甲基苯热裂解机理的理论研究  

THEORETICAL STUDY ON PYROLYSIS MECHANISM OF TOLUENE

作　　者：乔占平 王惠[2] 赵文立[2] 冉新权[2] 

机构地区：[1]南阳师院化学系,河南南阳473069 [2]西北大学化学系,陕西西安710069

出　　处：《燃料化学学报》2002年第1期49-53,共5页Journal of Fuel Chemistry and Technology

基　　金：陕西省自然科学基金 ( 2 0 0 1H0 3);陕西省教育厅重大产业化培育基金 ( 01ZC0 4)~~

摘　　要：在半经验UAM1方法及从头算UHF 3 2 1G 水平的基础上 ,用考虑了电子相关效应的密度泛函UB3LYP 3 2 1G 方法对碳前驱体甲基苯的热裂解反应机理进行了研究 ,并对反应物、产物自由基及过渡态的结构进行了能量梯度法全优化。计算结果表明 ,甲基苯的热裂解温度较低时 ,首先支持苯环甲基上的C—H键断裂 ,继而发生生成联二甲苯的反应。随着温度的提高 ,生成苯自由基的反应比例将增加 ,同时发生少量的苯环上C—H键断裂的反应。该反应机理与实验结果相一致 ;用密度泛函方法UB3LYP 3 2 1G 计算的反应标准焓变ΔH与实验值吻合较好。On the basis of the calculating results by UAM1 and UHF/3-21G* methods,the pyrolysis mechanism of toluene has been studied at UB3LYP/3-21G* level. The geometries of the reactant, producted radicals and Transition State were optimized by energy gradient method. The results showed that C-H bond of methyl on benzene will split first at low temperature, followd by the formation of bibenzil. The rate of benzene radical formation increases with the increase of the temperature, and a few of C-H bonds on benzene will be broken at the same time. This mechanism is in accord with experimental result. In addition, the data of ΔH θ calculated at UB3LYP/3-21G* level coincide with the experimental data.

关 键 词：碳前驱体 甲基苯 热裂解机理 密度泛函 反应路径 碳材料 

分 类 号：O625.11[理学—有机化学]