Synergizing Pd₁Sb₂ Site with Neighboring Near-Surface Pd Site to Break the Trade-Off between Selectivity and Activity...

Catalytic hydrogenation of trace alkynes in excess alkenes is essential for producing polymer-grade olefins from steam cracking and alkane dehydrogenation, but achieving high selectivity without sacrificing activity remains a significant challenge. Herein, we report a catalyst design that synergistically integrates computationally proposed surface Pd₁Sb₂ trimer sites with near-surface Pd sites (Pd_ns) on the P6₃/mmc PdSb intermetallic catalyst to achieve the semihydrogenation of alkynes with both high activity and selectivity. Alkynes can be readily activated through strong σ-bonding on the Pd₁Sb₂ trimer sites, whereas alkenes are only weakly adsorbed via π-interactions due to their matched electronic structures and spatial configurations. Moreover, the neighboring Pd_ns cooperates with the Pd₁Sb₂ sites to achieve spontaneous dissociation of H₂ for subsequent hydrogenation. Consequently, the fabricated PdSb intermetallic catalyst exhibits ethylene and propylene selectivities of 96.50% and 98.65%, respectively, at nearly complete conversions of acetylene and propyne, under industrially relevant conditions, outperforming state-of-the-art catalysts. This study demonstrates a promising strategy that synergizes near-surface and surface ensemble sites to spatially and energetically match with the target reaction pathway, enabling the overcoming of the trade-off between activity and selectivity in hydrogenation.