Nanocrystalline gold supported on NaY as catalyst for the direct oxidation of primary alcohol to carboxylic acid with molecular oxygen in water

Au/NaY was prepared by deposition–precipitation (DP) method using HAuCl4 as gold source. The samples were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy and inductively coupled plasma atomic emission spectrometry. It was found that the adjustment of the surface acidity of NaY, the pH and concentration of HAuCl4 solution, and the temperature and time for DP affected the particle size, the loading and the morphology of Au on NaY. The catalytic performance of Au/NaY was studied in the oxidation of alcohols to the corresponding carboxylic acids with molecular oxygen as oxidant under basic conditions. About 100% conversion of benzyl alcohol with 95.2% isolated yield of benzoic acid was obtained at the reaction temperature of 80 °C for 8 h. The catalyst was recycled for four times without loss of catalytic activity. In addition, the catalyst worked well for the catalytic oxidation of various alcohols including aromatic and aliphatic alcohols to the corresponding carboxyl acids.

Figure optionsDownload high-quality image (134 K)Download as PowerPoint slideHighlights
► Au/NaY showed high catalytic activity for the oxidation of primary alcohol to acid.
► Pretreatment of NaY before loading of Au was essential.
► Preparation conditions affected loading amount, particle size and morphology of Au.
► These parameters determined the catalytic activity of Au/NaY.
► The catalyst was recyclable.