Promotional effect of vanadium on the selective catalytic oxidation of NH3 to N2 over Ce/V/TiO2 catalyst

• Ce/2V/TiO2 catalyst shows a high SCO activity and SO2 tolerance.
• Vanadium could enhance the dispersion of Ce4+ species and redox properties.
• SCO reaction follows an internal SCR mechanism over Ce/2V/TiO2 catalyst.

The promotional effect of vanadium on Ce/TiO2 catalyst for the selective catalytic oxidation of NH3 to N2 was investigated. The catalytic activity and SO2 tolerance of 10 wt% Ce/TiO2 catalyst were greatly enhanced by the addition of 2 wt% vanadium, in the temperature range of 250–350 °C. The NH3 conversion of 10 wt% Ce/TiO2 had been highly enhanced from 50 to 90% at 300 °C, after vanadium addition. The BET and XPS results indicated that the addition of vanadium could result in better dispersion of Ce4+ species on TiO2, leading to the enhancement of BET surface area. H2 temperature programmed reduction (TPR) results suggest that vanadium enhances the redox properties, and the absence of bulk CeO2 in high temperature (700 °C) peak indicates it could be attributed to the strong interactions among CeOx, VOx, and TiOx. More importantly, 10 wt% Ce/2 wt% V/TiO2 catalyst showed strong resistance to SO2 poisoning. DRIFT results suggest that the 10 wt% Ce/2 wt% V/TiO2 catalyst could reduce the formation of NH4HSO4 species, which was beneficial for easy decomposition, in the presence of SO2. In summary, these results indicated that the 10 wt% Ce/2 wt% V/TiO2 catalyst greatly improved SCO activity and SO2 tolerance.

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