Hydrothermal synthesis of leaf-like CeO 2 nanosheets and its MnO x /CeO 2 composites for catalytic combustion of chlorobenzene

Abstract

Leaf-like CeO₂ nanosheets with about 50 nm thickness have been successfully synthesized through a facile hydrothermal technique with Ce(NO₃)₃·6H₂O as cerium source, NH₄HCO₃ as the precipitants, and ethylenediamine as complexant. The morphology of CeCO₃OH precursor was used to control the structure of CeO₂. Uniform and independent leaf-like CeO₂ structures were obtained, and they were made up by a main stem and two groups of symmetric blade. Effect of the reaction time and the amount of ammonium hydrogen carbonate and ethylenediamine were investigated systematically. A series of MnO_x/CeO₂ were synthesized by incipient-wetness impregnation method and used to test the catalytic combustion of chlorobenzene (CB). The studies of the MnO_x/CeO₂ template showed that this kind of CeO₂ is beneficial to the dispersion of MnO_x on CeO₂ surface and the doping of Mn can increase the concentration of oxygen vacancy on the surface of catalysts. In addition, XPS result indicated that O_ads, Ce³⁺ and Mn⁴⁺ are helpful for oxidation reaction. The Mn/Ce (0.50) has the highest activity, which T90 (temperature at which 90% conversion) is about 236 °C and the conversion was maintained almost 80% for 1000 min, indicating the good stability of this catalyst.

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