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Structural Investigation of Zn(II) Insertion in Bayerite, an Aluminum Hydroxide
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2016-09-06 00:00:00 , DOI: 10.1021/acs.inorgchem.6b01436
Suraj Shiv Charan Pushparaj 1 , Nicholai Daugaard Jensen 1 , Claude Forano 2, 3 , Gregory J. Rees 4 , Vanessa Prevot 2, 3 , John V. Hanna 4 , Dorthe B. Ravnsbæk 1 , Morten Bjerring 5 , Ulla Gro Nielsen 1
Affiliation  

Bayerite was treated under hydrothermal conditions (120, 130, 140, and 150 °C) to prepare a series of layered double hydroxides (LDHs) with an ideal composition of ZnAl4(OH)12(SO4)0.5·nH2O (ZnAl4-LDHs). These products were investigated by both bulk techniques (powder X-ray diffraction (PXRD), transmission electron microscopy, and elemental analysis) and atomic-level techniques (1H and 27Al solid-state NMR, IR, and Raman spectroscopy) to gain a detailed insight into the structure of ZnAl4-LDHs and sample composition. Four structural models (one stoichiometric and three different defect models) were investigated by Rietveld refinement of the PXRD data. These were assessed using the information obtained from other characterization techniques, which favored the ideal (nondefect) structural model for ZnAl4-LDH, as, for example, 27Al magic-angle spinning NMR showed that excess Al was present as amorphous bayerite (Al(OH)3) and pseudoboehmite (AlOOH). Moreover, no evidence of cation mixing, that is, partial substitution of Zn(II) onto any of four Al sites, was observed. Altogether this study highlights the challenges involved to synthesize pure ZnAl4-LDHs and the necessity to use complementary techniques such as PXRD, elemental analysis, and solid-state NMR for the characterization of the local and extended structure of ZnAl4-LDHs.

中文翻译:

氢氧化铝Bayerite中Zn(II)插入的结构研究

在水热条件下(120、130、140和150°C)处理Bayerite,以制备一系列具有理想组成的ZnAl 4(OH)12(SO 40.5 · n H 2 O的层状双氢氧化物(LDHs)。(ZnAl 4 -LDHs)。通过批量技术(粉末X射线衍射(PXRD),透射电子显微镜和元素分析)和原子级技术(1 H和27 Al固态NMR,IR和拉曼光谱)对这些产品进行了研究。深入了解ZnAl 4的结构-LDH和样品组成。通过Rietveld对PXRD数据的完善研究了四个结构模型(一个化学计量模型和三个不同的缺陷模型)。使用从其他表征技术获得的信息对这些元素进行了评估,这些信息有利于ZnAl 4 -LDH的理想(无缺陷)结构模型,例如,例如27 Al魔角旋转NMR显示过量的Al以无定形硅藻土形式存在(Al (OH)3)和假勃姆石(AlOOH)。而且,没有观察到阳离子混合的证据,即在四个Al位点的任何一个上Zn(II)被部分取代。总而言之,这项研究突出了合成纯ZnAl 4所涉及的挑战-LDHs以及使用互补技术(例如PXRD,元素分析和固态NMR)表征ZnAl 4 -LDHs的局部和扩展结构的必要性。
更新日期:2016-09-06
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