活性炭纤维催化氧化NO的量子化学研究

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。

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

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 over ACFs surface was proposed. The results revealed that O₂ molecules are adsorbed on the ACFs surface, forming two simiquinones (C-O), and then the adsorbed NO(C-NO) is oxidized to -NO₂ by the simiquinones. On the other hand, the active oxygen atom (O^*), derived from free O₂ through catalytic process on the carbon surface, reacts with the adsorbed NO, forming -NO₂. However, O₂ adsorption is more thermodynamically favorable than NO. Based on statistical thermodynamic analysis, the transformation of NO to NO₂ was mainly attributed to the reaction between C-NO and O^* generated from the free O₂ in atmosphere.