摘要
The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2（CO3）3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2（CO3）3·3.4H2O is a kind of three-step competitive reaction, and controlled by an n-order initial reaction followed by n-order competitive reaction（FnFnFn model）. The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.
采用水热法合成单相La2（C O 3）3·3.4 H2O。采用XRD、FTIR以及DTA-T G对La2（C O 3）3·3.4 H2 O在3 0~1 0 0 0°C的热分解过程、中间及最终产物进行表征。在非等温条件下对L a2（C O3）3·3.4H2O在3 0~3 6 6°C范围内的热脱水动力学进行研究。采用Flynn-Wall-Ozawa及Friedman等转化法计算其反应活化能并对其反应阶段进行分析。采用多元非线性回归程序确定其最可能的反应机理及动力学参数。结果表明,L a2（C O3）3·3.4H 2O的热脱水为三步竞争反应,一个n序列初始反应后为n序列竞争反应（F nF nF n机理）。经最可能的反应机理计算所得的活化能与Friedman等转化法的计算结果非常接近,拟合后的TG及DTG曲线与原始曲线能较好地吻合。
基金
Project(201011005-5)supported by the National Land and Resources Public Welfare Scientific Research Project of China
Project(41030426)supported by the National Natural Science Foundation of China
Project(20095122110015)supported by Specialized Research Fund for the Doctoral Program of Higher Education of China
Project(2010-32)supported by Scientific Research Foundation of the Education Ministry for Returned Chinese Scholars,China
