SELECTIVE CATALYTIC REDUCTION OF NITRIC-OXIDE OVER VANADIA TITANIA CATALYSTS - TEMPERATURE-PROGRAMMED DESORPTION AND ISOTOPICALLY LABELED OXYGEN-EXCHANGE STUDIES/

Temperature-programmed desorption (TPD) and isotopicaly labeled oxygen -exchange studies were performed over titania-supported vanadia cataly sts and bare titania support. The catalysts were characterized using B ET surface area analysis, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and t hermal analysis techniques. The TPD experiments were performed over bo th the catalyst and the bare support using NO and NHS as adsorbates. T he exchange reactions performed were: [(NO)-N-14-O-16]->[(NO)-N-15-O-1 8] and [O-16(2)] ->[(18)O2]. Transient experiments, which involved ste p changes such as [NH3+O-2]->[O-2] were also performed to observe the transient behavior of various products. These results were combined wi th the earlier work, and conclusions were drawn regarding the adsorpti on/desorption and exchange characteristics of these catalysts in the S CR reaction.