Remarkable N₂ selectivity enhancement of NH₃-SCO reactions over V_0.5/Pt_0.04/TiO₂ catalyst through Cu-Er...

Pt-V bimetallic catalysts maybe promising substitutes to precious metal catalysts for selective catalytic oxidation (SCO) of NH₃. But it remains a major challenge for Pt-V bimetallic catalysts to pursue high NH₃ conversion rate and N₂ selectivity simultaneously. In this work, both Cu and Er were adopted to modify V_0.5/Pt_0.04/TiO₂ catalyst (denoted as V/PT), and the influences of Cu and Er doping amounts on NH₃-SCO performance of V/PT catalysts were investigated systematically. The results indicated that the co-modification of Cu and Er imposed little influence on NH₃ conversion efficiency, but significantly boosted N₂ selectivity. Compared with other Cu-Er-modified V/PT catalysts, CEV/PT-4 catalyst exhibited outstanding NH₃-SCO performance, which attained completely 100% NH₃ conversion efficiency and > 90% N₂ selectivity in the temperature range of 225-450 °C. It was significantly superior to the NH₃-SCO performance of most previously reported catalysts. The characterization results indicated that the adequate doping amounts of Cu and Er resulted in an obvious enhancement on redox property and surface acidity of CEV/PT-4 catalyst. It also led to abundant Pt⁰ and surface chemisorbed oxygen species on catalyst surface, which facilitated the oxidation of NH₃ to NO_x and enhanced i-SCR reactions. In situ DRIFTS results showed that -NH₂ species on the surface of CEV/PT-4 catalyst could actively react with nitrate species to generate N₂ and H₂O.