甲烷磺酸锌的热分析及脱水动力学

合成了水合甲烷磺酸锌,并通过热重及差式扫描量热技术,在动态空气气氛下对脱水及热降解过程进行了表征。经计算,水合甲烷磺酸锌含有4个结晶水,分2步失去(在30～88℃与88～170℃)。脱水后,330～480℃之间为无水盐的主要热降解过程,并利用X-射线衍射测定其中间产物。结果可知,在500℃时,四水甲烷磺酸锌热分解中间产物为含氧硫酸锌(Zn3O(SO4)2)。在810℃,最终分解为ZnO。讨论了不同升温速率(5、10、15和20℃/min)下Zn(CH3SO3)2·4H2O的脱水过程,并进行了非等温脱水动力学研究。利用几种等转换率法计算活化能E,结果较为一致,并计算出频率因子A及反应级数n。分别确定了两步脱水反应的速率方程。

Thermal Analysis and Dehydration Kinetics of Zinc(II) Methanesulfonate

The zinc(II) methanesulfonate was prepared, the dehydration and thermal decomposition of which were characterized in dynamic air atmosphere through TG and DSC analysis. The results show that it contains four molecules of crystallization water and dehydration in two steps (30～88 ℃ and 88～170 ℃). The main decomposition occurred between 330 ℃ and 480 ℃ after dehydration. The intermediate of tetrahydrate zinc methanesulfonate decomposition was identified by X-ray diffraction. It is shown that the intermediate is Zn_3O(SO_4)_2 at 500 ℃. Zinc(II) methanesulfonate decomposed to ZnO directly at 810 ℃. Dehydration of tetrahydrate zinc methanesulfonate in different heating rates (5,10,15,20 ℃/min) were studied and dehydration kinetics was discussed by noniso-temperature method. The activation energy E was calculated by several isoconversional method and nearly equal value was obtained. Additionally, reaction order n and pre-exponential factor A were evaluated. The equations of reaction rate of two steps dehydration were confirmed, respectively.