柠檬酸铈的热分解机理及反应动力学

Decomposition Mechanism and Non-isothermal Reaction Kinetics of Cerium Citrate

在程序升温条件下,用DSC、TG/DTG、固相原位反应池/FTIR联用技术,研究了柠檬酸铈的热行为、分解机理和常压非等温分解反应动力学参数,获得了相应的动力学方程。结果表明,柠檬酸铈的热分解反应存在1个脱水吸热阶段(Stage I)和2个放热阶段(Stage II和III);主放热分解阶段(Stage II)的表观活化能Ea和指前因子A分别为148.59kJ/mol和1011.64s-1;动力学方程可表示为:dα/dt=1011.81(1-α)[-ln(1-α)]1/3e-1.79×104/T;反应机理服从n=2/3的Avrami-Erofeev方程。由加热速率β→0的DSC曲线的初始温度(Te)和峰温(Tp)计算得柠檬酸铈的热爆炸临界温度值Tbe和Tbp分别为527.09K和542.71K。反应的ΔS≠、ΔH≠和ΔG≠分别为:16.82J.mol-1.K-1、163.11kJ/mol和158.74kJ/mol。

The thermal behavior, mechanism and kinetic parameters of the exothermic decomposition reaction of cerium citrate （CIT-Ce） in a temperature-programmed mode have been investigated by means of DSC, TG/DTG and condensed phase thermolysis/FTIR. The kinetic equations of the decomposition reaction have been obtained. The results show that there are one dehydration stage and two exothermic reaction stages in the decomposition of cerium citrate. The apparent activation energy and pre-exponential factor of the main exothermic decomposition reaction at 0.1MPa are 148.59kJ·mol^-1 and 10^11.64s^-1, respectively . The kinetic equation can be expressed as： da/dt=10^11.81（1-α）[-In（1-α）]^1/3e^-1.79×10^4/T and the mechanism obeys Avrami-Erofeev equation with n=2/3. The critical temperatures of thermal explosion of cerium citrate obtained from the onset temperature（Te） and the peak temperature （Tp） are ： Tbe = 527.09 K ,Tbp= 542.71K. △S^≠、△H^≠ and △G^≠ of the reaction are calculated as ： 16.82J·mol^-1·K^-1、163.11kJ·mol^-1 and 158.74kJ·mol^-1.