Microstructural manipulation of MFI-type zeolite films/membranes: Current status and perspectives

Microstructural manipulation has been proven to remarkably affect the performance of zeolite membranes/films in separation and catalysis. Accordingly, intensive research and significant progress have been achieved in the last decades on the microstructural manipulation of zeolite films/membranes. From the literature, various factors including supports, seed layer, growth methods, synthesis solution, crystallization condition, and post-treatment can result in the different microstructures of zeolite films/membranes including morphology, orientation, thickness, and composition of the dense layer. This review attempts to summarize the obtained progress in microstructural manipulation of MFI-type zeolite films/membranes and their relationship with the separation performance. Some key topics are detailed and discussed, including (1) controllable synthesis of orientated zeolite films/membranes; (2) rational design and synthesis of zeolite films/membranes with ultrathin separation layer; (3) construction of asymmetric zeolite membranes; (4) architectural design of zeolite films/membranes at the microscopic level (heteroatoms substituted zeolite films/membranes); (5) the challenges and strategies in scaling-up of zeolite film/membrane production. Concluding remarks and perspectives are also suggested in the end.