Pd Nanoparticles on Layered Double Hydroxide as Efficient Catalysts for Solvent-Free Oxidation of Benzyl Alcohol Using Molecular Oxygen: Effect of Support Basic Properties

摘要

Pd nanoparticles supported on basic layered double hydroxide (LDH) as highly efficient and reusable catalysts are prepared and characterized. The layered structure of LDH support could be reconstructed to different extent by controlling the activation conditions, which presented changing quantity of Br0nsted-base sites. Besides, with the changing calcination temperature the LDH substrate imposed a restricted nano-size effect on the supported Pd particles under identical reduction condition, which demonstrated a convenient approach for controlling the size of supported Pd particles. The resulting Pd/LDH samples were tested as heterogeneous catalysts for solvent-free oxidation of benzyl alcohol using molecular oxygen. The sample with a larger amount of Br0nsted-base sites is more active in the oxidation of benzyl alcohol, and after five catalytic runs it still gives benzaldehyde in excellent yields. The promotional effect of Br0nsted-base sites of the LDH support on the catalytic activity for benzyl alcohol oxidation over Pd/LDH is studied.