木质素热解机理的分子动力学模拟研究

Molecular Dynamic Simulation Study on Thermal Decomposition Mechanism of Lignin

为了理解木质素热解过程及其热解主要产物的形成演变机理,对木质素模型化合物的热解过程进行了分子动力学模拟,模拟基于AMBER力场,采用周期性边界条件,模拟温度在300～1200K。模拟结果表明热解可大致分为3个阶段:低温阶段(450K以下)、中温阶段(450～800K)、高温分解阶段(800K以上)。温度上升到400K时,开始有少量羟基和甲基断裂,随着温度的升高,在600K时连接苯丙烷结构单元的醚键开始发生断裂,整个分子发生解聚,形成各种分子碎片。结合相关文献的实验结果分析了热解产物的可能途径。

In order to understand the lignin thermal decomposition mechanism and the formation mechanism of main products from the microscopic, the thermal decomposition process of lignin model compound was simulated in pe- riodic boundary conditions by molecular dynamic method from initial temperature 300K to 1200K. The simulation re- suits show that the simulation process of pyrolysis of lignin model compound can be divided into three stages： Low temperature stage （below 450K）, intermediate temperature stage（450--800K） and high temperature decomposition stage（above 800K）. When temperature arrives at 400K, HO-C and CHa-O bonds begin to fracture. With the increase of temperature, at about 600K the ether bonds between benzene propane structure units begin to break, then the whole molecule depolymerizes and all kinds of fragments are formed. Based on related experimental results of refe- rences, the possible formation pathways of major products were analyzed.