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Various acidic components(MOx:phosphate,sulfate,tungstate and niobate)were loaded on Ce0.75Zr0.25O2powders by an impregnation method.The as-prepared catalysts were hydrothermally treated at 760 oC for 48 h in air containing 10 vol.%H2O to obtain the aged catalysts.The catalysts were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,H2programmed-reduction,NH3adsorption and deNOx activity measurements.The results showed that,among the catalysts investigated,the phosphated Ce0.75Zr0.25O2catalyst showed the highest hydrothermal stability.The remained high acidity of the phosphated catalyst with moderate redox property helped to maintain the excellent NH3-SCR activity of hydrothermally aged catalyst.Cerium tungstate led to the poor redox property of the tungstated catalyst although the acidity of catalyst was still high.The decomposition of sulfates at temperatures higher than 600°C restrained the usage of sulfated catalysts in high temperature conditions.The overall dehydration of niobate to niobium oxides led to the low acidity of hydrothermally aged Nb2O5-Ce0.75Zr0.25O2catalyst.
Various acidic components (MOx: phosphate, sulfate, tungstate and niobate) were loaded on Ce0.75Zr0.25O2powders by an impregnation method. The as-prepared catalysts were hydrothermally treated at 760 oC for 48 h in air containing 10 vol.% H2O to The catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, H2programmed-reduction, NH3adsorption and deNOx activity measurements. The results showed that, among the catalysts investigated, the phosphated Ce0.75Zr0.25O2catalyst showed the highest hydrothermal stability. The steady high acidity of the phosphated catalyst with moderate redox property helped to maintain the excellent NH3-SCR activity of hydrothermally aged catalyst. Cerium tungstate led to the poor redox property of the tungstated catalyst although the acidity of catalyst was still high. The decomposition of sulfates at temperatures higher than 600 ° C restrained the usage of sulfated catalysts in high temperature conditions. The overa ll dehydration of niobate to niobium oxides led to the low acidity of hydrothermally aged Nb2O5-Ce0.75Zr0.25O2catalyst.