中文摘要：

水热脱水提质能够有效地脱除褐煤等低阶煤内部水分与含氧官能团,提高褐煤的煤阶及应用价值。选用褐煤的简化含氧模型化合物苯甲酸和苯甲醛,在分子水平上对褐煤的脱氧反应机制进行研究。采用量子化学B3LYP/6-31G（d）密度泛函数方法,得到水热提质条件下反应过程中各反应物、中间体、过渡态和产物的几何构型和能量变化,进而得到反应过程的热力学和动力学参数。计算结果表明：在水热提质的压力条件下,苯甲酸脱羧基的反应能自发进行,而苯甲醛脱羰基的反应在较低温度时是热力学禁阻的,需要约500K以上时才是热力学可行的。同时,脱羧反应的活化能小于脱羰反应的活化能,说明羧基的反应活性强于羰基,脱除难度较低,所以CO2的生成温度低于CO。

英文摘要：

Hydrothermal dewatering（HTD） is an effective method to remove the inherent moisture and oxygen functional groups in brown coal.And then the coal rank and application value of brown coal can be upgraded.A comprehensive molecular modeling study was carried out to clarify mechanisms for deoxidization process from brown coal with simplified models（benzoic acid and benzaldehyde）.Geometry optimizations of reactants,intermediates,transition states and products were carried out by using density functional theory at the B3LYP/6-31G（d） level.Based on analysis of reaction pathways,the thermodynamic and kinetic parameters were calculated.Results show that the de-carboxyl reaction is a spontaneous process on thermodynamics,while the de-carbonyl reaction is inhibited at a low temperature.At the same time,the activation energy of decarboxylation is also lower than de-carbonyl reaction.It is more difficult to remove carbonyl,and the temperature of the CO2 generator is lower than that of CO.