Transesterification of croton megalocarpus oil to biodiesel over WO3 supported on silica mesoporous-macroparticles catalyst

Abstract

The transesterification of croton megalocarpus oil with methanol to fatty acid methyl ester (FAME) was carried out using WO3 supported on silica mesoporous-macroparticles (WO3/SMP) as a heterogeneous acid catalyst. The silica mesoporous-macroparticles (SMP) and WO3/SMP were synthesized by sol-gel and impregnation method, respectively. The catalysts were characterized with XRD, FTIR, N2 adsorption-desorption, SEM and TEM. The presence of WO3 gave a negative effect on the crystallinity and surface area of the SMP as evidenced by XRD and N2 adsorption-desorption studies, respectively. Pyridine adsorbed FTIR spectroscopy showed that the concentration of Brønsted and Lewis acid sites was dependent on the WO3 loading on SMP. 2 wt% of WO3 loading on SMP (2WO3/SMP) exhibited the highest intensity of Lewis acid sites which is vital in transesterification reaction. Under the optimum reaction condition determined through response surface methodology (RSM), 2 wt% WO3 loading, 4.5 wt% catalyst amount, 9:1 methanol to oil molar ratio, 45 min reaction time and 343 K reaction temperature yielded a 96% of biodiesel product. The highest catalytic activity of 2WO3/SMP may be attributed to the high Lewis acid sites content and the presence of both intra- and interparticle pores of the catalyst that facilitated and enhanced the transport of reactants and products during the reaction.