双金属Pd-Au /高取向热解石墨催化剂：从组成到成对的对氢加成选择性,The Journal of Physical Chemistry C

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双金属Pd-Au /高取向热解石墨催化剂：从组成到成对的对氢加成选择性
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-08-07 , DOI: 10.1021/acs.jpcc.8b06281
Andrey V. Bukhtiyarov ₁ , Dudari B. Burueva _{2,

3} , Igor P. Prosvirin _{1,

3} , Alexander Yu. Klyushin _{4,

5} , Maxim A. Panafidin ₁ , Kirill V. Kovtunov _{2,

3} , Valerii I. Bukhtiyarov ₁ , Igor V. Koptyug _{2,

3}

Affiliation

Pd和Au单金属和双金属（Pd–Au）模型催化剂是使用金属（Au和/或Pd）在超高真空条件下在有缺陷的高取向热解石墨（HOPG）表面上进行气相沉积制备的。在制备过程的每个阶段，使用X射线光电子能谱和扫描隧道显微镜对模型催化剂进行了研究。为了制备双金属催化剂，使用了不同的程序来获得不同结构的PdAu颗粒（Au_壳-Pd_核或合金化）。所有制备的催化剂均显示出相当窄的粒径分布，平均粒径在4–7 nm范围内。使用对氢增强的核磁共振波谱作为研究丙炔加氢中Pd–Au / HOPG，Pd / HOPG和Au / HOPG模型催化剂的工具。与Au样品相比，Pd，PdAu_合金和Au_壳-Pd_核样品显示在丙炔转化中具有催化活性，并且观察到成对的氢加成途径。此外，与单金属Pd样品相比，双金属样品在成对氢加成中的活性提高了2至5倍。结果表明，HOPG上负载的双金属Pd-Au颗粒的结构强烈影响其在丙炔加氢反应中的活性和/或选择性：具有Au_壳-Pd_核结构的催化剂比PdAu_合金具有更高的成对选择性。结构体。因此，所报道的方法可以用作研究模型双金属Pd-Au催化剂加氢反应中协同效应研究的有效工具，其中活性组分负载在平面载体上。

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Bimetallic Pd–Au/Highly Oriented Pyrolytic Graphite Catalysts: from Composition to Pairwise Parahydrogen Addition Selectivity

The model Pd and Au mono- and bi-metallic (Pd–Au) catalysts were prepared using vapor deposition of metals (Au and/or Pd) under ultrahigh vacuum conditions on the defective highly oriented pyrolytic graphite (HOPG) surface. The model catalysts were investigated using the X-ray photoelectron spectroscopy and scanning tunneling microscopy at each stage of the preparation procedure. For the preparation of bimetallic catalysts, different procedures were used to get different structures of PdAu particles (Au_shell–Pd_core or alloyed). All prepared catalysts showed rather narrow particles size distribution with an average particles size in the range of 4–7 nm. Parahydrogen-enhanced nuclear magnetic resonance spectroscopy was used as a tool for the investigation of Pd–Au/HOPG, Pd/HOPG, and Au/HOPG model catalysts in propyne hydrogenation. In contrast to Au sample, Pd, PdAu_alloy, and Au_shell–Pd_core samples were shown to have catalytic activity in propyne conversion, and pairwise hydrogen addition routes were observed. Moreover, bimetallic samples demonstrated the 2- to 5-fold higher activity in pairwise hydrogen addition in comparison to the monometallic Pd sample. It was shown that the structures of bimetallic Pd–Au particles supported on HOPG strongly affected their activities and/or selectivities in propyne hydrogenation reaction: the catalyst with the Au_shell–Pd_core structure demonstrated higher pairwise selectivity than that with the PdAu_alloy structure. Thus, the reported approach can be used as an effective tool for the synergistic effects investigations in hydrogenation reactions over model bimetallic Pd–Au catalysts, where the active component is supported on a planar support.

更新日期：2018-08-07

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