Preparation, mechanism and applications of oriented MFI zeolite membranes: A review

Oriented MFI zeolite membranes are membrane materials formed by closely stacking and crosslinking MFI grains or nanosheets in a specific direction. Compared with a-, c-, and (h0h)-oriented zeolite membranes, b-oriented membranes can effectively improve the molecular transmission rate and are widely used in the fields of mixture separation and catalysis. However, twinning can easily occur during the zeolite membrane preparation, and controlling the membrane orientation is difficult owing to the limitations in the crystal growth kinetics. In this review, recent important progress in the preparation strategies and methods of oriented zeolite membranes are introduced, and the microscopic mechanism of the membrane orientation regulation is analyzed, including heterogeneous nucleation and homogeneous nucleation mechanisms. Moreover, the application status of oriented zeolite membranes in the fields of mixture separation and catalysis is summarized. Finally, current challenges and future development perspectives of oriented MFI zeolite membranes are addressed.