The Influence Factors of the Crystallinity and Crystal Size of ZSM-5 Zeolite

ZSM-5 zeolite was synthesized by seeding technique using silica sol and aluminum sulfate as raw materials.The effects of key factors,such as the mixing modes of material,aging time,crystallization temperature,crystallization time,alkalinity and dosage of H2O on the crystallinity and crystal size were investigated.The samples were characterized by XRD,SEM and LPSA etc.The result indicated that the high crystallinity ZSM-5 zeolite can only be synthesized with the high concentration aluminosilicate gel formed in the condition of certain high alkalinity.ZSM-5 zeolite crystallization proceeds is based on the solid-solid transformations mechanism.The higher of the crystallization temperature and the concentration of aluminosilicate gel,the higher of the relative crystallinity and average particle size,the sample of the highest crystallinity can be synthesized with the aging time of 24 h at room temperature and the crystallization time of 12~24 h at 180 ℃.The aging time have a small influence on the crystal size.