The Effect of the Metal Oxide as the Support for Silver Nanoparticles on the Catalytic Activity for Ammonia Ozonation

Ammonia is one of the common inorganic pollutants in surface waters. It can come from a wide range of sources through the discharge of wastewater (industry, agriculture, and municipal waters). Catalytic ozonation reaction can efficiently remove ammonia nitrogen without introducing other pollutants and improve the nitrogen selectivity of reaction products by controlling the reaction conditions. Catalysts based on silver nanoparticles (Ag NPs) have shown excellent O-3 decomposition performance; therefore, they are promising catalysts for catalytic ammonia ozonation due to their high reactivity, stability, and selectivity to N-2. In this study, we synthesized well-defined silver nanoparticles (Ag NPs) using a modified alkaline polyol method and then dispersed them on solid oxide supports (Fe3O4, TiO2, and WO3). Before being deposited on the oxide support, the silver nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-VIS spectroscopy. The obtained catalysts, Ag_Fe3O4, Ag_TiO2, and Ag_WO3 were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area analysis, UV-VIS spectroscopy, temperature-programmed reduction (H-2-TPR), and temperature-programmed desorption (TPD) of CO2 and NH3. It has been demonstrated that the nature of the support significantly influences the physicochemical properties of the catalysts, as well as their catalytic performance in ammonia ozonation reaction.