Mechanism of CO + NH3-coupled removal of NO from Fe/AC catalysts at medium and low temperatures

Abstract

Catalysts with different mass ratios (Fe: AC = 7.5, 10.0, and 12.5) were prepared using the equal-volume impregnation method. The 12.5Fe/AC catalyst exhibited the highest NO removal activity and best N2 selectivity at any given temperature. Furthermore, NO removal was mediated by redox reactions between Fe2+ and Fe3+ and dominantly occurred at the Fe2+ active sites. As the loading amount of active metal (Fe) increased, the diffraction ring gradually diffused, and the number of Fe oxide crystals, number of oxygen-containing functional groups, and content of chemically adsorbed oxygen increased. Chemically adsorbed oxygen plays a major role in NO removal. The NO removal mechanism of the Fe/AC catalyst is dominated by physical adsorption and the Langmuir–Hinshelwood mechanism at low temperatures and by the Eley–Rideal mechanism at medium and low temperatures.