Exploring the stability of BO_x at various inorganic supports

Oxidative dehydrogenation of propane (ODHP) is a promising alternative route for producing light olefins, especially propene. Since the discovery of the exceptional activity of h-BN and other boron-based solids, their role in ODHP has attracted strong interest but remains insufficiently understood. Here, we provide the first direct experimental evidence of volatile boron oxide (BOₓ) species under ODHP conditions, revealed by TPD-MS and supported by XPS and solid-state NMR analyses. Advanced MAS ssNMR showed preferential coordination of BOₓ to Al in SiO₂-Al₂O₃ supports. BOₓ dispersion and stability were found to be strongly support-dependent: silica-supported BOₓ facilitates sublimation of boron oxides and propane activation at lower temperatures compared to γ-Al₂O₃ or SiO₂-Al₂O₃. Despite this, all systems follow identical selectivity-conversion trends. These results highlight a mechanistic pathway where volatile boron intermediates influence catalytic performance, advancing fundamental understanding and suggesting new strategies for designing selective, energy-efficient catalysts.