New insight into simultaneous removal of NO and Hg0 on CeO2-modified V2O5/TiO2 catalyst: A new modification strategy

In this work, it was theoretically speculated that enhancing NO adsorption will simultaneously improve SCR performance and Hg-0 oxidation on a V-based SCR catalyst. As a result, CeO2 was selected as the modification component. The results indicated that CeO2 modification not only significantly improved SCR performance but also apparently enhanced Hg-0 oxidation. Hg-TPD results suggest that Hg-0 can be oxidized to Hg(NO3)(2) but that it was hard to desorb from the catalyst, leading to the blockage of active sites. It was found that HCl facilitated the desorption of adsorbed Hg(NO3)(2), which enabled the recovery of active sites. An innovative nitrate pathway for Hg-0 oxidation was proposed in this work. In situ FTIR experiments indicated that NO can strongly adsorb and generate more nitrite species on a V1CeTi catalyst, with bidentate nitrate species playing an important role in Hg-0 oxidation. Additionally, SO2 and H2O(g) showed no obvious influence on SCR performance, while decreasing the Hg-0 oxidation efficiency at high temperatures. X-ray photoelectron spectroscopy (XPS) analysis revealed that SO2 can react with CeO2 to form Ce-2(SO4)(3), which partially blocked the redox shift between Ce3+ and Ce4+. The proposed nitrate pathway in this work provided a new design and modification strategy for catalysts used for simultaneous removal of NO and Hg-0.