Investigation of Vanadyl Pyrophosphate Catalysts Synthesised from Three Different Routes.

Abstract

Three different methods were used to prepare vanadyl pyrophosphate
catalysts: (i) VPO, which is the classical organic way of
preparing vanadyl pyrophosphate by reacting V₂O₅ in a mixture of
isobutanol and benzyl alcohol prior to the addition of H₃PO₄;
(ii) VPA, the earliest way; of preparation by digesting V₂O₅ in concentrated
HCl prior to  H₃PO₄  addition, and (iii) VPD,  the latest
way of preparation by pieparing VOPO₄·2H₂O before reacting with
isobutanol. The precursors were then calcined in n-butane/air
(0.75% n-butane/air) for 75 h at 673 K. The catalysts obtained were
characterised by BET surface area measurements,  ICP,  XRD,  volumetric
titration and SEM-EDAX.