Enhancing Stability and Activity of Fe-Based Catalysts for Propane Dehydrogenation via Anchoring Isolated Fe-Cl Sites.

The eco-friendly features and desirable catalytic activities of Fe-based catalysts make them highly promising for propane dehydrogenation (PDH). However, simultaneously improving their stability and activity remains a challenge. Here, we present a strategy to address these issues synergistically by anchoring single-atom Fe-Cl sites in Al vacancies of AlO. The as-synthesized Fe-Cl/AlO catalyst exhibited greater charge transfer between Cl and Fe than that between O and Fe in conventionally impregnated single-atom Fe/AlO catalysts, resulting in higher effective magnetic moments for Fe-Cl/AlO compared to Fe/AlO. When tested in PDH, the durability of Fe-Cl/AlO exceptionally lasted for 250 h under continuous regeneration conditions comprising 60 % CH (40 % N), followed by pure CH at 600 °C while maintaining a high propylene space-time yield of 1.2 mol g  h, surpassing the performance of previously developed Fe-based PDH catalysts. We demonstrate that anchoring Fe-Cl into Al vacancies simultaneously enhances stability and suppresses coke formation, owing to unique atomically dispersed Fe-Cl active structures. Compared with Fe/AlO catalysts, charge transfer between Cl and Fe active centers reduces the activation energy barrier for C-H activation during CH dehydrogenation, thereby improving catalytic activity; this may be related to their spin state as observed in in-situ X-ray emission spectroscopy studies during PDH.