Highly efficient WO3-FeOx catalysts synthesized using a novel solvent-free method for NH3-SCR.

WO3-FeOx catalysts with various WO3 contents were synthesized through a facile solvent-free method, satisfying the selective catalytic reduction of NO (NH3-SCR). Strikingly, the optimum 30 %WO3-FeOx catalyst with the largest surface area exhibited the most outstanding catalytic activity, achieving the nearly 100 % NOx removal efficiency in a wide temperature window between 225-500 °C, which was better than that of Fe-W series catalysts reported in other studies. In addition, Raman and XPS results proved that the introduction of WO3 altered the electronic environment of Fe2O3, inducing the formation of Fe3O4 (Fe2+) and surface adsorbed oxygen. In situ DRIFTS demonstrated that the interaction between WO3 and Fe2O3 not only promoted the adsorption capacity of NH3 on the catalyst, but also contributed to the formation of adsorbed NOx species. NOx reduction reaction on WO3-FeOx catalyst proceeded via the Eley-Rideal and Langmuir-Hinshelwood mechanism synchronously. All of these factors, jointly, accounted for the superior catalytic activity and N2 selectivity of WO3-FeOx catalysts.