Detailed mass balances of the autohydrolysis of Eucalyptus globulus at 170 oC
Detailed mass balances of the autohydrolysis of Eucalyptus globulus at 170 oC
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DOI：
10.15376/biores.4.2.687-703
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发表时间：
2009-03
期刊：
影响因子：
1.5
通讯作者：
M. Leschinsky;H. Sixta;R. Patt
中科院分区：
文献类型：
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作者：
M. Leschinsky;H. Sixta;R. Patt
蓝桉的自水解在三种不同的强度水平下进行，预水解硫酸盐法制浆用于生产可溶纸浆等级。目的是为自水解过程建立一个详细的质量平衡，包括所有三个阶段的化学成分：自水解物、释放的气体和固体残渣。碳水化合物的测定采用了酸解结合气相色谱(GC)和硫酸全水解结合高效阴离子交换色谱(HPAEC)和脉冲安培检测(PAD)的方法；这使得能够可靠地定量纤维素和非纤维素多糖中的中性和酸性糖单元。蓝桉木材中存在的糖醛酸通过脱羧基逐渐降解，导致大量二氧化碳的形成。木屑中残留的木聚糖的乙酰化程度明显降低，而溶解的低聚木糖(XOS)中的结合乙酰基的数量随着自水解强度的增加而保持相对恒定。在自水解过程中溶解的木质素的大部分可以归因于木材的酸溶木素含量。只有少量的Klason木质素被溶解。
Autohydrolysis of Eucalyptus globulus was conducted at three different intensity levels typical for prehydrolysis kraft pulping as utilized for manufacturing dissolving pulp grades. The objective was to establish for the autohydrolysis process a detailed mass balance comprising the chemical composition of all three phases: the autohydrolysate, the released gas, and the solid residue. Carbohydrate determination involved both acid methanolysis combined with gas chromatography (GC) and sulfuric acid total hydrolysis with high performance anion exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD); this allowed reliable quantification of neutral as well as acidic sugar units in cellulosic and non-cellulosic polysaccharides. Uronic acids present in the Eucalyptus globulus wood were progressively degraded through decarboxylation, leading to substantial carbon dioxide formation. The degree of acetylation of xylan remaining in the wood residue was clearly reduced, while the amount of bound acetyl groups in dissolved xylo-oligosaccharides (XOS) stayed relatively constant as a function of autohydrolysis intensity. The bulk of the lignin that was dissolved during autohydrolysis could be attributed to the acid-soluble lignin content of the wood. Only small amounts of Klason lignin were dissolved.