Sol-gel synthesis and catalytic properties of vanadium phosphates

Vanadium phosphates with variable specific surface areas were synthesized f rom vanadium alkoxides and phosphoric acid by precipitation in various solv ents. The catalytic properties were studied in the reaction of methanol oxi dation. Although the specific activities increase with the specific surface areas (BET), the intrinsic activities seem to depend on the particle morph ology. The selectivities do not vary within a large range. The same method of precipitation was applied to prepare vanadium phosphates on a silica sup port. It is shown that the supported phase is highly dispersed, and that th ese supported catalysts are more stable than silica-supported vanadium oxid e for methanol oxidation.