毛竹半纤维素热解特性研究

Pyrolysis Characteristics of Hemicelluloses from Bamboo Stem

关键词:  毛竹竹竿  半纤维素  热重分析法  热解特性

Key Words:bamboo stem  hemicelluloses  thermal gravimetric analysis  pyrolysis characteristics

摘要:采用蒸馏水、2%NaOH和5%KOH从6月龄毛竹竹竿中分级抽提得到水溶性半纤维素HW和碱溶性半纤维素H1～H4。通过热重分析法在升温速率10℃/min条件下分析了这5种半纤维素的热解特性，并对快速热解区建立了一级反应动力学模型。毛竹半纤维素热解主要发生在180～400℃，失重33.91％～42.54％。在终止温度700℃时残渣率均较高，达到34.52%～51.31%。毛竹半纤维素组分活化能均较小，为26.068～51.938 kJ/mol。碱溶性组分的活化能大于水溶性组分的活化能，残留木素越多，半纤维素的活化能和终止温度时的残渣率就越高。

Abstract:Water-soluble hemicelluloses HW and four alkali-soluble hemicellulosic fractions H1~H4 were sequentially extracted from six-month-old bamboo stem by distilled water, 2% NaOH and 5% KOH. The thermal pyrolysis behavior of the five hemicellulosic fractions was characterized by using thermal gravimetric analysis (TGA) at the heating rate of 10℃/min, and the first-order reaction models were established in the fast pyrolysis temperature ranges. The fast decompositions of the five fractions happened in between 180~400℃ with weight losses 33.91%~42.54%. The residue percentages were 34.52%~51.31% at the final temperature of 700℃. The activity energies of all the hemicelluloses fractions were quite low with the values of 26.068~51.938 kJ/mol. The activity energies of alkali-soluble fractions were higher than that of water-soluble fraction. The hemicellulosic fractions containing higher lignin residue exhibited higher activity energy and residue rate at the final temperature of pyrolysis.