吡喃木糖和<em>O</em>-乙酰基吡喃木糖热解形成羟基乙醛的机理研究

田慧云; 胡斌; 张阳; 陆强; 董长青; 杨勇平

吡喃木糖和O-乙酰基吡喃木糖热解形成羟基乙醛的机理研究

华北电力大学生物质发电成套设备国家工程实验室, 北京 102206

基金项目: 国家高技术研究发展计划(863计划, 2012AA051803); 国家自然科学基金(51106052);中央高校基本科研业务费(2014ZD17)。

详细信息

通讯作者:
陆强(1982-), 男, 博士, 主要从事生物质高效热解转化研究, E-mail: qianglu@mail.ustc.edu.cn。

中图分类号: TK6
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出版历程
- 收稿日期: 2014-08-09
- 修回日期: 2014-10-09
- 刊出日期: 2015-02-28

Mechanism for the formation of hydroxyacetaldehyde by the pyrolysis of xylopyranose and O-acetyl-xylopyranose

National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing 102206, China

摘要

摘要: 以半纤维素主要成分木聚糖的两种单体——吡喃木糖和O-乙酰基吡喃木糖为模型化合物,运用密度泛函理论(DFT),采用B3LYP方法和6-31+G(d,p)基组进行计算,研究了吡喃木糖热解形成HAA的6条可能的反应路径和O-乙酰基吡喃木糖热解形成HAA的3条可能的反应路径。由此确定了吡喃木糖热解形成HAA的最优路径为:吡喃木糖首先开环得到链式木糖,然后C3羟基和C2氢脱水,随后经重排和逆醇醛缩合反应生成包含C4/C5的HAA;该路径的决速步骤为脱水反应,能垒为253.3 kJ/mol。O-乙酰基吡喃木糖热解形成HAA的最优路径为:O-乙酰基吡喃木糖首先支链断裂脱出乙酸(AA),开环后的链式中间体经氢转移反应得到包含C4/C5的HAA;该路径的决速步骤为最后的氢转移反应,能垒为317.6 kJ/mol。
- 吡喃木糖 /
- O-乙酰基 /
- 热解 /
- 羟基乙醛 /
- 密度泛函理论
Abstract: Xylopyranose and O-acetyl-xylopyranose, the two monomers of xylan, were employed as the model compounds to study the mechanism for the formation of hydroxyacetaldehyde (HAA) from xylan by pyrolysis. Six possible pathways from xylopyranose and three from O-acetyl-xylopyranose were proposed by employing the density functional theory (DFT) at B3LYP/6-31+G(d,p) level; the energetically favored pathways for HAA formation were revealed. Xylopyranose may undergo ring-opening, dehydration, rearrangement and retro-aldol reactions sequentially, to form HAA that contains C4/C5; the rate-determining step is the dehydration reaction, with an energy barrier of 253.3 kJ/mol. From O-acetyl-xylopyranose, the side chain is cleaved in the first place, forming acetic acid (AA) and a cyclic intermediate; the ring-opening and H-shift reactions happen afterwards from the cyclic intermediate to generate HAA containing C4/C5; the rate-determining step is the H-shif reaction, with an energy barrier of 317.6 kJ/mol.
- xylopyranose /
- O-acetyl /
- pyrolysis /
- hydroxyacetaldehyde /
- density functional theory

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参考文献(28)

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