Fluorido-bridged iron-based metal-organic frameworks for carbon dioxide capture in humid flue gas

The inevitable combustion of fossil fuels in human industrial activities results in significant greenhouse gas emissions, leading to the pressing challenge of CO2/N2 separation in humid flue gas. Iron-based Metal-organic frameworks (MOFs) have proven to be cheap, robust against water vapor attack due to the enhanced coordination bonds. In this study, we present two distinct MOFs i.e., DNL-9(Fe) and PCN-233(FeMII), constructed by Fe clusters and 2,5-furandicarboxylic acid ligands. Static adsorption experiments revealed that DNL-9(Fe), featuring an exclusive Fe-F-Fe spiral packing structure, exhibited higher surface areas and enhanced CO2 adsorption performance that outcompeted PCN-233 candidates. DNL-9(Fe) demonstrated a high IAST selectivity of CO2/N2 at 247 (15/85, v/v, P/P0 = 0.01), superior to the most of state-of-the-art Fe-MOFs reported up to date. The further theoretical calculations elucidated the binding sites of the framework with CO2 molecules. Importantly, DNL-9(Fe) showed sufficient water stability and cyclic separation, as confirmed by dynamic breakthrough tests, indicating it as a promising candidate for practical CO2 capture from humid flue gas.