Plasma-catalytic removal of toluene over CeO2-MnOx catalysts in an atmosphere dielectric barrier discharge

- High concentration of toluene is degraded in the plasma-catalytic system with CeO2-MnOx catalyst.
- The mobility of O and concentration of O vacancies can be improved due to the interaction between Ce and Mn.
- The formation of active oxygen species on the catalyst surface has three pathways.
- Gas phase and catalyst surface reaction mechanisms in the plasma-catalytic system are proposed.

The destruction of toluene in dielectric barrier discharge (DBD) reactor coupled with a series of CeO2-MnOx catalysts was investigated in this work. All catalysts prepared by sol-gel method were characterized in detail using N2 adsorption, XRD, TEM, H2-TPR, Raman, O2-TPD and XPS analysis technology. The effect of input power, molar ratio of Ce/Mn, gas flow rate and initial concentration of toluene on the removal efficiency of toluene and CO2 selectivity has been investigated. The plasma-catalytic system improves the removal efficiency and CO2 selectivity significantly compared with the plasma alone system. The catalytic performance of CeO2-MnOx catalysts are higher than pure CeO2 and MnOx, which might be contributed to the synergistic effect between CeO2 and MnOx (such as Mn3+/Mn2+ and Ce4+/Ce3+ redox couples) in the CeO2-MnOx catalysts. The highest removal efficiency of toluene (95.94%) and CO2 selectivity (90.73%) are acquired with Ce1Mn1 catalyst. The reason may be that: (1) the increased BET specific surface area and the decreased grain size can be obtained from CeO2-MnOx catalyst. (2) The formation of CeO2-MnOx solid solution resulted from the incorporation of Mn cations into the CeO2 lattice could generate more oxygen vacancies and improve the mobility of oxygen. On the basis of the analytic results of GC/MS, the pathways of toluene destruction in the plasma-catalysis system are discussed.

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