C_8H_3O_6NNa_2·H_2O脱水过程的热分析动力学

Kinetics of dehydration decomposition of C_8H_3O_6NNa_2·H_2O in non-isothermal conditions

目的获得化合物一水合5-硝基间苯二甲酸钠(C8H3O6NNa2.H2O)固态样品脱水过程的动力学三因子(反应级数n,表观活化能Ea、指前因子A)及相应的动力学方程。方法应用DSC技术获得化合物4个不同升温速率下的脱水过程曲线,利用多重扫描速率法,以"非模型等转化率法"为基础,采用8种积分法和微分法相结合的热分析动力学方法处理程序进行定量表征。结果标题化合物脱水阶段的反应为n=1/2的随机成核和随后生长机理,表观活化能Ea为196.13 kJ·mol-1,指前因子A为5.383×1021 s-1,动力学方程为dα/dT=5.383×1021/β(1-α)[-ln(1-α)]1/2exp(-2.359×104/T)。结论所得标题化合物脱水阶段动力学三因子数据和相应的动力学方程是可靠的。

Abstract： Aim To obtain the kinetic parameters （reaction order n, the apparent activation energy Ea, the pre- exponential factor A） and the most probable kinetic model function of the dehydration decomposition of solid com- pound CsHsO6NNa2 ~ H20. Methods From an analysis of the DSC curves at four different heating rates by inte- gral and differential methods based on model-free isoconversional methods. Results The most probable kinetic model function of the dehydration decomposition reaction is random nuclear producing and growing process of n = 1/2, and the apparent activation energy E, is 196. 13 kJ · mol^-1 and the pre-exponential factor A is 5. 383 × 10^21s^-1.the kinetic equation is da/dT=5.383×10^21/β（1-α）[-ln（1-α）]^1/2exp（-2.359×10^4/T）. Conclusion The most probable mechanism function and the corresponding kinetic parameters for the dehydration decomposition process of title compound provided a consultation on the similar process of other compounds.