Alkane oxidation over bulk and silica-supported VO(H2PO4)2-derived catalysts

XRD and LRS were used to characterize both supported and unsupported catalysts derived from VO(H2PO4)(2). Supported VO(H2PO4)(2)-derived catalysts were found to be more active but slightly less selective in butane oxidation to maleic anhydride than unsupported samples, but the difference in selectivity could be eliminated by adding a small amount of phosphorus to the supported samples. For butane oxidation, the activity of the catalysts was much enhanced by the presence of alpha(1)-VOPO4. The relative rates of oxidation of propane, butane, and pentane were consistent with alkane activation occurring predominantly at the secondary carbon.