High-throughput screening of MOF adsorbents and membranes for H-2 purification and CO2 capture

Abstract

Metal organic frameworks (MOFs) have emerged as great adsorbent and membrane candidates for separation of CO2/H-2 mixtures. The main challenge is the existence of thousands of MOFs, which requires computational screening methods to identify the best materials prior to experimental efforts. In this study, we performed high-throughput computational screening of MOFs to examine their adsorbent and membrane performances for CO2/H-2 separation. Grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations were used to compute various adsorbent and membrane performance metrics of 3857 MOFs. CO2/H-2 adsorption selectivities of MOFs at pressure swing adsorption (PSA) and vacuum swing adsorption (VSA) conditions were calculated to be in the range of 2.5-25 000 and 2.5-85 000, respectively, outperforming many zeolite adsorbents. Correlations between the ranking of MOF adsorbents at the PSA and VSA conditions were examined. H-2/CO2 selectivities and H-2 permeabilities of MOF membranes were computed as 2.1 X 10(-5)-6.3 and 230-1.7 X 10(6) Barrer, respectively. A high number of MOF membranes was identified to surpass the upper bound defined for gas permeabilities of MOFs. Structure performance relations revealed that MOFs with narrow pore sizes the best adsorbent materials for separation of CO2 from H-2, whereas MOFs with large pore sizes and high polymers due to high and low porosities are porosities are the best membrane materials for selective separation of H-2. Our results will guide the selection of MOF adsorbents and membranes for efficient H-2 purification and CO2 capture processes.