On the Reaction between Ammonium Metavanadate and Potassium Hydrogen Sulfate at Different Temperatures

The reaction products resulting from the interaction of ammonium metavanadate and potassium hydrogen sulfate were characterized by chemical and thermal analysis, X-ray diffraction patterns, ligand field spectra, and magnetic susceptibility. The interaction between the two salts was found to start as early as 50°C. The identity of the products depends essentially on the temperature and time of reaction in addition to the molar ratio of the reactants. The product compounds were composed, in general, of bronzes and polyvanadates in addition to some tetra- and pentavalent vanadium compounds. The production of tetravalent vanadium compounds may arise via the intervention of diamagnetic dioxovanadium (V) sulfite VO2(SO3)0.5 which is unstable above 200°C and transforms to vanadyl sulfate (VOSO4) which in turn reacts with K2SO4 forming K2VO(SO4)2.