Electron Withdrawal from Methane by Pt Atoms on Stannic Oxide for Highly Active Low-Temperature Combustion.

Supported Pt catalysts often exhibit limited effectiveness in achieving complete methane oxidation, which restricts their commercial application. However, Pt catalysts are particularly attractive, especially in sulfur-containing environments, where commercial Pd catalysts are more susceptible to sulfur poisoning. Therefore, developing highly active Pt sites and gaining a deeper understanding of the intrinsic mechanisms governing methane combustion over Pt catalysts is essential. In this study, we present a highly active stannic oxide supported platinum catalyst (Pt/SnO2) for stable low-temperature methane combustion, achieving a T90 as low as 390 °C at a high gas hourly space velocity (GHSV) of 60,000 mL·gcat-1·h-1. This performance surpasses that of most other Pt catalysts as well as Pd/SnO2 and benchmark Pd/Al2O3. The superior SO2 tolerance of Pt/SnO2 was demonstrated by the stability of methane conversion at 500 °C, with only a minor reduction observed during the long-term online test. Characterization results indicate that the Pt atoms on SnO2 are electron-deficient and predominantly adopt a crowded configuration. In situ studies and density functional theory (DFT) calculations reveal that the electron-deficient, crowded Pt atoms enhance the chemisorption of CH4 molecules by withdrawing the electrons from CH4, resulting in activated CH4 with an elongated C-H bond. This work provides an in-depth understanding of the nature of Pt active sites for high-performance methane combustion, offering valuable insights for the rational design of Pt-based catalysts.