Hole-Activated Lattice Oxygen Enables Pt-Free Propane Dehydrogenation by Eliminating the Hydrogen Recombination Bottleneck

Gallia-alumina (Ga_xAl_{2- x}O₃) enables efficient propane dehydrogenation (PDH) via C-H activation at Ga-O pairs, but the overall rate is limited by sluggish hydrogen recombination to H₂. Although Pt promotion alleviates this bottleneck, it introduces drawbacks including precious-metal cost and regeneration-induced sintering. Here, we show that Mg doping into Ga_xAl_{2- x}O₃ electronically activates lattice oxygen to enable rapid H₂ evolution directly on the oxide, eliminating the need for Pt promotion. Electron paramagnetic resonance spectroscopy reveals the formation of hole-type oxygen species upon Mg incorporation, while kinetic/isotopic measurements and theoretical calculations demonstrate substantially accelerated hydrogen recombination kinetics. In situ infrared spectroscopy further shows rapid depletion of surface hydrogen species, consistent with facilitated H₂ formation from Ga-H and O-H intermediates. At 853 K, Mg-doped Ga_xAl_{2- x}O₃ exhibits a threefold higher propylene formation rate than the undoped material at 97% propylene selectivity, outperforming benchmark PtSn/γ-Al₂O₃ and CrO_x/γ-Al₂O₃ catalysts. Furthermore, the fully oxide-based catalyst shows the slowest deactivation over 30 dehydrogenation-regeneration cycles. These findings establish lattice-oxygen electronic engineering as a practical strategy for achieving both high activity and exceptional regeneration stability in oxide-catalyzed dehydrogenation chemistry.