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

Abstract

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 ( E_Hg = 87.6%, E_NO = 82.84%) after 72 h reaction in SCR atmosphere at 150 °C.