Proceedings of International Forum for Green Asia 2017
Special issue of Evergreen - Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy

P-02

Coupling the detailed chemical kinetic models of primary and secondary
pyrolysis of lignin
Yuki Furutani1
1

Interdisciplinary Graduate School of Engineering, Kyushu University
accounted for 64 wt% of total tar (+C6) species generated
from primary pyrolysis.

1. Introduction
Lignin pyrolysis is divided into two stages: (a) primarypyrolysis, where volatiles escape from biomass particles;and (b) secondary vapor-phase reactions, where theproduced volatiles undergo further cracking, combine, orcondense in the vapor phase. Our research group has
developed a detailed chemical kinetic model (DCKM)
based on elementary reactions provide information on thepyrolysis behaviors of individual components.1) However,the DCKM has been limited to the secondary vapor-phasereaction and used the experimentally-measured volatilecomposition derived from primary pyrolysis as a boundary
condition. The purpose of this study is to develop theDCKM predicting both primary pyrolysis and secondary
vapor-phase reactions.

3. DCKM of secondary vapor-phase reaction
Our established DCKM1) did not involve the kinetic
database on vapor-phase reaction of monolignols as shownin Fig. 2. Thus, the pyrolytic pathways of all monolignols asshown in Fig. 2 were proposed, and the Arrhenius
parameters (k=ATnexp(-E/RT)) for each elementary
reaction step were calculated based on quantum chemical
calculation and transition state theory. Total 340 elementary
reaction rate constants were added into the original kinetic
database1). By using the volatile composition predicted by
the DCKM of primary pyrolysis as a boundary condition,
the simulation was performed at residence time of 0.1 andtemperature of 773 – 1223 K.
Fig.3 shows the comparison of the model prediction of theyields for various chemical species with the experiment ofYang et al.1) Our numerical results of char, CO, H2O, C6H6,C6H5OH, C2H4, C3H6 and CH3OH yields agreed well withthe experimental measurement. The model prediction
underestimated the yields of CO2 and CH4, andoverestimated the yield of H2. These differences could result
from the use of too simple a definition for characterizing theinitial lignin structures.

2. DCKM of primary pyrolysis
Initial lignin structure was characterized by linear
combination of three model components (LIGC, LIG-H,and LIG-O)2) based on a β-O-4 skeleton as shown in Fig. 1.
Hough et al.2) proposed the kinetic model consisting of 96
species and 404 elementary reactions.

Fig. 1: Three model components. The solid residue startwith P.
We employed this kinetic model to simulate the primarypyrolysis of enzymatic hydrolysis lignin under heating rateof 103 K/s and attainabletemperature of 773 – 1223
K, and predict the volatilecomposition derived fromprimary pyrolysis. Fig. 2
predicts that 3-hydroxy-1(4-hydroxy-3,5Fig. 2. Tar (+C6)
dimethoxyphenyl)propan1-one(HHDPP) composition at 1223 K

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Proceedings of International Forum for Green Asia 2017
Special issue of Evergreen - Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy

P-02

Fig.3: Comparison of predicted yields for various chemical
species with experimental data1)
References:
1) Yang, H. et al., Ind. Eng. Chem. Res, 54, 6855 (2015)2) Hough, B. R. et al, nd. Eng. Chem. Res, 55, 9147 (2016)7