Engineering silica membranes for separation performance, hydrothermal stability, and production scalability

Silica membranes have been successfully practiced for solvent dehydration and emerged as an exciting platform for gas separations (such as H2/CO2) due to their unique porous structures for molecular sieving, tunable chemistries, and excellent thermal and chemical stability. This review aims to provide a comprehensive update on the advancement of silica membranes for gas and liquid separations in the last decade. First, we summarize various techniques to fabricate membranes (particularly those at low temperatures) and describe the effect of processing parameters on the membrane structures. Second, penetrant transport mechanisms and molecular dynamic simulations are presented to elucidate the structure-properties relationship. Third, we highlight state-ofthe-art silica membranes with promising separation properties for gases, vapors, and liquids and various engineering strategies to improve hydrothermal stability, production scalability, and separation performance. Finally, we provide perspectives on the future development of these membranes for practical applications.