using methanol as acyl acceptor and H2SO4 as catalyst. On the opposite, the lowest biodiesel production yield (64.5 wt %) was observed in the CBR system. Moreover, when a low proportion of cosolvent (i.e 3:1 v/v solvent/cosolvent) was incorporated in the reaction, an increase in biodiesel production yields was observed. A higher cosolvent content in the reaction mixture provoked however a diminishment in FAAE (fatty acid alkyl esters) yield in both systems, due to a drastically reduction of alcohol-lipids molar ratio.