A study of some bivalent metal divanadates and their catalytic activity in the oxidation of propane

Abstract

The divanadates M₂V₂O₇ of a virtually unreducible and unoxidizable cation, Mg²⁺, of a reducible cation, Cu²⁺, and of an oxidizable cation, Mn²⁺, have been prepared and characterized by X-ray diffraction, surface area measurements, skeletal IR and UV-vis-NIR spectroscopies, and DTA-TG analyses. These materials have also been tested as catalysts for propane oxidative dehydrogenation at two different contact times. Mg divanadate is more active and more selective than Mn divanadate, while Cu divanadate is a little bit more selective than the Mg compound. The activity is likely mainly associated to the redox behavior of V cations which could be improved by reducible centers. Gas phase phenomena predominate at relatively low contact times and higher temperatures while true catalytic phenomena are observed at higher contact times and lower temperatures.