Abstract
Supported vanadium-containing catalysts were prepared by impregnation of Al-pillared clays with NaVO 3 precursor aqueous solutions. A montmorillonite and a saponite, both natural as well as previously pillared with Al 13-Keggin polycations, were used as supports, being impregnated with solutions of the precursor by means of the incipient wetness technique. The layered structure of the supports is maintained after impregnation, and even after calcination of the impregnated solids at 500 °C, although with a significant worsening of the textural properties of the solids, in particular, a loss of specific surface area. Three crystalline vanadium-containing phases were identified in the impregnated solids, namely, NaV 3O 8, AlVO 4 and V 2O 5 (shcherbinaite). The reduction of these phases to V 3+ species was observed as wide processes in the 450–750 °C range, all of them centred at ca. 600 °C.
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