Comparison of vanadium phosphate catalysts derived from VOPO4 center dot 2H(2)O prepared from H3PO4 and H4P2O7

Vanadium phosphate catalysts prepared from VOPO4. 2H(2)O are described and discussed. The use of H4P2O7 as a phosphorus source, as compared with H3PO4 , is shown to give an improved synthesis of VOPO4 . 2H(2)O. Reduction of VO PO4. 2H(2)O with alcohols from both the materials leads to the formation of VOHPO4.0.5H(2)O. However, the material derived from H4P2O7 has a higher in trinsic activity (mol maleic anhydride formed per unit surface area) than t hat derived from H3PO4. The final catalysts are shown to comprise (VO)(2)P2 O7 together with a range of V(V) VOPO4 phases and the origin of the enhance d activity is discussed in terms of the catalyst structure.