褐煤与水分子相互作用的量子化学计算  

Quantum chemical calculation of the interaction between lignite and water molecules

作　　者：徐志强[1] 刘向阳 涂亚楠[1] 刘定桦 任冠霖 XU Zhiqiang;LIU Xiangyang;TU Yanan;LIU Dinghua;REN Guanlin(School of Chemical&Environmental Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)化学与环境工程学院,北京100083

出　　处：《中国矿业大学学报》2022年第3期554-561,共8页Journal of China University of Mining & Technology

基　　金：国家自然科学基金面上项目(51974325)。

摘　　要：高含水量限制着褐煤的大规模利用,研究褐煤持水机理,揭示含氧官能团与水分子间氢键作用的本质,对指导褐煤脱水具有重要的理论意义.通过第一性原理分子动力学(AIMD)模拟褐煤表面水分子的有序结构,采用密度泛函理论(DFT)研究褐煤结构单元和水分子的相互作用.结果表明:界面处水分子分别在0.192 nm和0.322 nm附近形成了第1配位层和第2配位层;褐煤结构单元的负电势极值点主要分布于含氧官能团中氧原子附近,最大达到了-154.20 kJ/mol,正电势的极值点主要分布于含氧官能团和苯环中的氢原子附近,最大为221.08 kJ/mol.水分子处于羧基、羟基、羰基和醚键处的4种二聚体结合能分别为-47.76,-29.44,-40.45和-23.36 kJ/mol,其中静电作用分别占总吸引能的65.92%,67.45%,55.99%和65.19%.分子中原子理论(AIM)拓扑分析估算的总氢键结合能遵循羧基>羟基>醚键>羰基,处于羰基附近的水分子与褐煤结构单元的其他部分相互作用太强,使得水分子与羰基间的作用能最小.The high water content of lignite limits its large-scale utilization.It is of great theoretical significance to study the water-holding mechanism of lignite and reveal the nature of hydrogen bonding between oxygen-containing functional groups and water molecules for guiding the dewatering of lignite.The ordered structure of water molecules on the lignite surface and the interaction menchanism between lignite structural units and water molecules were studied by the ab initio molecular dynamics(AIMD)and density flooding theory(DFT)respectively.The results showed that the water molecules at the interface formed the first coordination layer and the second coordination layer near 0.192 nm and 0.322 nm,respectively.The extreme points of negative potential for the lignite structural unit were mainly located near the oxygen atoms in the oxygen-containing functional groups,with a maximum of-154.20 kJ/mol.Meanwhile,the extreme points of the positive potential were mainly located near the hydrogen atoms in the oxygen-containing functional groups and the benzene rings,with a maximum of 221.08 kJ/mol.The four dimer binding energies of water molecules near the carboxyl,hydroxyl,carbonyl and ether bonds were-47.76,-29.44,-40.45 and-23.36 kJ/mol,respectively.The electrostatic interactions accounted for 65.92%,67.45%,55.99%and 65.19%of total attraction energy,respectively.In addition,the results of atoms in molecules(AIM)topological analysis indicated that the total hydrogen bonding interaction energies were ranked as follows:carboxyl group>hydroxyl>ether bond>carbonyl group.Among these oxygen-containing functional groups,the water molecules in the vicinity of the carbonyl group were easier to interact with other parts of lignite structural unit,and thus the interaction energy between the water molecules and the carbonyl group was minimized.

关 键 词：褐煤 水分子 弱相互作用 密度泛函理论 

分 类 号：TD94[矿业工程—选矿]