Surface area and porosity, X-ray diffraction and chemical analyses

Texture, structure and composition of the fresh and the used EUROCAT oxide V2O5-WO3/TiO2 SCR catalysts have been investigated with aid of nitrogen adsorption/desorption at 77 K, mercury porosimetry, X-ray diffraction and chemical analyses. The BET specific surface area is around 47 and 46 m(2)/g for the fresh and the used catalyst, respectively. Both samples are essentially mesoporous, with pore diameters centred in the range 10-20 nm according to the data derived from the nitrogen adsorption and around 40 nm according to the mercury porosimetry. The anatase form of TiO2 and traces of orthorhombic V2O5 are the only crystalline phases identified in both materials. According to the chemical analysis there are no significant differences in the contents of the main constituting elements between the fresh and the used catalyst. Selective dissolution with NH3 aq. reveals that in the used catalyst the amount of vanadium component not susceptible to the treatment increases. (C) 2000 Elsevier Science B.V. All rights reserved.