V2O5/TiO2 and V2O5/TiO2–SO42− catalysts for the total oxidation of chlorobenzene: one-step sol–gel preparation vs. two-step impregnation

This paper examines the effect of the preparation method of sulfated and unsulfated V2O5/TiO2 catalysts on chlorobenzene total oxidation. In particular, the method of incorporation of vanadium, either by impregnation or by direct introduction of V during the preparation of TiO2 or TiO2–SO42− aerogel supports, is discussed. The obtained catalysts have been characterized by means of ICP-AES, N2 adsorption–desorption at 77 K, XRD, Raman spectroscopy, DRIFTS, XPS, H2-TPR and NH3-TPD. Without sulfate, the impregnated catalyst exhibits a higher V dispersion and performs better than the sol–gel catalyst. The beneficial effect of sulfate groups is clearly demonstrated as both the impregnated and one-pot sol–gel samples with sulfate markedly outperform the corresponding samples without sulfate. The sulfated one-pot sol–gel catalyst exhibits the best performance at high temperature, probably thanks to its sulfate-rich surface.