Organic-Free Interzeolite Transformation in the Absence of Common Building Units
Organic-Free Interzeolite Transformation in the Absence of Common Building Units
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DOI：
10.1002/chem.201901067
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发表时间：
2019-04-23
影响因子：
4.3
通讯作者：
Rimer, Jeffrey D.
中科院分区：
文献类型：
--
作者：
Qin, Wei;Jain, Rishabh;Rimer, Jeffrey D.
沸石晶体可用作合成中的晶种或铝硅酸盐源以控制多晶型物和/或减少用作结构导向剂的有机物的量。沸石间转化的一个经常引用的假设是沸石在结构上具有一些潜在的相似性，最显著的是在与无有机合成有关的情况下。在此，我们首次表明，ZSM-5（MFI）可以直接从USY（FAU）通过在没有结构导向剂和晶种的情况下缺乏共同的结构单元的母-子结构之间的沸石间转化而获得。我们表明，沸石间的转换导致晶体产品具有较少的缺陷。我们的研究结果还表明，ZSM-5是一个亚稳的中间体，经历进一步转化为丝光沸石（莫尔）和石英。MFI到莫尔的转变与所报道的转变导致摩尔体积减小的结构的趋势相反。在此，我们提出了机械参数，表明沸石间转化的驱动力比文献中提出的指导方针更复杂。
Zeolite crystals can be used as seeds or aluminosilicate sources in syntheses to control polymorphs and/or reduce the quantity of organics used as structure-directing agents. A frequently invoked hypothesis for interzeolite transformations is that zeolites share some underlying similarity in structure, most notably in cases pertaining to organic-free syntheses. Herein, we show for the first time that ZSM-5 (MFI) can be directly obtained from USY (FAU) through an interzeolite transformation between parent-daughter structures lacking common building units in the absence of a structure-directing agent and seeds. We show that interzeolite transformation leads to a crystalline product with fewer defects. Our findings also reveal that ZSM-5 is a metastable intermediate that undergoes further transformation to mordenite (MOR) and quartz. The MFI-to-MOR transition is counter to reported trends for which transformations lead to structures with reduced molar volume. Herein, we propose mechanistic arguments that suggest the driving force for interzeolite transformation is more complex than guidelines posited in the literature.