Characteristics of Au/HMS catalysts for selective oxidation of benzyl alcohol to benzaldehyde

Au/HMS catalysts are prepared by impregnation method and direct synthesized method and evaluated for the selective oxidation of benzyl alcohol. Among all the catalysts studied, Au/HMS catalyst prepared by impregnation method exhibits the best activity, the benzyl alcohol conversion of 42.9% and benzaldehyde selectivity of 95% can be achieved at 80 °C, 1 atm O₂ and existence of Na₂CO₃ aqueous solution. The Au/HMS catalysts are characterized by low-angle X-ray diffraction (XRD), wide-angle XRD, N ₂ adsorption/desorption and transmission electron microscopy (TEM) techniques. The effects of prepared method, gold particle size and HMS structure are investigated in detail. The active phase of gold catalysts for selective oxidation of benzyl alcohol is explored based on the catalytic performance and characterization results. Moreover, the possible activation mechanism for selective oxidation of benzyl alcohol on Au/HMS catalysts is studied by means of CO and O₂ adsorption in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS).