Thermal treatment optimization of porous MOF glass and polymer for improving gas permeability and selectivity of mixed matrix membranes

Abstract

Porous MOF glasses are candidate fillers for interfacial void mitigation in mixed matrix membranes (MMMs), however, the inevitable decreased porosity in the glassy state is not conducive to membrane performance optimization. The rational design of porous MOF glass based MMMs remains a great challenge to achieve both high permeability and selectivity. Herein, a novel agZIF-62/PIM-1 (agZIF-62, the glass phase of ZIF-62) membrane has been fabricated by an optimized in-situ thermal treatment of ZIF-62/PIM-1 precursor membranes. Thermal treatment eliminates interfacial non-selective voids between agZIF-62 and PIM-1, and simultaneously increases PIM-1 free volume. As a consequence, both permeability and selectivity are significantly enhanced. The agZIF-62/PIM-30% membranes exhibit superior and stable separation performances with a CO2/CH4 selectivity of 67 and CO2 permeability of 5914 Barrer, which are improved by 268% and 27% compared with the pristine PIM-1 membranes, surpassing 2019 upper bound.