Determining catalyst loading in reactive distillation column

Abstract

The widespread industrial application of reactive distillation technology is inseparable from the development of catalytic packing. However, systematic research on the heterogeneous catalyst loading in the reactive distillation column is vacant, and existing studies about catalyst loading on each stage and their distribution ignore the physical structure of the reactive distillation column. In this work, Modular Catalytic Structured Packing combining catalyst bags and structured packing sheets is applied in the modeling and optimization of reactive distillation processes. The catalyst loading on each stage is obtained from three parameters: the catalyst volume fraction of catalytic packing, the catalytic distillation column diameter, and the height of the theoretical stage. Using the effective diffusivity method, a simplified non-equilibrium stage model is chosen to simulate the reactive distillation process, and the bubble-point method for solving the non-equilibrium stage model’s equation system is introduced. The genetic algorithm optimizes both catalyst volume fraction and the number of theoretical stages in the reactive section. Case studies of methyl acetate esterification and ethyl tert-butyl ether (ETBE) synthesis show that greater theoretical stages of the reactive section and enough reflux ratio will reduce the demand of catalysts. Redistribution of catalyst is implemented by dividing the reactive section into several. The non-uniform distribution of catalyst will reduce both energy consumption and catalyst amount for the methyl acetate system, but insignificant for ETBE synthesis, due to different interactions of reaction and separation.