Gas Adsorption & Selectivity in Five Classes of MOFs: From CO2 to Hydrocarbon Separation

The rational selection of metal organic frameworks for gas separation applications remains challenging due to the complex interplay between framework topology, pore chemistry, size, and intermolecular interactions under operating conditions. In this study, a comprehensive simulation-based screening is carried out to evaluate the gas adsorption and separation performance of five MOFs, namely IRMOF-1, HKUST-1, ZIF-8, ZIF-68, and ZIF-69. Industrially relevant systems, including CO 2 /CH 4 , N 2 /O 2 /H 2 , and C 2 H 4 /C 2 H 6 , are systematically investigated. Molecular simulations are performed across the pressure range, 1-40 bar for pure components and binary mixtures at 298K to assess adsorption capacity and selectivity. Notably, the selectivity was sensitive to the molar ratio and pressure, underlining the importance of evaluating MOFs across a broad range of conditions for industrial relevance. For CO 2 − light gas mixtures, ZIF-68, 69 showed a non-monotonic dependence of selectivity on molar concentration. In contrast, for binary mixtures of light hydrocarbons (C 2 H 4 /C 2 H 6 ), all MOFs exhibited poor selectivity across all concentrations and pressures, with little variation in performance. This insensitivity suggests the limited capability of the selected MOFs to distinguish 1 between structurally similar hydrocarbon gases, which is in stark contrast to their behavior for light gas separations.