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.