Role of the In-Situ-Formed Surface (Pt–S–O)-Ti Active Structure in SO₂-Promoted C₃H₈ Combustion over a Pt/TiO₂ Catalyst

Abstract

Typically, SO₂ unavoidably deactivates catalysts in most heterogeneous catalytic oxidations. However, for Pt-based catalysts, SO₂ exhibits an extraordinary boosting effect in propane catalytic oxidation, but the promotive mechanism remains contentious. In this study, an in situ-formed tactful (Pt-S-O)-Ti structure was concluded to be a key factor for Pt/TiO₂ catalysts with a substantial SO₂ tolerance ability. The experiments and theoretical calculations confirm that the high degree of hybridization and orbital coupling between Pt 5d and S 3p orbitals enable more charge transfer from Pt to S species, thus forming the (Pt-S-O)-Ti structure with the oxygen atom dissociated from the chemisorbed O₂ adsorbed on oxygen vacancies. The active oxygen atom in the (Pt-S-O)-Ti active structure is a robust site for C₃H₈ adsorption, leading to a better C₃H₈ combustion performance. This work can provide insights into the rational design of chemical bonds for high SO₂ tolerance catalysts, thereby improving economic and environmental benefits.