Bifurcation study of kinetic effects in reactive distillation

Abstract

AbstractSimple distillation with multiple chemical reactions of arbitrary stoichiometry is described, with emphasis on effects of chemical kinetics. For low and high Damköhler number, the lightest and heaviest boiling components or azeotropes are known or can be found by known methods. In those limits, the products from a distillation can be anticipated and feasible separation structures can be identified. Feasible structures in these cases are not the same, however, and there are one or more transitions so that different structures can appear for different ranges of the Damköhler number. The transition points correspond to bifurcations, and using bifurcation analysis and continuation methods a systematic method that represents these changes was developed. The practical implication is that the feasibility and product purities for a reactive distillation may depend on production rate, catalyst level, and liquid holdup. The approach is illustrated for the production of methyl‐tert‐butyl ether (MTBE), where a critical Damköhler number for the disappearance of a distillation boundary is found. The influence of pressure on byproduct reactions in methyl acetate synthesis is also studied. A study of the synthesis of isopropyl acetate illustrates how the bifurcation method captures the essential kinetic effects in reactive distillation, including a critical Damköhler for the birth of a reactive azeotrope.