Vanadium containing heteropoly molybdates as precursors for the preparation of MoVP oxides supported on alumina catalysts for ammoxidation of m-xylene

Vanadium incorporated molybdophosphoric acid (MPAV) was used as a precursor to prepare MoVP oxide supported on alumina catalysts. The catalysts were prepared by impregnation of MPAV on alumina and subjecting them to calcination at 450 °C. The catalysts were characterized by X-ray diffraction, Fourier transform infrared, temperature programmed reduction and X-ray photo electron spectroscopy to study the nature of interaction of MPAV with Al2O3. The characterization results revealed the decomposition of MPAV Keggin ion on alumina and the formation of its constituent oxides during calcination. The nature of metal oxide species formed on the surface of alumina depended on MPAV loading and the V content. The crystalline nature of metal oxides derived from the decomposition of MPAVx increased with increase in vanadium content. The activity of the catalysts during the ammoxidation of m-xylene also depended on MPAV loading and the content of V, as they were responsible for the dispersion of the constituent metal oxides on alumina.

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► MPAV supported on alumina catalysts are active for ammoxidation of m-xylene.
► The ammoxidation activity depends on content of V in MPA and MPAV on support.
► Minimum amount of V is favorable in heteropoly molybdate.
► MoO3 and V2O5 derived from MPAV are responsible for ammoxidation activity.