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纤维素是生产生物质燃料,精细化工品的重要原料.热解是由纤维素解聚的重要手段之一.了解纤维素热解的反应机理对发展高效的生物质转化技术具有重要意义.我们利用密度泛函理论方法,以纤维素二聚体为模型,详细研究了其发生键均裂过程的热力学能量变化.发现糖苷键和侧链C—C键的均裂相对于C—OH键和O—H键均裂在热力学上更优.此外,我们发现不同物种的热力学稳定性与其在纤维素快速热解实验产物中的比例无关.最后我们发现温度对反应能否自发发生具有重要的影响,为通过调节温度来改变不同类型反应的选择性提供了一条思路.
Cellulose is an important raw material for the production of biomass fuels and fine chemicals. Pyrolysis is one of the important means for depolymerization of cellulose. Understanding the reaction mechanism of cellulose pyrolysis is of great significance for the development of efficient biomass conversion technologies. The density functional theory (DFT) method and the cellulose dimer model were used to study the thermodynamic energy changes of the homogeneously generated bonds. The results showed that the homolytic cleavage of the C-C bonds of the glycosidic bonds and the side chains relative to the C-OH bonds and In addition, we found that the thermodynamic stability of different species has nothing to do with its ratio in the experimental product of rapid pyrolysis of cellulose.Finally, we found that temperature has an important influence on the spontaneous occurrence of the reaction , Provides an idea for changing the selectivity of different types of reactions by adjusting the temperature.