Abstract
The modern technology for acetylene production is inevitably accompanied by the contamination of carbon dioxide and moisture impurities. Metal–organic frameworks (MOFs), with rational configurations of fluorine as the hydrogen-bonding acceptor (HBA), exhibit excellent affinities to capture acetylene from the gas mixtures. Currently, most research studies feature anionic fluorine groups as structural pillars (e.g., SiF62−, TiF62−, NbOF52−), whereas in situ insertion of fluorine into metal clusters is rather challenging. Herein, we report a unique fluorine-bridged Fe-MOF, i.e., DNL-9(Fe), which is assembled by mixed-valence FeIIFeIII clusters and renewable organic ligands. The fluorine species in the coordination-saturated structure offer superior C2H2-favored adsorption sites facilitated by hydrogen bonding, with a lower C2H2 adsorption enthalpy than other reported HBA-MOFs, demonstrated by static/dynamic adsorption tests and theoretical calculations. Importantly, DNL-9(Fe) shows exceptional hydrochemical stability under aqueous, acidic, and basic conditions, and its intriguing performance for C2H2/CO2 separation was even maintained at a high relative humidity of 90%.
Y.-M. G., T.-J. S. and S.-D. W. are grateful to the National Natural Science Foundation of China for funding (No. 21776266). X.-W. L. and Z. L. appreciate the funding (BAS/1/1375-01-01 and FCC/1/1972-88-01) from King Abdullah University of Science and Technology (KAUST). The authors also thank Prof. Alexandre Rykov at the Center for Advanced Mössbauer Spectroscopy in DICP, for Mössbauer spectroscopy measurement and analysis; and Dr Wen-Guang Yu and Dr Pei-Fang Yan for the help in TGA-DSC and IGA adsorption measurements.