High-performance crystal-glass composite membrane incorporating porous organic cages and coordination polymer for efficient CO2/CH4 separation

Abstract

Metal-organic framework glass shows great promise in gas separation applications, however, its inherent low porosity poses significant challenges to achieve the enhanced membrane permeability. In this work, we developed novel self-standing crystal-glass composite membrane via melt quenching process of porous organic cages and coordination polymer glasses. The resulting (CC3)_n/(a_gZn-P-dmbIm)_1-n membranes effectively combines the high porosity of CC3 with the excellent film-forming property of Zn–P-dmbIm glass, enabling efficient CO₂/CH₄ separation. Specifically, CO₂ molecules are preferentially adsorbed into the CC3 channels, followed by rapid permeation through the membrane, while the size exclusion restricts CH₄ molecules transport through the membranes. The obtained (CC3)_0.05/(a_gZn-P-dmbIm)_0.95 membrane achieves a high CO₂ permeability of 9358 Barrer, a CO₂/CH₄ selectivity of 24.2, and demonstrates 24-h operational stability. This study not only broadens the application scope of coordination polymer glasses in gas separation membranes but also provides novel insights for the design of high-performance crystal-glass composite membranes.