煤炭燃烧过程中N2O消除反应机理的密度泛函理论研究

用密度泛函理论B3LYP方法对煤炭燃烧过程中N₂O的消除反应进行研究。选用6-311++G**和aug-cc-pVTZ基组，优化了反应通道上反应物、过渡态和产物的几何构型。预测了它们的热力学性质(总能量、焓、熵和吉布斯自由能)及其随温度的变化。预测N₂O+CO反应的活化能为200 kJ·mol^-1，与实验值193±8 kJ·mol^-1较一致。计算了500~1 800 K 温度范围的反应速率常数。在N₂O的分解中，N₂O与H和CN自由基的反应为动力学优先进行的反应，其活化能为50~55 kJ·mol^-1。在B3LYP/aug-cc-pVTZ level水平下，N₂O+CN反应是热力学最有利的自发反应，其吉布斯自由能变化为-407 kJ·mol^-1。

Mechanism of N2O Destruction under Coal Combustion Conditions: Density Functional Theory Study

We have calculated the reactants, transition states and products of six reactions involving the N₂O destruction under coal combustion, by using the DFT-B3LYP method with the 6-311++G** and aug-cc-pVTZ basis sets. Optimized structures were obtained. Thermodynamic property changes (total energy, enthalpy, entropy and Gibbs free energy) along the reaction paths, as well as their variations with temperatures, were predicted. The predicted activation energy of ca. 200 kJ·mol^-1 for the reaction of N₂O+CO is in good agreement with experiment value of 193±8 kJ·mol^-1. Rate constants over the temperature range of 500~1 800 K were figured out. The reactions of N₂O with H and CN radicals are kinetically the leading roles in N₂O destruction, with activation energies of 50~55 kJ·mol^-1. The reaction of N₂O with CN radical is thermodynamically the most favorable process with Gibbs free energy changes of -407 kJ·mol^-1 at the B3LYP/aug-cc-pVTZ level.