Oxidative dehydrogenation of propane to propylene over VOx/CaO-γ-Al2O3 using lattice oxygen

Oxidative dehydrogenation (ODH) of propane to propylene is studied using a new vanadium catalyst supported on CaO-gamma-Al2O3 under a gas phase oxygen free atmosphere. The catalysts are synthesized with different CaO/gamma-Al2O3 ratios, keeping the vanadium loading at 10 percent. The prepared catalysts are characterized using various physicochemical techniques. Raman spectroscopy reveals that the catalysts have monovanadate and polyvanadate surface species (VOx) with minute crystal particles of V2O5. FTIR spectroscopy and XRD analysis confirm the presence of V2O5, CaO and gamma-Al2O3 in the catalyst. The catalysts show stable reduction and re-oxidation behavior in repeated TPR and TPO cycles, respectively. NH3-TPD shows that catalyst acidity decreases with increasing CaO content. The NH3-TPD kinetics analysis reveals that the activation energy of desorption increases with higher CaO, indicating stronger active site-support interactions. The ODH of propane experiments are conducted in a fluidized CREC Riser Simulator under gas phase oxygen free conditions. Among the studied catalysts, VOx/CaO-gamma-Al2O3 (1 : 1) displays the highest propane conversion (65%) and propylene selectivity (85%) and a low COx due to its excellent oxygen carrying capacity, balanced acidity and moderate active site-support interactions.