金属离子(Na^(+)、Ba^(2+)、Ca^(2+))抑制煤中含氧官能团活性的量子化学研究

Quantum chemical study on inhibition effect of oxygen-containing groups in coal by metal ions(Na^(+)、Ba^(2+)、Ca^(2+))

为探究煤矿阻化剂抑制煤自燃的机理,以煤分子侧链活性基团醛基(-CHO)、甲氧基(-OCH3)为研究对象,使用高斯量子化学模拟软件(Gaussian 16W),对-CHO、-OCH3活性基团及其与Na^(+)、Ba^(2+)、Ca^(2+)结合所形成配合物的几何构型、静电势、前线轨道、自然键轨道与电荷转移进行深入研究。计算结果表明:Na^(+)、Ba^(2+)、Ca^(2+)与活性基团结合形成配合物后削弱了-CHO活性基团与-OCH3活性基团的亲电反应能力并使二者失去了亲核反应能力,降低了基团的化学活性;金属离子的加入使活性基团的能级差(ELOMO-EHOMO)和活性基团的最高占据分子轨道(HOMO)能量绝对值增大,增加了活性基团结构的稳定性;自然键轨道理论分析(NBO)结果说明-CHO与-OCH32种活性基团能够与Na^(+)、Ca^(2+)、Ba^(2+)3种金属离子发生较强的配位作用,活性基团中O上的电子转移到Na^(+)、Ca^(2+)和Ba^(2+)上形成了配位键;活性基团与金属离子的结合减少了基团与氧接触的机会,对煤炭自燃过程起到了抑制作用。

In order to explore the mechanism of inhibitor on coal spontaneous combustion,the oxygen-containing groups aldehyde(-CHO)and methoxy(-OCH3)in coal molecular side chain were selected as the subjects of the study.The geometric configuration,electrostatic potential,reaction tendency,frontier orbitals,natural bond orbitals and charge transfer of the oxygencontaining groups(-CHO and-OCH,)and their complexes with Na^(+),Ba^(2+)and Ca^(2+)were deeply studied by using Gaussian 16W simulation software.The results show that Na^(+),Ba^(2+)and Ca^(2+)tend to cooperate with the oxygen-containing groups to form complexes,which weakens the electrophilic reaction ability and disables the nucleophilic reaction ability of-CHO and-OCH3 oxygen-containing groups,thus reducing the chemical activity of oxygen-containing groups.Metal ions increase the energy level difference(ELOMO-EHOMO)and the absolute value of the highest occupied molecular orbital(HOMO)energy of oxygencontaining groups,and thereby increases the stability of oxygen-containing group.The results of natural bond orbital theory analysis(NBO)shows that-CHO and-OCH,oxygen-containing groups can coordinate steadily with Na^(+),Ca^(2+)and Ba^(2+),and the electrons of O in the two the groups transfer to Na^(+),Ca^(2+)and Ba^(2+)to form coordinate bonds.The combination of oxygen-containing groups with metal ions reduces the chance of contact between oxygen-containing groups and oxygen,which inhibits coal spontaneous combustion.