Fabrication of MIL-125 Membrane with Unprecedented CO2/N2 Selectivity Using Ti6-oxo Cluster Source

Using metal-oxo clusters as metal source of metal-organic framework (MOF) membranes warrants not only more precise control over their multiscale structure but also milder reaction conditions for maintaining membrane continuity. In this study, a Ti6-oxo cluster was utilized as the titanium source of Ti-MOF membranes. Compared with the Ti8-oxo cluster precursor, which resulted in the fabrication of MIL-125(Ti) membranes via ligand exchange, employing a Ti6- oxo cluster source resulted in more precise control over epitaxial growth kinetics of MIL-125(Ti) seeds and, therefore, the formation of well-intergrown c-oriented MIL-125(Ti) membranes with higher linker deficiencies in the framework. Gas permeation results revealed an ideal CO2/N2 selectivity of 52.7, which ranked the highest among pure MOF membranes tested under similar conditions, thereby showing great promise for efficient CO2 capture from flue gases.