Kinetics Modeling and Mechanism Study for Selective Esterification of Glycerol with Lauric Acid Using 12-Tungstophosphoric Acid Post-Impregnated SBA-15

Abstract

Multiple kinetics models including simple power law model and mechanism-based models (nucleophilic substitution, Langmuir–Hinshelwood, and Eley–Rideal kinetics models) were investigated for selective esterification of glycerol with lauric acid using post-impregnated 12-tungstophosphoric acid SBA-15. Rate equations for all suggested models and mechanisms were derived, and appropriate experimental works were carried out. The model that best describes the studied reaction is found to be a combination of both a nucleophilic substitution mechanism and the Langmuir–Hinshelwood kinetics model with high accuracy and reliability of the model observed. The mechanism scheme describing the reaction from the bulk up to reactant molecular level and the interaction between reactant molecules on catalyst surface was outlined. Activation energy (Ea) of the studied reaction is found to be 35.62 kJ mol–1 with an Arrhenius constant, A, of 1141.2 L mol–1 g cat–1 h–1, which shows 40 wt %-HPW/IM to have a relatively low activat...