Autor/a:
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Albani, Davide; Shahrokhi, Masoud; Chen, Zupeng; Mitchell, Sharon; Hauert, Roland; López, Núria; Pérez-Ramírez, Javier
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Abstract:
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Ensemble control has been intensively pursued for decades to identify sustainable alternatives
to the Lindlar catalyst (PdPb/CaCO3) applied for the partial hydrogenation of alkynes
in industrial organic synthesis. Although the geometric and electronic requirements are
known, a literature survey illustrates the difficulty of transferring this knowledge into an
efficient and robust catalyst. Here, we report a simple treatment of palladium nanoparticles
supported on graphitic carbon nitride with aqueous sodium sulfide, which directs the formation
of a nanostructured Pd3S phase with controlled crystallographic orientation, exhibiting
unparalleled performance in the semi-hydrogenation of alkynes in the liquid phase. The
exceptional behavior is linked to the multifunctional role of sulfur. Apart from defining a
structure integrating spatially-isolated palladium trimers, the active ensembles, the modifier
imparts a bifunctional mechanism and weak binding of the organic intermediates. Similar
metal trimers are also identified in Pd4S, evidencing the pervasiveness of these selective
ensembles in supported palladium sulfides. |