Fates of hemicellulose, lignin and cellulose in concentrated phosphoric acid with hydrogen peroxide (PHP) pretreatment

Research output: Contribution to journalArticleScientificpeer-review

Details

Original languageEnglish
Pages (from-to)12714-12723
Number of pages10
JournalRSC Advances
Volume8
Issue number23
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

Researchers

  • Qing Wang
  • Dong Tian
  • Jinguang Hu
  • Fei Shen
  • Gang Yang
  • Yanzong Zhang
  • Shihuai Deng
  • Jing Zhang
  • Yongmei Zeng
  • Yaodong Hu

Research units

  • Sichuan Agricultural University
  • University of British Columbia

Abstract

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(5H)-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.

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