The selective hydrogenation of propyne over a Pd-black model catalyst was investigated under operando conditions at 1 bar making use of advanced X-ray diffraction (bulk sensitive) and photo-electron spectroscopy (surface sensitive) techniques. It was found that the population of subsurface species controls the selective catalytic semi-hydrogenation of propyne to propylene due to the formation of surface and near-surface PdCx that inhibits the participation of more reactive bulk hydrogen in the hydrogenation reaction. However, increasing the partial pressure of hydrogen reduces the population of PdCx with the concomitant formation of a β-PdHx phase up to the surface, which is accompanied by a lattice expansion, allowing the participation of more active bulk hydrogen which is responsible for the unselective total alkyne hydrogenation. Therefore, controlling the surface and subsurface catalyst chemistry is crucial to control the selective alkyne semi-hydrogenation.

中文翻译：

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吸附和地下碳物种在Pd-黑催化剂上选择性炔烃加氢中的作用：本体和表面的Operando研究。

利用先进的X射线衍射（体感）和光电子能谱（表面灵敏）技术，在1 bar的操作条件下，研究了Pd-black模型催化剂上丙炔的选择性氢化。已发现，由于表面和近表面PdCx的形成抑制了反应性更大的氢参与氢化反应，因此，地下物种的种群控制了丙炔向丙烯的选择性催化半氢化反应。但是，增加氢气的分压会降低PdCx的数量，并伴随形成直至表面的β-PdHx相，并伴随晶格膨胀，从而允许更多的活性氢参与非选择性反应。总炔烃加氢。因此，