基于密度泛函理论的木糖热解制备糠醛的反应机理  

Mechanism of Xylose Pyrolysis to Furfural Based on Density Function Theory

作　　者：张航[1] 邓胜祥[1] 田红[2] 曹小玲[2] ZHANG Hang DENG Shengxiang TIAN Hong CAO Xiaoling(Department of Energy Science and Engineering, Central South University, Changsha 410083, China School of Energy and Power Engineering, Changsha University of Science ＆ Technology, Changsha 410015, China)

机构地区：[1]中南大学能源科学与工程学院,湖南长沙410083 [2]长沙理工大学能源与动力工程学院,湖南长沙410015

出　　处：《石油学报（石油加工）》2017年第2期356-363,共8页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家自然科学基金项目(51276023);国家自然科学基金国际(地区)合作与交流项目(513101410)资助

摘　　要：在密度泛函理论(DFT)的基础上,采用B3LYP/6-311G方法对木糖热解制备糠醛的反应机理进行动力学分析。木糖热解制备糠醛的反应过程包括开环反应、半缩醛反应和两步消去反应,据此设计6条热解反应路径。对路径中的各构象进行能量梯度全优化和振动频率计算,结果表明,3种反应类型中,消去反应的活化能最小,而开环反应所需的能量相比其他反应类型都要大。对于木糖,呋喃环的消去反应比吡喃环的消去反应容易发生。Path2A和Path1B的消去反应活化能在所有路径中最低,为67kJ/mol;而Path2A的开环反应活化能为128kJ/mol,大于Path1B相应反应的活化能102kJ/mol,所以Path1B为最优反应路径,其次是Path2A。On the basis of density functional theory（DFT）,B3LYP/6-311 G method was used to investigate xylose pyrolysis mechanism from the perspective of kinetics.Reaction process of xylose pyrolysis to furfural consists of ring opening reaction,hemiacetal and two elimination reactions.Therefore,six reaction paths were designed about xylose pyrolysis to furfural.For each reaction path,the equilibrium geometries were optimized and the vibrational frequencies were calculated.Comparing the six paths,it is found that among the ring opening reaction,hemiacetal and elimination reactions,the activation energy of elimination reaction was the least and that of the opening reaction was the largest.For xylose,the activation energy of pyran ring elimination was much more than furan ring.The third step of elimination activation energy of Path2 Aand Path1B were all 67kJ/mol,the lowest among all the paths,while ring opening activation energy of Path2 A was 128kJ/mol,more than 102kJ/mol to Path1 B.So that Path1 B was the best reaction path,followed by Path2 A.

关 键 词：密度泛函理论 木糖 热解 糠醛 活化能 

分 类 号：TK224[动力工程及工程热物理—动力机械及工程]