Metal occupancy and its influence on thermal stability of synthetic saponites
Metal occupancy and its influence on thermal stability of synthetic saponites
复制标题
金属占有率及其对合成皂石热稳定性的影响
DOI：
10.1016/j.clay.2016.10.006
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发表时间：
2017-01-01
影响因子：
5.6
通讯作者：
Zhu, Jianxi
中科院分区：
文献类型：
--
作者：
Zhang, Chaoqun;He, Hongping;Zhu, Jianxi
Due to high surface acidity and thermal stability, saponite has important applications in various fields. In this study, saponites with different Mg/Zn ratios (0-6) and a fixed Si/Al ratio of 5.43 were synthesized under hydro thermal condition. The resultant synthetic saponites were characterized by using XRD, FTIR, TG, SEM and MAS NMR. The characterization results demonstrated that, with a decrease of Mg/Zn ratio, both the crystallinity and layer stacking order of saponite were increased, and rose-like morphology was observed in Zn-saponite. Al3+ preferentially occupied tetrahedral sites in Si-O tetrahedral sheet in all synthetic saponites. A decrease of Mg/Zn ratio in octahedral sheet could improve the substitution extent of Al3+ for Si4+ and resulted in an increase of Al(IV)/Al(VI) ratio in the resultant saponite, which might be a crucial factor to control the crystal growth of saponite. The dehydroxylation temperature of saponite depended strongly on the Mg/Zn ratio and the replacement of Al3+ for mg(2+) and Zn2+ in octahedral sheets, due to their different bond strength. A 'one-to-one' mode was proposed for the substitution of Al3+ for Mg2+ and Zn2+ in octahedral sheets of the synthetic saponites. (C) 2016 Elsevier B.V. All rights reserved.
