二氧化锰低温分解动力学研究

采用热重分析仪在5种升温速率下对二氧化锰矿进行热重试验,研究预处理过程中二氧化锰的低温分解行为,并通过物相分析验证热重试验结果及反应推论,应用非模型等转化率法及Popscu法对两步反应动力学求解,得到各自的反应机理函数。结果表明,二氧化锰升温过程发生了两步反应,第一步反应产物为Mn2O3,反应机理为dα/dt=(3.96×109/β)(1-α)e-1.86×105/RT,为一级简单反应,符合Mample单行法则动力学机理特征;第二步产物为Mn3O4,反应机理为dα/dt=(3.28×1024/β)e-2.81×105/RT×(3/2)(1-α)-ln(1-α)]1/3,符合Avarami-Erofeev方程动力学机理特征。两步反应的反应机理均为随机成核和随后生长。

Study on Decomposition Dynamics of Manganese Dioxide at Low Temperature

Manganese dioxide was thermo-gravimetrically analyzed at five different heating rates with thermogravimetric analyzer to manifest its decomposition behaviors at low temperature, and the products of these reactions were verified with XRD spectrums. The mechanisms of these reactions were analyzed by MFK method and Popscu method. The results show that there are two reactions in the process of heating. The product of the first reaction is Mn2O3. The speed function of the first reaction is , and reaction order is 1, which corresponds with the principle of Mample single law. The product of the second reaction is Mn3O4. The speed function of the second reaction is , corresponding with the principle of Avarami-Erofeev law. The mechanisms of the above two reactions are random nucleation and subsequent growth.