Synergistic catalysis of nano-Pd and nano rare-earth oxide/AC: complex nanostructured catalysts fabricated by a photochemical route for selective hydrogenation of phenol

Abstract

Cyclohexanone is an important industrial intermediate in the manufacture of polyamides in the chemical industry, but direct selective hydrogenation of phenol to cyclohexanone under mild conditions to achieve both high conversion and selectivity is a challenge. Here we report novel complex nanostructured catalysts Pd/@-CeO₂/AC and Pd/@-La₂O₃/AC prepared by a photochemical route. These catalysts were characterized by XRD, BET, TEM, H₂-TPR and XPS. The results showed that Pd nanoparticles were well-dispersed on CeO₂/AC or La₂O₃/AC, and the complex nanostructured catalysts exhibit a synergistic effect between nano-Pd and nano-La₂O₃/AC or nano-CeO₂/AC. These catalysts had an excellent catalytic performance for the hydrogenation of phenol, achieved 100% conversion and a selectivity higher than 96% within 3 h at 70 °C and 0.7 MPa H₂ pressure. The results indicated that the remarkable performance may result from the synergistic effect between active component Pd and rare-earth oxide, their complex nanostructured properties and the high dispersion of Pd particles on the large surface area. Furthermore, this work revealed synergistic catalysis of nano-metal Pd and nano rare-earth oxide and opened a new direction of synergistic catalysis of nanostructured catalysts.