摘要
以工业ZSM-5分子筛作为硅源,采用水热法制备ZSM-5/Y复合结构分子筛,并对其进行了X射线衍射(XRD)、N2吸附(BET)、核磁共振(NMR)和扫描电镜(SEM)表征。结果表明,产物同时具有ZSM-5分子筛和Y型分子筛的晶相结构特征。晶种的加入能有效地提高晶化反应进程。NaOH溶液的碱性越高,对ZSM-5的溶解性越高。随着晶化时间的延长,属于ZSM-5分子筛的特征峰强度降低、Y分子筛的特征峰强度升高。在晶化时间为10、20和30h时,对体系中加入铝源和晶种进行了研究。结果发现,复合结构分子筛的合成过程伴随着分子筛上骨架硅解离、部分骨架铝解离、硅源和铝源在分子筛骨架外及骨架上晶化形成新的晶体的过程。推断ZSM-5/Y复合结构分子筛形成机制有两种:(1)铝源和溶液中溶解的硅结合;(2)铝源直接和ZSM-5分子筛骨架上的硅结合。
ZSM-5/Y composite zeolite was prepared using thermal method and characterized by X-ray diffraction （XRD）, N2 industrial ZSM-5 zeolite as the silicon source by hydro- adsorption （BET）, nuclear magnetic resonance （NMR）, and scanning electron microscopy （SEM）. The characterization results indicated that ZSM-5/Y composite zeolite possed the crystalline structures of both ZSM-5 zeolite and Y zeolite. The seed can effectively promote the crystallization process. The solubility of ZSM-5 zeolite in solution was increased with increasing the alkaline of NaOH solution. When prolonging the crystallization time, the characteristic peak intensity of ZSM-5 zeolite decreased and that of Y zeolite increased. The addition of aluminum source and seed were investigated when crystallization time were 10,20 and 30 h. The results suggested that the synthesis of composite zeolite was accompanied by the dissociation of framework silicon, the partial dissociation of framework aluminum and the formation of new crystals in or on the outside of zeolite skeleton by silicon and aluminum source. Two types of formation mechanisms of ZSM-5/Y composite zeolite were speculated： （1） aluminum combined with the silicon dissolved in solution; （2） aluminum combined directly with the framework silicon on ZSM-5 zeolite.
出处
《化工新型材料》
CAS
CSCD
北大核心
2012年第10期96-98,105,共4页
New Chemical Materials
基金
自然科学基金:(20806007)
