(177g) An Optimized Procedure for Selective Removal of Efal (Extra Framework Aluminum) in Y-Zeolites

Zeolites with low aluminum content (high Si/Al ratio) are more favorable for catalytic applications. Zeolite-Y is the prominent member of zeolite family cannot be directly synthesized with Si/Al ratios over ~2.5. Hence, post-synthetic modification such as dealumination is found to be most feasible way to increase the Si/Al ratio in the framework.^1-4 In general, dealumination refers to the removal of aluminum from zeolitic framework by chemical reactions. Most often, the ‘Al’ removed from zeolitic framework will fall into non-framework (extra framework). Due to EFAl species the degree of crystallinity to be reduced in zeolites, which leads to complicated issues on catalytic applications. To avoid this, selective removal of extra framework aluminum (EFAl) is important for various catalytic applications. In this study, an optimized procedure is developed to remove only EFAl species from commercial Zeolite-Y. Various concentration of water glass was added to commercial zeolites and treated at various temperatures (25 to 100 °C) and duration (0-6 hrs). An optimized procedure is being developed to remove just EFAl from zeolite materials. All the samples were well characterized by XRD, N₂adsorption-desorption measurements, ICP-AES, TEM and NMR.

Keywords:Dealumination, extra framework, Si/Al ratio, zeolites

References

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