Catalysts for highly water-resistant catalytic decomposition of ozone: Hausmannite Mn3O4 on exposed (101) crystal surface.

ABSTRACT

Recently, ozone pollution has gradually replaced PM2.5 as the main pollutant affecting air pollution. In this study, we synthesized a series of Mn3O4 catalysts by hydrothermal method changing the precursors and tested their activities at different relative humidity, gas volume space velocity of 150,000 h-1 and 5 ppm ozone. Remarkably, Mn3O4-SO4 prepared with MnSO4 as precursor showed excellent catalytic ozone decomposition activity, almost completely converting 5 ppm of ozone at different relative humidity ranges. Finally, the most active Mn3O4-SO4 catalyst was tested for its usability limit at RH= 90%, after 28 h of testing under high humidity conditions, it had retained successfully the complete decomposition of low concentrations of ozone. The catalysts were characterized by XRD, Raman, HRTEM, XPS, BET, H2O-TPD and in situ IR NH3 adsorption. The characterization analysis revealed that the Mn3O4-SO4 surface could exposed a highly active (101) crystalline surface with high specific surface area, excellent hydrophobicity as well as ozone adsorption capacity, which were highly favorable for ozone decomposition under high humidity conditions. In this work, Mn3O4 exhibits good catalytic activity, which provides an additional option for future studies of manganese oxides.