Efficient NH₃-SCR removal of NO_x with highly ordered mesoporous WO₃(χ)-CeO₂ at low temperatures

To eliminate nitrogen oxides (NO_x), a series of highly ordered mesoporous WO₃(χ)-CeO₂ nanomaterials (χ represents the mole ratio of W/Ce) were synthesized by using KIT-6 as a hard template, which was used for selective catalytic reduction (SCR) to remove NO_x with NH₃ at low temperatures. Moreover, the nanomaterials were characterized by TEM, XRD, Raman, XPS, BET, H₂-TPR, NH₃-TPD and in situ DRIFTS. It can be found that all of the prepared mesoporous WO₃(χ)-CeO₂ (χ = 0, 0.5, 0.75, 1 and 1.25) showed highly ordered mesoporous channels. Furthermore, mesoporous WO₃(1)-CeO₂ exhibited the best removal efficiency of NO_x, and its NO_x conversion ratio could reach 100% from 225 ° C to 350 ° C with a gas hourly space velocity of 30 000 h^-1, which was due to higher Ce³⁺ concentrations, abundant active surface oxygen species and Lewis acid sites based on XPS, H₂-TPR, NH₃-TPD and in situ DRIFTS. In addition, several key performance parameters of mesoporous WO₃(1)-CeO₂, such as superior water resistance, better alkali metal resistance, higher thermal stability and N₂ selectivity, were systematically studied, indicating that the synthesized mesoporous WO₃(1)-CeO₂ has great potential for industrial applications.