Nitroaromatic compounds, especially 4-nitrophenol, are considered to be toxic water pollutants, and hydrogenation of them into useful aniline derivatives is of interest from view point of synthetic and environmental scientists. Here, a metal-organic-framework (MOF) based on Zn(II) and terpyridinylbenzoic acid ligand and 2-aminoterephthalic acid connector was synthesized and used as support for the immobilization of Pd nanoparticles to develop an efficient catalyst for the hydrogenation of nitroaromatic compounds. A distribution of small and spherical Pd nanoparticles over the surface of the MOF was revealed from SEM and TEM images, in which the lattice fringes of the Pd NPs are shown with lattice spacing values of 0.23 nm. In the XRD pattern peaks appeared at 2θ = 40°, 46°, 68°, and 82°, which are characteristic of metallic palladium and confirm the formation of Pd NPs on the surface of the MOF. The successful formation of Pd NPs on the surface of the MOF was also confirmed by XPS analysis, in which the C, N, O, and Zn peaks of MOF structure along with the Pd 3d peak are shown. The synthesized Pd NPs supported on the MOF efficiently catalyzed hydrogenation of nitroaromatic compounds to the corresponding aniline derivatives. The study of the hydrogenation reaction kinetics, revealed that the hydrogenation of 4-nitrophenol follows pseudo-first order kinetic. The catalyst could be recycled and reused for four runs, without considerable loss in catalytic activity.
