Formation process and pervaporation of high aluminum ZSM-5 zeolite membrane with fluoride-containing and organic template-free gel

The formation progress of the high aluminum ZSM-5 zeolite membrane was investigated and characterized with the organic template-free and fluoride-containing initial synthesis gel. The nano spherical Silicalite-1 seed crystals were dissolved into amorphous by the fluoride-containing precursor synthesis gel. The amorphous contained elementary structural units (TO4) and isolated five-membered ring structure of MFI zeolites. These were retained to provide the nucleation sites for high aluminum ZSM-5 zeolite. The ZSM-5 zeolite nucleus was grown into fine needle-like ZSM-5 zeolites, which were gradually grown into twin crystals, aggregation and compact ZSM-5 zeolites layer on the support without the organic template initial synthesis gel. In addition, the high aluminum ZSM-5 zeolite membranes kept the identical morphology and structure for separation of high concentration acetic acid (H2O/HAc) or inorganic acid (1 M H2SO4) aqueous mixtures by XRD, SEM and NMR characterization. Furthermore, the membrane had a good dehydration performance and acid-stability by pervaporation. The flux and separation factor of the membrane for 10 wt% H2O/HAc mixtures were 0.98 kg∙m−2∙h−1 and 3200 at 348 K, respectively.