A comparative study of biodiesel production using methanol, ethanol, and tert-butyl methyl ether (MTBE) under supercritical conditions

•Biodiesel production in supercritical MeOH, EtOH, and MTBE were compared.•Biodiesel yield increased with reaction time and temperature for all cases.•Supercritical methanol gave the highest biodiesel yield under the same reaction conditions.•At 350 °C, 20 MPa, 10, 30, and 30 min gave the optimum yield for MeOH, EtOH, and MTBE, respectively.•The second-order kinetic model expressed good agreement with experimental data.

In this study, biodiesel production under supercritical conditions among methanol, ethanol, and tert-butyl methyl ether (MTBE) was compared in order to elucidate the differences in their reaction behavior. A continuous reactor was employed, and experiments were conducted at various reaction temperatures (270–400 °C) and reaction times (3–30 min) and at a fixed pressure of 20 MPa and an oil-to-reactant molar ratio of 1:40. The results showed that under the same reaction conditions, the supercritical methanol method provided the highest yield of biodiesel. At 350 °C and 20 MPa, canola oil was completely converted to biodiesel after 10, 30, and 30 min in the case of – supercritical methanol, ethanol, and MTBE, respectively. The reaction kinetics of biodiesel production was also compared for supercritical methanol, ethanol, and MTBE.