Πέμπτη 27 Δεκεμβρίου 2018

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 MnOx/CeO2 were synthesized by incipient-wetness impregnation method and used to test the catalytic combustion of chlorobenzene (CB). The studies of the MnOx/CeO2 template showed that this kind of CeO2 is beneficial to the dispersion of MnOx 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 Oads, 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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