Oxidative Dehydrogenation of n-Butane to C4 Olefins Using Lattice Oxygen of VOₓ/Ce-meso-Al₂O₃ under Gas-Phase Oxygen-Free Conditions
2020
Khan, Muhammad Y. | Adamu, Sagir | Lucky, Rahima A. | Razzak, Shaikh A. | Hossain, Mohammad M.
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.
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