CHEMICAL ENGINEERING TRANSACTIONS VOL. 29, 2012 A publication of The Italian Association of Chemical Engineering Online at: www.aidic.it/cet Guest Editors: Petar Sabev Varbanov, Hon Loong Lam, Jiří Jaromír Klemeš Copyright © 2012, AIDIC Servizi S.r.l., ISBN 978-88-95608-20-4; ISSN 1974-9791 DOI: 10.3303/CET1229100 Please cite this article as: Edreder E. A., Mujtaba I. M. and Emtir M. M., (2012), Simulation of middle vessel batch reactive distillation column: application to hydrolysis of methyl lactate, Chemical Engineering Transactions, 29, 595- 600 595 Simulation of Middle Vessel Batch Reactive Distillation Column: Application to Hydrolysis of Methyl Lactate Elmahboub A. Edreder a , Iqbal M. Mujtaba b , Mansour M. Emtir* c a Libyan Petroleum Institute, P. O. Box 6431, Tripoli, libya b University of Bradford, School of Engineering Design &Technology West Yorkshire BD7 IDP, UK * c Academy of graduate studies, P. O. Box 79031, Tripoli, Libya memtir@yahoo.com The middle vessel column (MVC) is a combination of a batch rectifier (conventional column) and a batch stripper (inverted column). Therefore it is possible to obtain a light and a heavy fraction simultaneously from the top and the bottom of the column while an intermediate fraction may also be recovered in the middle vessel. Several researchers in the past have proposed the esterification of lactic acid (impure) with alcohol to obtain lactate ester which is then separated by distillation. To the best of our knowledge, simulation of middle vessel batch reactive distillation column for hydrolysis system has not yet been explored. In this work, the hydrolysis reaction of methyl lactate to produce lactic acid (LA) is carried out in a middle vessel column with fixed batch time while control variables are treated as a piecewise constant reflux ratio (multiple time intervals) and a single reboil ratio. For MVC, the LA being the heaviest in the reaction mixture, reflux and reboil ratios policy plays an important role to achieve high purity of LA. 1. Introduction The use of conventional batch distillation for some reactions would result in removal of reactants as the distillation proceeds thus lowering conversion and yield of product. Therefore, it is very important to select the right batch distillation column for each type of chemical reaction. Conventional batch distillation (CBD) is not suitable when all reaction products have higher boiling temperatures than those of the reactants. Inverted batch distillation (IBD) is suitable for such situation. For cases where some of the reaction products have higher and some lower boiling points than those of the reactants, then neither the conventional nor the inverted batch distillation are exactly suitable/efficient. For such reaction schemes, the Middle Vessel Batch Distillation Column (MVC) will be the most suitable one because the light and heavy products can now be withdrawn simultaneously from the column, thus pushing the reaction further to the product side (Mujtaba, 2004). In MVC (Figure 1) the separation section is divided, as in the usual continuous distillation column, into rectifying and stripping sections, with a feed tray in the middle. This configuration was first mentioned by Robinson and Gilliland (1950) Hasebe et al. (1992); Mujtaba and Macchietto (1992); Barolo et al. (1996); and Greaves et al. (2003) reported further use of MVC. Several researchers in the past have proposed the esterification of lactic acid (impure) with alcohol to obtain lactate ester which is then separated by distillation. Seo et al. (1999) investigated two reactions, esterification followed by hydrolysis for recovery of lactic acid by batch reactive distillation using cation exchange resin as a catalyst.