撞击诱导硝基甲烷分子第一步分解反应的动力学计算  

Kinetics and thermodynamics of nitro-methane decomposition reaction

作　　者：葛素红[1] 董光兴[1] 孙桂华[1] 宋晓书[2] 

机构地区：[1]河西学院物理与机电工程学院,张掖734000 [2]贵州师范大学物理与电子技术学院,贵阳550001

出　　处：《原子与分子物理学报》2017年第1期78-86,共9页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11264008)

摘　　要：本文基于分子温度与压强的关系,计算在不同压强下基态和最低三态硝基甲烷的分子温度,对应计算其沿着CN键裂解反应的热化学和动力学参数.发现基态的硝基甲烷沿着CN键的分解反应是吸热反应,不具自发性,反应转换温度为1550.2 K,平衡常数在80-1202 K温度范围内很低.最低三态的硝基甲烷沿着CN键的裂解是放热反应,反应的Gibbs自由能在80-2558.5 K范围内为负,有好的自发性,且反应较为彻底.298.15-2558.5 K温度范围内反应活化能随着温度的升高而改变,使反应速率随着温度的升高而急剧增大.对应硝基甲烷爆压15 GPa,其分子温度为4617.6 K,该温度下三态分子分解反应的反应速率为1.088×10~8cm^3·mol^(-1)·s^(-1).推算硝基甲烷沿着CN键分解反应混合物的终态温度,当混合物为硝基、甲基和基态的硝基甲烷分子时,反应的终温为1611.37 K,等效能为1676.47 cm^(-1).当混合物为硝基、甲基、基态和最低三态的硝基甲烷分子时,反应的终温为1184.79 K,等效能为1232.65 cm^(-1).两种情况下终态等效能都足以维持硝基甲烷分子沿C-N键裂解反应的发生.这个能量也足以导致混合物中的NO_2分解为NO和O,这与实验检测的结论相一致.Kinetics and thermodynamics properties of decomposition reaction of nitro - methane （NM） rupturing from C -N bond via the lowest singlet and triplet states have been computed under shocked. It is observed that the decomposition reaction of NM of the lowest singlet state is an endothermic reaction, it cannot react spontaneously, its converted temperature is 1550. 2 K. The equilibrium constant of this reaction is quite small at the temperature ranging in 80 - 1202 K. But the decomposition reaction of NM of the lowest triplet state is an exothermic reaction, the free energy is negative, namely it can react spontaneously. The rates of this reaction at the tempera- ture ranging from 298. 15 K to 2558.5 K have been calculated and found that the rates is increasing rapidly with increasing temperature. The temperature of molecule is 4617. 6 K under 15 GPa, which corresponds to the pressure of Chapman - Jouguet of NM, the rate of the decomposition reaction of NM of the lowest triplet state is 1. 088 × 10^8 cm^3 · mol^- 1 · s^ - 1 under this temperature. Furthermore, the final temperature of the reaction is calculated, and we found that when mixture is made up of NO2, CH3, and CH3NO2（^1A1 ） the final temperature is 1611.37 K, this temperature is equivalent to 1676.47 cm^-1 But when mixture is made up of NO2, CH3, CH3NO2（^1A1 ）, and CH3NO2 （^3A1 ）, the final temperature is 1184. 79 K, this temperature is equivalent to 1232. 65 cm^-1. Both of them is enough to furnish the energy in which the decomposition of NO2 can react, or the decomposition of CHaNO2 （ ^3A1 ） can react.

关 键 词：活化自由能 反应速率 平衡常数 硝基甲烷 

分 类 号：O643[理学—物理化学]