关键词: 木质素, 热裂解产物, 环类化合物, 裂解气相色谱质谱

Abstract: 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 B3LYP/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 be obtained as the temperature was over than 800℃, and their corresponding products were phenanthrene, biphenyl and pyrene, respectively.

Key words: lignin, pyrolysis products, cyclic compound, pyrolysis gas chromatography mass spectrometry(Py-GC/MS)