Highly efficient degradation of sulfur-containing volatile organic compounds by amorphous MnO2 at room temperature: Implications for controlling odor pollutants

Abstract

Sulfur-Containing Volatile Organic Compounds (S-VOCs) are notorious for global air pollution due to their odorous characteristics and exhibiting adverse health effects. Nevertheless, the catalytic degradation of S-VOCs at low temperatures is still a tremendous challenge for air purification. In this study, methyl mercaptan (CH3SH), a typical S-VOCs contaminant, could be completely removed by amorphous MnO2 with high efficiency (100 %) for 40 h at room temperature, and demonstrating significantly enhanced stability (over 100 h) in the presence of 20 %RH (Relative humidity), which is far superior to the performance of previous reported catalysts. The amorphous MnO2 with surface-rich oxygen vacancies can trigger the formation of more reactive oxygen species (ROS) and stronger O2 adsorption capability comparing with the crystalline MnO2, the corresponding results are characterized by XPS and EPR. Moreover, In Situ-DRIFTS coupled with DFT calculations revealed that the CH3SH could be transformed into CO32-/SO42- by ROS. Unexpectedly, the amorphous MnO2 also displayed excellent activity and stability towards to other typical S-VOCs, which is beneficial for the actual industrial application. The findings can provide novel insights into the design of highly efficient and stable catalysts to eliminate odor gaseous pollutants over a broad operating concentration window at room temperature.