N2O在焦炭表面异相生成和分解机理的密度泛函理论研究

选用合理简化的焦炭模型，对煤焦燃烧过程中N₂O的异相生成和分解机理进行了分子水平上的研究。采用UB3LYP/6-31G(d)密度泛函理论方法优化得到了反应路径上反应物、产物、中间体和过渡态的几何构型和各中间反应的活化能和反应焓变。NO与其预先吸附在焦炭表面解离生成的表面氮组分反应生成N₂O的路径有两个,需要克服的势垒分别为69.3kJ/mol和200.0kJ/mol；NO亦可直接与焦炭中的吡啶氮结合释放出N₂O，该反应路径所需克服的最大势垒为418.0kJ/mol。N₂O可在焦炭表面分解释放出N₂，异相分解反应为一步反应，计算所得活化能为100.8kJ/mol。N₂O的异相生成和异相分解反应均为放热反应。采用经典过渡态理论计算得到了各路径中速率控制步骤的反应速率常数。低温条件下，N₂O的异相分解反应速率略低于其异相生成速率，随着温度的升高，两者逐渐接近，说明高温条件有利于N₂O的异相分解。

A density functional study of heterogeneous formation and decomposition of N_2O on the surface of char

A comprehensive density functional study was carried out to get an insight into the mechanisms of heterogeneous formation and decomposition of N2O on the char surface by using a char model with zig-zag configuration.The geometry optimizations of reactants,intermediates,transition states and products were made by using density functional theory at the UB3LYP/6-31G(d) level.On the basis of the reaction pathways analysis,the energies of optimized geometries were calculated and corrected with zero point energy;...