褐煤表面含氧官能团对水分子的吸附机理  

ADSORPTION MECHANISM OF WATER MOLECULE ONTO OXYGEN CONTAINING FUNCTIONAL GROUPS OF LIGNITE

作　　者：夏阳超 刘晓阳[1] 刘生玉[1] 

机构地区：[1]太原理工大学矿业工程学院,太原硕士生030024

出　　处：《煤炭转化》2016年第4期1-5,9,共6页Coal Conversion

基　　金：国家自然科学基金资助项目(21376161)

摘　　要：运用量子化学密度泛函理论(DFT)研究了褐煤表面含氧官能团对水分子的吸附机理,结果表明,氢键作用为主要作用力,水分子在羧基上吸附时形成两个氢键,最短氢键长度为0.173 3nm.在酚羟基和醇羟基上吸附时,含氧官能团作为氢键供体,水分子作为氢键受体是最优吸附构型,氢键长度分别为0.187 6nm和0.192 7nm.在羰基和醚键上吸附时形成的氢键长度分别为0.196 1nm和0.206 0nm.由Mulliken电荷布局可知,吸附后含氧官能团中氧原子得电子,O—H,CO和C—O键的强度被削弱,从而键长被拉长.吸附能计算结果符合吸附平衡距离变化规律,含氧官能团对水分子的吸附强弱顺序为:羧基>酚羟基>醇羟基>羰基>醚键.水分子在酚羟基上的吸附符合Lennard-Jones理论,水分子离酚羟基约0.188 5nm处的吸附能最低,此为稳定吸附平衡态,吸附能为-45.63kJ/mol.The adsorption mechanism of lignite surface oxygen containing functional groups adsorbing water molecules was studied using the quantum chemistry density functional theory（DFT）.The results show that the hydrogen bonding interaction is the main force.Two hydrogen bonds are formed when water molecule adsorbed on the carboxyl group with the shortest hydrogen bond of 0.173 3nm.When water molecules adsorbed on the phenol hydroxyl and alcoholic hydroxyl,optimal adsorption configuration is that oxygen containing functional groups act as the hydrogen bond donor and water molecules as the hydrogen bond acceptor,and the hydrogen bonds length are 0.187 6nm and 0.192 7nm respectively.When water molecules adsorbed on the carbonyl and ether linkage,the hydrogen bonds are formed with length of 0.196 1nm and 0.206 0nm respectively.Mulliken Population analysis show that the oxygen atoms in oxygen containing functional groups acquire electrons,the O—H,C=O and C—O bond are impaired,and the bond length are elongated.The calculation results of adsorption energy agree with the change rule of adsorption equilibrium distance.The order of adsorption strength from large to small for water molecule adsorbed on the oxygen containing functional groups is carboxyl,phenol hydroxyl,alcohol hydroxyl,carbonyl,ether linkage.The result of water molecule adsorbed on phenol hydroxyl in line with the theory of Lennard-Jones,the stable adsorption equilibrium is achieved at a distance of about 0.188 5nm and the adsorption energy is-45.63kJ/mol.

关 键 词：褐煤 含氧官能团 量子化学 几何吸附构型 吸附能 

分 类 号：TQ530[化学工程—煤化学工程]