Optimization of a novel liquid phase capillary discharge plasma reactor for continuous methyl ester synthesis

Conventional transesterification processes not only require large amounts of methanol and catalysts but are also time-consuming and operate at high temperatures. Advanced methods such as non-thermal plasma have been studied for biodiesel production because they mainly reduce the temperature as well as the reaction time. In this study, a liquid-phase capillary discharge plasma reactor was developed for the continuous production of biodiesel from sunflower oil at ambient temperature and pressure. The four main operational parameters were examined each with three levels, including molar ratio (4, 6, 8), catalyst concentration (0.5, 1, 1.5 wt%), applied voltage (10, 15, 20 kV), and reactant flowrate (2, 4, 6 ml/s). The response surface method (RSM) was used to optimize FAME content. The results show that the capillary discharge reactor is possible to continuously produce 95.9 % methyl ester content (FAME- content) in a MeOH/oil molar ratio of 6.2:1, catalyst concentration of 1.2 wt %, applied voltage of 18 kV and flow rate of 4.6 ml/s. The power consumed in this process was 46.16 kJ/lit. These results indicate that the studied technology is able to continuously produce methyl ester with high conversion efficiency at low temperatures and with minimum amounts of inputs compared to common methods.