Oxidative Dehydrogenation of n-Butane to C4 Olefins Using Lattice Oxygen of VO _x/Ce-meso-Al₂O₃under Gas-Phase Oxygen-Free Conditions

High-performance, fluidizable VOx/Ce-meso-Al2O3 catalysts were prepared by an excessive solvent approach. The prepared catalysts were characterized using various physicochemical techniques in order to secure desired properties. XRD, Raman, and FTIR analyses indicated the presence of amorphous VOx phases on Ce-meso-Al2O3. Nitrogen adsorption isotherm analysis confirmed a mesoporous framework with a high surface area of the catalysts. H2-TPR reduction showed an active and stable behavior of the catalysts in repeated reduction and oxidation cycles. The NH3-TPD and NH3 desorption kinetics analysis revealed that the synthesized catalysts have moderate acidities and low activation energies of NH3 desorption, suggesting weak metal-support interactions. The VOx/Ce-meso-Al2O3 catalysts were evaluated for n-butane oxidative dehydrogenation (BODH) using a fluidized CREC riser simulator under gas-phase oxygen-free conditions. The reaction time and reaction temperature were varied between 5 and 25 s and 450-575 °C, respectively. It was found that BODH with 0.2 wt % cerium-doped VOx/meso-Al2O3 catalysts gives the highest selectivity (62.3%) of C4 olefins with a conversion of 10.6% at 450 °C and 5 s. Furthermore, the fluidizable VOx/Ce-meso-Al2O3 catalyst showed a stable performance over repeated feed injections followed by catalyst regeneration cycles for BODH.