Enhanced catalytic activity of OMS-2 for carcinogenic benzene elimination by tuning Sr contents in the tunnels.

Cryptomelane-type manganese oxides (OMS-2) have been intensively investigated for application in the catalytic oxidation of carcinogenic benzene, and doping metal ions in the OMS-2 tunnels are widely used for modifying its catalytic activity. In this study, we reported a novel strategy of enhancing catalytic activity of OMS-2 for carcinogenic benzene elimination by tuning Sr concentration in the tunnels. The catalytic activity result revealed that an obvious decrease (△T = 27 °C and △T = 37 °C) in T and T (corresponding to benzene conversions at 50 % and 90 %, respectively; initial benzene concentration was 2000 mg m; contact time was 1.5 s) had been observed by increasing the Sr concentration in the OMS-2 tunnels. The origin of Sr doping effect on catalytic activity was theoretically and experimentally investigated by CO temperature-programmed reduction, O isotope labeling, and density functional theory calculations. The result confirmed that increasing Sr concentration in the tunnels not only promoted the lattice oxygen activity, but also facilitated the generation of more oxygen vacancy defects, thus considerably improving the catalytic activity of OMS-2.