Abstract: The effect of hydrothermal synthesis conditions on both relative crystallinity and phase purity of ZSM22 zeolites was investigated in SiO₂Al₂O₃K₂ODAHH₂O system, hereby DAH referring to 1,6diaminohexane as template. The resulting samples were characterized by powder Xray diffraction (XRD) and inductively coupled plasma (ICP) analyses in order to examine the structure, XRD phase, and chemical composition. As a result, several ZSM22 zeolites with the higher phase purity were synthesized at respective temperatures from 433 K up to 438 K by use of the different gels which involved SiO₂/Al₂O₃ molar ratios of 80~100 and OH^-/SiO₂ molar ratios of 0.33~0.35. It is found that the relative crystallinity and phase purity of ZSM22 zeolites markedly varied as a function of crystallization temperature, SiO₂/Al₂O₃ and OH^-/SiO₂ molar ratios. In fact, an adequate increase in crystallization temperature improves on ZSM22 phase purity, followed a significant enhancement of relative crystallinity. Although the ZSM5 crystal growth takes place predominantly in the solid phase, the decrease in the range of SiO₂/Al₂O₃ ratio less than 80 leads to a gradual increase in the ZSM5 phase fraction while the increase in SiO₂/Al₂O₃ ratio larger than 110 also enhances the phase fraction of cristobalite. Furthermore, Si/Al atomic ratios in ZSM22 framework located the range of 41.8~53.4, and by correlating the Si/Al ratio of ZSM22 framework with the SiO₂/Al₂O₃ ratio of aluminosilicate gels, it is noted that the nominal ratios in ZSM22 framework tended to shift towards the center of the Si/Al ratio interval mentioned above.

Key words: Zeolite synthesis,    , ZSM22,    ,  Competing phase,   ,  ZSM5,    , Cristobalite,    ,  Relative crystallinity,   ,  Phase purity

摘要： 在SiO₂Al₂O₃K₂ODAHH₂O（1,6己二胺，DAH）体系中，研究水热合成条件对ZSM22沸石相对结晶度和相纯度的影响。采用X射线衍射（XRD）和电感耦合等离子体（ICP）技术表征合成产物的结构、物相及化学组成。结果表明，合成胶n(SiO2)/n(Al₂O₃) 在 80~110，n(OH-)/n(SiO2) 在 0.33~0.35和433~438 K条件下，合成出系列相纯度较高的ZSM22沸石。产物相对晶度和相纯度依赖于合成胶硅铝物质的量比、碱度和晶化温度。适当升高晶化温度有利于提高产物的相纯度和相对结晶度；n(SiO₂)/n(Al₂O₃)在80~110之外，合成胶硅铝物质的量比的降低或提高分别导致ZSM5或方石英相分率的逐渐增加。此外，纯ZSM22骨架n(Si)/n(Al)分布于41.8~53.4；与n(SiO₂)/n(Al₂O₃)关联可知，n(Si)/n(Al)比值向该区间中心呈收敛趋势。

关键词: 沸石合成 , ZSM-22 竞争相 , ZSM-5 , 方石英 , 相对结晶度 , 相纯度