School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, United Kingdom.
Langmuir. 2010 Nov 2;26(21):16568-77. doi: 10.1021/la101597q.
We report the preparation of Au-Pd nanocrystalline catalysts supported on activated carbon prepared via a sol-immobilization technique and explore their use for the direct synthesis of hydrogen peroxide and the oxidation of benzyl alcohol. In particular, we examine the synthesis of a systematic set of Au-Pd colloidal nanoparticles having a range of Au/Pd ratios. The catalysts have been structurally characterized using a combination of UV-visible spectroscopy, transmission electron microscopy, STEM HAADF/XEDS, and X-ray photoelectron spectroscopy. The Au-Pd nanoparticles are found in the majority of cases to be homogeneous alloys, although some variation is observed in the AuPd composition at high Pd/Au ratios. The optimum performance for the synthesis of hydrogen peroxide is observed for a catalyst having a Au/Pd 1:2 molar ratio. However, the competing hydrogenation reaction of hydrogen peroxide increases with increasing Pd content, although Pd alone is less effective than when Au is also present. Investigation of the oxidation of benzyl alcohol using these materials also shows that the optimum selective oxidation to the aldehyde occurs for the Au/Pd 1:2 molar ratio catalyst. These measured activity trends are discussed in terms of the structure and composition of the supported Au-Pd nanoparticles.
我们报告了通过溶胶固定化技术制备的负载在活性炭上的 Au-Pd 纳米晶催化剂的制备，并探索了它们在直接合成过氧化氢和苯甲醇氧化中的应用。特别是，我们研究了一系列具有不同 Au/Pd 比的 Au-Pd 胶体纳米粒子的合成。使用紫外-可见光谱、透射电子显微镜、STEM HAADF/XEDS 和 X 射线光电子能谱对催化剂进行了结构表征。在大多数情况下，Au-Pd 纳米粒子被发现是均匀的合金，尽管在高 Pd/Au 比下观察到 AuPd 组成的一些变化。对于 Au/Pd 摩尔比为 1:2 的催化剂，观察到合成过氧化氢的最佳性能。然而，随着 Pd 含量的增加，过氧化氢的竞争加氢反应增加，尽管单独的 Pd 不如同时存在 Au 时有效。使用这些材料研究苯甲醇的氧化也表明，对于 Au/Pd 摩尔比为 1:2 的催化剂，最佳选择性氧化为醛。这些测量的活性趋势根据负载的 Au-Pd 纳米粒子的结构和组成进行了讨论。
