One-step non-hydrolytic sol-gel preparation of efficient V2O5-TiO2 catalysts for VOC total oxidation

Vanadia-titania catalysts are highly regarded for the control of industrial and domestic gas effluents. They are particularly used for the abatement of volatile organic compounds and for the removal of aromatic, polyaromatic and polychlorinated air pollutants like furans and dioxins. Here, mixed oxide catalysts are formed by non-hydrolytic condensation of chloride precursors with diisopropyl ether in non-aqueous medium. Calcination was applied to provoke the migration of the vanadium oxide toward the surface of the anatase particles, leading to well-spread vanadia species. The materials are made of mesoporous spherical particles of a few microns, themselves constituted by the aggregation of 10-25 nm sized particles. Their chemical composition is precisely controlled. The samples are characterized by ICP-AES, N-2-physisorption, XRD, XPS, SEM and TOF-SIMS. Their performances as total oxidation catalyst are evaluated in the deep oxidation of benzene, chosen as a model atmospheric pollutant. The activity of the materials compares well with that of catalysts prepared by classical wet impregnation. Along with the V surface concentration, the environment in which V surface species are located is identified as a key parameter. The superior activity of polymeric species as compared to isolated ones is shown. (C) 2009 Elsevier B.V. All rights reserved.