Theoretical Simulation of CH4 Separation from H2 in CAU-17 Materials

Abstract

By combining grand canonical Monte Carlo simulations and dispersion-corrected density functional theory (DFT-D3), the adsorption and separation properties for gases (including H2 and CH4) in the recently synthesized metal–organic frameworks CAU-17 were investigated. By systematically screening the separation properties of 6 binary mixtures, extremely high CH4/H2 selectivity was found for CAU-17, when comparing with several classic porous materials (including IRMOF-1, UMCM-1, Cu-BTC, COF-5, and ZIF-8). Moreover, the functionalized CAU-17 also expressed the extraordinarily high CH4/H2 selectivity. Then the origin for high CH4/H2 selectivity in CAU-17 materials was further investigated in depth. The CH4 uptakes in CAU-17 materials are higher than those in classic porous materials, while the H2 loadings are in contrary to CH4. The difference in isosteric heats of adsorption for CH4 and H2 is the key factor for high CH4/H2 selectivity. In addition, the investigation on the capacity of three channels for CH4 an...