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Title: Gas- and solid/liquid-phase reactions during pyrolysis of softwood and hardwood lignins
Authors: Asmadi, Mohd
Kawamoto, Haruo  kyouindb  KAKEN_id
Saka, Shiro  kyouindb  KAKEN_id
Author's alias: 河本, 晴雄
Keywords: Lignin
Gas phase
Solid/liquid phase
Issue Date: Nov-2011
Publisher: Elsevier B.V.
Journal title: Journal of Analytical and Applied Pyrolysis
Volume: 92
Issue: 2
Start page: 417
End page: 425
Abstract: Pyrolytic reactions of Japanese cedar (Cryptomeria japonica, a softwood) and Japanese beech (Fagus crenata, a hardwood) milled wood lignins (MWLs) were studied with thermogravimetry (TG) and by pyrolysis in a closed ampoule reactor (N2/600 °C). The data were compared with those of guaiacol/syringol as simple lignin model aromatic nuclei. Several DTG peaks were observed around 300–350, 450, 590 and 650 °C. The first DTG peak temperature (326 °C) of beech was lower than that (353 °C) of cedar. This indicates that the volatile formation from cedar MWL is slightly delayed in heating at 600 °C. The gas-phase reactions via GC/MS-detectable low MW products were explainable with the temperature-dependent reactions observed for guaiacol/syringol in our previous paper. The methoxyl groups became reactive at ∼450 °C, giving O–CH3 homolysis products (catechols/pyrogallols) and OCH3 rearrangement products (cresols/xylenols). The former homolysis products were effectively converted into gaseous products (mainly CO) at >550–600 °C. However, the GC/MS-detectable tar yields, especially syringyl unit-characteristic products, were much lower than those from guaiacol/syringol. Thus, contributions of higher MW intermediates and solid/liquid-phase reactions are more important in lignin pyrolysis. From the results of stepwise pyrolysis of char + coke fractions at 450 and 600 °C, the methoxyl group-related reactions (450 °C) and intermediates gasification (600 °C) were suggested to occur also in the solid/liquid phase. This was consistent with the DTG peaks observed around these temperatures. These solid/liquid-phase reactions reduced the tar formation, especially catechols/pyrogallols and PAHs. Different features observed between these two MWLs are also focused.
Rights: © 2011 Elsevier B.V.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
DOI(Published Version): 10.1016/j.jaap.2011.08.003
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