Insight into the roles of HEPES and ethanol in one-pot preparation of ZrO2@Pt catalyst for efficient selective hydrogenation of nitrobenzene
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 ZrO 2 @Pt catalyst using ZrO 2 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 ZrO 2 was firstly functionalized to increase the number of hydroxyl group, Pt nanoclusters were formed simultaneously and uniformly coated on the ZrO 2 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 ZrO 2 surface and the reduction of Pt precursor under mild conditions. As-prepared ZrO 2 @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 H 2 pressure within 30 min, and the TOF reached as high as 3304 h −1 . Moreover, ZrO 2 @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 ZrO 2 @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.
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