Enhancement of the catalytic activity of Suzuki coupling reactions by reduction of modified carriers and promotion of Pd/H2-PrxOy surface electron transfer
Abstract
Among rare earth oxides (REO), mixed-valence praseodymium oxide (Pr3+/Pr4+) has the highest O mobility and very promising applications in multiphase catalysis. In this paper, Pd-loaded praseodymium oxide nanotubes were successfully prepared by immobilizing Pd nanoparticles on modified carriers. XPS characterization showed that the electron transfer process during the reaction could be regulated by changing the Pr3+/Pr4+ ratio of praseodymium oxide. Importantly, the H2-PrxOy carrier surface has much higher Pd electron density, and the electron-rich Pd nanoparticles make it easier to break the C–Br bond and transfer electrons from Pd to C and Br atoms, leading to the formation of ArPdIIBr intermediate complexes. In the Suzuki coupling reaction, Pd/H2-PrxOy exhibited higher catalytic performance under mild conditions. There is a strong correlation between the surface properties of the carriers and the catalytic activity of the Pd nanocatalysts. This provides a new strategy for the preparation of Suzuki coupling reaction catalysts.