Density functional theory study on the effect of Cα-OH functional group modification on the homolytic cracking reaction routes during the pyrolysis of lignin dimer [基于密度泛函理论研究木质素二聚体Cα-OH基团的修饰对其热解均裂历程的影响]

作者：Duan Y.; Cheng H.; Wu S.-B.^*

来源：Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology, 2019, 47(12): 1440-1449.

• Cα-OH functional group
• Density functional theory
• Homolysis
• Lignin
• Pyrolysis
• Β-O-4 bonding

Density functional theory method was used to calculate the bond dissociation energies of the Caromatic-Cα, Cα-Cβ, Cβ-O bond, and Caromatic-O bonds in four lignin dimer model compounds, viz., (2-(2-methoxyphenoxy)-1-phenylethan-1-ol, 2-(2-methoxyphenoxy)-1-phenylethan-1-one, 1-methoxy-2-(2-methoxy-2-phenylethoxy)benzene, and 2-(2-methoxyphenoxy)-1-phenylethyl acetate; the homolytic cracking reaction during pyrolysis of these dimers was then invetigated and the formation pathways of pyrolysis products of different dimers were analyzed. The results show that the homogenization of Cβ-O bond is the main reaction in the initial pyrolysis of dimer, whereas the homolysis of Cα-Cβ bond is a competitive reaction. After the oxidation and acetylation of Cα-OH, the bond dissociation energy of Cβ-O bond decreases, whereas the dissociation energy of Cα-Cβ bond increases, ccompanied with an increase in the probability of the Cβ-O bond dissociation and a decrease in the competitive ability of Cα-Cβ bond homolysis. For the pyrolysis of four model compounds, the main aromatic products include benzyl alcohol, toluene, benzaldehyde, guaiacol, etc. The selective modification of the Cα-OH functional groups can regulate the types of pyrolysis products. In particular, the product types for the pyrolysis of model compounds modified by oxidation become less, accompanied with an increase in the selectivity to ceratin products. Ethylbenzene and toluene can be produced from the hydrolysis of dimers modified by methylation and acetylation.

• 单位
  华南理工大学