Title:
Effects of Substituents on the Initial Pyrolysis Mechanism of Beta-O-4 Type Lignin Dimer Model Compounds
Author(s):
Jiang, X.Y., Lu, Q., Hu, B., Ye, X.N., Liu, J., Dong, C.Q.
Document(s):
Paper
Poster
Abstract:
The OCH3, OH and CH2OH substituents in lignin will affect the pyrolytic behavior and product distribution of lignin, but the fundamental mechanism about the effects is unclear at present. In this study, twelve ß-O-4 type lignin dimer model compounds containing OCH3, OH and CH2OH groups are selected to investigate the substituent effects on pyrolysis mechanism by using density functional theory (DFT) method. The calculation results indicate that concerted reactions are easier to occur than homolysis reactions during the initial pyrolysis process. Four pyrolysis pathways (Paths 1-4) are fundamental for all lignin dimers, and the reaction possibility is as follows: Path 4 > Path 3 > Path 1 > Path2. With the presence of substitutes, additional pyrolysis pathways will take place. The methoxyl-substituted phenethyl phenyl ether (o-CH3O-PPE or (o-CH3O)2-PPE) will go through an additional pathway (Path 5) which is only second to Path 4. The a-OH-PPE has another two unique pyrolysis pathways, namely Paths 6 and 7 which can hardly take place due to high energy barriers. The ß-CH2OH-PPE will undergo a unique pathway (Paths 8) to decompose, of which the energy barrier is higher than those of Paths 3 and 4, but far lower than those of Paths 1 and 2.
Keywords:
lignin, pyrolysis, lignin model compounds, substituents, density functional theory, beta-O-4 linkage
Topic:
Biomass Conversion Technologies for Liquid and Gaseous Fuels, Chemicals and Materials
Subtopic:
Pyrolysis and other biomass liquefaction technologies
Event:
25th European Biomass Conference and Exhibition
Session:
3AV.3.50
Pages:
1190 - 1193
ISBN:
978-88-89407-17-2
Paper DOI:
10.5071/25thEUBCE2017-3AV.3.50
Price:
FREE
