Fluorine-Stabilized High-Valence Cobalt on Silicalite-1 Zeolite Synergizing with Adjacent Silanol Groups for Propane Dehydrogenation via Polarized C–H Bond Activation

Propane dehydrogenation (PDH) is vital to meet the rapid global demand for propylene. However, non-noble cobalt-based catalysts still suffer from inefficient C–H activation, necessitating precise microenvironment engineering. Herein, an NH4F-assisted in situ crystallization strategy for silicalite-1 (S-1) zeolite is developed to tailor both the framework structure and Co oxidation state. OH-FTIR spectra confirm that fluorine (F) incorporation heals silanol defects. At optimal F/Si = 0.23, F mediates interfacial interaction between high-valence Coδ+ sites and Si–O–F moieties. Energy-dispersive X-ray (EDX) mapping further reveals spatial colocalization of F and Co species. In the PDH reaction, electron-deficient Coδ+ species promote polarization and weakening of the inert C–H bonds of propane, initiating dehydrogenation; the activated H atoms are subsequently transferred to adjacent silanol groups (Si–OH), where they recombine on adjacent surface sites and desorb as H2. Consequently, the optimized Co2/S-1-23F (where “23F” refers to an F/Si molar ratio of 0.23 used in the synthesis gel) catalyst achieves 57.4% initial propane conversion and >97% propylene selectivity at 550 °C. Comprehensive characterizations indicate that F acts as a dual electronic and structural additive, and optimal PDH performance originates from balanced multifunctionality instead of maximum fluorine loading, offering a practical strategy for designing high-performance non-noble PDH catalysts.