Mixed matrix membrane with amorphous metal-based complexes displays high CO2 separation performance

Design and exploration of advanced nanofillers that can be highly compatible with the existing polymeric membrane materials remain a subject of future study for mixed matrix membranes for gas separation. In this study, we propose the use of the newly synthesized metal-based complex (Zn-SiF6-py) as a promising filler to prepare high-performance PIM-1 based mixed matrix membranes for efficient CO2 separation. Results demonstrated that the as-synthesized Zn-SiF6-py features an amorphous mesoporous structure, and the inclusion of ZnSiF6-py in the PIM-1 matrix can concurrently elevate the CO2 permeability and CO2/N2 selectivity. The significant improvements in membrane separation performance can be ascribed to the combined effects of additional gas transport channels and abundant active sites to CO2 molecules provided by Zn-SiF6-py fillers as well as a rigidified polymer region at the filler/matrix interface. Consequently, the optimized mixed matrix membrane at only 5 wt% filler loading achieves a CO2 permeability of 6268 Barrer and a CO2/N2 selectivity of 26.3, surpassing the 2008 Robeson upper bound.