Kinetics of the esterification of palmitic acid with methanol catalyzed by 12-tungstophosphoric acid supported on ZrO2

A series of catalysts containing 5-25 wt% 12-tungstophosphoric acid supported on hydrous zirconia were prepared and their catalytic activity evaluated for the esterification of palmitic acid with methanol. These catalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, surface area (BET method), and potentiometric titration for the estimation of acidity. The catalyst with 20 wt% TPA calcined at 300 A degrees C exhibited the highest activity. The effects of reaction variables such as catalyst loading, methanol to acid molar ratio and reaction temperature were studied. The pseudo-homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic models were applied to correlate the experimental kinetic data and kinetic parameters were evaluated. The LHHW model gave the best fit.