Computational screening of ZIFs for CO2 separations

Abstract

Using molecular simulations, we studied a diverse collection of zeolite-imidazolate frameworks (ZIFs) to evaluate their performances in adsorption- and membrane-based gas separations. Molecular simulations were performed for both single-component gases (CH4, CO2, H-2 and N-2) and binary gas mixtures (CO2/CH4, CO2/N-2, CO2/H-2 and CH4/H-2) to predict the intrinsic and mixture selectivities of ZIFs. These two selectivities were compared to discuss the importance of multi-component mixture effects on making predictions about the separation performance of a material. Gas separation performances of ZIFs were compared with other nanoporous materials and our results showed that several ZIFs can outperform well-known zeolites and metal-organic frameworks in CO2 separations. Several other properties of ZIFs such as gas permeability, working capacity and sorbent selection parameter were computed to identify the most promising materials in adsorption- and membrane-based separation of CO2/CH4, CO2/N-2, CO2/H-2 and CH4/H-2.