This paper reports a number of recent developments in the intercalation chemistry of Al(OH)3. From Rietveld refinement and solid-state NMR, it has been possible to develop a structural model for the recently reported [MIIAl4(OH)12](NO3)2·yH2O family of layered double hydroxides (LDHs). The M2+ cations occupy half of the octahedral holes in the Al(OH)3 layers, and it is thought that there is complete ordering of the metal ions while the interlayer nitrate anions are highly disordered. Filling the remainder of the octahedral holes in the layers proved impossible. While the intercalation of Li salts into Al(OH)3 is facile, it was found that the intercalation of MII salts is much more capricious. Only with Co, Ni, Cu, and Zn nitrates and Zn sulfate were phase-pure LDHs produced. In other cases, there is either no reaction or a phase believed to be an LDH forms concomitantly with impurity phases. Reacting Al(OH)3 with mixtures of MII salts can lead to the production of three-metal MII–MII′–Al LDHs, but it is necessary to control precisely the starting ratios of the two MII salts in the reaction gel because Al(OH)3 displays selective intercalation of M nitrate (Li > Ni > Co ≈ Zn). The three-metal MII–MII′–Al LDHs exhibit facile ion exchange intercalation, which has been investigated in the first energy dispersive X-ray diffraction study of a chemical reaction system performed on Beamline I12 of the Diamond Light Source.
本文报告了 Al(OH)3 插层
化学的一些最新进展。通过里特维尔德细化和固态核磁共振,可以为最近报道的 [MIIAl4(OH)12](
NO3)2-yH2O 层状双氢氧化物(LDHs)家族建立一个结构模型。M2+ 阳离子占据了 Al(OH)3 层八面体空穴的一半,人们认为
金属离子完全有序,而层间
硝酸根阴离子则高度无序。事实证明,不可能填满层中剩余的八面体孔。虽然
锂盐很容易插层到 Al(OH)3 中,但我们发现 MII 盐的插层却更加反复无常。只有
钴、
镍、
铜和
锌的
硝酸盐和
硫酸锌才能生成相纯的 LDH。在其他情况下,要么没有发生反应,要么认为是 LDH 的相与杂质相同时形成。将 Al(OH)3 与 MII 盐混合物反应可生成三
金属 MII-MII′-Al LDH,但必须精确控制反应凝胶中两种 MII 盐的起始比例,因为 Al(OH)3 对
硝酸 M 有选择性插层作用(
锂 >
镍 >
钴 ≈
锌)。三
金属 MII-MII′-Al LDHs 表现出简便的离子交换插层,钻石光源 I12 光束线首次对
化学反应体系进行了能量色散 X 射线衍射研究。