Enhanced Catalytic Performance and Sulfur Dioxide Resistance of Reduced Graphene Oxide-Promoted MnO2 Nanorods-Supported Pt Nanoparticles for Benzene Oxidation

Abstract

The reduced graphene oxide (rGO)-promoted α-MnO2 nanorods-supported Pt (xPt-yrGO/α-MnO2, x = 0.93 wt%, y = 0.5, 1.0, and 2.0 wt%) nanocatalysts were prepared using a polyvinyl alcohol (PVA)-protected reduction method. After an appropriate loading of Pt on α-MnO2, the strong metal–support interaction between Pt and α-MnO2 was beneficial for an increase in catalytic activity. The simultaneous addition of rGO to α-MnO2 not only provided a more amount of benzene adsorption sites, but also acted as an electron transfer channel to accelerate charge migration, thus further improving catalytic activity of α-MnO2. Among all of the catalyst samples, 0.94Pt-1.0rGO/α-MnO2 showed the best catalytic performance with 90% benzene conversion at 160 °C and a gas hourly space velocity (GHSV) of 60,000 mL/(g h), which was better than that over the other Pt-based catalysts. The results of in situ DRIFTS characterization revealed that phenol, benzoquinone, and carboxylate species were the intermediates and eventually oxidized to CO2 and H2O. When sulfur dioxide was present, catalytic activity of α-MnO2 decreased due to the formation of manganese sulfate that blocked the active sites, while the loading of Pt and rGO hindered the chemisorption of SO2 and prevented the active sites of the catalyst from being poisoned by SO2, thus enhancing sulfur resistance of the catalyst. The 0.94Pt-1.0rGO/α-MnO2 catalyst presented in this work can be considered as a cost-effective and promising catalyst for the oxidative removal of volatile organic compounds.