Stabilization of palladium nanoparticles on chitosan derived N-doped carbon for hydrogenation of various functional groups

Abstract

We report the synthesis of uniformly dispersed and stable palladium nanoparticles (Pd NPs) on N-doped graphitic carbon (N-C) derived from benign chitosan. The Pd@N-C nanocatalyst was synthesized by carbonization of Pd-chitosan complex at 800 °C under a nitrogen atmosphere, wherein chitosan obtained from fishery bio-waste served as carbon and nitrogen source. The as-synthesized nanocatalyst was characterized by several techniques; the elemental mapping by SEM and TEM analysis confirmed the uniform distribution of the Pd nanoparticles on the surface of N-doped carbon with an average size in the range of 2–6 nm. Temperature programmed chemisorption studies showed 32.27% Pd metal surface area available for reaction. This catalyst with low loading of active palladium metal was used for the hydrogenation of various reducible groups including >C=C<, >C≡C<, -NO2, -CHO and epoxides at room temperature (30 °C) and moderate H2 pressure (5 bar). The catalyst offered nearly complete conversion with >99% selectivity towards desired product. The excellent performance of the catalyst may be attributed to the dual role of N-rich carbon source which acts as a stabilization platform for palladium nanoparticles and also provides a basic environment. Furthermore, the catalyst can be easily recovered and recycled for five cycles without any significant loss in catalytic activity and selectivity.