Efficient synthesis of biodiesel from waste cooking oil using solid acid catalyst comprising 12-tungstosilicic acid and SBA-15

Biodiesel synthesis by transesterification of low-cost feedstock, waste cooking oil was carried out over 12-tungstosilicic acid anchored to SBA-15. The effect of different reaction parameters like % loading, catalyst amount, mole ratio, time and temperature were studied for the supreme conversion. The catalyst was recycled up to four times after simple work up without notable loss in the activity. The maximum conversion (86%) was achieved for waste cooking oil with oil:alcohol ratio of 1:8 w/w, catalyst amount of 0.3 g at 65 °C in 8 h. The detailed kinetic studies were also performed on the esterification of oleic acid in order to evaluate the activation energy (Ea) and rate constant (k).