Departament de Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain) http://www.icrea.cat/Web/ScientificForm.aspx?key=292; Faculty of Chemistry and Pharmacy, University of Sofia, 1126 Sofia (Bulgaria).
Angew Chem Int Ed Engl. 2014 Dec 1;53(49):13371-5. doi: 10.1002/anie.201405738. Epub 2014 Oct 7.
Heterogeneous catalysis is commonly governed by surface active sites. Yet, areas just below the surface can also influence catalytic activity, for instance, when fragmentation products of catalytic feeds penetrate into catalysts. In particular, H absorbed below the surface is required for certain hydrogenation reactions on metals. Herein, we show that a sufficient concentration of subsurface hydrogen, H(sub) , may either significantly increase or decrease the bond energy and the reactivity of the adsorbed hydrogen, H(ad) , depending on the metal. We predict a representative reaction, ethyl hydrogenation, to speed up on Pd and Pt, but to slow down on Ni and Rh in the presence of H(sub) , especially on metal nanoparticles. The identified effects of subsurface H on surface reactivity are indispensable for an atomistic understanding of hydrogenation processes on transition metals and interactions of hydrogen with metals in general.
多相催化通常由表面活性位控制。然而，表面以下的区域也会影响催化活性，例如当催化进料的碎片产物渗透到催化剂中时。特别是，金属上某些加氢反应需要表面以下吸附的氢 H。在此，我们表明，取决于金属，表面以下的氢 H(sub) 的足够浓度可能会显著增加或降低吸附氢 H(ad) 的键能和反应活性。我们预测在 H(sub) 存在下，代表性反应乙基加氢在 Pd 和 Pt 上会加速，但在 Ni 和 Rh 上会减慢，尤其是在金属纳米粒子上。表面活性位下 H 对表面反应性的影响对于理解过渡金属上的加氢过程以及一般的氢与金属的相互作用是不可或缺的。
