Highly Efficient RuO_x/NbO_x-ZrO_x Catalysts for Ammonia Removal via Tuning Acidic Active Species

Synthesis of Pt/Ce/ZrO2–S Bifunctional Catalyst for Ammonia Removal via Tuning Acidic and Redox Sites

“…Notably, the P/C/Z-S catalyst exhibited the highest proportion of Ce 3+ /(Ce 3+ + Ce 4+ ), which indicated that sulfuric acid treatment of ZrO 2 support facilitated the transformation of surface Ce species from Ce 4+ to Ce 3+ . It reported that abundant Ce 3+ favored the enhancement of adsorbed oxygen concentration on catalyst surfaces, which was attributed to Ce 3+ inducing the generation of more oxygen vacancies and unsaturated chemical bonds on catalyst surfaces. − As depicted in Figure C, the peaks at 184.3 and 182.2 eV were attributed to Zr 3d 3/2 and Zr 3d 5/2 , respectively, representing the presence of Zr 4+ species . The binding energy of Zr species in P/Z, P/Z-S, and P/C/Z catalysts was essentially consistent.…”

“…All profiles were fitted to two peaks. The peak at 529.5–529.7 eV attributed to lattice oxygen (O lat ), while the peak at 531–531.6 eV belonged to adsorbed oxygen (O ads ). , It is well known that surface-adsorbed oxygen usually had better activity compared with lattice oxygen, which was attributed to its excellent mobility . Therefore, the ratio of O ads /(O ads + O lat ) was calculated for all catalysts and the results are presented in Table .…”

“…Among the existing NH 3 removal methods, selective catalytic oxidation (SCO) is considered the most effective technique. − During the past decades, a great deal of effort has been devoted to enrich surface acidic and redox active sites with the aim to develop high-performance catalysts with superior N 2 selectivity. − Li et al introduced Nb species into RuO x /ZrO x catalysts, which resulted in the formation of an amorphous Nb 2 Zr 6 O 17 structure through strong interactions between ZrO 2 and Nb 2 O 5 . RuO x /NbO x -ZrO x catalyst achieved an NH 3 conversion of 100% and a a N 2 selectivity of 90% at 300 °C.…”