Effect of carbon oxygen functionalization on the activity of Pd/C catalysts in hydrogenation reactions

This paper presents a study onthe effects of oxygen functionalities on a mesoporous and graphitized carbon support(GNP, Graphene Nanoplatelets),on thecatalytic activity of Pd/GNPcatalystsin hydrogenation reactions. A functionalization method in liquid phase has been employed,using different oxidants (HNO3, H2O2, KMnO4),with the aim to tune the amount and the type of introduced oxygen functionalities. PreformedPd nanoparticles have been used as Pd-precursor to limit differences in metal particle size and dispersion on differently functionalized carbon. Thecatalytic behaviour inbenzaldehyde hydrogenation/hydrogenolysis to benzyl alcohol and toluenerevealed that theintroduction of oxygen functionalities has a generallydetrimental effect.NMR relaxometry studies highlighted the weakerinteraction between the carbonyl group and the functionalized Pd/GNPsurfacethan the non-functionalized Pd/GNPdemonstrating that the origin of the different catalytic activity lies on the first step of the reaction. O-functionalities also impacted on the Pd0/Pd2+ratio at the surfacewhich is an establishedparameter correlated to the reactionrate.