Highly active and stable CuxFey/AC-H catalysts with CuFe2O4 for NO reduction by CO in the presence of H2O and SO2 under regeneration gas

Abstract

For industrial flue gas, the synergistic removal of NOx and CO pollutants is in high demand but still has not been realized due to the presence of O2. We propose firstly that activated carbon regeneration gas provides suitable O2-free conditions for NO reduction by CO, but high contents of 5% SO2 and 5% H2O affect the catalyst activity. Here, we report a bimetallic modified catalyst CuxFey/AC-H that exhibits high catalytic activity under the abovementioned conditions due to the high amount of CuFe2O4. By regulating the Cu/Fe ratio, the formation of CuFe2O4 active sites is promoted, which improves the redox properties, adsorption and activation capacity of NO, the ratio of high valence metal, and content of synergistic oxygen vacancies. Based on in situ DRIFTS and fixed-bed FTIR/MS combined platform, it was found that the side reaction of H2O with the intermediate of −NCO forms NH3 above 250 °C and with CO forms H2 above 400 °C·NH3 and H2 provide additional reaction pathways of Fast-SCR and H2-SCR to significantly improve the reaction activity with 92.0% of NO conversion at 450 °C and 108,000 mL g−1h−1 on Cu2Fe2/AC-H. According to DFT calculations, CuFe2O4 active sites provide the high binding energy of sulfation, and then Cu2Fe2/AC-H demonstrates excellent activity and long-term stability with 72.2% of NO conversion at high contents of SO2 and H2O for 48 h. And CuxFey/AC-H provides great potential prospects for the application of NO reduction by CO under activated carbon regeneration gas.