MECHANISTIC STUDIES OF SELECTIVE CATALYTIC REDUCTION OF NITRIC-OXIDE WITH AMMONIA OVER V2O5 TIO2 (ANATASE) CATALYSTS THROUGH TRANSIENT ISOTOPIC LABELING AT STEADY-STATE/

Isotopic tracers studies were performed to investigate the reaction ne twork of selective catalytic reduction (SCR) on vanadia catalysts supp orted over titania. The catalysts were characterized using BET surface area analysis, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermal ana lysis techniques. The product analysis was carried out by a combinatio n of chemiluminescence NO, analysis, gas chromatography-mass spectrome try, and chemical titration methods. The isotopic labeling experiments were performed under steady-state conditions by using N-15- and O-18- containing species. The results obtained in these experiments were com bined with the nitric oxide and oxygen exchange experiments to arrive at conclusions regarding the pathways of the SCR reactions. The role o f ammonia oxidation has been quantified in the overall SCR reaction ne twork at higher temperatures.