以两种季铵碱为模板剂合成A形体富集Beta沸石及其晶化过程

以三甲基环己基氢氧化铵和二甲基乙基环己基氢氧化铵为模板剂或结构导向剂(SDA), 采用超浓水热方法合成了A形体富集的Beta沸石, 用粉末X射线衍射(XRD)、 扫描电子显微镜(SEM)、 ²⁹Si固体魔角自旋核磁共振(²⁹Si MAS NMR)以及氮气吸附等表征手段对其进行了详细表征, 探索了最优合成条件, 研究了其晶化过程. 结果表明, 在晶化初期产物中己出现A形体过量特征, 随着晶化的进行, A形体的过量程度无显著变化.

Synthesis and Crystallization Process of Polymorph A Enriched Beta Zeolite in the Presence of Two New Quaternary Ammonium Bases†

In the presence of trimethyl-cyclohexyl ammonium hydroxide or ethyl-dimethyl-cyclohexyl ammo-nium hydroxide, chiral polymorph A enriched Beta zeolites were synthesized. The products were further cha-racterized by X-ray powder diffraction(XRD), scanning electron microscope(SEM), ²⁹Si magic-angle spinning nuclear magnetic resonance(²⁹Si MAS NMR) and nitrogen adsorption-desorption analyses. The crystallization process of the polymorph A enriched Beta zeolite in the presence of trimethyl-cyclohexyl ammonium hydroxide and the influence of the water content in the initial mixture on the enrichment of the polymorph A were investigated. The results showed that the appropriate water content in the initial mixture was critical for the formation of polymorph A enriched Beta zeolite, the enrichment of chiral polymorph A occurred in the early stage of crystallization and the degree of the enrichment of polymorph A did not change during the crystallization.