亚/超临界乙醇-纤维二糖二元组分的分子动力学模拟  

Molecule Dynamic Simulations of Ethanol-Cellobiose Binary Reaction System in Sub-Supercritical

作　　者：汤成正[1] 吴芳[1] 战晓青 李璐[1] 李雁[1] 解新安[1] 

机构地区：[1]华南农业大学食品学院,广东广州510642

出　　处：《造纸科学与技术》2014年第4期18-23,共6页Paper Science & Technology

基　　金：国家自然科学基金资助项目(21176097);广东省科技计划国际合作项目(2009B050700037)

摘　　要：采用分子动力学方法研究了纤维二糖（纤维素模型物）与亚/超临界乙醇二元组分交互作用下微观结构变化与动力学参数。模拟发现纤维二糖和乙醇二元组分体系温度从450K上升至550K,密度从414.23kg/m3下降至241.52 kg/m3而出现分子涨落聚集现象。随着温度和压强的升高（450~550K、5~15MPa）,乙醇与纤维二糖分子间径向分布函数峰值左移且逐渐增大,峰宽变宽,分子间相互作用逐渐增强;压强和温度的进一步升高（600K,20MPa）,乙醇的自扩散系数增大,乙醇与纤维二糖分子极性大大降低,产生的游离基相互结合,配位数降低。本研究为亚/超临界乙醇促进纤维素的液化作用在分子水平上给出了初步的解释,并为建立纤维素液化过程的反应动力学模型提供思路,为生物质的转化提供多方面的基础数据。The microstructure changes and kinetic parameters of ethanol and cellobiose binary reaction system in sub - supereritical states （ T = 450 - 600K, P = 5 - 20MPa） were investigated by molecular dynamics simulation （MD） . The results show that the change of temperature and pressure has great effect on the radial distribution function of cellobiose - ethanol. With the increase of temperature （450K to 550K） , the binary components shows aggregation phenomenon which is even more evident in the low -density region（ p = 241.52kg ~ m-3） due to densi- ty fluctuations. With the rise of temperature and pressure （450 -550K, 5 -15MPa）, the peak value of radial dis- tribution function of cellobiose - ethanol increases and shifts left ; the peak width widens gradually ; the interactional force is strong between the ethanol and eellobiose molecule. When the state reaches 600 K and 20MPa, the diffu- sion coefficients increase, the coordination number decreases, while the structure becomes loose and the molecular polarity is greatly reduced and some free radicals are produced and combined. The simulation results give a prelimi- nary explanation for the sub - supercritical ethanol liquefaction of cellulose at the molecular level, and provide ideas for establishing kinetic model of the cellulose liquefaction process.

关 键 词：亚 超临界乙醇 纤维素二糖 密度涨落 径向分布函数 扩散系数 

分 类 号：O641[理学—物理化学]