High dispersion of active metal is an inevitable requirement to improve the catalytic performance of supported metal catalysts and achieving this goal always requires the support with a large specific surface area. Here we innovatively prepared a ZrO2@Pt catalyst using ZrO2 with a small specific surface area as the core which is coated with highly dispersed Pt nanoclusters (<2 nm). In this process, the surface of ZrO2 was firstly functionalized to increase the number of hydroxyl group, Pt nanoclusters were formed simultaneously and uniformly coated on the ZrO2 surface. In this work, much attention was paid to the role of 2-[4-(2-hydroxyethyl)-1-piperazinyl] ethanesulfonic acid (HEPES) and ethanol in the one-pot preparation process. The results showed that HEPES acted as a reductant, while treatment with ethanol promoted both the generation of hydroxyl groups on ZrO2 surface and the reduction of Pt precursor under mild conditions. As-prepared ZrO2@Pt catalyst showed excellent catalytic performance in the selective hydrogenation of nitrobenzene; nitrobenzene was completely converted to aniline with 100 % selectivity at room temperature and 8 bar H2 pressure within 30 min, and the TOF reached as high as 3304 h−1. Moreover, ZrO2@Pt also exhibited a good reusability and a broad substrate applicability. The results of both DRIFTS analysis and DFT calculation demonstrated that the hydrogenation of nitrobenzene on ZrO2@Pt catalyst followed the condensation reaction pathway. Our findings can provide a new approach to obtaining highly dispersed metal nanoparticles on the support with a small specific surface area.

中文翻译：

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深入探讨HEPES和乙醇在一锅法制备ZrO@Pt催化剂用于硝基苯高效选择性加氢中的作用


活性金属的高分散性是提高负载型金属催化剂催化性能的必然要求，而实现这一目标往往需要载体具有大的比表面积。在此，我们创新性地以比表面积较小的ZrO2为核心，并包覆高度分散的Pt纳米团簇（<2 nm），制备了ZrO2@Pt催化剂。在此过程中，ZrO2表面首先被功能化，增加羟基数量，同时形成Pt纳米团簇并均匀地包覆在ZrO2表面。本工作重点研究了2-[4-(2-羟乙基)-1-哌嗪基]乙磺酸(HEPES)和乙醇在一锅法制备过程中的作用。结果表明，HEPES起到还原剂的作用，而乙醇处理在温和条件下既促进了ZrO2表面羟基的生成，又促进了Pt前驱体的还原。所制备的ZrO2@Pt催化剂在硝基苯选择性加氢中表现出优异的催化性能；在室温和 8 bar H2 压力下，硝基苯在 30 分钟内以 100% 的选择性完全转化为苯胺，TOF 高达 3304 h−1。此外，ZrO2@Pt还表现出良好的可重复使用性和广泛的基材适用性。 DRIFTS分析和DFT计算结果表明硝基苯在ZrO2@Pt催化剂上的加氢遵循缩合反应路径。我们的研究结果可以提供一种在具有小比表面积的载体上获得高度分散的金属纳米颗粒的新方法。