title: Direct evidence from in situ FTIR spectroscopy that o-quinonemethide is a key intermediate during the pyrolysis of guaiacol.
abstract: Although o-quinonemethide (6-methylene-2,4-cyclohexadien-1-one) has been proposed as a key intermediate in char formation during the pyrolysis of guaiacol (2-methoxyphenol), direct evidence of this (e.g., spectroscopic data) has not yet been provided. Using in situ FTIR spectroscopy, the pyrolysis of guaiacol was investigated from 30 °C to 630 °C at 40 °C/min. The IR profiles showed direct evidence of o-quinonemethide production at about 350 °C, which vanished rapidly at around 420 °C in the vapor phase, indicating char formation. In addition, at 400 °C, salicyl aldehyde was observed, which decomposed slowly at about 500 °C. In combination with the known products of guaiacol pyrolysis, these results allowed the major reaction pathways of guaiacol pyrolysis to be discerned. Density functional theory calculations were performed, and the results were found to be in good agreement with the experimentally obtained IR profiles. These findings provide guidance on how to suppress secondary reactions of guaiacol during lignin pyrolysis. Graphical abstract On-line analysis of pyrolysis process of guaiacol using in situ FTIR.
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China. shubinwu@scut.edu.cn.
authors.forename: Shubin
authors.initials: S
authors.lastname: Wu
authors.affiliation: School of Science, Guizhou Minzu University, Guiyang, Guizhou, 550025, China.
authors.forename: Jinbao
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhang
mesh_terms: D006139:Guaiacol / Q000737:chemistry*; D006358:Hot Temperature; D011804:Quinolines / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D011804:Quinolines; D006139:Guaiacol
keywords: Guaiacol; In situ FTIR; Lignin pyrolysis; o-Quinonemethide