Catalysis Today 60 (2000) 147–157 Recovery of dilute acetic acid through esterification in a reactive distillation column B. Saha * , S.P. Chopade 1 , S.M. Mahajani 2 Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK Abstract The recovery of acetic acid from its dilute aqueous solutions is a major problem in both petrochemical and fine chemical industries. The conventional methods of recovery are azeotropic distillation, simple distillation and liquid–liquid extraction. Physical separations such as distillation and extraction suffer from several drawbacks. The esterification of an aqueous solution (30%) of acetic acid with n-butanol/iso-amyl alcohol is a reversible reaction. As excess of water is present in the reaction mixture, the conversion is greatly restricted by the equilibrium limitations. The esters of acetic acid, namely, n-butyl acetate and iso-amyl acetate, have a wide range of applications. In view of the appreciable value of these esters, the present work was directed towards recovery of 30% acetic acid by reaction with n-butanol and iso-amyl alcohol in a reactive distillation column (RDC) using macroporous ion-exchange resin, Indion 130, as a catalyst bed, confined in stainless steel wire cages. Experiments were conducted in order to achieve an optimum column configuration for the synthesis of n-butyl acetate/iso-amyl acetate in an RDC. The effect of various parameters, e.g. total feed flowrate, length of catalytic section, reflux ratio, mole ratio of the reactants, location of feed points and effect of recycle of water were studied. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Reactive distillation; Esterification; Acetic acid; n-Butanol; iso-amyl alcohol; n-Butyl acetate; iso-amyl acetate; Ion-exchange resin 1. Introduction Reactive distillation is an emerging technology that has considerable potential as an alternative process for carrying out equilibrium limited liquid phase chem- ical reactions. It is a unit operation that combines simultaneous chemical reaction and multicomponent distillation in the same vessel, which in turn reduces reactor and recycle costs. Ion-exchange resins (IERs) also find application in reactive distillation columns (RDCs) wherein they play a dual role of catalyst as * Corresponding author. 1 Also at: Department of Chemical Engineering, Michigan State University, East Lansing, MI 48824-1226, USA. 2 Also at: Chemical Engineering Department, Monash University, Clayton, Victoria 3168, Australia. well as tower packing. Extensive survey of the lit- erature on reactive distillation have been published by Sharma [1], Gaikar and Sharma [2], Buzad and Doherty [3] and Sharma [4]. Reactive distillation processes are now commer- cially exploited for the manufacture of methyl-tert- butyl ether (MTBE), an important anti-knock agent to replace tetraethyl lead in gasoline [5] and methyl ac- etate which is used as an intermediate in the manufac- ture of a variety of chemicals, e.g. acetic anhydride [6]. The world’s first technology for the commercial pro- duction of methylal by the reactive distillation method has been described by Masamoto and Matsuzaki [7]. Recently, acetalization reactions have been studied to synthesise methylal [8], ethylal [9] and 1,3-dioxolane [10] in RDCs. Ion-exchange resin catalysed ketaliza- tion of acetone with 1,4- and 1,2-diols was studied by 0920-5861/00/$ – see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S0920-5861(00)00326-6