Green and facile synthesis of carbon nanotube supported Pd nanoparticle catalysts and their application in the hydrogenation of nitrobenzene

Carbon nanotubes (CNTs) supported Pd nanoparticle (NP) catalysts (Pd/CNTs) were prepared by a green and facile synthesis method based on hydrogen-bonding self-assembly. The size and loading of Pd NPs on catalysts were easily controlled by tuning both the relative amount of citrate to Pd salt in the solution and the relative amount of Pd NPs to CNTs. The size of Pd NPs on as-prepared catalysts can be tuned in the range of 3–6 nm, and Pd loading can be controlled in the range of 0–19 wt%. The catalysts were characterized by Brunauer–Emmett–Teller measurement, x-ray diffraction spectroscopy, and x-ray photoelectron spectroscopy. The performance of Pd/CNTs catalysts was evaluated in the hydrogenation of nitrobenzene. Compared with the catalysts prepared by the impregnation method or supported on conventional supports, Pd/CNTs catalysts show relatively higher activity and selectivity. The recyclability tests indicate that the Pd/CNTs catalysts can be used at least five times without significant loss in activity and selectivity.