Mechanistic Switch between Oxidative (Andrussow) and Nonoxidative (Degussa) Formation of HCN on Pt(111) by Density Functional Theory
Mechanistic Switch between Oxidative (Andrussow) and Nonoxidative (Degussa) Formation of HCN on Pt(111) by Density Functional Theory
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通过密度泛函理论研究 Pt(111) 上 HCN 的氧化 (Andrussow) 和非氧化 (Degussa) 形成之间的机理转换
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发表时间：
2011
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通讯作者：
N. López
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作者：
J. Gómez;N. López
我们用密度泛函理论研究了氨气和甲烷在铂(111)面上生成HCN的反应全过程。在工业上，该反应可以在氧化或非氧化条件下进行，因此，我们描述了氧在反应机理中的作用。密度泛函理论计算表明，反应网络非常复杂，包括脱氢步骤、HxC−Nhy(x=0−2，y=0−2)偶联、C−含N物种的脱氢和异构化。在非氧化性条件下(德古萨过程)，生成C-−-N的主要反应路径是通过部分氢化的化合物，特别是那些来自HxC+NH_2(x=0，1)的化合物与生成的中间体的后续脱氢反应。在富氧条件下(安德鲁索)，主要的C-−-N键形成步骤切换到HC+N或C+N。氧化和非氧化条件之间的机械切换是由中间体相对稳定性的变化驱动的。
We have investigated the full reaction path leading to the formation of HCN from ammonia and methane on Pt(111) by means of density functional theory. Industrially, the reaction can take place under oxidative or nonoxidative conditions, and thus, we have described the effect of oxygen in the reaction mechanism. DFT calculations show that the reaction network is very complex, including dehydrogenation steps, HxC−NHy (x = 0−2, y = 0−2) couplings, de/hydrogenation of C−N-containing species, and isomerization. Under nonoxidative conditions (Degussa process), the main reaction path for C−N formation takes place through partially hydrogenated compounds, in particular, those coming from HxC + NH2 (x = 0, 1) coupling with subsequent dehydrogenation of the resulting intermediate. Under oxygen-rich conditions (Andrussow), the main C−N bond formation step switches to HC + N or C + N. The mechanistic switch between oxidative and nonoxidative conditions is driven by the change in the relative stability of the intermed...