MCM-22分子筛静态水热晶化法合成的优化

系统地考察静态水热晶化法合成条件如硅源、晶化时间、凝胶配比及成胶老化方式等对MCM-22合成的影响,并通过XRD、SEM和FT-IR等方法对合成的MCM-22分子筛进行表征.研究结果表明:硅酸、硅溶胶、硅胶在适当比例下都能合成出较纯的MCM-22分子筛,但其聚集形貌及晶粒大小有所不同;晶化时间为8～10 d,MCM-22分子筛结晶度较高;凝胶的初始配比对产物物相的影响较大,最佳条件为n(SiO2)/n(Al2O3)=30～60,n(OH-)/n(SiO2)=0.15～0.25,n(HMI)/n(SiO2)=0.35～0.6,n(H2O)/n(SiO2)=20～45;成胶老化方式对MCM-22分子筛的晶化影响不大.

Optimization for Synthesis of MCM-22 Zeolite under Static Hydrothermal Crystallization Conditions

MCM-22 zeolite was synthesized in static hydrothermal systems and characterized by XRD, SEM and FT-IR. The effect of different synthesis parameters, such as silica source, crystallization time, the gel composition, including SiO2/Al2O3 mole ratios, OH^-/SiO2 mole ratios, HMI/ SiO2 mole ratios, and H2O/SiO2 mole ratios, and aging conditions in the synthesis of MCM-22 zeolite was investigated. The results indicated that pure MCM-22 zeolite could be synthesized by using silicic acid, silica sol or silica gel as silica sources in proper condition, and their morphologies and particle sizes were different. A MCM-22 zeolite with higher crystallinity could be efficiently obtained within 8-10 days. The compositions of products were affected by the compositions of the gel system, and the optimal synthesis conditions were： n（SiO2）/n（A1203）= 30-60, n（OH^-）/n（SiO2） = 0.15 -0.25, n（HMI）/n（SiO2） = 0.35 -0.6, n（H2O）/n（SiO2） = 20 - 45. The aging step during the preparation of the gel was not closely related to the phases of the product.