Stabilizing Pd Catalysts on Pentacoordinated Al ³⁺ Sites of Alumina for Efficient Hydrogenation of Hexafluoropropylene

Achieving high dispersion and stability of noble metals on conventional supports remains a key challenge in catalysis. Herein, we address this issue by designing an alumina support enriched with pentacoordinated Al ³⁺ (Al ³⁺ penta) sites, which serve as effective anchoring centers for Pd species. The catalyst was applied to the gas‐phase hydrogenation of hexafluoropropylene (HFP), a critical step in the synthesis of the low‐global‐warming‐potential refrigerant HFO‐1234yf. Comprehensive characterization, including ²⁷ Al MAS NMR, XPS, and HRTEM suggest that the Al ³⁺ penta sites strongly interact with Pd, forming Pd‐O‐Al bridge structures, thereby suppressing Pd aggregation and enhancing Pd dispersion. The optimized 0.5 wt% Pd/EA‐Al ₂ O ₃ catalyst achieved approximately 92% HFP conversion at 90°C, significantly outperforming conventional Pd/γ‐Al ₂ O ₃ counterpart. This work underscores the decisive role of Al ³⁺ penta sites in regulating metal‐support interactions and provides a viable strategy for designing efficient catalysts with reduced noble‐metal loadings.