基于量子化学的木质素热裂解中环类化合物形成的理论及实验研究  

Theoretical and Experimental Study on Cyclic Compound Formation in Lignin Pyrolysis Based on Quantum Chemistry

作　　者：田红[1] 陈斌斌[1] 罗海银 姚灿[1] 

机构地区：[1]长沙理工大学能源与动力工程学院,湖南长沙410114

出　　处：《林产化学与工业》2016年第3期1-8,共8页Chemistry and Industry of Forest Products

基　　金：国家自然科学基金资助项目(51276023);湖南省教育厅资助项目(10C0384);湖南省重点实验室开放基金资助项目(2011KFJJ007)

摘　　要：利用傅里叶变换红外光谱仪分析木质素微观结构,应用裂解气相色谱-质谱联用技术（Py-GC/MS）进行木质素的热裂解产物分析。研究结果表明：300和400℃时没有检测到多环芳烃等复杂结构,可见在该温度下,裂解产物并未发生二次缩合作用;在800℃下,苯和甲苯的GC含量增加,苯酚基本保持不变,并开始出现多环芳烃化合物。以密度泛函理论B3LYP/6-31G（d,p）为基础对木质素的裂解反应过程进行了分子动力学模拟研究,对比分析实验数据和模拟数据,推断出木质素热裂解中环类化合物的形成演化机理：300~400℃主要发生CC键的断裂和羟基脱落（路径R5-1）以及C1—Cα键的断裂（路径R5-2）;400~800℃发生的C1—Cα键断裂反应（路径R4-1）,苯环上甲氧基官能团脱去反应（路径R4-4）和苯环上甲氧基均裂（路径R5-3）;与苯环上甲氧基官能团均裂反应（路径R4-3）相比,苯环C1—Cα断裂反应（路径R4-2）发生的可能性更大;路径2、路径3和路径5的产物量均在800℃左右达到最大,其产物分别为联苯、菲以及芘。The microstructure of lignin was analyzed by using Fourier transform infrared spectrometer（FT-IR）,and the pyrolysis products of lignin were analyzed by gas chromatography mass spectrometry（Py-GC/MS）.The results showed that the second condensation reaction of the cracking product did not occur at 300 and 400 ℃,and the complex structures such as polycyclic aromatic hydrocarbons were not detected.At 800 ℃,the relative contents of benzene and toluene increased while the phenol content was stable.Meanwhile,the polyaromatic hydrocarbons were observed.The molecular dynamics simulation of the cracking reaction process of lignin was carried out based on the density functional theory B3 LYP/6-31G（d,p）.The comparison between the calculated and experimental results showed that the fracture of CC bond,the loss of hydroxyl（path R5-1） and the fracture of C1—Cα bond（path R5-2） appeared at 300-400 ℃.The fracture of C1—Cα bond（path R4-1）,the detachment of methoxyl functional groups on the benzene ring（path R4-4） and the homolytic reaction of methoxyl functional groups on the benzene ring（path R5-3） were proceeded at 400-800 ℃;C1—Cα bond（path R4-2） was fractured,more likely than the homolytic reaction of methoxyl functional groups on the benzene ring（path R4-3）.The products of paths 2,3 and 5 could beobtained as the temperature was over than 800℃,and their corresponding products were phenanthrene,biphenyl and pyrene,respectively.

关 键 词：木质素 热裂解产物 环类化合物 裂解气相色谱质谱 

分 类 号：TQ35[化学工程] TK16[动力工程及工程热物理—热能工程]