Simulation Studies of Reactive Distillation for Ethyl Acetate Production through Esterification

Abstract

Reactive distillation (RD) is an integrated operation that combines a chemical reaction step with separation of the products in the same vessel. Reactive distillation is potentially attractive whenever a liquid phase reaction must be carried out with a large excess of one reactant. Under such circumstances, conventional processes incur large recycle costs for excess reactant. Reactive distillation, on the other hand can be carried out closer to stoichiometric feed conditions, thereby eliminating recycle costs. Both homogeneous and heterogeneous catalysed chemical reactions can be carried out in a reactive distillation column. Process development, design and operation of RD processes are highly complex tasks. The potential benefits of this intensified process come with significant complexity in process development and design. Through RD implementation, chemical equilibrium limitation can be overcome, an equilibrium reaction can be driven to completion by separation of products from the reacting mixture (i.e., reaction conversion can approach 100%). Higher conversions are obtained due to shifting of the equilibrium to the right. Ethyl acetate is produced by the esterification reaction of ethyl alcohol and acetic acid using catalysts such as sulphuric acid, para toluene sulphonic acid or ion exchange resins. This equilibrium limited reaction and its process conditions are suitable for the RD implementation. The system is strongly non-ideal due to the presence of ethanol, acetic acid, and water. The separation of pure components is very difficult due to the existence of five normal azeotropes, namely, ethanol–water; water–acetic acid, ethyl acetate–ethanol, ethyl acetate–water, and ethanol–ethyl acetate–water. In this work, the simulation of reactive distillation of ethyl acetate production (C2H5COOCH3), using acetic acid (CH3COOH) and ethanol (C2H5OH), in a plate column are done using RADFRAC module of ASPEN Plus. The results show that the Wilson model for liquid phase activity with SRK model for vapor phase, and UNIQUAC model for liquid phase predict the experimental data most closely. However, the segmental model approach has improved the simulation predictions for the entire column.