Synthesis of palladium-chelated poly(triazine imide) heterogeneous nanocatalysts for reduction of p-nitrophenol to p-aminophenol

摘要

In this work, state-of-the-art Pd-chelated poly(triazine imide) (Pd-PTI) nanocatalysts were synthesized with PTI, as cheap solid support, and different Pd contents by an easy co-precipitation method for conducting the model reduction reaction of p-nitrophenol to p-aminophenol. The electron microscopy observations (i.e., scanning electron microscopy and transmission electron microscopy), quantitative dispersive X-ray spectroscopy and elemental mapping images demonstrated that Pd nanoparticles (NPs) were homogeneously loaded on the surface of highly crystalline two-dimensional (2-D) PTI nanosheets. Among the all prepared Pd-PTI nanocatalysts, the PTI-1500-Pd indicated the highest pseudo-first-order rate constant of 12.7 x 10(-3) s(-1), which was significantly higher than that of the recently reported Pd-based nanocatalysts. This catalyst showed ultrahigh, superior catalytic efficiency (>= 99) and stability properties for the hydrogenation of p-nitrophenol within 40 s under mild conditions and possessed excellent recovery (>= 90) of expensive Pd NPs after five consecutive cycles. The high-catalytic performance of the PTI-1500-Pd nanocatalyst is related to specific properties of the highly crystalline structure, high-surface area and very available surface amine groups of 2-D PTI nanosheets, which functioned as an active site for immobilizing ultrafine Pd-0 NPs.