Chemoselective hydrogenation of cinnamaldehyde: A comparison of the immobilization of Ru-phosphine complex on graphite oxide and on graphitic surfaces

The homogeneous complex Ru(PPh3)(3)Cl-2 has been immobilized onto three different carbon materials: graphite, carbon nanofibers, and graphite oxide (GO). All the supports were previously functionalized with (bis(2-aminoethyl)amine). For graphite oxide, a second functionalization strategy using N-[3-(trimethoxysilyl)propyl]-etylenediamine (TPEN) was also followed. XRD, NMR, TG, TPD, DRIFTS, and XPS techniques were applied for the characterization of the functionalized supports and the hybrid catalysts. The hybrid catalysts have been tested in the hydrogenation of cinnamaldehyde and, although less active, they showed selectivities comparables to that for the homogeneous complex. The different behavior observed for the samples after recycling and reusing can be related to the ligand-support interaction type. While activity and selectivity are preserved for the Ru grafted on the covalent-functionalized GO-TPEN, variations in activity and selectivity are observed for the amine-functionalized samples. (C) 2011 Elsevier Inc. All rights reserved.