Pervaporation-aided esterification of oleic acid

Abstract

Esterification of oleic acid with ethanol in the presence of p-toluenesulfonic acid was carried out at temperatures up to 383 K and initial molar ratios of ethanol to oleic acid, m0, up to 6. A kinetic equation having both a term of rate reduction due to water and a m0-dependent rate constant are presented. The esterification, aided with pervaporation through asymmetric polyimide membranes, was carried out at 348 K and 371 K under atmospheric and elevated pressures respectively. Almost complete conversion was attained for m0 of 2 in a short time with a low concentration of the catalyst at 371 K. Only water and ethanol permeated through the membranes. The permeation flux was expressed by the product of the permeability constant, P, and the permeant concentration of the liquid. P depended on the concentration of oleic acid and ethyl oleate at 371 K, but not at 348 K. A model in which the kinetic equation is combined with the permeation flux equation taking both volume change and sampling loss of the reaction mixture into consideration represented the experimental time course of the reaction sufficiently well. The influence of operating parameters on the reaction time required for a conversion of 98% and on the productivity was investigated by simulation from the model. © 1993, The Society of Chemical Engineers, Japan. All rights reserved.