Palladium Nanosheet-Carbon Black Powder Composites for Selective Hydrogenation of Alkynes to Alkenes

Ultrathin palladium nanosheets on carbon black grains have been straightforwardly prepared under reductant-free conditions using ultrasonication. The as-prepared composites (showing a quite unusual morphology of Pd-deposits) have been scrutinized as catalysts in the selective alkyne-to-alkene hydrogenation under mild operational conditions. Their activity, selectivity, and robustness in the process are outstanding, opening new horizons for simpler synthetic procedures for this class of composites. Moreover, the tight anchorage of the large and thin metal sheets to the carbon grains of the support dramatically reduces the active phase surface mobility during catalysis. Besides preserving the catalyst performance, this peculiar palladium morphology strongly limits the environmental risks stemming from metal nanoparticles leaching in heterogeneous catalysts.