煤炭燃烧过程中N20消除反应机理的密度泛函理论研究

摘要

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 reactions of N20 with H and CN radicals are kinetically the leading roles in N20 destruction,with activation%用密度泛函理论B3LYP方法对煤炭燃烧过程中N20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N20+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500-1800 K温度范围的反应速率常数.在N20的分解中,N20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·tool-1.在B3LYP/aug-CC-pVTZ level水平下,N20+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.