SO2-resistant hollow carbon spheres encapsulated Pt nanoparticles for benzene oxidation

Abstract

In the catalytic combustion of volatile organic compounds (VOCs) using noble metal catalysts, resistance to SO2 poisoning poses a significant challenge. To tackle this problem, Pt nanoparticle catalysts encapsulated in hollow carbon spheres (Pt@HCS catalysts) are synthesized. The Pt@HCS catalyst exhibits excellent benzene conversion, achieving 100 % conversion at 165 °C under an air velocity of 20,000 mL/(g h). Compared to the conventional supported Pt/HCS catalyst, the Pt@HCS catalyst demonstrates a significantly improved resistance to SO2 poisoning. In the presence of 25 ppm SO2, the Pt@HCS catalyst is capable of maintaining a 100 % benzene conversion rate within 24 h, whereas the conversion rate of Pt/HCS drops substantially to approximately 52 %. It is confirmed that the hollow porous structure provided a larger specific surface area and more adsorption sites, thereby facilitating benzene oxidation. More importantly, in situ DRIFTS reveals that the adsorption and desorption processes of SO2, along with the generation of substances like SO32−, are strictly limited to the surface of the carbon shell, thereby preserving the integrity of the internal reaction environment. Multiple characterizations combined with density functional theory (DFT) have demonstrated a unique separation effect over Pt@HCS, whereby the hydroxyl groups on the carbon shell preferentially capture SO2 while allowing benzene molecules to enter the cavities of the catalyst. In this way, any internal ingress of SO2 and competition with benzene for Pt adsorption is effectively avoided. This study offers a potential solution to enhance the performance of noble metal catalysts in the presence of sulfur compounds.