| In this thesis,nano-ZSM-5 aggregates were synthesized in hydrothermal and low-solvent system respectively.In the hydrothermal system,traditional hydrothermal synthesis,precursor induced synthesis and confined space synthesis were researched,and different size and morphology of nanocrystal aggregates were synthesized.In the low-solvent system,crystal nucleation and growth mechanism,confined space synthesis and dry-gel conversion were combined and monthlic nano-ZSM-5 aggregates were synthesized by conversion from the wall structure of the mesoporous materials.In the hydrothermal system,from traditional hydrothermal synthesis to precursor induced synthesis,the method to induce SDAs and increase crystallinity was researched,and simultaneously,the effect of different precursors and its content on the product were dissgussed.Seed-induced synthesis worked to reduce the use of organic templates and to a great extent enhance the zeolite crystallinity,however,the induction of seeds favors to get larger aggregates and the synthesized zeolite particles own a strong growth direction.Morever,soft templates also were applied in the synthesis of zeolite nanocrystals.This synthesis method involves crystallization of the zeolite within the hydrogel polymer network,where zeolite crystals were confined in the hydrogel network,and as a result,it is easier to get smaller nano-ZSM-5 aggregates since zeolite particles could hardly aggregate to grow in the network.In the low-solvent system,crystal nucleation and growth mechanism,confined space synthesis and dry-gel conversion were combined and monthlic nano-ZSM-5 aggregates were synthesized.Novelty,the size and morphology of the product ZSM-5 aggregates approximately replice the character of raw mesoporous materials.Moreover,as the ZSM-5 particles were separated by the inhibits generated from incompletely decomposed P123 micelles,the nanoparticles could get higher crystallinity by recrystallization instead of growing large by coalesce. |
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