Nanofiber-like mesoporous alumina supported palladium nanoparticles as a highly active catalyst for base-free oxidation of benzyl alcohol

A nanofiber-like mesoporous alumina supported palladium catalyst, Pd/γ-Al2O3-fibr, was successfully prepared by a hydrothermal method and used in the aerobic oxidation of benzyl alcohol to benzaldehyde with molecular oxygen under base-free conditions. The material was characterized by N2 physisorption, FT-IR, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photo-electron spectroscopy (XPS). XRD and TEM results revealed that the palladium nanoparticles were uniformly dispersed in the framework of nanofiber-like mesoporous γ-alumina. The higher activity of Pd/γ-Al2O3-fibr compared to Pd/γ-Al2O3 and Pd/SBA-15 in the aerobic oxidation of benzyl alcohol reaction suggested that the unique fibrous architecture of our material and synergic effect between Pd species and γ-Al2O3 are beneficial to enhance the reactivity of palladium NPs. Furthermore, the unique architecture of Pd/γ-Al2O3-fibr catalyst also offers it good mass-transfer property and accessibility, which make it an effective catalyst for aerobic oxidation of steric bulk alcohol substrate. The Pd NPs supported on nano-fibrous mesoporous alumina in this paper is demonstrated to be a recoverable noble metal-based nanocatalyst with easy accessibility and may be great potential as a promising candidate for numerous catalytic applications.