Tracking the structural changes in pure and heteroatom substituted aluminophosphate, AIPO-18, using synchrotron based X-ray diffraction techniques.
Tracking the structural changes in pure and heteroatom substituted aluminophosphate, AIPO-18, using synchrotron based X-ray diffraction techniques.
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DOI：
10.1039/c3cp00015j
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发表时间：
2013-07
期刊：
影响因子：
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通讯作者：
M. Martis;Andrew J. P. Smith;C. Tang;J. Parker;T. Hyde;M. J. Watson;X. Baucherel;S. Kohara;T. Wakihara;G. Sankar
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文献类型：
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作者：
M. Martis;Andrew J. P. Smith;C. Tang;J. Parker;T. Hyde;M. J. Watson;X. Baucherel;S. Kohara;T. Wakihara;G. Sankar
我们报告了在热去除堵塞小孔纳米多孔沸石固体AlPO-18、SAPO-18、CoAlPO-18、ZnAlPO-18和CoSAPO-18的孔的有机模板分子期间发生的结构变化。煅烧过程是形成活性催化剂的必要步骤。使用时间分辨高分辨率粉末衍射（HRPD）和高能X射线衍射（HEXRD）技术在不同温度下进行的研究表明，发生的变化取决于纳米多孔固体中存在的杂原子的类型。虽然时间分辨的HRPD显示在物理吸附的水分子的去除和随后的有机模板的去除期间晶格参数的明显变化，HEXRD数据显示在煅烧过程期间AlPO-18、SAPO-18、CoAlPO-18、CoSAPO-18和ZnAlPO-18中的各种近邻距离的变化。特别是HEXRD揭示了在合成材料中存在与Al（III）离子配位的水分子。在除去模板和水后，这些固体在升高的温度下显示出细胞体积的收缩，而第一和第二相邻距离几乎保持不变。
We report the structural changes that occur during the thermal removal of organic template molecules that occlude the pores of small pore nanoporous zeolitic solids, AlPO-18, SAPO-18, CoAlPO-18, ZnAlPO-18 and CoSAPO-18. The calcination process is a necessary step in the formation of active catalysts. The studies performed using time-resolved High Resolution Powder Diffraction (HRPD) and High Energy X-ray Diffraction (HEXRD) techniques at various temperatures reveal that changes that take place are dependent on the type of heteroatom present in the nanoporous solids. While time-resolved HRPD shows clear changes in lattice parameters during the removal of physisorbed water molecules and subsequent removal of the organic template, HEXRD data show changes in various near neighbour distances in AlPO-18, SAPO-18, CoAlPO-18, CoSAPO-18 and ZnAlPO-18 during the calcination process. In particular HEXRD reveals the presence of water molecules coordinated to Al(III) ions in the as-synthesised materials. Upon removal of the template and water, these solids show contraction in the cell volume at elevated temperatures while first and second neighbour distances remained almost unchanged.