Dual organic-structure directing agents in the synthesis of high-silica MOR Zeolite: Cooperation or competition?
Dual organic-structure directing agents in the synthesis of high-silica MOR Zeolite: Cooperation or competition?
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DOI：
10.1016/j.micromeso.2023.112569
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发表时间：
2023-03
影响因子：
5.2
通讯作者：
Lei Wang;Hongyue Pan;Jingyun Qian;Kexin Yan;Xuedong Yang;Li Liu;G. Song;Hongjun Zhu
中科院分区：
文献类型：
--
作者：
Lei Wang;Hongyue Pan;Jingyun Qian;Kexin Yan;Xuedong Yang;Li Liu;G. Song;Hongjun Zhu
通过传统的水热合成策略构建给定沸石拓扑的高硅骨架仍然是一个悬而未决的问题。在这项工作中，我们报道了高硅MOR沸石（Si/Al比：~30）是通过双OSDA组合策略在固定碱度（OH−/SiO2）比约为0.4的条件下制备的。此外，我们发现大体积的TEA+阳离子和较小的中性杂环分子作为孔隙填充剂被切断，共同挤压钠阳离子的占据，导致高硅MOR沸石的钠含量较低。然而，这种合作行为很容易被高于0.5的高碱度比例所破坏。随着碱度比的增加，钠离子可以重新占据占据的位点，并以相对较低的Si/Al比促进MOR框架的形成。粉末X射线衍射晶体学和组合光谱策略揭示了高硅MOR沸石中不同双OSDA组合的性质以及推导的富铝T位点，为未来沸石型催化剂的目标设计提供了参考。
Constructing a high-silica framework of a given zeolite topologyviaa conventional hydrothermal synthetic strategy is still an open question. In this work, In this contribution, we report the high-silicaMORzeolite (Si/Al ratio: ∼30) was fabricated by a dual OSDA combination strategy at a fixed alkalinity (OH−/SiO2) ratio of around 0.4. Additionally, we found that bulky TEA+cation and smaller neutral heterocycle molecules severed as the pore-filling agent and cooperatively squeeze the occupation of sodium cation resulting in the low sodium content of high-silicaMORzeolite. However, such cooperative behavior can be easily spoiled by the high alkalinity ratio above 0.5. With the increment of the alkalinity ratio, the sodium cations can retake the occupied sites and facilitate theMORframework with a relatively low Si/Al ratio. As unveiled by the powder X-ray diffraction crystallography and combined spectroscopy strategies, the nature of different dual OSDA combinations occluded in the high-silicaMORzeolite with deduced aluminum enriched T sites provide the reference for the forthcoming target design of zeotype catalysts.