Synthesis Of Dispersible Zeolite Nano-crystals By Steam-Assisted Concentrated Gel Crystallization

Nanozeolites have a wide range of potential applications in many fields such as zeolite synthesis,zeolite membrane preparation,drug delivery materials and sensor devices because of their unique morphology,diffusivity and surface properties.At present,the methods for synthesizing zeolite nanocrystals mainly include conventional hydrothermal method,soft and hard template method,adding crystal growth modifier,seeding method,and microwave-assited method,etc.However,these methods are usually only applicable to a certain type of zeolite.Therefore,it is meaningful to develop a fast,simple and efficient general synthetic strategy for the synthesis of zeolite nanocrystals.This thesis presents a new synthetic strategy which converts concentrated gel into high-quility nanozeolites with the assistance of steaming.The method does not require the use of organic additives other than the structure directing agents,seeds and fluorine.Zeolite nanocrystals synthesized by steam-assisted concentrated gel crystallization exhibit high crystallinity,uniform particle size distribution,good dispersibility and good colloidal stability.Using this method,Silicalite-1,ZSM-5,SiBeta,Al-Beta,Sn-Beta,Ti-Beta,SAPO-34 and SSZ-13 have been successfully synthesized,implyign it is a potentially general synthetic strategy.