Issue 6, 2016

Pyrolysis reaction networks for lignin model compounds: unraveling thermal deconstruction of β-O-4 and α-O-4 compounds

Abstract

Although lignin is one of the main components of biomass, its pyrolysis chemistry is not well understood due to complex heterogeneity. To gain insights into this chemistry, the pyrolysis of seven lignin model compounds (five β-O-4 and two α-O-4 linked molecules) was investigated in a micropyrolyzer connected to GC-MS/FID. According to quantitative product mole balance for the reaction networks, concerted retro–ene fragmentation and homolytic dissociation were strongly suggested as the initial reaction step for β-O-4 compounds and α-O-4 compounds, respectively. The difference in reaction pathway between compounds with different linkages was believed to result from thermodynamics of the radical initiation. The rate constants for the different reaction pathways were predicted from ab initio density functional theory calculations and pre-exponential literature values. The computational findings were consistent with the experiment results, further supporting the different pyrolysis mechanisms for the β-ether linked and α-ether linked compounds. A combination of the two pathways from the dimeric model compounds was able to describe qualitatively the pyrolysis of a trimeric lignin model compound containing both β-O-4 and α-O-4 linkages.

Graphical abstract: Pyrolysis reaction networks for lignin model compounds: unraveling thermal deconstruction of β-O-4 and α-O-4 compounds

Supplementary files

Article information

Article type
Paper
Submitted
21 Sep 2015
Accepted
12 Nov 2015
First published
12 Nov 2015

Green Chem., 2016,18, 1762-1773

Pyrolysis reaction networks for lignin model compounds: unraveling thermal deconstruction of β-O-4 and α-O-4 compounds

Y. S. Choi, R. Singh, J. Zhang, G. Balasubramanian, M. R. Sturgeon, R. Katahira, G. Chupka, G. T. Beckham and B. H. Shanks, Green Chem., 2016, 18, 1762 DOI: 10.1039/C5GC02268A

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