Synthesis and characterization of ultra-fine ZSM-5 zeolite

The influence of different types of structure-directing agents(SDA),crystallization temperature and content of alumina source on the crystallization of ultra-fine ZSM-5 zeolite was studied.Scanning electron microscope(SEM),transmitting electronic microscopy(TEM) and X-rays diffraction(XRD) techniques were used to characterize the morphology of the ultra-fine zeolite.The results indicated that the type of SDA had great influence on the crystallization of zeolite.Tetrapropylammonium hydroxide(TPAOH) acted as an excellent SDA for the preparation of ultra-fine ZSM-5 zeolite.Comparatively,the proper temperature for the static crystallization of ultra-fine crystals was in the range from 70 ℃ to 120 ℃ with TPAOH as the SDA.The existence of alumina in the sol-gel inhibited the formation of the crystal nuclei of ZSM-5 zeolite.As a result,without the addition of alumina source,crystallization of zeolite was much faster than that with the existence of alumina source,while an increase in the content of alumina source led to slower crystallization and a much smaller crystal size of zeolite crystallized at the same time of crystallization.