The morphology control of zeolite has attracted extensive attention because of its close relationship with catalytic performance. How to control the crystal morphology of EUO zeolite on premise of low silica to alumina ratio is a challenging task. This study provides a novel route for controlling the morphology of Al-rich EUO zeolite via inter-zeolite transformation from Si-rich *MRE zeolite within 24 h. The morphology change from nanocrystals to coffin-like single crystal exhibits the merits of inter-zeolite transformation strategy in morphology control. Characterization tracking reveals that the deposition of aluminum species on parent *MRE zeolite is not uniform and migration between different precursors happens during the crystallization. No obvious mass transfer is observed between the liquid and solids after 2 h indicating it may follow a solid phase crystallization mechanism. Compared with conventional EUO samples, the EUO zeolite obtained by inter-zeolite transformation exhibits higher p-xylene selectivity. This approach not only provides a novel morphology control strategy for Al-rich EUO zeolite, but also promotes the understanding of the zeolite crystallization through inter-zeolite transformation route.
Aluminum-rich ZSM-5 zeolite membranes are prepared on α-alumina support through organic template free precursor gels by secondary hydrothermal synthesis , microstructure of the membrane through the different Si/Al ratio and alkali metal fluoride synthesis gel are discussed in this work. Alkali metal fluorides have a significant influence on the synthesis of aluminum-rich ZSM-5 zeolite membranes without organic template, which are realized by the synergistic reaction of the “bridging” and “salting-out” effects. Sodium fluoride and potassium fluoride could produce dense and needle-like zeolites layer on the supports by an extremely low Si/Al ratio synthesis gel (Si/Al <10). When the Si/Al ratio of the initial synthesis gel is 18.52, the compact and prismatic ZSM-5 zeolites are fully covered on the supports with sodium fluoride, potassium fluoride or lithium fluoride. There are few of ZSM-5 zeolites could form on the support by cesium fluoride containing synthesis gel.
危险品化学品经营许可证（带存储）