Effect of SCR Atmosphere on the Removal of Hg⁰ by a V₂O₅–CeO₂/AC Catalyst at Low Temperature

A series of V2O5-xCeO2/AC (noted as V–Ce/AC) catalysts were synthesized by the impregnation method, which combined the advantage of AC and V–Ce. The effects of SCR atmosphere on Hg0 removal were systematically investigated at low temperature. The experimental results indicated that NO had a positive effect on Hg0 removal. In addition, an interesting experimental phenomenon was found that NH3 also showed a positive effect on Hg0 removal, which is different from many studies that have reported a negative effect of NH3 on Hg0 removal by other catalysts. NH3-TPD experiment showed that there was no apparent competition between NH3 and Hg0. An FT-IR gas analyzer and in situ DRIFTS were used to study the mechanism for the effect of NH3 on the catalyst surface and found that a small part of NH3 was overoxidized to NO2 in this catalytic system. O2 acted as a promoter in the whole process of NO and Hg0 removal. However, H2O showed an inhibiting effect on Hg0 and NO removal over V–Ce/AC catalysts, which may be caused by the competitive adsorption of H2O and pollutants (NO and Hg0). Additionally, 1 V-8Ce/AC catalyst exhibited high stability (EHg = 87.6%, ENO = 82.84%) after 72 h reaction in SCR atmosphere at 150 °C.