Dynamics of a chromatographic reactor: Esterification catalyzed by acidic resins

Reactive chromatography, i.e., coupling chemical reaction and selective sorption, allows us to drive the chemical reaction beyond equilibrium and to separate its products. Chromatographic reactors exhibit a complex dynamical behavior, whose analysis is the objective of this work. The synthesis of ethyl acetate and water from ethanol and acetic acid on a commercial polystyrene-divinylbenzene acidic resin is considered. The results of experiments run in a laboratory-scale chromatographic reactor are reported. Experimental data are in good agreement with the results obtained using a fully predictive equilibrium dispersive model. This exploits an accurate description of both the multicomponent sorption equilibria on the resin, based on the extended Flory-Huggins model, and the kinetics of the heterogeneously catalyzed chemical reaction. The chromatographic reactor exhibits a rather rich dynamical behavior, which is a consequence of the dual role, as a catalyst and as a selective sorbent, played by the resin. In particular, it is characterized by the development of composition fronts traveling along the fixed bed column at well-defined propagation velocities. By interpreting the obtained results in terms of these classical nonlinear chromatography concepts, a deep insight into the dynamical behavior of the chromatographic reactor can be achieved. These findings can be usefully summarized in a master plot which allows us to identify the different dynamic regimes in the operating parameter space.