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High-Throughput Screening of MOF Adsorbents and Membranes for H₂ Purification and CO₂ Capture

Avci, Gokay, Velioglu, Sadiye, Keskin, Seda
ACS applied materials & interfaces 2018 v.10 no.39 pp. 33693-33706
adsorbents, adsorption, carbon dioxide, hydrogen, molecular dynamics, polymers, screening, zeolites
Metal organic frameworks (MOFs) have emerged as great adsorbent and membrane candidates for separation of CO₂/H₂ 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/H₂ 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/H₂ 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. H₂/CO₂ selectivities and H₂ permeabilities of MOF membranes were computed as 2.1 × 10–⁵–6.3 and 230–1.7 × 10⁶ Barrer, respectively. A high number of MOF membranes was identified to surpass the upper bound defined for polymers due to high gas permeabilities of MOFs. Structure–performance relations revealed that MOFs with narrow pore sizes and low porosities are the best adsorbent materials for separation of CO₂ from H₂, whereas MOFs with large pore sizes and high porosities are the best membrane materials for selective separation of H₂. Our results will guide the selection of MOF adsorbents and membranes for efficient H₂ purification and CO₂ capture processes.