Raman spectroscopy and quantum theory calculations on complexes in the KF-AlF3-Al2O3 system
Raman spectroscopy and quantum theory calculations on complexes in the KF-AlF3-Al2O3 system
复制标题
DOI：
10.1016/j.molliq.2020.115267
复制
发表时间：
2021-01-20
影响因子：
6
通讯作者：
Wang, Zhaowen
中科院分区：
文献类型：
--
作者：
Lin, Ming;Hu, Xianwei;Wang, Zhaowen
利用原位高温拉曼光谱和量子力学计算研究了KF-AlF3-Al2O3体系的离子结构。KF-AlF3- al2o3体系中KF与AlF3摩尔比不同的配合物分别为AlF63-、AlF52-、AlF4-、Al2OF4、Al2OF84-、Al2OF62-和Al2O2F42-。对Al2OF4、Al2OF84-、Al2OF62-和Al2O2F42-的结构进行了优化，其中K+、Al2OF4具有D-2d点群对称性，K4Al2OF8和K2Al2OF6具有C-2v点群对称性，K2Al2O2F4具有C-2h点群对称性。对比理论拉曼光谱，Al2OF84-、Al2OF62-和Al2O2F42-的实验主拉曼波段分别为495 cm（-1）、465 cm（-1）和410 cm-1。体系中含氧络合离子的形态和含量与KF与AlF3的摩尔比和氧化铝的浓度有关。在1003k温度下，KF-AlF3-Al2O3体系中存在AlF63-、AlF52-、AlF4-和Al2OF4， kf与alf3的摩尔比为1.22。当温度为1273 K时，KF-AlF3-Al2O3体系的kf - alf3与alf3的摩尔比为2，当氧化铝浓度小于等于10 wt%时，体系中存在AlF63-、AlF52-、AlF4-、Al2OF4和Al2OF84-，当氧化铝浓度达到12 wt%时，体系中出现Al2OF62-和Al2O2F42。在KF-AlF3-Al2O3体系中，kf与alf3的摩尔比为3，温度为1273 K，氧化铝浓度小于等于10 wt%时，体系中含有AlF63-、AlF52-、AlF4-、Al2OF4和Al2OF84-。当氧化铝浓度增加到14 wt%时，Al2OF62-和Al2O2F42-开始出现，AlF4-消失。随着氧化铝浓度的增加，Al2OF62-和Al2O2F42-的含量增加。得到了形成各种含氧配合物的离子反应。这些化学反应的发生与体系中KF与AlF3的摩尔比和氧化铝浓度有关。采用kf - alf3与alf3摩尔比分别为1.22、2和3的kf - alf3熔融体系作为铝电解质时，阳极放电离子为Al2OF84-（除kf - alf3摩尔比为1.22且Al2OF4在阳极放电的体系外），阴极放电离子为Al2OF4。(C) 2021 Elsevier B.V.版权所有
The ionic structure of the KF-AlF3-Al2O3 system was studied using in situ high-temperature Raman spectroscopy and quantum mechanics calculations. The complexes in the KF-AlF3-Al2O3 system with different molar ratios of KF to AlF3 were AlF63-, AlF52-, AlF4-, Al2OF4, Al2OF84-, Al2OF62-, and Al2O2F42-. The structures of Al2OF4, Al2OF84-, Al2OF62-, and Al2O2F42- were optimized considering that the counterion K+, Al2OF4 exhibits D-2d point group symmetry, K4Al2OF8 and K2Al2OF6 exhibit C-2v point group symmetry, and K2Al2O2F4 exhibits C-2h point group symmetry. The experimental main Raman bands of Al2OF84-, Al2OF62-, and Al2O2F42- were at 495 cm(-1), 465 cm(-1), and 410 cm-1, respectively, after comparing their theoretical Raman spectra. The forms and contents of the oxygen-containing complex ions in the system were related to the molar ratio of KF to AlF3 and to the concentration of alumina. AlF63-, AlF52-, AlF4-, and Al2OF4 were found in the molten KF-AlF3-Al2O3 system with a KF-to-AlF3 molar ratio of 1.22 at a temperature of 1003 K. In the KF-AlF3-Al2O3 system with a KF-to-AlF3 molar ratio of 2 at a temperature of 1273 K, when the alumina concentration was less than or equal to 10 wt%, it contained AlF63-, AlF52-, AlF4-, Al2OF4, and Al2OF84-, and when the alumina concentration reached 12 wt%, Al2OF62- and Al2O2F42 appeared. In the KF-AlF3-Al2O3 system with a KF-to-AlF3 molar ratio of 3 at a temperature of 1273 K, when the alumina concentration was less than or equal to 10 wt%, the system contained AlF63-, AlF52-, AlF4-, Al2OF4, and Al2OF84-. When the alumina concentration increased to 14 wt%, Al2OF62- and Al2O2F42- began to appear but AlF4- disappeared. As the concentration of alumina increased, the contents of Al2OF62- and Al2O2F42- increased. The ionic reactions that formed the various oxygen-containing complexes were obtained. The occurrence of these chemical reactions was related to the molar ratio of KF to AlF3 in the system and the alumina concentration. When the KF-AlF3-Al2O3 molten system with KF-to-AlF3 molar ratios of 1.22, 2 and 3 were used as the aluminum electrolytes, the ion discharged at the anode was Al2OF84- (except for the system with a KF-to-AlF3 molar ratio of 1.22 in which the Al2OF4 was discharged at the anode), and the ion discharged at the cathode was Al2OF4 according to wave function analyses. (C) 2021 Elsevier B.V. All rights reserved.