CH3CH2O与HO2抽氢反应与主通道速率常数的理论研究  

Theoretical study on the hydrogen abstraction and the main channel rate constant of CH3CH2O and HO2

作　　者：李明静 张宇航 王凯 王志银[1] 张田雷[1] LI Ming-jing;ZHANG Yu-hang;WANG Kai;WANG Zhi-yin;ZHANG Tian-lei(Shaanxi Province Key Laboratory of Catalytic Fundamentals ＆Applications, School of Chemical ＆ Environment Science Shaanxi University of Technology, Hanzhong 723000, Chin)

机构地区：[1]陕西省催化基础与应用重点实验室陕西理工大学化学与环境科学学院

出　　处：《分子科学学报》2018年第3期211-217,共7页Journal of Molecular Science

基　　金：陕西理工大学大学生创新创业项目(2017113)

摘　　要：在B3LYP//6-311＋＋G（2df,2p）水平完成了对CH3CH2O与HO2反应各驻点物种的几何构型优化,并在相同水平上对相关物种进行了频率分析和内禀反应坐标（IRC）计算.为得到较准确的单点能信息,同时采用CCSD（T）/cc-pVTZ方法对反应途径中各驻点进行单点能校正.标题反应的单、三重态势能剖面图揭示,反应在单、三重态势能面上均有3条抽氢通道.其中单重态通道分别生成1CH3CHO＋H2O2（R1）,CH3CH2OH＋1O2（R2）和1CH2CH2O＋H2O2（R3）,三重态通道分别生成3CH3CHO＋H2O2（R4）,CH3CH2OH＋3O2（R5）和3CH2CH2O＋H2O2（R6）;势垒高度揭示三重态在动力学和热力学上比单重态更具优势.200K1200K区间内标题反应速率常数计算结果表明,除通道R5的速率常数几乎不随温度变化外,所有其他通道的速率常数均随温度升高而增大（即速率呈现正温度系数效应）,同时发现抽氢通道R5的分支比始终大于94%,因而是绝对优势通道.The geometries,vibrational frequencies of all the stationary points involved in CH3CH2O and HO2 reactions were calculated using density functional B3 LYP method with the 6-311＋＋G（2 df,2 p）basis sets.The connections between reactants,intermediates,transition states and products were confirmed by the intrinsic reaction coordinate（IRC）calculations.The single-point energies along the minimum energy potential were calculated at the CCSD（T）/cc-pVTZ level of theory.Direct H-abstraction channels are identified for both the singlet and triplet reactions,among which three channels,1 CH3 CHO＋H2O2（R1）,CH3CH2OH＋1 O2（R2）and 1 CH2CH2O＋H2O2（R3）occur on the singlet state potential energy surfaces（PES）,and three channels,3 CH3 CHO＋H2O2（R4）,CH3CH2OH＋3 O2（R5）and 3 CH2CH2O＋H2O2（R6）proceed on the triplet state PES.Comparison of the PES of the singlet state with the triplet state reveals that the later is more favorable in the kinetics and thermodynamics.Except for the channel R5（its rate constants hardly varies with temperature）,the title reaction rate constant for the other channels increases with increasing temperature（i.e.the rate is positive temperature coefficient）in the range 200 Kto 1 200 K.The branch ratio of channel R5 is higher than 94%in the whole temperature range,thus it has the absolute advantage.

关 键 词：CH3CH2O HO2 反应机理 速率常数 

分 类 号：O643[理学—物理化学]