煤表面对单氧分子的物理吸附机理  

Physical Mechanism of a Single Oxygen Molecule Adsorbs to the Coal Surface

作　　者：邓存宝[1] 王继仁[1] 叶兵[1] 邓汉忠[1] 

机构地区：[1]辽宁工程技术大学安全科学与工程学院,辽宁阜新123000

出　　处：《中国矿业大学学报》2008年第2期171-175,共5页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(50474010);国家"十一五"科技攻关项目(2006BAK03B05)

摘　　要：煤的氧化自燃是由煤表面对氧的吸附开始.应用量子化学密度泛函理论,研究了煤表面对氧分子的物理吸附机理和吸附过程.结果表明,煤表面与氧分子组成的吸附态中,煤表面苯环碳原子的电子向氧分子中的氧原子转移,导致氧原子的净电荷增加;单氧分子在苯环位置吸附时,其O-O键的伸缩振动频率向低波数位移;单氧分子在侧链位置吸附时,υC14-H16和υO24-O25红外光谱的振动频率变小,分子之间的作用力减弱了分子的伸缩振动.氧与苯环吸附时的吸附能为30.94 kJ/mol,与氨基基团吸附时的吸附能为71.81 kJ/mol.煤表面侧链吸附放出的热量大于与苯环吸附所放出的热量,侧链吸附对煤的氧化自燃的贡献大于苯环的吸附.The adsorption of oxygen to the coal surface is the first step of spontaneous combustion. The physical adsorption mechanism of an oxygen molecule to a coal surface has been studied by density functional theory （DFT）. The results show that the electrons of a carbon atom in a benzene ring situated on the coal surface shift to an oxygen atom in an oxygen molecule, which results an increase in net electric charge on that oxygen atom. When a single oxygen molecule reacts with a benzene ring in this way the frequency of O-O bond-stretching shifts to the lower wave numbers. When the oxygen molecule interacts with a side chain the vibration frequencies UC14-H16 and VO24-O25 decrease because the intermolecular forces weaken these stretching vibrations. The adsorption energy when oxygen is absorbed by the benzene ring is 30. 94 kJ/mol but the energy of adsorption by the amidogen group is 71.81 kJ/mol, The energy from side chain adsorption is more than from benzene ring adsorption, so side chain adsorption contributes more to coal spontaneous combustion than does benzene ring adsorption.

关 键 词：煤炭自燃 吸附 密度泛函 非晶体微观吸附机理 

分 类 号：TQ028[化学工程]