温度对CaCO_3分解反应动力学参数的影响

Effect of temperature on kinetic parameters of decomposition reaction of calcium carbonate

采用自建的大剂量热重分析仪对分析纯CaCO3进行煅烧分解的热重试验,得到了温度对CaCO3分解过程动力学参数的影响规律。分析结果表明:CaCO3分解反应性指数随温度升高呈阶段性增长,而动力学参数随温度升高呈阶段性减小,但均可分为3个阶段,且不同阶段的温度转折点相同;相边界反应(圆柱形对称)机理较适合N2环境气氛下CaCO3热分解反应,反应活化能和指前因子的对数随温度的升高变化规律相似,二者线性关系良好,存在动力学补偿效应;根据补偿系数推导出CaCO3煅烧的等动力学温度约842℃,反应速率常数为0.104 9min-1。

In order to investigate the influence of temperature on behavior of calcium carbonate decomposition,especially on kinetic parameters of the decomposition reaction,the analytically pure calcium carbonate was calcined on a self-built large dose thermogravimetric analyzer.The results indicated that,with an increase in the reaction temperature,the reactivity index of calcium carbonate decomposition increased at stage state while the kinetic parameters decreased at stage state.Moreover,both the reaction indices and the kinetic parameters can be divided into three stages and the temperature turning points in different stages were the same.The phase boundary reaction(cylindrical symmetry) theory was more suitable for calcium carbonate calcination under N2 atmosphere.The change trend of the logarithm of reaction activation with temperature was similar as that of the pre-exponential factor.There existed good liner relationship and kinetic compensation effect between them.The isokinetic temperature of the CaCO3 calcination was 842 ℃ and the reaction rate constant was 0.104 9 min-1 derived by the compensation coefficients.