(449bz) In silico Screening of Metal-Organic Frameworks for CO2/CH4 and CO2/N2 Separation

Authors: 
Qiao, Z., National University of Singapore
Zhang, K., National University of Singapore
Jiang, J., National University of Singapore
We report a molecular simulation study to screen 4764 computation-ready, experimental metal-organic frameworks (CoRE-MOFs) for CO2 separation from flue gas (CO2/N2) and natural gas (CO2/CH4). Quantitative relationships are established, for the first time, between metal type and adsorbent evaluation criteria (adsorption selectivity and capacity, working capacity and regenerability). It is found that alkalis exist in 75% of alkali-MOFs as nonframework ions or open metal sites, and 75% of alkaline-MOFs contain alkalines as open metal sites; thus alkali and alkaline-MOFs exhibit high adsorption selectivity and large capacity. Combining selectivity, working capacity and regenerability, however, alkali and alkaline-MOFs possess the lowest performance for CO2 separation. Among ~1000 lanthanide-based CoRE-MOFs, 50% contain lanthanides as open metal sites and have the highest performance. Best 30 CoRE-MOFs are identified for CO2/N2 and CO2/CH4 separation, and they mostly contain lanthanides. Furthermore, we predict the breakthrough curves in two identified CoRE-MOFs and demonstrate their superior separation performance. This modelling study highlights the central importance of adsorbent evaluation by holistic criteria, and suggests that lanthanides could be the first choice in the design of new MOFs for CO2 separation.