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

Abstract

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.