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

NH 3 oxidation over V-0.5Ce(SO 4 ) 2 /Ti catalyst used for NH 3 -SCR was investigated and compared to that occurred over a commercial V-W/Ti catalyst. It was found that much more significant NH 3 oxidation into N 2 and N 2 O occurs over V-0.5Ce(SO 4 ) 2 /Ti than commercial V-W/Ti catalyst at high temperatures (>300 °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(SO 4 ) 2 /Ti should contribute to its higher NH 3 conversion values. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies suggested the formation of -NH imido species, based on which a successive NH 3 dehydrogenation-like mechanism is proposed, which consistently explains well the experimental observations. [ABSTRACT FROM AUTHOR]