A phosphate-modified irregular Pd catalyst derived from heteropolyoxopalladate (Pd15.4) clusters for selective hydrogenation of acetophenone.

Selective reduction of ketones to alcohols occupies a pivotal position in the fine chemicals industry, wherein precise modification of catalytic active sites represents a promising approach for developing highly selective catalysts. Here we report a strategy to enhance the selectivity toward 1-phenylethanol by modifying the active sites of irregular Pd nanoparticles with phosphate species. Phosphate modification is achieved via hydrogen reduction of preformed, well-defined heteropolyoxopalladate clusters (Na12[Pd0.4Na0.6Pd15P10O50H6.6]·36H2O, Pd15.4). Experimental results demonstrate that the electron-rich phosphate groups interact with Pdδ+ species on irregular Pd nanoparticles, thereby enhancing selectivity by regulating substrate adsorption preferences. Meanwhile, the introduced phosphate species facilitate the proton transfer process and alter the reaction pathway, enabling the catalyst to maintain high catalytic activity. By supporting the phosphate-modified irregular Pd nanoparticles on a TiO2 support, a heterogeneous catalyst with excellent selectivity, activity, and stability is successfully constructed. This work provides an effective catalytic system for pharmaceutical synthesis that demands high selectivity and offers important insights into active-site modification strategies.