Reaction kinetics of D-xylose in sub- and supercritical water
Reaction kinetics of D-xylose in sub- and supercritical water
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DOI：
10.1016/j.supflu.2010.08.013
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发表时间：
2010-11-01
影响因子：
3.9
通讯作者：
Smith, Richard L., Jr.
中科院分区：
文献类型：
--
作者：
Aida, Taku Michael;Shiraishi, Naohiro;Smith, Richard L., Jr.
在高温（350和400 ℃）和高压（40-100 MPa）下，用流动装置研究了D-木糖在水中的反应，以阐明反应途径和反应动力学。D-木糖的反应产物为糠醛、D-木酮糖、甘油醛、乙醇醛、二羟基丙酮、异丁醛、乳酸和甲醛。实验结果表明，脱水反应途径，逆羟醛反应途径和Lobry de Bruyn-Alberta货车Ekenstein（LBET）途径的证据从D-木酮糖。提出的反应途径和动力学模型与实验结果雅阁。动力学常数与水的密度（压力）相关。在400摄氏度和40 MPa下0.52 g/cm（3）的水密度下，从D-木糖到D-木酮糖的反应通过LBET途径发生，逆反应可以忽略不计。在400 ℃下，将水密度从0.52 g/cm 3增加到0.69 g/cm 3降低了正向LBET途径的动力学速率常数，并增加了反向LBET途径的动力学速率常数。恒温条件下，D-木酮糖脱水生成糠醛的动力学速率常数随水密度的增加而增大。在400 ℃下，随着水密度的增加，D-木糖的逆羟醛缩合反应的动力学速率常数增加，而D-木酮糖的逆羟醛缩合反应的动力学速率常数减小。皇冠版权所有（C）2010由爱思唯尔B. V.出版保留所有权利。
Reactions of D-xylose were investigated with a flow apparatus in water at high temperatures (350 and 400 degrees C) and high pressures (40-100 MPa) to elucidate the reaction pathway and reaction kinetics. The products obtained from the reaction of D-xylose were furfural, D-xylulose, glyceraldehyde, glycolaldehyde, dihydroxyacetone, pyruvaldehyde, lactic acid and formaldehyde. Experimental results showed evidence of a dehydration reaction pathway, a retro-aldol reaction pathway and a Lobry de Bruyn-Alberta van Ekenstein (LBET) pathway from D-xylulose. The proposed reaction pathway and kinetic model were in accord with the experimental results. The kinetic constants showed dependence with water density (pressure). At 400 degrees C and water density of 0.52 g/cm(3) at 40 MPa, the reaction from D-xylose to D-xylulose occurred by the LBET pathway with the reverse reaction being negligible. At 400 degrees C, increasing the water density from 0.52 to 0.69 g/cm3 decreased the kinetic rate constant of the forward LBET pathway and increased that of the reverse LBET pathway. The kinetic rate constant of the dehydration of D-xylulose to furfural increased with increasing water density at constant temperature. The kinetic rate constant of the retro-aldol reaction of D-xylose increased, and the retro-aldol reaction of D-xylulose decreased with increasing water density at 400 degrees C. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.