Selective Catalytic Reduction of Nitric Oxide over Vanadia/Titania Catalysts: Temperature-Programmed Desorption and Isotopically Labeled Oxygen-Exchange Studies

Abstract

Temperature-programmed desorption (TPD) and isotopically labeled oxygen-exchange studies were performed over titania-supported vanadia catalysts and bare titania support. The catalysts were characterized using BET surface area analysis, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermal analysis techniques. The TPD experiments were performed over both the catalyst and the bare support using NO and NH[sub 3] as adsorbates. The exchange reactions performed were: [[sup 14]N[sup 16]O] [yields] [[sup 15]N[sup 18]O] and [[sup 16]O[sub 2]] [yields] [[sup 18]O[sub 2]]. Transient experiments which involved step changes such as [NH[sub 3] + O[sub 2]] [yields] [O[sub 2]] were also performed to observed the transient behavior of various products. These results were combined with the earlier work, and conclusions were drawn regarding the adsorption/desorption and exchange characteristics of these catalysts in the SCR reaction.