Boosted NH₃ Selective Catalytic Oxidation Activity over V-Pt-Ti Catalysts: Insight into Preparation Method Effects

In this work, V-Pt-Ti catalysts were synthesized employing impregnation (IP), precipitation (PC), sol-gel (SG), thermal decomposition (TD), and hydrothermal (HD) methods. A systematic study has been carried out to investigate impacts of various preparation methods on the performance of NH₃ selective catalytic oxidation (SCO) at temperatures from 150 °C to 450 °C. N₂ adsorption/desorption, XPS, XRD, H₂-TPR, NH₃-TPD, O₂-TPD, SEM, TEM, and in situ DRIFTS were adopted to characterize the physico-chemical property of V-Pt-Ti catalysts. The results suggested that V-Pt-Ti catalysts synthesized by precipitation methods (denoted as VPT-PC) exhibited notably better SCO performance across the 150-450 °C temperature range compared with those produced by impregnation (IP), sol-gel (SG), thermal decomposition (TD), and hydrothermal (HD) methods. The outstanding performance of the VPT-PC catalyst could be ascribed to its larger surface area, higher relative contents of Pt⁰, V⁵⁺, and O_α, more abundant surface acid sites, and better redox property. In situ DRIFTS results suggested that NO₂ species could participate in NH₃ oxidation reaction on the surface of the VPT-PC catalyst, which was beneficial for improving the SCO activity.