Adsorption of nitric oxide and ammonia on vanadia-titania catalysts: ESR and XPS studies of adsorption

Abstract

The adsorption of NO and NH3 on V205/Ti02 catalysts has been studied by ESR and XPS at temperatures and pressures close to those used for industrial tail gas cleanup from power plants and HNO, plants, using NO reduction with ammonia. The paper extends and confirms earlier studies on pure V20s and Ti02 samples.' The reduction of the vanadia sites by adsorbed NH3 occurs over the whole range of temperatures studied while NO adsorption is observed on the titania support. Reduction of NO to N2 occurs on the reduced vanadia sites, which are reoxidized in the process. The reduced vanadia sites, however, are blocked by chemisorbed NH,, preventing the reduction of NO which causes a drop in the NO molar conversion. The presence of oxygen (or water) in the reaction mixture plays a major role in the selectivity of the vanadium oxide catalyst since it interacts with NH, at the reduced vanadia sites, resulting in the elimination of the NH3 poisoning of the reduced surface sites at temperatures above 550 K. 1989, 55, 15 1. (14) Inomata, M.; Miyamoto, A.; Murakami, Y. J . C a r d 1980, 62, 40. (15) Odenbrand, C U. I.; Lundin, S. T.; Anderson, L. A. H. Appl. Carol.

Inhibiting and deactivating effects of water on the selective catalytic reduction of nitric oxide with ammonia over MnO /Al2O3

“…11. Clearly, water exhibits a reversible, positive effect on the selectivity, as was reported on other oxidic catalysts [ 7,12,13,32,36] the non-selective catalytic reduction of nitric oxide appears to be stronger than the inhibition of the SCR reaction.…”

Low-Temperature Selective Catalytic Reduction (SCR) of NO with NH3 by Using Mn, Cr, and Cu Oxides Supported on Hombikat TiO2

“…Thus, reaction of diene 2 with quinone 3 [3] (obtained by ortho-methylation of 1,2,4-trimethoxybenzene [4] followed by oxidative demethylation [5] Thus, reaction of diene 2 with quinone 3 [3] (obtained by ortho-methylation of 1,2,4-trimethoxybenzene [4] followed by oxidative demethylation [5] …”

Catalytic Activity Studies of Vanadia/Silica–Titania Catalysts in SVOC Partial Oxidation to Formaldehyde: Focus on the Catalyst Composition

“…For the V/Ti catalyst the O 1s spectrum shows a peak centered at 530.41 eV and a tail extending to higher binding energy (centered at 531.92 eV). Odriozola et al [36] explained that for the O 1s peak at ca. 532 eV, a so-called tail can be resolved and explained by the presence of hydroxyl species.…”