Effect of seed crystal and solvent on the structure and morphology of ZSM-5/SAPO-5 composite molecular sieves

 ZSM-5/SAPO-5 composite molecular sieves of core/shell structure were synthesized by embedding method and characterized by XRD and SEM; the effect of gel composition on their structure and morphology was investigated. The composite molecular sieves synthesized exhibit a binary structure with ZSM-5 as core and SAPO-5 as shell. The crystallinity and particle morphology of the composite molecular sieves are influenced by seed crystal and solvent used during synthesis. Through adding seed crystal, the crystallinity of the composite molecular sieves increases and the particles are mainly in elliptic morphology; by using a mixture of water and alcohols as solvent during synthesis, the particle morphology is mainly of sphericity, while the crystallization rate as well as the maximum crystallinity of the composite molecular sieves decreases.