Amorphous Vanadium Phosphate Catalysts from Supercritical Antisolvent Precipitation

Crystalline vanadium phosphate catalysts (VPO) are the only example of a commercial heterogeneous partial oxidation catalyst for the activation of alkanes. The origin of activity is generally accepted as being associated with the crystallinity of the compounds. Here we describe a new preparative route to VPO using antisolvent precipitation with supercritical CO2 to generate amorphous microspheroidal VPO, which produces a material with an activity per unit area comparable to those of conventional crystalline VPO catalysts. This finding throws doubt on the currently accepted view for the origin of the activity of VPO catalysts and the role of crystalline phases.