CIESC Journal ›› 2012, Vol. 63 ›› Issue (2): 599-605.DOI: 10.3969/j.issn.0438-1157.2012.02.037

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Hydrolysis of sweet sorghum bagasse hemicellulose with liquid hot water and its mechanism

YU Qiang,ZHUANG Xinshu,YUAN Zhenhong,WANG Wen,QI Wei,WANG Qiong,TAN Xuesong   

  1. Guangzhou Institute of Energy Conversion, Key Laboratoryof Renewable Energy and GasHydrate, 
    Chinese Academy ofSciences, Guangzhou 510640, Guangdong, China
  • Received:2011-07-06 Revised:2011-09-22 Online:2012-02-05 Published:2012-02-05

高温液态水中甜高粱渣半纤维素水解及其机理

余强,庄新姝,袁振宏,王闻,亓伟,王琼,谭雪松   

  1. 中国科学院广州能源研究所,中国科学院可再生能源与天然气水合物重点实验室,广东 广州510640
  • 通讯作者: 余强

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