Performances of V2O5-based catalysts obtained by grafting vanadyl tri-isopropoxide on TiO2-SiO2 in SCR

A V2O5-based catalyst obtained by grafting vanadyl tri-isopropoxide on a Ti O2-SiO2 support obtained by grafting titanium alkoxide on silica has been s tudied as to the selective catalytic reduction (SCR) of NO with ammonia. Th e performances obtained have been compared with those of other catalysts in which V2O5 was supported, respectively, on the same support by impregnatin g it with ammonium vanadate and on TiO2 both by grafting vanadyl tri-isopro poxide and by impregnating it with ammonium vanadate. The first mentioned c atalyst turned out to be the best as to activities and selectivities. All t he used catalysts and supports have been characterised using many technique s in order to explain the different performances observed. As it will be se en, activities and selectivities, in the mentioned reaction, are mainly aff ected by three factors that are: (i) V2O5 dispersion largely favoured by th e grafting technique; (ii) the morphological properties of TiO2 surfaces th at cannot be foreseen but only investigated when TiO2 is obtained by grafti ng titanium alkoxide on the surface of another oxide and (iii) the type of surface acidity, retaining ammonia reagent. (C) 2001 Elsevier Science B.V. All rights reserved.