Reaction properties of ruthenium over Ru/TiO2 for selective catalytic oxidation of ammonia to nitrogen

Abstract The objective of this study was to investigate reaction characteristics of selective catalytic oxidation of ammonia to nitrogen (NH3-SCO) using ruthenium-based catalysts. Ruthenium was compared with platinum, a metal generally used as an NH3 oxidation catalyst. Experiment was carried out by depositing active metal onto TiO2. 1Ru/TiO2 was superior to 1Pt/TiO2 in NH3 conversion and N2 yield. Therefore, various analyses were conducted to determine the influence of catalytic properties of 1Ru/TiO2 on reaction activity. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Field Emission-Transmission Electron Microscope (FE-TEM) analyses confirmed that ruthenium was present in RuO2. Such a structure was confirmed to be excellent for adsorption ability of NH3 and oxygen through analysis of NH3-TPD, NH3-TPO, H2-TPR, and O2-chemisorption. In addition, in situ diffuse reflectance infrared Fourier transform spectroscopy (DIRFTS) analysis suggested that Ru/TiO2 had excellent ability to convert NH3 to NO. The converted NO then reacted with adsorbed NH3 to generate N2. Based on results of NH3 injection at various concentrations, it was found that the rate at which NH3 was converted to NO from the Ru/TiO2 surface affected N2 selectivity.