Reaction kinetics and chemical equilibrium of homogeneously and heterogeneously catalyzed acetic acid esterification with methanol and methyl acetatehydrolysis

The reaction kinetics and chemical equilibrium of the reversible esterifica tion of methanol with acetic acid were investigated. This system is of majo r importance as a model reaction for reactive distillation. The reaction ha s been catalyzed both homogeneously by acetic acid itself and heterogeneous ly by an acidic ion-exchange resin (Amberlyst 15). The chemical equilibrium composition was measured for various temperatures and starting composition s of the reactants and products. Kinetic information was obtained at temper atures between 303.15 and 343.15 K at various starting compositions coverin g concentration ranges from-the stoichiometric regime to the dilute regions . Both the esterification and the hydrolysis reaction were investigated to yield a model which is applicable for any starting composition. The homogen eous reaction has been described with a simple power-law model. The use of activities in the kinetic model instead of mole fractions results in a much smaller residual error. To compare pseudohomogeneous and adsorption-based kinetic models for the heterogeneously catalyzed reaction, independent bina ry liquid adsorption experiments were used to fit the adsorption constants to keep the number of adjustable parameters the same for each model. The us e of activities instead of mole fractions results in a slight improvement o f the kinetic model only, while incorporating adsorption information into t he kinetic model results in a much better fit. The chemical equilibrium com position calculated from the kinetic model is in agreement with the measure d chemical equilibrium.