High load mixed matrix membrane by metal-organic polyhedra for enhanced gas separation

Mixed matrix membranes (MMMs) are emerging as a competitive option in gas separation owing to their ability to mitigate the trade-off. Metal-organic polyhedra (MOPs) are a family of self-assembled structures consisting of metal ions and ligands, which are nanoscale cage-like molecules with independent units and excellent dispersion properties, while maintaining the similar pore structure of metal-organic frameworks (MOFs). Herein, Zr-MOP was incorporated as a filler in polybenzimidazole (OPBI) to achieve a high MOP loading of 50 wt%. The membrane with highly dispersed MOPs effectively prevents the excessive collaps of OPBI under the thermal treatment at 600 °C. The synergistic combination of Zr-MOP and OPBI yields perfectly dense, defect-free membranes with uniform pores and superior gas molecular selectivity. The optimal Zr-MOP 50 wt% @OPBI 600 membrane exhibited a remarkable He/CH 4 selectivity of 785, which is 4 times higher than the pristine OPBI membrane, alongside a high He permeability of 147 Barrer. Furthermore, the membrane demonstrated excellent high-pressure stability and long-term durability.