丙酮是半纤维素热解过程中重要的酮类产物,但其生成机理仍不清楚。本文以典型的半纤维素基单糖——木糖为模型化合物,基于密度泛函理论方法计算其分解生成丙酮的可能路径,同时讨论了温度对丙酮形成路径竞争性的影响。结果表明,木糖热解过程中,四碳中间体3-羰基丁醛是形成丙酮的重要中间体。木糖热解最可能经3-戊酮糖分解路径形成C1-C2-C3位或C3-C4-C5位丙酮,同时也易经D-木糖分解路径形成C3-C4-C5位丙酮,高温下木糖热解生成C2-C3-C4位丙酮的比例增多。
Acetone is an important ketone product in hemicellulose pyrolysis, whereas, its formation mechanism is still unclear. In this paper, xylose, a typical hemicellulose monosaccharide, was selected as a model compound. Density functional theory (DFT) calculations were employed to reveal the possible pathways for generating acetone in xylose pyrolysis. The influence of temperature on the competitiveness of possible pathways was also discussed. The results showed that 3-carbonyl butyraldehyde, a four-carbon-intermediate, was an important intermediate for the formation of acetone during the pyrolysis of xylose. The decomposition pathways of 3-ketopentose were the most favorable for acetone formation from the C1-C2-C3 and C3-C4-C5 segments of xylose. The decomposition of D-xylose can also easily results in the formation of C3-C4-C5 acetone. With the temperature increase, the proportion of C2-C3-C4 acetone increased correspondingly.
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