碱式碳酸镁的热分解研究

通过TGA、DSC热分析法,研究了碱式碳酸镁的热分解过程。发现碱式碳酸镁分两个阶段分解,并测得每一阶段的特征温度和吸热值。由Kissinger与Ozawa-Doyle两种方法求得两个阶段热分解反应的表观活化能Ea和指前因子lgA。用常见的固体热分解机理函数拟合了ln[G(α)/T2]~1/T曲线,用Coats-Redfern法确定了碱式碳酸镁热分解过程第一阶段的机理是三维扩散机理D3,第二阶段的机理是随机成核和核生长机理F1,获得其动力学方程。采用DSC方法测试了碱式碳酸镁的比热容,用最小二乘法拟合曲线,获得其比热的表达式为Cp=-3.890 2+0.207 2T-0.002 58T2+1.386 3×10-5T3-2.755 4×10-8T4。

Investigation in thermal decomposition of basic magnesium carbonate

Thermal decomposition of the basic magnesium carbonate were investigated by TGA and DSC.Basic magnesium carbonate decomposition was discussed in two phases.MgO,CO2 and H2O are the main products.The special temperature and endothermic enthalpy were measured in each phase.The apparent activation energy Ea and lgA by the two methods of Kissinger and Ozawa-Doyle were calculated.Some thermal decomposition mechanism functions were used to fit ln[G(α)/T 2]~1/T curve.It was obtained from Coats-Redfern's equation that the mechanism functions of the two decomposition stages are D3 and F1,respectively.And then,the kinetic equation was deduced.The specific heat capacity was measured by DSC.In the end the function was calculated which is Cp=-3.890 2+0.207 2T-0.002 58T 2+1.386 3×10-5T 3-2.755 4×10-8T 4.