Interaction between SO2 and Fe–Cu–Ox/CNTs–TiO2 catalyst and its influence on NO reduction with NH3

• Interaction between Fe-Cu–Ox/CNTs–TiO2 and SO2 without NH3 was studied.
• A disproportionation reaction of SO2 was confirmed.
• The S species adsorbed on the catalyst surface influenced the NO reduction route.
• A NOx conversion of 81.3% was achieved under a GHSV of 150,000 h−1.

Interaction between SO2 and titania-carbon nanotubes (CNTs) supported iron-copper oxides catalyst in the absence of NH3 was studied. After the catalyst was pretreated by SO2, S2− ions were detected indicating the existence of a disproportionation reaction of SO2 over catalyst surface. The S species adsorbed on the catalyst surface affected the behaviors of adsorption and oxidation of NH3 and NO, thus influenced the NO reduction route. Over catalysts pretreated at low temperatures, the de-NOx reaction is mainly through the adsorbed NH3 and gaseous NOx. While over catalysts pretreated at high temperatures, the reaction between adsorbed NO and gaseous NH3 becomes the main route. The reduction of Cu2+ to Cu+ by SO2 is a possible reason for catalyst deactivation at low temperatures, but it also suppressed NH3 oxidation, which improved the NO removal efficiency to 81.3% under a GHSV of 150,000 h−1 at 350 °C.

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