论文部分内容阅读
以四乙基氢氧化铵为有机结构导向剂,采用超浓水热方法,从氟离子体系合成出手性多形体A(简称A形体)富集的全硅beta沸石.在同样的初始混合物中引入铝源后,所合成的beta沸石中A形体含量明显降低,产物为普通的硅铝beta沸石.用粉末X射线衍射、元素分析、热重-差热分析、氮气吸附、扫描电子显微镜和固体魔角自旋核磁共振等表征手段对全硅beta沸石和硅铝beta沸石进行了详细的表征,并研究了其晶化过程.结果表明,铝源的引入可以加速beta沸石的晶化,得到的硅铝beta沸石晶体粒径明显减小.在硅铝beta沸石的晶化过程中生成了五配位铝物种,五配位铝物种可能是导致产物中A形体含量降低的原因.
Tetraethylammonium hydroxide was used as the organic structure directing agent and the ultra-concentrated hydrothermal method was used to synthesize the all-silico-enriched zeolite Beta from the fluoride ion system.The same initial mixture was introduced into the same initial mixture After the aluminum source, the content of A-form in the synthesized zeolite beta is obviously reduced, and the product is a common Si-Al-beta zeolite.Using powder X-ray diffraction, elemental analysis, TG-DTPA, N2 adsorption, scanning electron microscopy Angle spin NMR and other characterization methods were used to characterize all-Si-beta zeolites and Si-Al-beta zeolites and study their crystallization process.The results show that the introduction of aluminum source can accelerate the crystallization of the beta zeolites and the obtained silicon The crystal size of Al-beta zeolite is obviously reduced.The pentacoordinated aluminum species is formed during the crystallization of Si-Al-beta zeolite, and the five-coordinated aluminum species may be responsible for the decrease of A-form content in the product.