Finding high-performance MOFs for effective SF6/N2 separation through high-throughput computational screening and machine learning

Abstract

Given the rapidly expanding pool of synthesized and hypothetical metal-organic frameworks (MOFs), testing every single material for SF6/N-2 separation by iterative experimental methods or computationally demanding molecular simulations is not practical. In this study, we integrated high-throughput computational screening and machine learning (ML) approaches to evaluate SF6/N-2 mixture adsorption and separation performances of over 25 000 different types of synthesized and hypothetical MOFs (hypoMOFs), representing the largest set of structures studied for SF6/N-2 separation to date. SF6/N-2 mixture adsorption data that we produced for synthesized MOFs using molecular simulations were utilized to develop ML models to accurately and quickly predict SF6 and N-2 uptakes, SF6/N-2 selectivities, SF6 working capacities, adsorbent performance scores, and regenerabilities of both synthesized and hypoMOFs. Results showed the MOF space that we studied exhibits very high SF6/N-2 selectivities in the range of 1.8-4204 at 1 bar in addition to high SF6 working capacities between 0.04-5.68 mol kg(-1) at an adsorption pressure of 1 bar and desorption pressure of 0.1 bar at room temperature. The top-performing MOF adsorbents for SF6/N-2 mixture separation were identified to have Zn, Cu, Ni metals;terphenyl, pyridine, naphthalene linkers;and medium pore sizes. Our comprehensive computational approach offers a highly efficient alternative to brute-force computer simulations by enabling the rapid assessment of the MOF adsorbents for SF6/N-2 separation and provides molecular insights into the key structural features of the most promising adsorbents.