• Sn-Promoted Pt-based Propane Dehydrogenation Catalysts Prepared by Surface Organometallic Chemistry

Propane dehydrogenation (PDH) catalysis has attracted increasing attention due to the central role of propene as a chemical feedstock and the expanded availability of shale gas. Despite its industrial importance, a detailed understanding of the benchmark Pt–Sn/γ-Al₂O₃ catalyst employed in the UOP Oleflex process remains incomplete, owing to intrinsic constraints of conventional impregnation-based synthesis methods and the lack of well-defined model systems. Here, we combine the surface organometallic chemistry (SOMC) approach with rigorous, stepwise characterization – notably through solid-state NMR (ssNMR) and X-ray absorption spectroscopy (XAS) – to prepare and interrogate surface-controlled SnII/γ-Al₂O₃ and Pt–Sn/γ-Al₂O₃ model catalysts and elucidate structure–activity relationships. Grafting Sn(OtBu)4 onto g-Al2O3 followed by high vacuum treatment yields isolated SnII supported sites, while subsequent grafting of (tmeda)PtMe2 and hydrogenolysis generates small Pt-Sn nanoparticles of a narrow size distribution, together with Pt or Sn single sites. Catalytic PDH studies confirm the promoter effect of Sn, resulting in enhanced productivity, selectivity and stability, while postmortem analyses of the spent catalyst indicate that catalyst deactivation is predominantly associated with coke formation.