Chemical Equilibrium and Reaction Kinetics of Heterogeneously Catalyzed n-Hexyl Acetate Esterification

In the framework of a project on reactive distillation, reaction equilibrium and kinetics of the esterification of n-hexanol and acetic acid, yielding n-hexyl acetate and water, were investigated. Chemical equilibrium and auto-catalyzed reaction kinetics were measured using batch reactors whereas a plug flow reactor was chosen to study the heterogeneously catalyzed reaction. The catalyst was Amberlyst CSP2. Dihexyl ether and hexene were observed as byproducts. The study covers temperatures between 20 and 130 °C, with a focus on the technically important range of 80-120 °C. Feed compositions were varied so that the entire concentration range relevant for reactive distillation was covered. On the basis of the experimental results, a thermodynamically consistent reaction model is developed. Two model types are tested, a pseudo-homogeneous and an adsorption-based model, for which the adsorption constants were determined from independent adsorption experiments of the immersion type carried out in the present work. Despite its simplicity, the pseudo-homogeneous model gives better results and is recommended for further use.