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

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 24 h to 96 h 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 40 wt% loading: a dramatic increase of CO2 permeability from 47.7 Barrer to 260.7 Barrer with almost unchanged CO2/CH4 selectivity from 29.26 to 27.75.