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 Cu 3 (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 CO 2 permeability from 47.7   Barrer to 260.7   Barrer with almost unchanged CO 2 /CH 4 selectivity from 29.26 to 27.75.