Thermal induced in-situ defect engineering of ZIF-8 in mixed matrix membranes with significantly enhanced gas separation properties

Defect engineering of metal organic frameworks (MOFs) is an emerging effective approach for manipulating their microporosity structure. They are very promising but challenging to achieve significant gas separation performance improvements for mixed matrix membranes (MMMs) fabrication. Herein, we propose a novel thermal induced in-situ defect engineering strategy of ZIF-8 in MMMs by carefully post controlled annealing (above polyimide matrix T g and below ZIF-8 T d ). Attractively, the thermal-triggered polyimide matrix (P84 HT) crosslinking repairs interfacial voids between ZIF-8 and P84 HT. The resulting advanced MMMs exhibit more gas sorption sites and diffusion pathways owing to the missing Zn-N bond of ZIF-8, while exciting enhancement of H 2 /CH 4 and H 2 /N 2 separation performance is obtained compared with the pristine P84 HT membrane. Furthermore, after in-situ defect engineering at 400 °C, the H 2 permeability of the advanced MMMs with 20 wt% ZIF-8 loading is 123.8 Barrer, 19.4 times higher than the pristine P84 HT membrane (6.4 Barrer), while the H 2 /CH 4 and H 2 /N 2 selectivity almost remains essentially unchanged. More importantly, this facile but very effective method demonstrates a new direction to regulate structure of polyimide/MOFs based MMMs for gas separation.