CH_2与NO反应机理的理论研究

Theoretical Investigation on the Reaction Mechanism of CH_2 with NO

CH2自由基是烃类燃烧过程中产生的重要物质,NO是主要的环境污染物,研究二者之间的反应具有重要的现实意义.用从头算(abinitio)方法从理论上对CH2和NO的反应进行研究,采用G2MP2方法计算各反应通道上所有驻点的构型参数、振动频率和高级能量,根据相对能量绘制的势能剖面图详细给出了CH2和NO的反应机理.反应中,NO横向进攻CH2中心形成富能中间体H2CNO(IM1),而后经复杂的异构化或解离途径生成产物.计算的各个通道的反应热与实验结果符合较好.根据势能面,预测生成CO+NH2和H+HNCO是反应的主要通道,这与实验事实相一致.

CH_2 radical is an important species in the process of hydrocarbon burning and NO is the major environmental pollutant, so study on them has practical significance. In this paper the reaction of CH_2 with NO radicals has been studied theoretically by using ab initio MO method. The structure parameters, vibration frequencies and energy of each stationary point for all reaction channels are given by using the G2MP2 method, and the particular reaction mechanism has been given by the potential energy surface which is drawn according to the relative energy. The reaction takes place as the NO radical attacks breadthwise the center of CH_2 to form an energy-rich intermediate H_2CNO(IM_1), in turn, the products have been produced by complicated isomerization or dissociation reaction. The reaction heat for each channel is in agreement with the experiment result. The productions of CO+NH_2 and H+HNCO are the major reaction channels according to the potential energy surface, and this result is accordant to the experiment.