Abstract: Sweet sorghum bagasse（SSB）was hydrolyzed with liquid hot water in a flowthrough reactor with the objective of achieving complete saccharification of hemicellulose of SSB and understanding the hydrolysis mechanismThe effect of reaction temperature (155—235℃)and flow rate (5—30 ml·min-1)on the concentration of xylose, glucose, arabinose, their total sugars and their degradation products (furfural, 5HMF, acetic acid, glucuronic acid, formic acid and glycolic acid)in the liquid fractions was investigatedThe experimental results indicated that xylose was more sensitive to temperature and flow rate than arabinose and glucoseThe concentration of total xylose including xylose monomer and xylose oligomer dropped dramatically when temperature was higher than 195℃A lower flow rate (5 ml·min-1）resulted in a higher furfural yield due to longer residence time for xylose in the reactorIn contrast, a higher flow rate (30 ml·min-1）would reduce the thickness of stagnant fluid layer surrounding the solid particles and lower resistance to penetration of water into the solids for hydrolysis and diffusion of oligomers into solutionIt was hypothesized that the major xylan in SSB hemicellulose was O-acetyl4-O-methylglucuronoarabinoxylanXylose, arabinose, glucose and their oligosaccharides could be considered as the primary productsGlucuronic acid and acetic acid were produced from the decomposition of glucuronic and Oacetyl groups in the branched chain of hemicelluloseFurfural and 5hydroxymethyl2-furaldehyde (5-HMF)were the direct degradation products of sugarsMoreover, glucuronic acid would be further oxidatively degraded into glycolic acidLow molecular weight organic acids, such as formic acid were the further degradation products.

Key words: liquid hot water, sweet sorghum bagasse, hydrolysis, hemicellulose, mechanism

摘要： 为了回收甜高粱渣中的半纤维素衍生糖并了解其水解机理，在自行设计的Flowthrough反应器中对甜高粱渣进行了高温液态水水解，分别考察了不同反应温度和反应液流量下水解液中产物的生成情况。研究表明，相对葡萄糖和阿拉伯糖而言，木糖的生成受反应温度和反应液流量影响更大。温度高于195 ℃时糖降解加剧，总木糖浓度不断降低；低流量（5 ml?min-1）条件下生成的木糖不能被及时排出而进一步降解。通过产物分析可知，甜高粱渣半纤维素中含有典型的O-乙酰基-4-O-甲基葡萄糖醛酸基阿拉伯糖基木聚糖结构，木糖、葡萄糖、阿拉伯糖、各种低聚糖、乙酸和葡萄糖醛酸等是半纤维素水解的直接产物，糠醛和5-羟甲基糠醛等是糖类的降解产物， 甲酸等小分子酸是它们的进一步降解产物。

关键词: 高温液态水, 甜高粱渣, 水解, 半纤维素, 机理