Analysis of Cross-Linking Behavior during Pyrolysis of Cellulose for Elucidating Reaction Pathway

• Published in: Energy & fuels 2009-12, Vol.23 (12), p.5765-5772
• Main Authors: Chaiwat, Weerawut, Hasegawa, Isao, Tani, Takaaki, Sunagawa, Kenshi, Mae, Kazuhiro
• Format: Article
• Language: English
• Subjects: Catalysis and Kinetics
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef900674b

The analyses of structure change during pyrolysis of cellulose at different heating rates were investigated to clarify the existent behavior of the cross-linking reaction. For structural analyses of cellulose precursors, FTIR spectra and XRD patterns confirmed that the dehydration reaction to produce water and cross-liked precursor simultaneously occurred with the glycosidic reaction to produce tar during pyrolysis. On the basis of the assumptions that hydroxyl groups in cellulose converted to water, a new parameter index, so-called the degree of dehydration during pyrolysis, X p, including its distribution in char (X c) and tar (X t), was determined. For the cross-linking analyses at low heating rate, cross-linking reaction may occur until approximately 360 °C where X c reached its maximum, while the cross-linked tar seems to be released above 360 °C. For tar analyses, cross-linked dimer can be observed for slow pyrolysis, whereas tar products obtained by flash pyrolysis showed relatively higher yield in cellobiosan with no cross-linked volatiles. Finally, based on previous kinetic models, the modified pathway of cellulose pyrolysis was proposed by considering the proposed parameter related to the dehydration.