Nonequilibrium modeling of reactive distillation: a dusty fluid model for heterogeneously catalyzed processes

Abstract

We have developed a nonequilibrium model for heterogeneous catalytic distillation in which we have explicitly taken into account simultaneous mass transfer and reaction inside the catalyst particle. This was done by using a finite difference approximation of the dusty fluid model. Calculations were done for a methyl tert-butyl ether (MTBE) column and a tert-amyl methyl ether (TAME) column. It was found that there are hardly any differences between a pseudohomogeneous nonequilibrium model and a dusty fluid nonequilibrium model, for the TAME process. The simulation results for the TAME process compare favorably with the experimental data of Mohl et al. (Chem. Eng. Sci. 1999, 54, 1029). For the MTBE process the pseudohomogeneous model predicts multiple steady states. However, the window of opportunity for multiple steady states seems to disappear entirely using the dusty fluid model. The explanation for the contrasting behavior of the TAME and MTBE processes has to do with the fact that the latter is significantly more sensitive to increased mass-transfer resistances.