Preparation of ternary Pd/CeO2-nitrogen doped graphene composites as recyclable catalysts for solvent-free aerobic oxidation of benzyl alcohol

The heterogeneous catalysts based on ternary Pd/CeO 2 -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 CeO 2 dramatically enhanced the dispersion of Pd nanoparticles, reduced their particle size and inhibited the Pd oxidation formation. With high lattice oxygen storage capability of CeO 2 , 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/CeO 2 , verifying the synergistic effect among Pd, CeO 2 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/CeO 2 -NG composite has great application potential in the fields of organic synthesis, electrochemical biosensors and fuel cells.