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首页> 外文期刊>RSC Advances >Fates of hemicellulose, lignin and cellulose in concentrated phosphoric acid with hydrogen peroxide (PHP) pretreatment
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Fates of hemicellulose, lignin and cellulose in concentrated phosphoric acid with hydrogen peroxide (PHP) pretreatment

机译：用过氧化氢（PHP）预处理浓磷酸中的半纤维素，木质素和纤维素的命运

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Xylan, de-alkaline lignin and microcrystalline cellulose were employed as representative models of hemicellulose, lignin and cellulose in lignocellulosic biomass. These three model compounds, together with the real-world biomass, wheat straw were pretreated using the newly developed PHP pretreatment (concentrated phosphoric acid plus hydrogen peroxide) to better understand the structural changes of the recovered solid and chemical fractions in the liquid. Results showed that almost all xylan and higher than 70% lignin were removed from wheat straw, and more than 90% cellulose was recovered in the solid fraction. The pretreated model xylan recovered via ethanol-precipitation still maintained its original structural features. The degree of polymerization of soluble xylooligosaccharides in liquid was reduced, resulting in the increase of monomeric xylose release. Further xylose oxidization via the path of 2-furancarboxylic acid → 2(5 H )-furanone → acrylic acid → formic acid was mainly responsible for xylan degradation. The chemical structure of de-alkaline lignin was altered significantly by PHP pretreatment. Basic guaiacyl units of lignin were depolymerized, and aromatic rings and side aliphatic chains were partially decomposed. Ring-opening reactions of the aromatics and cleavage of C–O–C linkages were two crucial paths to lignin oxidative degradation. In contrast to lignin, no apparent changes occurred on microcrystalline cellulose. The reason was likely that acid-depolymerization and oxidative degradation of cellulose were greatly prevented by the formed cellulose phosphate.
机译：木聚糖，脱碱性木质素和微晶纤维素被用作木质纤维素生物质中半纤维素，木质素和纤维素的代表性模型。使用新开发的PHP预处理（浓磷酸加过氧化氢）对这三种模型化合物以及现实的生物质麦秸进行了预处理，以更好地了解液体中回收的固体和化学部分的结构变化。结果表明，几乎所有木聚糖和70％以上的木质素均已从麦草中去除，固体部分中回收了90％以上的纤维素。通过乙醇沉淀回收的预处理模型木聚糖仍保持其原始结构特征。液体中可溶性低聚木糖的聚合度降低，导致单体木糖释放增加。木糖通过2-呋喃羧酸→2（5H）-呋喃酮→丙烯酸→甲酸的进一步氧化主要是木聚糖的降解。 PHP预处理可显着改变脱碱性木质素的化学结构。木质素的碱性愈创木基单元解聚，芳环和侧链脂族链部分分解。芳烃的开环反应和C–O–C键的断裂是木质素氧化降解的两个关键途径。与木质素相反，微晶纤维素上没有发生明显变化。原因可能是所形成的磷酸纤维素极大地防止了纤维素的酸解聚和氧化降解。

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