Highly dispersed Pt nanoparticles supported UiO-66 catalysts were successfully prepared by the incipient wetness impregnation method. Their thermal catalytic performances were evaluated by toluene degradation. The physicochemical properties of the samples were characterized using a series of characterization methods. The catalytic activity of catalysts remained essentially unchanged in the high weight hourly space velocity, stability and water resistance test, which also indicated good catalytic performance. In the reusability test, the catalytic performance was found to be enhanced after the reaction, because of the catalyst might follow a Pt0-PtO synergistic catalytic mechanism (similar to Mars-van Krevelen mechanism) and there was a phase transition between Pt0 and PtO during the reaction. Firstly, the toluene adsorbed on the catalyst surface was oxidized by the activated lattice oxygen of the PtO. Then, consumption of oxygen atoms led to formation of oxygen vacancies, and finally the molecular oxygen adsorbed by Pt0 was activated and passed to the PtO to supplement the oxygen vacancies, forming a redox cycle. In addition, the possible catalytic oxidation mechanism of toluene was also revealed.
Keywords: Catalytic oxidation; Pt(0)-PtO; Pt/UiO-66 catalysts; Synergistic catalytic mechanism; Toluene.
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