纤维素在超临界乙醇中的液化及其模型化合物的热解过程分子模拟  

Liquefaction of Cellulose in Supercritical Ethanol and Molecular Simulation on Pyrolysis Process of its Model Compound

作　　者：陈勇强 解新安[1] 孙娇[1] 李璐[1] 李雁[1] CHEN Yong-qiang;XIE Xin-an;SUN Jiao;LI Lu;LI Yan(College of Food Science,South China Agricultural University,Guangzhou 510642,Guangdong,P.R.China)

机构地区：[1]华南农业大学食品学院,广东广州510642

出　　处：《林产工业》2022年第1期6-13,共8页China Forest Products Industry

基　　金：国家自然科学基金项目(21576107,21176097)。

摘　　要：采用超临界乙醇溶剂对玉米秸秆纤维素进行液化,通过GC-MS和FT-IR对生物油组分和残渣进行表征,结果表明:生物油组分主要包括酮类、酯类、醛类、苯类、酸类和醇类等平台化合物。不同反应温度对生物油的组分分布有不同的影响,其中酮类化合物的相对含量随着温度的升高而降低,而酯类的含量则逐渐增大。基于试验结果,选择左旋葡聚糖为模型化合物。基于密度泛函理论基组水平,计算左旋葡聚糖各化学键的Mulliken数,并依次设计2条初始开环路径及其对应的9条可能的反应裂解路径,模拟了左旋葡聚糖在乙醇环境中脱水、开环、裂解生成小分子物质的反应过程,计算其反应势能。通过比较反应势能,得到各反应路径的反应能垒顺序为:Path6<Path3<Path11<Path9<Path7<Path4<Path8<Path5<Path10,其中Path6的反应能垒最低(204.25 kJ/mol),是热力学支持的最优反应路径。In this paper,the liquefaction of corn stalk cellulose was analyzed in supercritical ethanol solvent,and the compounds of bio-oil and cellulose residues were characterized by GC-MS and FT-IR.The results showed that the components of bio-oil mainly included ketones,esters,aldehydes,benzenes,acids and alcohols.Different reaction temperatures had different effects on the components distribution,and the contents of ketones decreased with the increase of temperature,while the contents of esters gradually increased.Based on the experimental results,levoglucosan was selected as the model compound.The mechanism was investigated using density functional theory to calculate the strength of each levoglucosan bonds.Two initial open-loop paths and nine corresponding possible reaction cracking paths were designed successively,then simulate the reaction process of dehydration,ring-opening and cleavage of levoglucosan in ethanol and activation energies for each pathway were calculated.By comparing,the order of each pathway energy barrier was Path6<Path3<Path11<Path9<Path7<Path4<Path8<Path5<Path10.Thus,Path6 was the optimal path that determined based on its thermodynamic parameters with an energy barrier of 204.25 kJ/mol.

关 键 词：纤维素液化 超临界乙醇 左旋葡聚糖 热解 密度泛函理论 分子模拟 

分 类 号：TS6[轻工技术与工程] TQ35[化学工程]