Enhanced resistance to poisoning of Pd in alkynes semi-hydrogenation by metal–ligand electronic interactions

Given that the retention of nitrogen readily renders active site poisoning, designing versatile catalysts characterized by notable selectivity and even resistance to poisoning for alkyne semi-hydrogenation under nitrogen-containing conditions is considerably challenging. In this article, oxanilide-decorated Pd/C (Pd/C-oxa) catalyst is facilely synthesized by leveraging impregnation-coordination, which exhibit remarkable performance in the semi-hydrogenation of nitrogen-containing alkynes, with ultrahigh turnover frequency (TOF) of 15,831 h⁻¹ and selectivity of 97.2%. Strikingly, it still sustains TOF of 12,137 h⁻¹ in a sulfur-containing system, demonstrating distinguished tolerance to sulfur. Comprehensive studies corroborate that oxanilide tunes the electron density of Pd by constructing metal–ligand electronic interactions, facilitating hydrogen activation. Simultaneously, the reaction microenvironment is optimized, which effectively promotes the desorption of nitrogen-containing olefins and attenuates the aggregation of nitrogen on the Pd surface. This strategy is universal and holds promising industrial applications, making it appropriate for use in commercial Pd/C catalysts as well.