基于分子层面研究海藻多糖与纤维素分子共热解协同现象

MOLECULAR DYNAMIC SIMULATION STUDY ON SYNERGISTIC CO-PYROLYSIS BEHAVIORS OF MIXED CELLULOSE AND SEAWEED POLYSACCHARIDE

通过对海藻多糖、纤维素模型化合物的共热解过程进行分子动力学模拟,探究其协同耦合现象。选取海藻内2种主要的多糖分子（硫酸多糖、褐藻糖胶）和陆生生物质的主要成分纤维素为研究对象。模拟基于Amber力场和ReaxFF力场发现：虽然海藻多糖与纤维素热解特性有许多相似之处,但分子结构上的差异使两者在热解过程中表现出不同的热力学特征。其中最明显的是两者热解温度范围不完全重叠,多糖分子提前热解产生大量的氢提供给纤维素,使纤维素热解更充分。共热解与单独热解叠加的模拟结果相比较,分子裂解碎片数目差异较大,共热解可促进两者的热解,提高热解转化率,增加中温段的产气率。

In order to understand the synergistic coupling pyrolysis mechanism between seaweed polysaccharide andcellulose,the molecular dynamics simulation method is used to analyse the co-pyrolysis of the model compoundmolecular of seaweed polysaccharide and cellulose.The molecular simulations are based on the AMBER force field andthe Reax FF force field,and the objects are cellulose molecule and two major kinds of seaweed polysaccharidemolecules：enteromorpha clathrata sulfated polysaccharide and fucoidan.The simulation results showed that there are alot of similarities in the pyrolysis characteristics of seaweed polysaccharide and cellulose,but the differences inmolecular structure make the different thermodynamic characteristics in the pyrolysis process.One of the most obvious isthat the pyrolysis temperature range is not completely overlap.The polysaccharide molecules produce hydrogen tocellulose,so that the cellulose pyrolysis more completely.Compared with the single pyrolysis,the number of molecularfragments increased.Co-pyrolysis could increase the pyrolysis conversion rate and oil production,and increase gasproduction rate in the middle temperature section.