Hydrostable Fluorinated Metal-Organic Frameworks for CO2 Capture from a Wet Flue Gas: Multiscale Computational Screening.

Abstract

Metal-organic frameworks (MOFs) are promising adsorbents for CO₂ capture due to readily tunable porosity and diverse functionality; however, their performance is deteriorated by the presence of H₂O in a flue gas. Fluorinated MOFs (FMOFs) may impede H₂O interaction with frameworks and enhance CO₂ adsorption under humid conditions. In this study, a multiscale computational screening study is reported to identify the top FMOFs for CO₂ capture from a wet flue gas. Initially, geometric properties as well as heats of H₂O adsorption are used to shortlist FMOFs with a suitable pore size and weak H₂O affinity. Then, grand-canonical Monte Carlo simulations are conducted for adsorption of a CO₂/N₂/H₂O mixture with 60% relative humidity in 5061 FMOFs. Based on the adsorption performance, 19 FMOFs are identified as top candidates. It is revealed that the position of F atom, rather than the amount, affects CO₂ adsorption; moreover, N-decorated FMOFs are preferential for selective CO₂ adsorption. Finally, the hydrostability of the top FMOFs is confirmed by first-principles molecular dynamics simulations. From a microscopic level, this study provides quantitative structure-performance relationships, discovers hydrostable FMOFs with high CO₂ capture performance from a wet flue gas, and would facilitate the development of new MOFs toward efficient CO₂ capture under humid conditions.