Constructing a core–shell Pt@MnOx/SiO2 catalyst for benzene catalytic combustion with excellent SO2 resistance: new insights into active sites

Abstract

SO₂ poisoning of catalysts is a prevalent issue in the catalytic combustion of volatile organic compounds (VOCs), as it can directly impact their conversion efficiency. In this study, we adopted a novel strategy of directly coating platinum (Pt) with metal oxide MeO_x (Me = Cr, V, Mn) as a shell to form a core–shell Pt@MeO_x substance on mesoporous silica (SiO₂) nanospheres. The construction of such a core–shell protective structure can protect the active Pt site well from SO₂ toxicity. The experimental results show that the addition of the MnO_x shell does not reduce the activity of the Pt/SiO₂ catalyst, while T₅₀ is decreased and T₉₀ is maintained at 166 °C. At the same time, the Pt@MnO_x/SiO₂ catalyst also has the best anti-SO₂ performance (with continuous injection of 10 ppm SO₂ for 23 hours, the benzene conversion rate remained above 80%). Moreover, even under the conditions of high SO₂ concentration (30 ppm), the benzene conversion of the Pt@MnO_x/SiO₂ catalyst is still only slightly reduced. A series of characterization studies established that an abundant Pt–O–Mn active interface was generated by the strong interactions between the MnO_x shell layer and Pt species. The Mn species at the interface can serve as a sacrificial site to inhibit SO₂ poisoning of the Pt active site. Simultaneously, Mn species can be redispersed in a sulfur-containing atmosphere, thus supplementing the number of sacrificial sites to mitigate the decline in catalyst activity caused by SO₂. This is a pioneering and meaningful contribution to the field of VOC elimination, providing innovative research insights into the design of sulfur-resistant catalysts.