CATALYTIC CARBON MOLECULAR SIEVE HOLLOW MEMBRANES FOR PROPANE DEHYDROGENATION

Abstract

Steam cracking and fluid catalytic cracking have been struggling to fulfill the rising global propylene (C3H6) demand. Propane dehydrogenation (PDH) has been used as an on-purpose propylene production process to fill the propylene supply-demand gap but is limited by thermodynamic equilibrium and low conversion. This work developed catalytic carbon molecular sieve (CMS) hollow fiber membrane reactors, which comprised a porous core layer with dispersed catalyst particles and a dense separation layer for selective hydrogen removal and enhanced propane conversion. Compared with conventional packed-bed PDH membrane reactors, the catalytic CMS hollow fiber membrane reactor allows closer catalyst-membrane contact. Single-gas permeation at room temperature showed that the catalytic CMS hollow fiber membrane had outstanding hydrogen/propane separation performance, which is crucial to effectively removehydrogen to enhance propane conversion. A one-dimensional plug-flow model was developed to predict the PDH performance of the catalytic CMS hollow fiber membrane reactor. The model showed that the catalytic CMS hollow fiber would significantly enhance propane conversion over the equilibrium conversion. The effect of membrane separation layer thickness, catalyst loading, and reaction temperature on membrane reactor performance was investigated using the model. The results will provide guidance on the optimization of the design and operation of a catalytic CMS hollow fiber membrane reactor for more energy-efficient PDH.