Infrared spectroscopic study of the effects of hydration and reduction of V2O5/Al2O3 catalyst on ammonia adsorption

Abstract

The effects of hydration and reduction of V2O5/Al2O3 catalyst (14.7% V2O5) on ammonia adsorption have been studied by infrared spectroscopy. Both the oxidation-reduction state of the catalyst and the degree of surface dehydration have an influence on the proportions of Broensted and Lewis acidic adsorption sites in the surface. For adsorption at room temperature, the proportion of ammonia bound to Broensted acidic sites in the form of NH4+ is highest with oxidized and weakly dehydrated catalyst surfaces, decreasing as the degree of reduction and dehydration temperature are increased. Negligible proportion of this form is present on strongly reduced catalyst dehydrated at 763 K.