Post-treatment effect on gas separation property of mixed matrix membranes containing metal organic frameworks

Abstract

In this work a series of mixed matrix membranes (MMMs) containing metal organic frameworks (MOFs) were fabricated to investigate the influence of post-treatment on their gas separation properties. It was revealed that gas permeabilities increased considerably as treatment temperature increased from 150°C to 180°C and remained almost unchanged after 200°C; gas permeability of MMMs from 200°C treatment was about 3 times higher when compared with MMMs treated at 150°C. From results of physical characterization including TGA, XRD, SEM, ATR-FTIR and nitrogen absorption it was inferred that higher temperature treatment induced gas permeability increase should be mainly attributed to more effective removal of residual solvent in micro-pores of MOFs; and gas permeation properties of MMMs with different treatment durations from 24h to 96h further confirmed our conclusion. This heat treatment induced permeability increase phenomenon was further verified by varying the polymer and MOF combinations. At the end Cu3(BTC)2/ODPA–TMPDA MMMs with different MOF loadings were prepared and the one with best performance appeared at 40wt% loading: a dramatic increase of CO2 permeability from 47.7Barrer to 260.7Barrer with almost unchanged CO2/CH4 selectivity from 29.26 to 27.75.