Noble gas separation by a MOF with one-dimensional channels

Abstract

Noble gas separation by microporous materials is a promising alternative to energy-intensive cryogenic distillation method by reducing the separation cost; however, developing novel microporous materials with excellent noble gas separation performance is still challenging due to closing chemical and physical properties among the gases. In this study, we propose to separate the noble gases (He, Ne, Ar, Kr and Xe) utilizing a metal organic framework (MOF), named SIFSIX-3-Zn, with ultra-micron sized 1-dimenssional (1D) channels (3.84??). Density functional theory (DFT) calculations reveal that the 1D channels provide significant adsorption potential differences among the noble gas molecules in various sizes: the larger the molecular size, the stronger the adsorption potential. Grand canonical Monte Carlo (GCMC) simulations verify that the MOF exhibits exceptional equilibrium separation performance of noble gases. Remarkably, Xe/He and Xe/Ne adsorption selectivity can be as high as 645 and 596, respectively, at 298?K and 10?kPa. While Xe/Kr selectivity in mixed gas is around 12 with a Xe adsorption amount of about 2.27?mmol/g at 273?K and 100?kPa, making SIFSIX-3-Zn one of the promising materials for equilibrium separation of Xe/Kr mixtures.