Biodiesel Production by Esterification of Oleic Acid and Transesterification of Soybean Oil Using a New Solid Acid Catalyst Comprising 12-Tungstosilicic Acid and Zeolite Hβ

A series of catalysts containing 10–40 wt % of 12-tungstosilicic acid anchored to zeolite Hβ were synthesized and characterized by different physicochemical techniques. Their catalytic activity was evaluated for esterification of free fatty acid and oleic acid as well as transesterification of soybean oil with methanol. The effects of reaction variables such as catalyst loading, methanol to acid ratio, reaction time, and temperature on the conversion were studied. The kinetic study was carried out for esterification of oleic acid, and its Arrhenius constant (A) and activation energy (Ea) were evaluated. The maximum conversion obtained for esterification of oleic acid and transesterification of soybean oil were 86% and 95%, respectively. Also the catalyst was recycled up to four cycles without any loss in the conversion.