期刊
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
卷 106, 期 -, 页码 138-146出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jaap.2014.01.011
关键词
Cellulose pyrolysis; Activation; Active cellulose; Reducing end; Hydrogen bond; Acid catalyst
资金
- Kyoto University Global COE program Energy Science in the Age of Global Warming
- [20380103 2008.4-2011.3]
- Grants-in-Aid for Scientific Research [23658142] Funding Source: KAKEN
The idea of active cellulose is based on the initial induction period that is observed during thermogravimetric analysis of cellulose. The role of the reducing ends of cellulose samples (Avicel PH-101 and Whatman No, 42) was studied in relation to active cellulose formation, because our previous studies suggested that these end groups have lower thermal stabilities. Elimination of the reducing ends from Avicel PH-101 by reduction with NaBH4 substantially prolonged the induction period. These features were only characteristic of Avicel PH-101, with a leveling-off degree of polymerization (DP) of (DP) over bar (n) 218. Formation of water-soluble oligosaccharides was also lower (240 degrees C/60 min). For Whatman No. 42 cellulose with a higher DP ((DP) over bar (n) 2170), similar elimination of the reducing ends had almost no effect on the weight-loss behavior. The reducing group analysis data showed that a large number of new reducing ends were formed in Whatman cellulose during DP reduction as the initial pyrolysis process. Based on these differences arising from the initial DP of cellulose, a mechanism for active cellulose was proposed: thermal decomposition of reducing end groups, which are originally present or are formed during pyrolysis in crystalline cellulose, activates the following pyrolysis reactions. The molecular mechanism for activation is also discussed; we propose that it includes hydrogen-bond rearrangement in the initiation of pyrolytic reactions such as depolymerization (transglycosylation) and dehydration, based on our previous proposal that proton donation (acting as an acid catalyst) through hydrogen bonding is a fundamental mechanism for these pyrolytic reactions. (C) 2014 Elsevier B.V. All rights reserved.
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