Insights into the Oxidative Dehydrogenation of Ethylbenzene with CO2 Catalyzed by the Ordered Mesoporous V2O5–Ce0.5Zr0.5O2–Al2O3

The ordered mesoporous V2O5 (9 wt %)–Ce1–xZrxO2 (7 wt %)–Al2O3 (VCA-x, x = 0, 0.5, and 1) was successfully synthesized by combining the hydrothermal and the modified evaporation-induced self-assembly methods. The mixed oxides were evaluated as a catalyst for the oxidative dehydrogenation of ethylbenzene with CO2 (CO2-ODEB) under industrial relevant conditions, and VCA-0.5 showed the best performance during the 50 h test. Although the coke deposition could really cover the active site, block the pore channel, and decrease the specific surface area of the catalyst, the loss of the active V with a high oxidation state was rigorously revealed as the critical cause of the catalyst deactivation. Moreover, the best performance of VCA-0.5 was well explained as the efficient stabilization of V5+ by the redox cycle of Ce3+/Ce4+. This finding is beneficial to promote the advancement of an active and stable V2O5-based catalyst for CO2-ODEB.