Selective hydrogenation of phenol is a sustainable alternative to cyclohexane oxidation for the production of cyclohexanone. However, over-hydrogenation of cyclohexanone to cyclohexanol is thermodynamically favorable, limiting its selectivity. Here, we report an unprecedented cyclohexanone selectivity (>99.9%) in continuous-flow phenol hydrogenation using an electron-deficient Pd catalyst. The Pd atom exists in a unique Pd–N₅C₄ structure in which it is coordinated with four quasi-planar N atoms and one axial N atom in the first shell and an additional four C atoms in the second shell that lie on the curved surface of a pore in ordered mesoporous carbon. The Pd site has a d charge depletion of 1.18 e that prevents cyclohexanone adsorption, which is therefore exclusively produced. Bonding the Pd atom to a curved plane of carbon atoms is an effective way to control the d charge of Pd and increase its selectivity for the green synthesis of fine chemicals.

苯酚选择性加氢是环己烷氧化生产环己酮的可持续替代方案。然而，环己酮过度氢化为环己醇在热力学上是有利的，限制了其选择性。在这里，我们报告了使用缺电子 Pd 催化剂的连续流苯酚氢化中前所未有的环己酮选择性（> 99.9％）。 Pd 原子存在于独特的 Pd–N ₅ C ₄结构中，其中与第一个壳层中的四个准平面 N 原子和一个轴向 N 原子以及位于弯曲上的第二个壳层中的另外四个 C 原子配位有序介孔碳的孔表面。 Pd 位点的d电荷损耗为 1.18 e，可防止环己酮吸附，因此仅产生环己酮。将Pd原子键合到碳原子曲面上是控制Pd电荷并提高精细化学品绿色合成选择性的有效方法。