Elucidation of reactions preceding tarry material formation in hydrothermal reaction field.

尽管在超临界水气化和生物质水热预处理中，焦油原料的产生在升温阶段非常重要，但其反应机理还不是很清楚。本研究以葡萄糖为模型化合物，在管式反应器中进行水热条件下的反应，测定了特定温度和反应时间下果糖、红宝石、甘油醛、脱水葡萄糖和5-羟甲基呋喃的产率。参考已有文献，确定了反应网络，并用最小二乘法确定了各反应的Arrhenius参数。结果表明，葡萄糖分解的反应级数随温度变化，表明主要反应路径随水热反应场的变化而变化。利用这些反应速率参数，计算了不同升温速率下的产物产率。升温速率越低，5-羟甲基呋喃甲醛的产率越高。在改变加热速度的情况下进行了试验运行，发现加热速度越低，焦油原料的产率越高。对水溶性产物的分析表明，一种相对分子质量在120左右的化合物正在发生聚合。在以往对热糖的研究中，分子量为126的5-羟甲基呋喃甲醛被认为是产生有色产物的原因，结合本研究的结果，强烈建议5-羟甲基呋喃甲醛聚合有助于焦油材料的生产。

In spite of the importance of tarry material production during heating up period in supercritical water gasification and hydrothermal pretreatment of biomass, the reaction mechanism is not sufficiently understood. In this study, glucose was selected as a model compound, reaction was made to proceed in tubular reactors under hydrothermal conditions, and yield of product compounds including fructose, erythrose, glyceraldehyde, anhydroglucose, and 5-hydorxymethylfurfuraol were determined for specific temperature and reaction time. Referring previous literatures, reaction network was determined, and Arrhenius parameters of each reaction were determined by the least-square method. As a result, reaction order for glucose decomposition was found to change with temperature, indicating main reaction paths to change with hydrothermal reaction field. With these reaction rate parameters, yield of products for different heating rate was calculated. For a lower heating rate, the yield of 5-hydroxymethylfurfural increased. Experimental runs were conducted where heating rate was changed, and it was found that when heating rate is lower, the higher was the yield of tarry material. Analysis of water-soluble products indicated that polymerization of a compound whose molecular weight was around 120 was taking place. In previous studies of heating sugars, 5-hydroxymethylfurfural, whose molecular weight is 126, has been nominated as a cause of colored product, and consideration with the result of this study, it is strongly suggested that 5-hydroxymethylfurfural polymerization contributes to the production of tarry materials.