Enhanced stability of nitrogen-doped carbon-supported palladium catalyst for oxidative carbonylation of phenol

Abstract

Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry. Herein, a heterogeneous Pd catalyst (Pd/NCF) was prepared by supporting Pd ultrafine metal nanoparticles (NPs) on nitrogen-doped carbon; synthesized by using F127 as a stabilizer, as well as chitosan as a carbon and nitrogen source. The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate, exhibiting higher stability than Pd/NC prepared without F127 addition. The hydrogen bond between chitosan (CTS) and F127 was enhanced by F127, which anchored the N in the free amino group, increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd NPs. This process helped to improve metal dispersion. The increased metal-support interaction, which limits the leaching and coarsening of Pd NPs, improves the stability of the Pd/NCF catalyst. Furthermore, density functional theory calculations indicated that pyridine N stabilized the Pd2+ species, significantly inhibiting the loss of Pd2+ in Pd/NCF during the reaction process. This work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.