The hydrogenation of phenol to cyclohexanone is an important industrial reaction and supported palladium catalysts are the most popular catalysts applied nowadays. Hitherto, there has been no success in using ruthenium catalysts for this reaction because of their poor catalytic performance, in spite of the fact that ruthenium is a frequently used metallic component in hydrogenation catalysts. Herein, we report our effort in creating a meso-structured catalyst composed of ruthenium clusters enclosed in the super cages of X-zeolite, which is prepared by mixing precursors of ruthenium and X-zeolite at the beginning stage of preparation, i.e., before the crystallization of the zeolite. This well-defined Ru catalyst exhibits excellent catalytic performance for the selective hydrogenation of phenol, similar to palladium catalysts. The results demonstrate that the joint effects of the 3D negatively charged grid of X-zeolite and the enclosed electron-deficient ruthenium clusters enhance the activity of metallic ruthenium and suppress the further hydrogenation of the valuable product cyclohexanone, which is not possible with traditional Ru catalysts. This investigation reveals the fact that although catalytic reactions are always initiated on the active centers of the catalyst at dimensions on the atomic scale, the effect of the neighboring environment surrounding the active species might extend it to the meso-scale, which should not be ignored as it might induce electronic and structural changes in the active species as well as possibly dramatic changes in the performance of the catalyst. The meso-structured catalyst integrated active species and the neighboring environment as a whole should be considered in discussing the performance of catalysts.

中文翻译：

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3D带电网格可产生高性能催化剂：X沸石中包裹的钌簇可将苯酚加氢成环己酮

苯酚加氢成环己酮是重要的工业反应，负载型钯催化剂是当今最流行的催化剂。迄今为止，尽管钌是氢化催化剂中经常使用的金属成分，但由于钌催化剂的催化性能差，因此未成功用于该反应。本文中，我们报告了我们的工作，以创建由包围在X沸石超级笼中的钌簇组成的介孔结构催化剂，该催化剂是通过在制备初期将钌和X沸石的前体混合而制备的，即，在沸石结晶之前。与钯催化剂相似，这种定义明确的Ru催化剂对苯酚的选择性加氢显示出优异的催化性能。结果表明，X沸石的3D带负电荷的网格和封闭的电子缺陷钌簇的联合作用增强了金属钌的活性，并抑制了有价值的产物环己酮的进一步氢化，这是传统Ru催化剂无法实现的。 。这项研究揭示了一个事实，尽管催化反应总是在原子尺度上的尺寸范围内在催化剂的活性中心上引发，但周围围绕活性物种的环境的影响可能会将其扩展至介观尺度，它不应该被忽略，因为它可能引起活性物质的电子和结构变化，以及催化剂性能的巨大变化。在讨论催化剂的性能时，应考虑内消旋结构的催化剂结合的活性物种和整个周围环境。