Calorimetric Study of Vanadium Pentoxide Catalysts Used in the Reaction of Ethane Oxidative Dehydrogenation

Article abstract of DOI:10.1021/j100184a035

Vanadium pentoxide catalysts have been studied in the partial oxidation reaction of ethane in the 723-843 K temperature range.The relationship between the acid-base properties and the catalytic behavior was investigated.The number and character of acidic sites of V2O5 catalysts were determined by studying the adsorption of a basic molecule using microcalorimetry.The reducibility level and the evolution of the surface state, as well as the heat evolved, were studied by using a pulse method with pure ethane only.The reaction of ethane oxidative dehydrogenation was studied by a continuous flow method and the activation energies for the formation of C2H4 and CO were calculated.The selectivity of the catalyst was interpreted in connection with the acid-base properties.The strong sites were observed to decrease rapidly with time on stream, although the catalysts were still active.Temperature-programmed reduction of V2O5 using a TG-DSC coupling was also investigated with hydrogen, ethylene, or ethane as reducers.The different heats of reduction are given.It was observed that C2H4 is a much more efficient reducing agent than H2 and C2H6.Following each reduction, reoxidation studies by oxygen were performed in the same equipment showing clearly different steps in the reoxidation process.