In Silico Design of Metal Organic Frameworks with Enhanced CO₂ Separation Performances: Role of Metal Sites

In this study, grand canonical Monte Carlo simulations were performed to investigate the impact of metal centers on CO₂/H₂ mixture adsorption and separation performance of two different metal organic framework (MOF) series, M-HKUST-1 and M-HATGUF, where M represents different metals: Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Ru, and Zn. Results show that the type of metal site affects the CO₂ and H₂ uptakes of MOFs, and as a result, adsorbent performance metrics of MOFs such as selectivity, working capacity, regenerability, and adsorbent performance score significantly vary depending on the metal type. Cr-HKUST-1 and Cd-HKUST-1 were identified to have 11% and 38% enhanced CO₂/H₂ selectivities in addition to 27% and 60% enhanced adsorbent performance scores compared to original Cu-HKUST-1, respectively. CO₂/H₂ selectivity of HATGUF was found to be almost doubled by changing the metal from Cu to Cd in addition to 142% increase in the adsorbent performance score of HATGUF. Our results revealed that changing the metal type of MOFs offers a great opportunity in the way of improving the CO₂/H₂ separation performance of materials. Considering the very large number of available MOFs and metals, these results will be useful to design new MOFs by directing the selection of metals that will lead to high-performance adsorbents for CO₂ capture.