12-Tungstophosphoric Acid Anchored to Zeolite Hβ: Synthesis, Characterization, and Biodiesel Production by Esterification of Oleic Acid with Methanol

Heterogeneous acid catalysts comprised of 12-tungstophosphoric acid (10-40 %) and zeolite Hβ were synthesized, and 30 % loaded catalyst was characterized by various physicochemical techniques. The use of synthesized catalyst was explored for biodiesel production by esterification of free fatty acid, oleic acid with methanol. The effect of various reaction parameters such as catalyst concentration, acid/alcohol molar ratio, and temperature were studied to optimize the conditions for maximum conversion. The catalyst showed high activity in terms of high conversion (84%) and a high turnover number, 1048. The kinetic study as well as Koros–Nowak test were carried out, and it was found that esterification of oleic acid follows first order kinetics with the calculated activation energy Ea = 45.2 kJ mol–1 and pre-exponential factor A = 5.4 × 104 min–1. The catalyst showed potential of being used as a recyclable catalytic material after simple regeneration without significant loss in conversion. As an application...