Analysis of Heterogeneously Catalyzed Ester Hydrolysis Reactions in a Fixed-Bed Chromatographic Reactor

Reactive chromatography is based on a combination of chemical reactions and chromatographic separations performed in a single apparatus. In comparison with sequentially connected conventional reactors and separators its performance promises the advantage to improve objectives as productivity, purity and selectivity. However, industrial applications of reactive chromatography are still absent due to technical problems and lack of accurate data and models. In an attempt to contribute to the development and application of this promising technique, in this dissertation several ester hydrolysis reactions performed in fixed-bed chromatographic reactors have been studied theoretically and experimentally. Whether reactive chromatography can be applied successfully for a certain chemical reaction depends on reaction stoichiometries and rates, and on interactions of the species involved with the stationary phases applied. Therefore, theoretical tools are desirable to evaluate feasibility before going into further details. In this work, a new modeling approach consisting out of two steps is proposed for conceptual design of fixed-bed chromatographic reactors. In a first step, an extended equilibrium model is used to study feasibility of joint complete conversion and complete separation. In a second step, a more detailed equilibrium-dispersion model is used to simulate and optimize the performance of fixed-bed chromatographic reactors. In order to verify theoretical predictions, the hydrolysis reactions of methyl formate, ethyl formate, methyl acetate and ethyl acetate were investigated experimentally in fixed-bed chromatographic reactors. These four ester hydrolysis reactions are characterized by different behavior regarding reaction kinetics. An ion exchange resin was used as adsorbent and catalyst. To model the relevant subprocesses, chemical and adsorption equilibria, dispersion coefficients, and other parameters were determined experimentally. In particular, the influence of the temperature on these parameters was quantified. Furthermore, the reaction rate constants were estimated for the four reactions using curve fitting procedures based on comparing simulated and experimentally determined elution vi profiles. Finally, the equilibrium-dispersion model was used to simulate the performance of the fixed-bed chromatographic reactor and a wide parameter range. The results obtained and the modeling approach presented can be used to study other reaction system, other modes of operation of reactive chromatography and other integrated reaction-separation processes.