摘要
为了探究热解温度对木质素热解产物分布的影响,本工作采用密度泛函方法B3LYP/6-31G(d,p),以β-O-4型木质素二聚体为模化物,在不同热解温度下,对该模化物两种主要热解反应途径中的反应物、产物、中间体和过渡态进行了能量梯度全优化以及振动频率计算。根据计算结果中的动力学和热力学参数的变化规律,分析了热解温度对热解产物分布的影响。计算结果表明:Cβ-O键均裂的反应是主要的反应路径,当热解温度低于700 K时,主要产物为化合物4、化合物7、化合物15以及小分子甲醛和乙烯,化合物10、化合物11、化合物13、化合物14和CO在产物中的含量所占比例相对较少;当热解温度高于700 K时,产物中化合物15和乙烯继续占据主要产物的地位,且含量持续升高,同时,化合物7和甲醛的含量所占比例减少,而化合物10、化合物11和CO含量增多,成为主要产物;Cα-Cβ键均裂的反应是主要的竞争反应,随热解温度升高,其主要生成物化合物4和乙醛含量持续升高,而化合物25和甲醛在产物中所占比例变化不大,化合物20和CO的比例则明显减少。
In order to explore the influence of pyrolysis temperature on the distribution of pyrolysis products of lignin,the theoretical calculations of two main pyrolysis reactions in the pyrolysis process ofβ-O-4 lignin dimer were carried out for each step at different pyrolysis temperatures by density functional theory B3LYP/6-31G(d,p).The energy gradients of reactants,products,intermediates and transition states for each reaction pathway were optimized,and vibration frequencies of which were calculated at different temperatures.The influence of pyrolysis temperature on the distribution of pyrolysis products was analyzed based on the variation of kinetics and thermodynamics parameters.The calculation results showed that the reaction after the cleavage of Cβ-O bond was the main reaction.When the pyrolysis temperature was below 700 K,the main products of the reaction were compounds 4,7,15 and small molecules including formaldehyde and ethylene,while the proportions of compounds 10,11,13,14 and CO in the product were relatively low.When the pyrolysis temperature was higher than 700 K,the proportions of compound 15 and ethylene increased continuously,which were still the main products.At the same time,the proportions of compound 7 and formaldehyde decreased,while the proportions of compounds 10,11 and CO increased.The cleavage reaction of Cα-Cβbond was the main competing reaction.With the increasing pyrolysis temperature,the proportions of the main products including compound 4 and acetaldehyde increased continuously,the proportions of chemical 20 and CO decreased obviously,and the proportions of compound 25 and formaldehyde in the products changed a little.
作者
何正文
田红
黄章俊
胡章茂
刘威
HE Zhengwen;TIAN Hong;HUANG Zhangjun;HU Zhangmao;LIU Wei(School of Energy and Power Engineering,Changsha University of Science and Technology,Changsha 410015,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2020年第6期180-185,共6页
Materials Reports
基金
国家自然科学青年基金(51706022)
湖南省自然科学基金青年基金(2018JJ3545)
湖南省自然科学基金(2018JJ2442)~~
关键词
木质素
热解温度
热解产物分布
密度泛函理论
lignin
pyrolysis temperature
distribution of pyrolysis products
density functional theory
