ChemInform Abstract: Comparison of Vanadium Phosphate Catalysts Derived from VOPO4×2H2O Prepared from H3PO4 and H4P2O7.

Vanadium phosphate catalysts prepared from VOPO4 ·2H2O are described and discussed. The use of H4P2O7 as a phosphorus source, as compared with H3PO4, is shown to give an improved synthesis of VOPO4·2H2O. Reduction of VOPO4·2H2O with alcohols from both the materials leads to the formation of VOHPO4·0.5H2O. However, the material derived from H4P2O7 has a higher intrinsic activity (mol maleic anhydride formed per unit surface area) than that derived from H3PO4. The final catalysts are shown to comprise (VO)2P2O7 together with a range of V(V) VOPO4 phases and the origin of the enhanced activity is discussed in terms of the catalyst structure.