Transition metal modified lacunary heteropoly compounds as catalysts for oxidation of light paraffins

Lacunary tungstophosphoric heteropoly compounds (HPW11) of Keggin structure modified with transition metal ions (Fe2+, Fe3+ and Mn2+) were applied as catalysts for oxydehydrogenation (ODH) of propane. The activity of iron modified HPW11 was unstable in the reaction under investigation. High activity and selectivity for oxydehydrogenation reaction were achieved as a result of modification of heteropoly compounds with excess of manganese ions. Thermal treatment (400-500 degreesC) of HPW11, modified with excess of manganese ions, resulted in the formation of a very active oxide Eke system. Lacunary heteropoly compounds play the role of a precursor for the formation of catalysts active for ODH. Stoichiometric HPW11 containing Mn2+ in the Keggin structure showed rather low activity. (C) 2002 Elsevier Science B.V. All rights reserved.