Matsuda Kaito, Okuda Ayaka, Iio Nana, Tarutani Naoki, Katagiri Kiyofumi, Inumaru Kei
Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1, Kagamiyama, Higashihiroshima, Hiroshima 739-8527, Japan.
Inorg Chem. 2024 Aug 26;63(34):15634-15647. doi: 10.1021/acs.inorgchem.4c01186. Epub 2024 Aug 12.
Layered double hydroxides (LDHs) exhibit diverse chemical compositions and are being designed for promising applications such as CO adsorbents. Although many researchers have analyzed CO gas evolution and structural transformation behavior at elevated temperatures, there are still inconsistencies in results on the effect of different metal ions in LDHs. In this study, on the basis of atomic/molecular-level findings from our previous study on multistep structural/chemical transformation of Mg-Al LDHs, we analyzed the quantitative gas evolution behavior and structural transformations of -Al-CO LDHs with different divalent metal ions ( = Mg, Zn, or Co, /Al = 2) at elevated temperatures. Our quantitative analysis revealed that all three LDH samples undergo the three-step chemical transformations: release of interlayer water, partial dehydroxylation of the hydroxyl layers, and complete dehydroxylation of layers and decomposition of interlayer CO. However, the temperature range for each step differs, as do the structural transformations for each sample: the layered structure collapses in the first step for Zn-Al LDH and Co-Al LDH, and the third step for Mg-Al LDH. Our results provide for quantitative and concrete understanding of the effect of divalent metal ions in LDHs on thermal decomposition.
层状双氢氧化物（LDHs）具有多种化学成分，正被设计用于如一氧化碳吸附剂等有前景的应用。尽管许多研究人员已经分析了高温下一氧化碳气体逸出和结构转变行为，但关于层状双氢氧化物中不同金属离子的影响，研究结果仍存在不一致之处。在本研究中，基于我们之前关于镁铝层状双氢氧化物多步结构/化学转变的原子/分子水平研究结果，我们分析了含不同二价金属离子（=镁、锌或钴，/铝 = 2）的 -铝-一氧化碳层状双氢氧化物在高温下的定量气体逸出行为和结构转变。我们的定量分析表明，所有三个层状双氢氧化物样品都经历了三步化学转变：层间水的释放、羟基层的部分脱羟基化以及层的完全脱羟基化和层间一氧化碳的分解。然而，每一步的温度范围不同，每个样品的结构转变也不同：锌铝层状双氢氧化物和钴铝层状双氢氧化物在第一步层状结构坍塌，而镁铝层状双氢氧化物在第三步。我们的结果为定量和具体理解层状双氢氧化物中二价金属离子对热分解的影响提供了依据。
