Decoupling reaction network and designing robust VO_x/Al₂O₃ catalyst with suitable site diversity for promoting CO₂-mediated oxidative dehydrogenation of propane

Detailed thermodynamic analysis was utilized to decouple the complex reaction network of CO₂-mediated oxidative dehydrogenation (CO₂-ODH) of propane and unravel critical catalyst design requirements. Inspired by the unmatched ability of boron-based catalysts in limiting cracking and overoxidation reaction pathways, we exploited controlled integration of both VOx and BOx active phases onto a γ-Al₂O₃ support and constructed a highly efficient CO₂-ODH catalyst via scalable mechanochemical synthesis route. The solvent- and template-free synthetic design strategy regulated crucial properties of the catalysts and endowed suitable site diversity as evidenced from N₂-adsorption analysis, XRD, HRTEM, Raman analysis, NH₃-TPD, H₂-TPR, and UV–Vis diffuse reflectance spectroscopy. Consequently, excellent propane conversion and propylene yield of 61 and 34 % respectively over 12 h time on stream (TOS) at 650 °C were realized with a catalyst composed of 5 wt% vanadium and 7 wt% boron. In situ DRIFT measurement revealed insight into the dynamic changes on the catalyst surface and the corresponding evolution of reaction intermediates during the CO₂-ODH process. Overall, the thermodynamic investigation re-emphasized the critical importance of effective kinetic control while the synthetic protocol illustrated a promising avenue for rational design of CO₂-ODH catalysts to harness the unique advantages of boron and metal oxide-based catalysts simultaneously.