Preparation of COFs Supported Pd as an Efficient Catalyst for the Hydrogenation of Aromatic Nitro

The preparation of high-performance supported Pd catalysts for the hydrogenation of aromatic nitro is of great importance. In this paper, covalent-triazine framework (CTF), an organic porous crystalline material connected by covalent bonds, was employed as the support for the preparation of Pd heterogeneous catalyst. The framework of CTF was maintained due to the utilization of cyclohexene as a moderate reductant for PdCl2. The catalysts were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The influence of reaction conditions (temperature, pressure, reaction time, concentration substrate and catalyst dosage) were investigated. At very mild reaction conditions (30 °C, 0.1 MPa H2, 2 mg Pd/CTF), the nitrobenzene was nearly stoichiometric hydrogenated to aniline. The Pd/CTF was effective for the conversion of a series of aromatic nitro compounds to the corresponding aromatic amines with good yield. The results showed that Pd/CTF has good catalytic activity and stability in the heterogeneous catalytic hydrogenation.Graphical Abstract