Palladium nanoparticles supported on α-zirconium phosphate nanosheets as a highly efficient heterogeneous catalyst for the Heck reaction

Abstract

BackgroundDevelopment of more efficient catalysts for Heck reaction is an urgent task. Traditionally, palladium-based catalysts have played an important role in the construction of the CC bonds in the Heck reaction. MethodsBy using layered phosphate (α-ZrP) as the host material, a novel composite Pd@ZrP is prepared by assembling the precursor Pd(NH3)42+ with the exfoliated α-ZrP nanosheets followed by in-situ reduction. The Pd nanoparticles (NPs) with an average diameter of 5.17 nm are uniformly dispersed on the surface of the α-ZrP nanosheets, and their particle sizes ranged from 3 to 7 nm. The catalytic performance of the prepared Pd@ZrP composite is evaluated by selecting the Heck reaction of iodobenzene and methyl acrylate as a model reaction. Significant findingsThe Pd@ZrP composite exhibits excellent catalytic efficiency, achieving 95.8% conversion within 30 min and a conversion frequency (TOF) value of 937.3 h–1 at 100 °C. The reaction conditions are optimized in terms of the catalyst amount, the reaction time and temperature. In addition, the composite can be easily recovered by centrifugation and reused five times without a significant decrease in catalytic activity. The superior catalytic behaviors can be attributed to Pd NPs uniformly distributed on the surface of α-ZrP nanosheets, as well as the large specific surface area and the porous structure of Pd@ZrP composite.