Production of iso-Amyl Acetate: Heterogeneous Kinetics and Techno-feasibility Evaluation for Catalytic Distillation

Abstract

Esterification reactions are typically equilibrium limited, and face challenges with product purification. They are carried out commercially using either large excess of one of the reactants, or by removing one of the products continuously in a reactive distillation column (RDC). In the present work, we studied the kinetics of esterification reactions of dilute acetic acid with iso-amyl alcohol to produce a value added ester (iso-amyl acetate) using ion-exchange resins, Purolite® CT-175 and CT-275 as catalysts in a batch reactor. The effect of agitation speed, catalyst particle size, reaction temperature, acetic acid concentration, acetic acid to iso-amyl alcohol molar ratio and catalyst loadings were investigated to optimise the reaction conditions. The non-ideality of each species in the reacting mixture was accounted for by using the activity coefficient via the use of the UNIFAC group contribution method. The kinetic data were correlated with Langmuir-Hinshelwood-Hougen-Watson (LHHW) and Eley-Rideal (E-R) models. The detailed kinetic data and a reliable rate expression for the esterification of acetic acid with an aliphatic alcohol (iso-amyl alcohol) would be useful for the simulation and design of an RDC for removing dilute acetic acid from aqueous streams. Another objective of this work was to evaluate the techno-feasibility of this operation through a systematic procedure of residue curve map (RCM). RCM gives a design engineer an idea of the existence of any separation boundaries imposed by the singular points corresponding to the reactive or kinetic azeotropes and thereby provide an insight into the feasibility of the desired operation. In the present study, RCM was generated for the quaternary system (acetic acid - iso-amyl alcohol - iso-amyl acetate - water) under different conditions to work out the feasibility of the operation. This map also suggests possible column sequencing or configurations to achieve a desired duty in an RDC.