The production of biodiesel from microalgae is complicated by the energy and cost associated with biomass harvesting, dewatering, and oil separation. We previously reported on a two-step method to produce biodiesel from wet algal biomass through hydrothermal carbonization and in situ supercritical ethanol (trans)esterification. Here we demonstrate the use of rare-earth metal triflates (Sc(OTf) 3 and In(OTf) 3) to catalyze the conversion of fatty acids (FAs) and glycerides in both model systems and carbonized algal solids to ethyl esters. High yields (>90%) were obtained at moderate temperatures (190-235 °C), in short times (5-30 min), and with industrially relevant amounts of ethanol (10:1-15:1 molar ratio EtOH:FA), catalyst (1 mol% to FA), and water (2-10 wt%).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)