Functionalized Poly(ethylene glycol)-Stabilized Palladium Nanoparticles as an Efficient Catalyst for Aerobic Oxidation of Alcohols in Supercritical Carbon Dioxide/Poly(ethylene glycol) Biphasic Solvent System

The functionalized Poly(ethylene glycol) (PEG)-stabilized Pd(0) nanoparticles have been utilized to selectively oxidize alcohols to the corresponding aldehydes or ketones in supercritical carbon dioxide (scCO2)/PEG (PEG-2000) biphasic system. It was demonstrated that the Pd(0) nanocatalyst was more active and selective, in comparison with the commercially available Pd/C catalyst, PVP-stabilized Pd nanocatalyst and Pd(0) catalyst without stabilization. The effects of CO2 pressure, reaction time and temperature on activity and selectivity were also further investigated in detail. The scCO2/PEG biphasic system was proved to be not only cheap and clean, but also recyclable for the aerobic oxidation of alcohols.