ChemInform Abstract: The Influence of Support on the Activity of Monolayer Vanadia‐Titania Catalysts for Selective Catalytic Reduction of NO with Ammonia.

Abstract

V2O5-TiO2 catalysts, prepared by VOCl3 grafting into the TiO2 surface and those modified by W6+ insertion into TiO2, are characterized by XPS, XRD, EPR, SIMS, electric conductivity, DRS UV/vis, BET, ICP, and X-ray fluoresecence methods. As revealed from the catalytic activity data, the specific activity, activation energy, and turnover frequency do not depend substantially on the crystal structure of TiO2. Reoxidation of reduced vanadia species, whose activation energies coincide with that of the SCR process, seems to be rate-limiting for this process. A common reaction mechanism is assumed for the SCR of NO by NH3 with and without O2. About 30% of the supported vanadia penetrates into the sublayers of titania independent on the method of vanadia introduction. -(MARSHNEVA, V. I.; SLAVINSKAYA, E. M.; KALINKINA, O. V.; ODEGOVA, G. V.; MOROZ, E. M.; LAVROVA, G. V.; SALANOV, A. N.; J. Catal. 155 (1995) 2, 171-183; Inst. Catal., Novosibirsk 630090, Russia; EN)

Influence of attrition milling on V/Ti catalysts for the selective oxidation of ammonia

“…It is known that ammonia adsorbed on Brönsted acid sites is desorbed at lower temperatures than that on Lewis acid sites[9,27]. For V 2 O 5 /TiO 2 catalysts, ammonia is reportedly desorbed from the Brönsted acid sites with an activation energy of 12-14 kcal/mol and from the Lewis acid sites with an activation energy of 24-27 kcal/mol[28]. The present NH 3 -TPD analysis shows that the NH 3 desorption peak was the largest in the temperature range of 80-400 °C for the sample prepared using an attrition milling time of 3 h. It appears that milling induced an increase in of Brönsted and Lewis acid sites on the catalyst surface with the use of a milling time of up to 3 h. The total acidity (mmol/m 2 ) was calculated from the desorption peak to compare the amount of NH 3 adsorbed on the acid sites of the catalysts; the results are shown in…”