Improving the Maximum Conversion of Ethanol Esterification

Abstract

In this study, the (catalysed) esterification process of acetic acid with ethanol producing ethyl acetate and water is modelled using detailed mass and energy balances and thermodynamic properties within gPROMS modelling software (version 3.0.3, 2004). The basic model was taken from Mujtaba and Macchietto (1997) assuming no azeotrope formation in the system. Kinetic (hydrochloric acid as a catalyst at 100 °C) and vapour-liquid equilibrium models are taken from Bogacki et al. (1989) and Suzuki et al. (1970) respectively. Physical properties are calculated using the Ideal Physical Properties Foreign Objective (IPPFO) package interfaced to gPROMS. The performance of the batch reactive distillation is evaluated in terms of the maximum conversion of ethanol to ethyl acetate. Five cases with varying amounts of reactants (including the cases with the reduced amount of water in the feed and keeping the amount of acetic acid and ethanol fixed) are utilized to improve the conversion of ethanol to ethyl acetate. Both piecewise constant and linear reflux ratio profiles (single time interval) are considered as a control variable for the base case while the piecewise constant single reflux ratio strategy is adopted for other optimized cases. The results show that both the maximum conversion and distillate product (base case) are improved using the linear reflux strategy as a control variable compared to those with a constant reflux ratio profile. Increasing the amount of water in the feed leads to a reduction in the conversion and distillate product; moreover, the column was operated at a higher reflux ratio compared to the case without any water in the feed.