Abstract: The chemical structure of hemicellulose isolated from sugarcane bagasse was characterized by FT-IR，1H-NMR，13C NMR and ion chromatography. The pyrolysis characteristics and kinetics of hemicellulose at different heating rates were studied by thermogravimetric analysis (TG) coupled with Fourier transform infared spectromotry (FTIR). Results show that sugarcane bagasse hemicellulose are composed mainly of L-arabino-D-xylans with minor quantities of galactose，glucose，glucuronic acid and glacuronic acid，which is a typical structure of straw hemicellulose. The pyrolysis process of sugarcane bagasse hemicellulose can be divided into four stages，and the major reaction stage takes place between 200 to 315 ℃ with a shoulder-shaped peak at about 230 ℃. The pyrolysis remnants of coke have a higher proportion about 20% at 700 ℃. The pyrolysis kinetics can be simplified as a first-order reaction and the activation energies at different stages are 118 kJ/mol，50 kJ/mol，144 kJ/mol and 34 kJ/mol，respectively. During the hemicellulose pyrolysis process，the free water released out firstly，followed by the depolymerization and dehydration. The fission of glucosidic bond and carbon-carbon bond produce hydrocarbons，alcohols，aldehydes，acids etc.，which may decompose further into CO2，CO and other gases. FTIR analysis showed that the gaseous products are mainly vapor，CO2，CO，CH4 and other small-molecule compounds.

摘要： 利用FT-IR、离子色谱、1H-NMR及13C NMR等手段对蔗渣半纤维素的化学结构进行了表征，并利用热重-傅里叶红外光谱（TG-FTIR）联用技术对蔗渣半纤维素在不同的升温速率下的热失重行为进行了研究。结果表明，蔗渣半纤维素主要由大量的阿拉伯糖木聚糖组成，此外还含有葡萄糖、半乳糖及葡萄糖醛酸和半乳糖醛酸，具有草类原料中典型的半纤维素结构。蔗渣半纤维素的主要热失重区间为200～315 ℃，并在230 ℃左右出现一个肩状峰，在700 ℃时焦炭残留物比例较高，约在20%。采用一级四段模型对半纤维素的热裂解过程进行了模拟，得到各段的活化能分别为118 kJ/mol、50 kJ/mol、144 kJ/mol和34 kJ/mol。蔗渣半纤维素热解气体析出过程复杂，初期先析出游离水，随后发生解聚和脱水反应，主要的苷键和碳碳键断开形成各种烃类、醇类、醛类和酸类等物质，这些大分子物质又裂解为CO2、CO等小分子气体。在线红外分析结果表明，蔗渣半纤维素热解气态产物主要有H2O、CO2、CO和CH4和其它产物。