Kinetics of the esterification of acetic acid with 2‐propanol: Impact of different acidic cation exchange resins on reaction mechanism

Abstract

AbstractThe kinetics of the esterification of acetic acid with the secondary alcohol, 2‐propanol, catalyzed by the cation exchange resins, Dowex 50Wx8‐400, Amberlite IR‐120, and Amberlyst 15 has been studied at temperatures of 303, 323, and 343 K; acid to alcohol molar ratios of 0.5, 1, and 2; and catalyst loadings of 20, 40, and 60 g/L. The equilibrium constant was experimentally determined, and the reaction was found to be mildly exothermic. External and internal diffusion limitations were absent under the implemented experimental conditions. Systems catalyzed by gel‐type resins (Dowex 50Wx8‐400 and Amberlite IR‐120) exhibit some similarities in their reaction kinetics. Increase in reaction temperature, acid to alcohol ratio, and catalyst loading is found to enhance reaction kinetics for the three catalysts. The pseudohomogeneous (PH), Eley Rideal (ER), Langmuir Hinshelwood (LH), modified Langmuir Hinshelwood (ML), and Pöpken (PP) models were found to predict reaction kinetics with mean relative errors of less than 5.4%. However, the ML model was found to be better for predicting reaction kinetics in the systems catalyzed by gel‐type resins, while the PP model was better for the system catalyzed by the macroreticular catalyst, Amberlyst 15. The Eact for the forward reaction is found to be 57.0, 59.0, and 64.0 kJ/mole for the systems catalyzed by Dowex 50Wx8‐400, Amberlite IR‐120, and Amberlyst 15, respectively. For these three catalysts, the adsorption equilibrium constants of the components present in the system increase in the same order as do the solubility parameters of the component. Nonideality in the system is successfully accounted for by the UNIFAC model. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 593–612, 2006