Transesterification of soybean oil for biodiesel production over CaAlSi mixed oxide nanoparticles

CaAlSi mixed metal oxide nanoparticles with formula Ca₂Al₂SiO₇ and CaAl₂O₄ (with molar ratio of 70:30) was prepared by sol–gel method and used as a basic heterogeneous catalyst for transesterification of soybean oil with methanol to methyl esters (biodiesel). The catalyst was characterized using X-ray diffraction, scanning electron microscope, Fouier Transform Infrared, and Termal Gravimetric Analysis techniques. Effect of important reaction parameters such as methanol to oil molar ratio, reaction time, and amount of catalyst were examined. It was found that reaction of methanol and soybean oil with the molar ratio of 30 in the presence of 6 % catalyst (based on soybean oil weight) affords biodiesel almost quantitatively at 60 °C within 6 h. The catalyst can be easily recovered and reused for four cycles without significant loosing activity.