[Denitration mechanism of monoclinic-phase nano zirconium oxide-based catalysts]

The MnO(x)-CeO2/m-ZrO2 catalyst was prepared by impregnation with nano monoclinic-phase zirconium (m-ZrO2) as the supporter. The influence of active component and reaction temperature on the denitration performance of the catalyst was investigated, while the surface properties of the catalyst and the denitration mechanism were discussed. The denitration efficiency was improved as the active component increased and the reaction temperature rose. The denitration efficiency of 2.5% MnO(x)-CeO2/m-ZrO2 catalyst at 110 degrees C was 55.5% while that of 15% MnO(x)-CeO2/m-ZrO2 catalyst was 93.5%. The results of XRD, SEM, BET and H2-TPR showed that the surface structure of the loaded catalyst was beneficial for denitration and oxidation-reduction. NH3-TPD test demonstrated that NH3 was adsorbed at the Lewis acid sites and Brönsted acid sites on the surface of catalysts. Intermediate products NH2NO and NH4NO were generated from a series of reactions between NO and NH3 and finally transformed into N2 and H2O. Most of the denitration process happened at Lewis acid sites.