为研究镁粉在氮气中的反应机理和过程,采用从头算二阶多体微扰理论MP2/6-311+G(d)方法优化反应物、中间体和产物的几何构型,分析其电子结构,通过计算得到反应势能为435.18kJ/mol,氮化反应中镁和氮气形成中间体MgN₂的过程为反应控制步骤,并对反应机理进行了分析。利用热重法对镁与氮气的反应过程进行了测试,根据Flynn-Wall-Ozawa积分法、Starink微分法和一般积分法计算了反应的动力学参数,得到反应活化能、指前因子和动力学方程。研究表明氮化反应分为3个阶段,利用Flynn-Wall-Ozawa积分法、Starink微分法和一般积分法得到的氮化反应平均活化能分别为410.56kJ/mol、412.86kJ/mol和409.21kJ/mol,平均指前因子为4.52×10¹⁵s^-1,热分解动力学方程为dα/dt=1.64×10¹³[2-ln(1-α)]e^-59.18。

In order to study the reaction mechanism and process of Mg powder in N₂,the optimized geometries,dipole moment and frequencies of all the stationary points were calculated at MP2/6-311+G(d) level.The potential energy surface was 435.18kJ/mol.The reaction producing MgN₂ was the controlling step.The mechanism was analyzed.Thermal analysis of the reaction between Mg and N₂ was carried out by thermogravimetry.The kinetic parameters of thermal decomposition were calculated by Flynn-Wall-Ozawa(FWO) method,Starink method and general integral method.The activation energy,pre-exponential factor and kinetic equation of Mg were calculated by three thermal analysis kinetics equations.It shown that the nitridation reaction included three steps.The activation energy E obtained by FWO method,Starink method and general integration method were 410.56,412.86 and 409.21kJ/mol respectively.The pre-exponential factor A was 4.52×10¹⁵s^-1,and the kinetic equation of thermal decomposition was dα/dt=1.64×10¹³[2-ln(1-α)]e^-59.18.