Methods where vanadium in the precursor is reduced to V4+ in solution are well suited to the synthesis of vanadium-phosphorus catalyst because the high temperatures (500 to 800 °C) required to transform the precursor to the active catalyst are thus avoid, which is desirable from the chemical as well as structuro-physical aspects. The way of forming and activating the catalyst, i.e. the temperature regime of the treatment and the kind of the gas atmosphere, were found to affect appreciably the catalyst activity in the partial oxidation of butane to maleic anhydride.. Forming procedures resulting in sufficiently fine crystals and optimized lattice defects are suitable. The application of synthesis, forming and activation procedures exhibiting a low tendency to form, in the catalyst phase composition, condensed phosphates such as VO(PO3)2 or even V(PO3)3 is also beneficial to the catalyst activity. The catalytic properties of the vanadium-phosphorus catalyst which was prepared in concentrated HCl were improved considerably by doping the lattice with modifying metal cations.
Thermodynamic reassessment of Au-Pt-Sn system
