Novel microwave-assisted synthesis of magnetic palladium catalysts for the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde

Microwave (MW)-assisted hydrothermal synthesis of metal catalysts represents an innovative sustainable approach because of environmental friendly and less energy-demanding conditions with respect to conventional methods. On the other hand, catalysts separation and recycle represent fundamental steps for the overall economy and sustainability of industrial processes. Therefore, the use of heterogeneous catalysts with magnetic properties allows efficient separation from the reaction medium by simple application of an external magnetic field. Now we report a novel sustainable approaches for the microwave-assited synthesis of palladium nanoparticles supported on conventional supports (alumina, active carbon, polymeric supports) and on two diverse magnetic supports: maghemite and magnetite. All these catalytic systems are synthesized adopting new approaches which are characterized by a simple procedure, the use of a green solvent such as aqueous ethanol, short reaction times, an efficient heating source and the absence of any high-boiling stabilizing agent or organic surfactant. The obtained nanocatalysts were then characterized by FT-IR, TEM, XRD, BET and VSM analyses. They were employed in a model reaction, the selective hydrogenation of cynnamaldehyde to hydrocinnamaldehyde, with promising results.