Wu Qingyuan, Zhong Yuanyuan, Zhou Lu, Zhu Mengsi, Liu Shengjie, Qin Ruixuan, Zheng Nanfeng
New Cornerstone Science Laboratory, State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and National & Local Joint Engineering Research Center of Preparation Technology of Nanomaterials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361002, China.
J Am Chem Soc. 2024 Nov 27;146(47):32263-32268. doi: 10.1021/jacs.4c11726. Epub 2024 Nov 12.
The prevalence of electronic defects has not been successfully demonstrated in nonreducible oxides. This work presents a straightforward approach to the preparation of a yellow alumina rich in F-centers (oxygen vacancies containing free electrons), which is well characterized by systematic spectral methods. The surface electron density of the as-prepared F-center enriched alumina sample was estimated to be approximately 0.35 mmol·g. Free electrons on the surface can reduce palladium precursors in situ, leading to the deposition of fine Pd nanoparticles on alumina. The produced Pd nanocatalysts are highly effective in the selective hydrogenation of phenol to cyclohexanone, achieving a high catalytic performance under mild conditions (30 °C and 0.1 MPa of H). Systematic mechanism investigations reveal that hydroxyl radicals generated at the catalyst interfaces facilitate the activation of phenol. The activated phenol is then sequentially hydrogenated to give the intermediate 2-cyclohexenone and then the desired cyclohexanone. The catalyst system demonstrates efficacy in selectively hydrogenating substituted phenols into a wide array of functional ketones.
电子缺陷的普遍存在尚未在不可还原氧化物中得到成功证明。这项工作提出了一种直接的方法来制备富含F中心（含有自由电子的氧空位）的黄色氧化铝，通过系统的光谱方法对其进行了充分表征。所制备的富含F中心的氧化铝样品的表面电子密度估计约为0.35 mmol·g。表面的自由电子可以原位还原钯前驱体，导致在氧化铝上沉积细小的钯纳米颗粒。所制备的钯纳米催化剂在苯酚选择性加氢制环己酮反应中具有很高的活性，在温和条件（30°C和0.1 MPa氢气）下实现了高催化性能。系统的机理研究表明，催化剂界面产生的羟基自由基促进了苯酚的活化。活化后的苯酚随后依次加氢生成中间体2-环己烯酮，进而生成所需的环己酮。该催化剂体系在将取代苯酚选择性加氢生成多种功能酮方面表现出有效性。
