Recrystallization Of Magadiite Into ZSM-5and Ferrierite In The Presence Of Hexanediamine

Magadiite is a kind of phyllosilicates. Due to its excellent performance in ion exchange, adsorption, intercalation and expansion, magadiite has been widely applied in catalysis, adsorption and noval advanced materials and so on. In recent years, the preparation of zeolite molecular sieves by recrystallization of magadiite has attracted widespread interest. As a very attractive research field, the interesting features of magadiite pave the way for its use as precursor for the synthesis of zeolites, it can not only help people to achieve high selectivity and efficiency of synthetic zeolites, to fill up the deficiency of traditional methods, but also to discovery novel molecular sieve material and understanding of crystallization mechanism. In this paper, hydrothermal synthesis of magadiite using diatomite as raw material has been studied in details. Using the as-synthesized magadiite, ZSM-5and FER has been prepared successfully in the presence of Hexanediamine through recrystallization. A series of methods, including XRD, ICP, IR, scanning electron microscopy, thermogravimetry analysis, N2analysis and13CNMR analysis have been introduced to characterize the zeolites from the crystal phase, chemistry contents, images, thermal stability and BET surface area. The effects of key reaction parameters and the initial reactants on the recrystallization of zeolites have been examined. By using XRD, also the rules of recrystallization and phase transformation have been investigated. The main results are as follows:Using the synthetic magadiite, ZSM-5and FER have been prepared successfully in the presence of Hexanediamine through recrystallization. A series of methods have been introduced to characterize the ZSM-5and FER. The images of as-synthesized ZSM-5and FER reveals that they are composed of small hexagonal crystal agglomerates and lamellar crystals wich are stacking together, respectively. The SiO2/Al2O3of both ZSM-5and FER have large difference with the composition of the initial reactants. The organic template was removed when the sample was calcined at550℃for10h. The structure of ZSM-5and FER are retained when the temperature are below1200℃and1100℃, respectively. The acid stability are excellent for both the ZSM-5and FER. The influence of key reaction parameters on the formation of ZSM-5and FER were examined. The resultes indicate the feasibility of a synthetic route to ZSM-5and FER through recrystallization of magadiite in the presence of Hexanediamine and provide a new route to ZSM-5snd FER.The binary crystallization phase diagram has been proposed for interpretation of the rule of recrystallization and phase transformation. We also explored the decisive role of the initial SiO2/Al2O3molar ratio and alkalinity to the final products. The results show that low initial SiO2/Al2O3in25-30is the propitious to the generation of FER and35-50is suitable for ZSM-5. The template role and existential state of Hexanediamine have been discussed in detail by compared experiments of13CNMR spectra of Hexanediamine in synthesized zeolites and13CNMR spectra of liquid Hexanediamine.