Effect of Si/Al ratio in the framework on the pervaporation properties of hollow fiber CHA zeolite membranes

Abstract Hollow fiber supported CHA zeolite membranes with different Si/Al ratios in the framework were successfully synthesized by changing precursor compositions. The influence of precursor composition on the membrane composition, microstructure evolution and dehydration performances of CHA zeolite membranes, were extensively investigated. Pervaporation (PV) results indicated that the membrane separation performances were strongly influenced by both the framework Si/Al ratio and the microstructure of the membranes. The membranes with Si/Al ratio of ca. 2.7–2.8 composed of flake-like grains showed higher flux with relatively low selectivity, while the membrane with Si/Al ratio of >2.9 composed of block-shaped crystals exhibited higher separation factor of >10000. Both hydrothermal and acid stability of the membranes were dependent on the framework Si/Al ratio of CHA zeolite membranes.