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

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 MeOx (Me = Cr, V, Mn) as a shell to form a core-shell Pt@MeOx 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 MnOx shell does not reduce the activity of the Pt/SiO2 catalyst, while T-50 is decreased and T-90 is maintained at 166 degrees C. At the same time, the Pt@MnOx/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@MnOx/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 MnOx 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.