不同气氛下偏钛酸脱水行为动力学研究

Dehydration Kinetics Study on Metatitanic Acid in Different Atmosphere

偏钛酸脱水是制备二氧化钛化学过程的最后关键环节,借助同步热重仪测定了不同升温速率下偏钛酸热分析曲线,研究了不同气氛下其脱水行为动力学和机理。结果表明偏钛酸的脱水行为会受氧气的影响。偏钛酸在含氧气氛下先快速脱水,后缓慢脱水至反应完成,而在无氧气氛下(氩气和氮气)则以缓慢的速度进行脱水。利用无模函数法和有模函数法进行动力学计算后发现:偏钛酸的脱水行为在空气气氛下符合Avrami-Erofeev方程,脱水过程受晶核的形成和生长控制;而在无氧的气氛下符合幂函数法则,反应机理为一维相边界反应。研究结果将为进一步认知偏钛酸煅烧分解及相关含水钛氧化合物的脱水过程提供重要参考。

The last key step in the preparation of titanium dioxide was dehydration of metatitanic acid.The kinetics and mechanism of metatitanic acid dehydration under different heating rates were studied by means of synchronous thermogravimetry.The results show that the oxygen atmosphere would affected the dehydration process.Metatitanic acid was dehydrated quickly in oxygen atmosphere,then slowly until the reaction completed,while carried out at a slow rate in anaerobic atmosphere(argon and nitrogen).Using the method of non-mode function and mode function to calculate the kinetics of dehydration of metatitanic acid.The dehydration reaction in the air atmosphere meeted the Avrami-Erofeev equation which controlled by the formation and growth of the crystal nucleus.When the dehydration reaction in the anaerobic atmosphere,according to the Mampel Power law,it was consistent with the one-dimensional boundary reaction.The results will provide an important reference for further understanding the calcination and decomposition of titanate,and the dehydration process of related hydrous titanium oxides.