Effect of ceria morphology on the activity of MnOx/CeO2 catalysts for the catalytic combustion of chlorobenzene

Abstract

The effect of CeO₂ morphology on the performance of a MnO_x/CeO₂ catalyst was investigated for the catalytic combustion of chlorobenzene (CB), which was used as a model compound for chlorinated volatile organic compounds (CVOCs). The catalytic activity tests revealed that MnO_x/CeO₂ nanoparticles (NPS) achieved relatively higher CB conversions than MnO_x/CeO₂ nanorods (NR). The MnO_x/CeO₂ catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) N₂ adsorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H₂-TPR). The characterization of the MnO_x/CeO₂ catalysts indicated that CeO₂-NPS had a higher exposure of the (100) crystal plane and possessed more Mn⁴⁺ species, oxygen vacancies and surface-adsorbed oxygen. It was suggested that the CeO₂-NPS had a stronger interaction with MnO_x species, which resulted in greater catalytic activity in the combustion of CB. The catalytic activity of MnO_x/CeO₂-NPS could be attributed to higher concentrations of Mn⁴⁺ species, oxygen vacancies, and surface-adsorbed oxygen, which were associated with the exposed (100) crystal planes. Therefore, these results demonstrated that the catalytic performance of the MnO_x/CeO₂ catalyst was greatly affected by the CeO₂ morphology. Therefore, catalytic materials that have increased activity can be obtained through morphology-controlled synthesis.