Influence of the acid–base/redox properties of TiOx-sepiolite supported vanadium oxide catalysts in the gas-phase selective oxidation of toluene

Catalytic behaviour in the selective oxidation of toluene of a series of vanadium systems supported on TiOx-coated sepiolite (6, 12 and 25 wt.% TiO2) with a vanadia loading around the theoretical monolayer (10 wt.%) has been investigated. The surface acid–base/redox properties of the solids were also evaluated by using 2-propanol conversion and pyridine chemisorption. The reducibility of surface vanadia species was studied by H2-TPR. Surface properties of vanadia species and, consequently, their catalytic behaviour were influenced by titania loading on sepiolite. Thus, the vanadium systems with the highest titania loading were the most active and selective in toluene oxidation. Furthermore, this behaviour seems to be mainly related to the density of the active sites capable of being reduced and producing propanone in the vanadium systems.