Preparation of ternary Pd/CeO_2-nitrogen doped graphene composites as recyclable catalysts for solvent-free aerobic oxidation of benzyl alcohol

摘要

The heterogeneous catalysts based on ternary Pd/CeO2-nitrogen-doped graphene (NG) were prepared and utilized for solvent-free aerobic oxidation of benzyl alcohol to benzaldehyde in the presence of green oxidant O-2. Characterization results revealed that CeO2 dramatically enhanced the dispersion of Pd nanoparticles, reduced their particle size and inhibited the Pd oxidation formation. With high lattice oxygen storage capability of CeO2, excellent electrical conductivity of NG and high catalytic activity of Pd, the ternary catalyst was designed by combining the complementary superiorities of these three components. The ternary composite Pd/5CeO(2)-NG exhibited significantly higher catalytic activity with turnover frequency (TOF) of 30.74 s(-1) for solvent-free aerobic oxidation of benzyl alcohol compared with the corresponding binary composites including 5CeO(2)-NG, Pd/NG and Pd/CeO2, verifying the synergistic effect among Pd, CeO2 and NG. The ternary composite was stable and could be recycled up to 6 times without remarkable loss in the activity and selectivity towards benzaldehyde. Owing to its excellent activity, high selectivity, and exceptional stability and recyclability, the Pd/CeO2-NG composite has great application potential in the fields of organic synthesis, electrochemical biosensors and fuel cells.