褐煤吸附水分子三聚体机理研究

Mechanism of water molecules trimer adsorption by lignite

通过量子化学理论计算,构建褐煤分子片段模型,研究其与水分子三聚体之间在微观上的相互作用。对优化后的平衡构型进行分子表面静电势,约化密度梯度函数(RDG)与AIM拓扑分析。结果表明:对于褐煤分子中存在的各种含氧官能团,它们的反应活性从大到小依次为羧基、羟基、甲氧基、甲基。在吸附了水分子后,褐煤构型的静电势分布并未产生较大变化,而静电势局部极大值与极小值点对应区域的面积则有所增加,提供了更多的活性位点。褐煤吸附水分子的作用为物理吸附,以氢键作用为主,同时有少部分范德华弱相互作用。水分子之间形成的氢键作用可能会导致褐煤分子扭曲变形。

The interaction between molecular surface model fragments of lignite and water molecules trimer was studied by quantum chemistry theory.The molecular surface electrostatic potential,the reduced density gradient function(RDG)and the AIM topology of the optimized equilibrium configuration was analyzed.The results show that,the order(from high to low)of reaction activity of oxygen containing functional groups in the lignite molecule was as follows:carboxyl,hydroxyl,methoxy,methyl.Water molecules had negligible effect on electrostatic potential of the equilibrium configuration system,but they increased the maximum and minimum value point area of the electrostatic potential,and provided more active points.The adsorption reaction of water molecules and lignite surface molecular models was part of physical adsorption.The interaction between lignite and water trimer was mainly hydrogen bonding,followed by van Edward weak interaction.The hydrogen bonding between water molecules may lead to distorted deformation of the lignite molecules.