摘要
采用碳酸氢钠和氯化镨制备八水碳酸镨颗粒后,运用TG-DSC技术,在不同程序升温下,研究八水碳酸镨(Pr2(CO3)3·8H2O)的热分解过程。分别采用Ozawa-Flynm-Wall法、Kissinger法、Crane法和Coats-Redfem法确定其热分解动力学参数。TG-DSC表明,八水碳酸镨热分解过程为3个阶段,第一阶段为脱水反应,第二阶段碳酸镨分解为Pr2CO5,第三阶段为Pr2CO5分解为Pr6O11。运用Coats-Redfem积分法得出第二阶段反应的反应机理受二维扩散机理控制,第三阶段反应的反应机理受成核和生长机理控制。在确定了八水碳酸镨热分解反应机理函数的前提下,实验计算得出三阶段反应的表观活化能E分别为47.24kJ·mol^-1、220.94kJ·mol^-1、120.71kJ·mol^-1;指前因子A分别为5.80×10^4S^-1、1.35×10^11S^-1、6.22×10^2S^-1;第一阶段和第二阶段反应级数约为1,第三阶段反应级数为0.88。
Praseodymium carbonate octahydrate was prepared by using praseodymium chloride and sodium bicarbonate.The thermal decomposition process of praseodymium carbonate octahydrate(Pr2(CO3)3·8H2O)was studied by TG-DSC technique at different temperature programs.The thermal decomposition kinetic parameters were determined by Ozawa-Flynm-Wall,Kissinger,Crane and Coats-Redfem methods,respectively.Curve of TG-DSC shows that the thermal decomposition process of praseodymium carbonate octahydrate is divided into three stages,the first stage is dehydration reaction,the second stage is decomposition of praseodymium carbonate to Pr2CO5,the third stage is the decomposition of Pr2CO5 to Pr6O11.According to Coats-Redfem integral,the reaction mechanism of the second stage is controlled by two-dimensional diffusion mechanism,and the reaction mechanism of the third stage is controlled by nucleation and growth mechanism.By the decomposition mechanism of praseodymium carbonate,the apparent activation energy of the three stages can be calculated to be 47.24,220.94,120.71 kJ·mol^-1,respectively.The pre-exponential factor A is 5.80×10^4,1.35×10^11,6.22×10^2 S^-1,respectively.The reaction series of the first and second stages are all about 1,and the third stage is 0.88.
作者
邓庚凤
谢耀
李志午
邓超群
汪晨阳
曾青云
DENG Geng-feng;XIE Yao;LI Zhi-wu;DENG Chao-qun;WANG Chen-yang;ZENG Qing-yun(School of Metallurgy and Chemistry Engineering,Jiangxi University of Science and Technology,Ganzhou 341000,China)
出处
《稀土》
EI
CAS
CSCD
北大核心
2019年第4期1-10,共10页
Chinese Rare Earths
基金
国家自然科学基金项目(51564022)
