High-throughput screening of Metal-Organic frameworks for helium recovery from natural gas

Due to their unique physical properties, metal-organic frameworks (MOFs) are promising materials for gas separation. In this study in silico screening of 5112 MOFs was performed both for adsorption-based and for membrane-based helium recovery from natural gas. Optimal ranges corresponding to the most promising MOFs were determined for 6 structural parameters: pore limiting diameter, largest cavity diameter, accessible surface area, accessible pore volume, density and porosity. The effect of the three-component gas mixture composition, temperature and pressure drop on the structure - adsorption and membrane performance relationships was studied. Metal atoms were shown to affect the adsorption and diffusion properties primarily via the formation of the pore structure topology rather than via contribution to the adsorbate-MOF intermolecular interaction. Therefore, the search for efficient MOFs for helium recovery from natural gas should be primarily based on selection of MOFs with optimal structural parameters. Based on the high-throughput screening of MOF structures, it can be inferred that MOFs cannot compete with zeolite 5A in terms of the performance-cost ratio for adsorption-based separation He from crude helium. In the case of membrane-based separation, it has been shown that the search for MOF materials simultaneously selective to N2 and CH4 is more promising than the search for He-selective solid porous materials for application in He recovery from natural gas.