Mechanistic investigation of NH3 oxidation over V-0.5Ce(SO4)2/Ti NH3-SCR catalyst

NH3 oxidation over V-0.5Ce(SO4)(2)/Ti catalyst used for NH3-SCR was investigated and compared to that occurred over a commercial V-W/Ti catalyst. It was found that much more significant NH3 oxidation into N-2 and N2O occurs over V-0.5Ce(SO4)(2)/Ti than commercial V-W/T-i catalyst at high temperatures (> 300 degrees C). According to the kinetics and characterization results obtained, stronger surface redox properties and a relatively higher concentration of polymerized vanadates present on V-0.5Ce(SO4)(2)/Ti should contribute to its higher NH3 conversion values. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies suggested the formation of -NH imido species, based on which a successive NH3 dehydrogenation-like mechanism is proposed, which consistently explains well the experimental observations.