Palladium nanoparticles stabilized by polyethylene glycol: Efficient, recyclable catalyst for hydrogenation of styrene and nitrobenzene

We developed an efficient, simple chemical reduction method to produce highly active palladium (Pd) nanoparticles in polyethylene glycol (PEG) with no other stabilizer. The as-prepared Pd/PEG catalyst demonstrated a remarkable catalytic activity toward hydrogenation of both styrene and nitrobenzene under mild conditions. The Pd-PEG catalyst could be easily removed from the reaction mixture and its recyclability with no loss of activity was possible for seven times in case of styrene and three cycles for nitrobenzene. The catalytic performance was found to depend essentially on the catalyst and target concentrations and the reaction time. The catalyst was fully characterized by a variety of techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and N-2 adsorption-desorption isotherm. The reactivity of the Pd/PEG catalyst toward hydrogenation reactions is attributed to the high degree of dispersion of Pd(0) nanoparticles in PEG with small average particle size distribution of 5 nm. Results of the synthesis and characterization of Pd/PEG catalyst and its catalytic performance for hydrogenation reactions are presented and thoroughly discussed. (C) 2011 Elsevier Inc. All rights reserved.