Role of V2O5-WO3/H2Ti3O7-nanotube-model catalysts in the enhancement of the catalytic activity for the SCR-NH3 process

In this work, a series of titanic acid nanotubes (TANs) were synthesized through the hydrothermal method. TiO2-nanocrystals as starting materials were used. V2O5-WO3 was incorporated to the TANs by wet impregnation. The catalysts were characterized by XRD, BET, XPS, FTIR and STEM. The catalytic tests were focused on the Selective Catalytic Reduction of NO by NH3 (SCR-NH3). It was observed that the catalytic activity of the V2O5-WO3/TAN catalysts was strongly improved for the SCR-NH3 process in a wide temperature interval in comparison with the V2O5-WO3/TiO2 traditional catalysts. The strong tubular structure, titanic acid phase (H2Ti3O7), good thermal stability (up to 460 degrees C) and high specific surface area (314 m(2)/g) help to promote the NO conversion between 300 and 440 degrees C. The highest catalytic activity can be correlated with the presence of acid sites. Bronsted acid sites increase significantly the light-off conversion at low temperatures. Lewis acid sites promote the NO reduction at high temperature. The V2O5-WO3/TAN catalyst showed very high activity (81%) at high temperatures (350-450 degrees C) even in the presence of water (10 vol.%) and SO2 (50 ppm) in the feed stream. Besides, the sulfated and hydrated catalysts recovered their original catalytic activity. (C) 2014 Published by Elsevier B.V.