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在无有机模板剂体系中研究了不同硅铝比和晶粒度Beta沸石晶种的结构导向行为,采用X射线衍射、X射线荧光光谱、扫描电镜、透射电镜、紫外-拉曼光谱、红外光谱和N2物理吸附等方法对不同晶化时间固相产物和Beta沸石产物进行了表征.结果表明,不同Beta沸石晶种,包括全硅晶种,均能够导向合成Beta沸石,而且晶种在晶化诱导期都发生溶解.但是,晶种的硅铝比、晶粒度、预处理(焙烧)以及晶种加入的时间对晶种的溶解行为、Beta沸石晶化过程和产物都有重要影响.形貌研究还发现,含铝晶种不仅溶解后的残体通过提供晶核聚集的“固载化”表面导向了新生Beta沸石小晶体的密集生长,而且溶解下来的结构片段也提供了分散的晶核导向形成相对分散的Beta沸石小晶体;全硅晶种则仅通过溶解下来的结构片段提供分散的晶核.在无模板体系中,使用适当高硅铝比、小晶粒和经过焙烧处理的Beta沸石作为晶种有利于合成得到高结晶度的Beta沸石纯相.
In the absence of an organic template, the structural orientation behavior of zeolites with different Si / Al and grain sizes was studied. The XRD, XRD, SEM, TEM, And N2 physisorption methods were used to characterize the products with different crystallization time and Beta zeolite.The results showed that different Beta zeolite seeds, including all-silicon seeds, can all be used to guide the synthesis of Beta zeolite, and the crystallization of seeds However, the ratio of Si / Al, grain size, pretreatment (roasting) and time of seed addition have an important influence on the dissolution behavior of zeolite, Beta zeolite crystallization process and product. Metallographic studies also found that not only the dissolved aluminum-bearing seeds dissolve into densely packed beta zeolite small crystals by providing a “solid-supported” surface where the nuclei accumulate, but the fragmented structures also provide dispersion Of the crystal nuclei to form relatively dispersed Beta zeolite small crystals; all-silicon seed crystals provide dispersed nuclei only through the dissolved structure fragments.In a template-free system, a suitable high Si / Al ratio, small grains, Calcined zeolite Beta as the seed crystal zeolite Beta synthesized facilitate phase pure high crystallinity.