A new biodiesel production by water addition to supercritical tert-butyl methyl ether using a plug flow reactor

•Biodiesel was synthesized from rapeseed oil, MTBE, and water.•The supercritical reaction was carried out in a plug flow reactor.•Biodiesel yield of 77.39% was achieved at water of 8.2 wt% and 300 °C in 30 min.•The water on supercritical MTBE improves kinetics parameters.•The reaction is endothermic, endergonic, and unspontaneous.