Kinetics study of propyl acetate synthesis reaction catalyzed by Amberlyst 15

The reaction kinetics of esterification of acetic acid with n-propanol was investigated. The reaction was catalyzed by the commercial cation-exchange resin Amberlyst 15, and the kinetic data were obtained in a batch reactor within the temperature range 338-368 K. The chemical equilibrium constant, K-eq, was first determined experimentally; the result shows that K-eq is about 20 and slightly temperature dependent. Altogether 14 sets of kinetic data were then measured. The influences of operating parameters such as temperatures, initial molar ratios, and catalyst concentrations were checked. The pseudo-homogeneous (PH), Rideal-Eley (RE), and Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic models were developed to interpret the obtained kinetic data. The parameters of the kinetic models were identified by the software DIVA, and the confidence interval of each parameter was also estimated. Both the chemical equilibrium constant and kinetic models were formulated in terms of the liquid phase activity, which was described by the nonrandom two-liquid (NRTL) model. The LHHW model gives the best fitting result, followed by the RE model and the PH model, whereas the confidence intervals rank in the reverse order. in addition, an effective solution was proposed to overcome a convergence problem occurring in the LHHW model parameter identification, which has been reported several times in the literature. (c) 2007 Wiley Periodicals, Inc.