Optimization of V2O5-MgO/TiO2 catalyst for the oxidative dehydrogenation of propane effect of magnesia loading and preparation procedure

The effect of magnesia loading and preparation procedure of vanadia on titania catalysts on the physicochemical characteristics and the performance in propane oxidative dehydrogenation were investigated. A series of magnesia promoted vanadia catalyst (5 wt% V2O5) with varying amounts of MgO (1.9-10 wt%) were synthesized by synchronous and sequential deposition on titania support. The catalysts were characterized using several techniques (BET, XRD, H-2-TPR and NH3-TPD). Both MgO loading and preparation procedure affect the catalyst surface properties and the behavior in the oxidative dehydrogenation of propane. Magnesia addition results in drastic increase in propene selectivity, while the effect on activity is negative. The activity is inversely related with the magnesia loading. Deposition of V2O5 on previously prepared MgO/TiO2 presents a beneficial effect in the activity of the sample. The role of acidity and reducibility is explored. There is no correlation between reducibility and activity of the catalysts, whereas the acidity seems to influence the catalytic performance. Catalyst containing 5 wt% V2O5 and 1.9 wt% MgO prepared by sequential deposition of V2O5 on already doped with MgO titania exhibits the most interesting results.