活性炭纤维催化氧化NO的量子化学研究

A quantum study on the mechanism of NO oxidation over the activated carbon fiber catalysts

利用密度泛函理论的B3LYP方法,6-31G(d)基组,在zigzag型的四并苯模型上对NO、O2分子在活性炭纤维(ACFs)表面的吸附行为进行研究,并探讨了ACFs催化氧化NO的主要机理路径。研究结果表明,环境气氛中的O2分子可以先吸附于ACFs表面形成两个半醌基(C-O),之后C-O和吸附态的NO(C-NO)发生氧化反应生成-NO2;游离态的O2也可以经过ACFs表面的催化作用形成活性氧原子(O*)从而直接和吸附态的NO反应生成-NO2。与NO相比,O2分子的吸附能大,在同NO的竞争吸附中占据优势,结合统计热力学分析,吸附态的NO和游离态的O2所产生的活性氧原子发生氧化反应是NO转化为NO2的主要途径。

The adsorption of NO, O2 molecules on the surface of activated carbon fibers （ ACFs ） were comprehensively investigated using a simplified zigzag model based on density functional theory.The ACFs model, products, stable intermediates were optimized at B3LYP/6-31G （ d） level and the catalytic oxidation mechanism of NO vo re ACFs surfaec was rp oposed.The resutl s revealed that O2 moleclue s are adsorbed on the ACFs surface, forming tw o simiquinones （ C-O） , and thne the adsorbed NO（ C-NO） is oxidized to -NO2 by the simqi uinones.On the other hand, the ca tive oxygen atom （ O＊） , derived from free O2 through caat lytic process on the cabr on surfca e, reacts with the adsorbed NO, forming -NO2 .However, O2 adsortp ion is more thermodynamically favorable than NO.Based on statistical thermodynamic analysis, the trans formation ofN O to NO2 was mainly attributed to the reaction between C-NO and O＊ generated from the free O2 in atmosphre e.