Transient Kinetics of SO2 Oxidation Over SCR-DeNOx Monolith Catalysts

A dynamic kinetic study of the undesired oxidation of SO 2 over a commercial V 2 O 5 −WO 3 /TiO 2 monolith catalyst for the SCR-DeNO x process is herein presented. Transient SO 2 conversion data were systematically collected during experiments involving step changes of temperature, area velocity, and feed composition (SO 2, O 2, H 2 O, and NH 3 ). Characteristic times of the system response were of a few hours: peculiar SO 3 emission peaks were apparent upon increasing the reaction temperature and the H 2 O feed content. The data were well interpreted by a dynamic kinetic model assuming that buildup−depletion of surface sulfate species is rate controlling. The model accounts successfully also for the transient effects resulting from the interaction between the SCR-DeNO x reaction (NO x reduction with NH 3 ) and the oxidation of SO 2 .