Synthesis Of Zeolite ZSM-5 And Zeolite Membranes

ZSM-5 zeolite is a soft of mesporous zeolite with high Si/Al ratio. Having high thermal stability,acidresistivity,hydrophobicity,ion exchangeability,excellent shape selectivity and acidity, the zeolite has attracted particular attention in petrochemical industries.This work studies on the synthesis of ZSM-5 zeolite with different templates such as n-butylamine,tetrapropyl amine bromide,anmonia and no template. The experimental results have shown that high-purity ZSM-5 zeolite was obtained if proper reaction condition was controlled. Under the condition synthesized with organic amine, the pH range of synthesis solution and the range of composition of inventory Si/Al were broader. But ZSM-5 zeolite synthesized without template didn't need calcinations to remove amine. Therefore, the process can be simplified. The specific surface areas of ZSM-5 synthesized with different templates vary as follows:organic amine >inorganic> no template.Furthermore, supported ZSM-5 zeolite membrane was prepared by secondary hydrothermal synthesis using n-butylamine as template. Every aspect involved in its synthesis was discussed systematically, such as different methods of introduced seeds to support,pretreatment to the surface of supports and synthesis conditions. The results indicate that compact ZSM-5 zeolite membranes were synthesized on the supports seeded with different methods, including rubbing method,droping method and dipping method. But the membranous layer was thinnest though rubbing method. Aging solution was more beneficial to synthesize ZSM-5 zeolite membrane. The influence of temperature can not been ignored and the synthesis period was shortened at higher temperature. For example, compact zeolite membranes were synthesized after 12h under 180℃. While the synthesis time needs 120h under 120℃. The growth process of zeolite membranes was analysed by SEM photographs, that is, crystal nucleus wasn't formed in the growth process of crystals, yet seeds, as crystal nucleus, grew on the support surface using up nutritional ingredient in the pregnant liquor and continuous zeolite membranous layer was grown consequently on the support. In addition, the pretreatment of microwave plasma technic to the seeded layers on the support can improve dispersion of the seeds. It could not only reduce the sizeies of crystals of zeolite ZSM-5 membrane but also result in thinner membranous layers.