Rigid-interface-locking of ZIF-8 membranes to enable for superior high-pressure propylene/propane separation

ZIF-8 membranes are promising for C3H6/C3H8 separation due to its proper pore size between C3H6 and C3H8. However, challenges from the defective grain-boundary (poor reproducibility), inferior pressure-resistant, and insufficient synthesis parameters regulation hinder its advancement. Herein, we demonstrate an interface engineering method that can simultaneously deal with these two issues by coating a polymeric layer on the surface of ZIF-8 membrane which can seal the grain boundaries and lock the pressure-induced linker rotation. Accordingly, by optimizing the polymer chain rigidity and the corresponding thickness layer, the resultant membrane with locked rigid interface demonstrates desired C3H6 permeance and C3H6/C3H8 separation factor above 45 GPU and 105, respectively, and stabilized performance up to 7 bar. Such performance is superior to most of the recently reported work in the literature. This strategy provides inspiration for considering the polymer chain rigidity regulation in the membrane coating layer and its effect on developing advanced composite membranes for energy-efficient separations.