Insights into the vanadia catalyzed oxidative dehydrogenation of isobutane with CO2

Vanadia-based catalysts were prepared using the sal-gel method and were subjected to the oxidative dehydrogenation of isobutane with CO2. The materials were extensively characterized by using X-ray diffraction, N-2 adsorption-desorption, O-2-temperature programmed oxidation, temperature programmed surface reaction, and in situ Fourier transform infrared techniques. Catalytic results indicate that a high selectivity toward total C-4 olefins over 85% was obtained over all of the catalysts. On the contrary, the highest conversion of isobutane was observed over 12 wt% V2O3/Ce0.6Zr0.4O2(7 wt%)-Al2O3, and a more stable performance was achieved over 6 wt% V2O5-Ce0.6Zr0.4O2(7 wt%)-Al2O3. The catalytic activity for the titled reaction was found to be dependent on the dispersion and crystallinity of the VOx species over the catalyst, and the deposition of the heavier coke over the catalyst was revealed to be the main reason for the catalyst deactivation. Moreover, the benefit of CO2 toward the titled reaction was clearly revealed from TPSR results, and the reaction was confirmed to follow the redox mechanism. (C) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.