Hydrogenation of nitrobenzene over Pd/C catalysts prepared from molecular carbonyl–phosphine palladium clusters

Molecular phosphine–carbonyl palladium clusters were anchored onto a phosphine-functionalized carbon support (CPPh2) by ligand exchange. This support was characterized by solid-state NMR prior to reaction with the clusters. The same clusters were also deposited on the non-functionalized support (CSX+). Characterization by SEM and XPS showed that the surface was more uniform when using the functionalized support. After thermal activation, the Pd/C materials obtained were characterized by CO chemisorption, XPS, SEM, TEM, powder XRD and analyzed for metal loading by ICP-OES. Again, the solids prepared with the functionalized support presented a more uniform surface. TEM indicated that small nanoparticles (1–10 nm) were present on the surface with narrow size distributions. The activated Pd/C materials proved to be efficient catalysts for the hydrogenation of nitrobenzene into aniline. They were competitive with commercial and literature catalysts. Moreover, the catalysts prepared using the functionalized support were more active and more stable than when using CSX+.

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► A phosphine-functionalized carbon was used for covalent anchoring of clusters.
► Pd clusters were covalently fixed onto a carbon support and activated thermally.
► Small nanoparticles were obtained from anchored Pd clusters.
► The cluster-derived Pd nanoparticles were active for nitrobenzene hydrogenation.
► Catalysts derived from functionalized supports showed higher activity and stability.