In-depth study of continuous production of biodiesel using supercritical 1-butanol

The continuous production of biodiesel from canola oil in supercritical 1-butanol (SCB) was thoroughly examined in order to investigate the detailed reaction behavior and elucidate the reaction kinetics. A continuous reactor was employed, and experiments were carried out at reaction temperatures of 270-400 °C, residence times of 5-30 min, a pressure of 20 MPa, and an oil-to-1-butanol molar ratio of 1:40. The factors affecting the product yield, such as temperature and time, were investigated and discussed in detail. The result showed that the highest biodiesel yield of 94.73 mol% was achieved at 400 °C within 14 min. The detailed kinetic model describing the transesterification of canola oil in SCB agreed well with the experimental data. The corresponding reaction rate constants and activation energies were determined. In comparison to supercritical methanol, supercritical ethanol, and supercritical 1-propanol, the reactivity of SCB was the lowest.