Mesoporous SrTiO3 perovskite as a heterogeneous catalyst for biodiesel production: Experimental and DFT studies

A pure mesoporous SrTiO3 with a honeycomb pore structure is synthesized by the sol-gel method and applied to catalyze transesterification of palm oil with methanol for the biodiesel production. The catalyst is characterized by XRD, CO2/NH3-TPD, N2 adsorption-desorption, SEM-EDX, Raman and XPS to reveal its catalytic performances. The highest FAME yield of 93.14% is achieved in transesterification with the molar ratio of methanol to oil of 15:1 and catalyst concentration of 6 wt% at 170 C for 3 h. Besides, the catalyst is highly tolerant of FFAs and moisture, where the FAME yields of 83.80% and 86.50% are achieved even with the oleic acid and water addition of 10 wt% and 5 wt%. Meanwhile, the catalyst is found to be an effective catalyst for the simultaneous esterification and transesterification. The molecular simulation results show that the Ti sites are more easily attacked by FFAs and the Sr active sites are thus retained for the adsorption of methanol to catalyze transesterification, which explains the bifunctionality of the catalyst.