Transesterification of croton megalocarpus oil over tungsten trioxide loaded on silica mesoporous-macroparticles

Abstract

Production of biodiesel has been seen as a quantum jump in recent years due to its ability to mitigate greenhouse gas (GHG). Biodiesel produces better quality of exhaust gas emission that helps in minimizing the greenhouse effect. In this study, non-edible Croton megalocarpus oil was converted to biodiesel by transesterification process in heterogeneous catalysis over tungsten trioxide supported on silica mesoporous-macroparticles (WO3/SMP). The SMP was successfully synthesized by hydrolysis of TEOS in the mixed solvent of water and acetone using CTAB as template at room temperature. Meanwhile, WO3/SMP catalysts were prepared by impregnation, followed by drying and calcination at 823 K. The properties of WO3/SMP were characterized using XRD, FTIR, N2 physisorption, FESEM and TEM. The 2WO3/SMP catalyst has high surface area, large pore size, and high acidity. The enhancement of Lewis acid sites induced high activity in the transesterification of Croton megalocarpus oil. Increased acidity effectively enhanced the catalytic performance of 2WO3/SMP as a heterogenous catalyst in biodiesel production. The optimal parameters obtained for the transesterification process were: reaction temperature (348 K), reaction time (68 min), and methanol to oil molar ratio (1:7), and catalyst dosage (4.wt%). Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the catalyst dosage (3 to 6 wt.%), methanol to oil molar ratio (4 to 13), reaction temperature (318 to 363 K), and reaction time (45 to 112 min) of the transesterification process. Using the optimal conditions determined by RSM, the conversion yield of Croton megalocarpus oil reached 93.1 % at 345 K with the methanol to oil molar ratio of 9:1, reaction time of 45 min, and catalyst dosage of 4.5 wt.%, respectively. Overall, this study shows that WO3/SMP has the potential to be applied as a catalyst in future biodiesel production.