Tuning the selectivity of phenol hydrogenation using Pd, Rh and Ru nanoparticles supported on ceria- and titania-modified silicas

Abstract The large-scale production of biomass-derived fuels generates large amounts of lignocellulosic residues that may further be converted into bio-derived value-added chemicals. Here, we investigate the selective hydrogenation of phenol as a model compound for lignocellulosic derivatives. Pre-formed PVP-stabilized nanoparticles (NPs) of Pd, Ru and Rh prepared using an organometallic approach were immobilized on different magnetic silica-based supports modified with TiO2 or CeO2. In phenol hydrogenation studies, the Pd NP catalysts show high selectivity towards cyclohexanone, while Ru and Rh NP catalysts primarily afford cyclohexanol. Titania-containing supports increase the selectivity towards cyclohexanol for both Pd- and Rh-based catalysts. Interestingly, the combination of Ru NPs and titania-modified silica results in 100 % selectivity of cyclohexanol. After removal of the PVP-stabilizer by thermal treatment, the catalyst combining Pd NPs and titania-modified silica leads to 100 % selectivity towards cyclohexanone. Despite the difficulties associated with the de-polymerization of biomass residues, the development of new catalyst materials for highly selective transformations of biomass-derived platform molecules contributes to a sustainable production of various value-added chemicals for manifold applications.