High-throughput screening of metal-organic frameworks for CO₂ capture in the presence of water

Competitive coadsorption of water is a major problem in the deployment of adsorption-based CO₂ capture. Water molecules may compete for adsorption sites, reducing the capacity of the material, and dehumidification prior to separating CO₂ from N₂ increases process complexity and cost. The development of adsorbent materials that can selectively adsorb CO₂ in the presence of water would be a major step forward in the deployment of CO₂ capture materials in practice. In this study, large-scale computational screening was carried out to search for metal-organic frameworks (MOFs) with high selectivity toward CO₂ over H₂O. Calculating framework charges for thousands of MOFs is a significant challenge, so initial screening used a fast, but approximate, charge calculation method. On the basis of the initial screening, 15 MOFs were selected, and Monte Carlo simulations were carried out to compute the adsorption isotherms for these MOFs using more accurate framework charges calculated by density functional theory. A detailed investigation was performed on the effect of using different methods for calculating partial charges, and it was found that electrostatic interactions contribute the majority of the adsorption energy of H₂O in the selected MOFs.