Tuning the structure and reactivity of zeolite-confined Pt catalysts by Ga incorporation for enhanced propane dehydrogenation

Pt-based catalysts confined within silicalite-1 (S-1) zeolites offer promising selectivity for propane dehydrogenation (PDH), but their long-term stability remains limited due to metal sintering and coke deposition. In this study, a series of Pt@S-1 catalysts with systematically varied Ga contents were synthesized via ligand-assisted hydrothermal encapsulation of Pt and in situ Ga incorporation. Structural characterizations reveal that Ga is introduced as both framework (Ga F ) and extra-framework (Ga EF ) species. Under H 2 treatment, Ga EF partially transforms into either PtGa alloy nanoparticles and Ga δ+ species, leading to the formation of Pt-Ga δ+ -H ensembles within the zeolite channels. These Ga-related species were associated with improved Pt dispersion, suppressed sintering, and reduced coke formation. The optimized catalyst, 1Pt24Ga@S-1, exhibited the most favorable PDH performance, achieving an initial propane conversion of 38.2 % and a propylene selectivity of 94.8 %. Under H 2 co-feeding (C 3 H 8 :H 2 = 1:1), it achieved a propylene production rate of 7.97 mol C3H6 ·g Pt -1 ·h -1 . The deactivation constant decreased from 0.247 h -1 for the undoped catalyst to 0.086 h -1 with Ga incorporation, and further declined to 0.008 h -1 under H 2 , reflecting improved stability. These results suggest that Ga incorporation contributes to both structural and electronic modifications of confined Pt species, offering insights into the design of more stable and selective PDH catalysts.