Polyurea-supported metal nanocatalysts: Synthesis, characterization and application in selective hydrogenation of o-chloronitrobenzene

Polyurea (PU) spheres with size of 2–10   μm were derived through the polymerization of CO 2 with 1,4-butanediamine, and characterized by FTIR spectroscopy, scanning electron microscopy and TG analysis. It was demonstrated that the PU spheres displayed flower-like morphology with the betel thickness around 30   nm, and they had high thermal stability. The resultant PU spheres were used to immobilize metal particles, and a series of PU-supported metal nanocatalysts including Pt/PU, Au/PU, Pd/PU were prepared via just mixing the metal precursors with the PU spheres in water, followed by the reduction of metal ions by NaBH 4 . Transmission electron microscopy examination indicated that the metal nanoparticles were distributed uniformly on the surface of the PU spheres with mean particle size less than 3.0   nm, and the Pt particles existed mainly in the form of metallic state as confirmed by the X-ray photoelectron spectroscopy analysis. The performance of the Pt/PU catalyst was tested in the catalytic hydrogenation of o -chloronitrobenzene, and a high selectivity of 99.5% toward o -chloroaniline at complete conversion of o -chloronitrobenzene was obtained at room temperature.