Simultaneous removal of elemental mercury and NO in simulated flue gas over V2O5/ZrO2-CeO2 catalyst

• V/ZrCex was synthesized by a co-precipitation method for simultaneous removal of NO and Hg0.
• The influence mechanism of SO2 was systematically investigated.
• A connection between Hg0 oxidation and NO conversion was also studied.
• The reaction mechanism of simultaneous removal of Hg0 and NO was speculated.

A series of V/ZrCex catalyst synthesized by a co-precipitation method was employed to investigate the simultaneous removal of NO and elemental mercury (Hg0) in simulated flue gas. The catalysts were characterized using BET, SEM, XRD, H2–TPR, XPS, and FT–IR. V/ZrCe0.6 with CeO2/ZrO2 molar ratio of 0.6 showed excellent SCR activity (87.3%) and high Hg0 oxidation efficiency (77.6%) in SCR atmosphere (NH3/NO = 1). The results indicated that the Hg0 had little impact on NO conversion, while the coexistence of NO and O2 would be beneficial for the Hg0 oxidation. Hg0 oxidation was inhibited in SCR atmosphere owing to the presence of NH3. The characterization results demonstrated that the superior performance of V/ZrCe0.6 catalyst might be attributed to lower crystallinity, better texture properties, strong redox ability and high reactive nitrate together with NH3 species. The redox equilibrium (Ce3+ + V5+ ↔ Ce4+ + V4+) contributed to the NO conversion and Hg0 oxidation. The bidentate sulfates formed by adsorbed SO2 could provide new acid sites for NH3 adsorption and increase the amount of NH4+, which reduced the poisoning effect of SO2 and H2O. Based on the experimental results, a mechanism for the simultaneous removal of NO and Hg0 was proposed for the V/ZrCe0.6 catalysts: 2NH3/NH4+(ad) + NO2(ad) + NO(g) → 2N2 + 3H2O + /2H+, Hg(ad) + Oβ → HgO(ad).

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