Strong Metal–Support Interaction over PtPdCu/Al₂O₃ toward Hydrogenation of Nitrobenzene

Multimetallic nanoparticles are an important class of catalysts with significant technological potential. In this work, trimetallic PtPdCu nanoparticles synthesized via a facile one-pot colloidal method were loaded on Al₂O₃. A two-step treatment, including ligand exchange and low-temperature annealing, was applied subsequently to remove the stabilizing ligands. We studied the effects of annealing temperature on the physicochemical properties of the supported PtPdCu nanoparticles and their catalytic activities for nitrobenzene hydrogenation. It is found that varying the annealing temperature of PtPdCu/Al₂O₃ catalysts not only effectively removes the surfactant, but also modulates the metal–support interaction between the metal nanoparticles and the support in terms of coverage of Al₂O₃ on metal nanoparticles, which further tunes the catalytic activity for nitrobenzene hydrogenation. The partially Al₂O₃-encapsulated PtPdCu exhibits better catalytic activity for hydrogenation of nitrobenzene to aniline over the fully Al₂O₃-encapsulated and surfactant-covered PtPdCu catalyst.