NO在焦炭表面的吸附特性

Characteristics of NO chemisorption on surface of char

为明确NO在焦炭表面异相还原的反应机理,选用合理简化的纯碳和含氮焦炭模型,使用密度泛函理论对NO在不同焦炭模型上的吸附特性进行研究。在B3LYP/6-31G(d)水平上优化焦炭模型及NO吸附产物,得到NO在不同模型上的吸附反应热。计算结果表明,NO在纯碳表面的吸附为放热过程;NO以N原子与焦炭氮结合的方式吸附在含氮焦炭表面为放热反应,以O原子与焦炭氮结合的方式吸附在锯齿型和扶手型含氮焦炭"空穴位"上为放热反应,吸附在扶手型含氮焦炭"外肩位"上为弱吸热反应。NO最倾向于吸附在锯齿型结构纯碳表面;当吸附在含氮焦炭上时,倾向于N—N结合方式的吸附。

To clarify the heterogeneous reduction reaction mechanisms, NO chemisorptions on several char models with different configurations were investigated using density functional theory in this paper. Char models and NO adsorption products were optimized at B3LYP/6-31G（d） level. The results show that NO chemisorption on the surface of pure carbon is exothermic. NO chemisorptions on nitrogen-containing char with the formation of N--N bond are exothermic processes. It is exothermic when N--O bond is formed with NO chemisorption on nitrogen-containing char with zigzag or ＂hole＂ armchair configuration in side-on mode. Chemisorption of NO on nitrogen-containing char with ＂shoulder＂ armchair configuration in side-on mode is endothermic. NO molecules prefer to chemisorb on pure carbon with zigzag configuration. Chemisorption of NO on nitrogen-containing char with the formation of N--N bond is preferred.