More Insights into Support and Preparation Method Effects in Gold Catalyzed Glycerol Oxidation

Background: Materials containing supported gold nanoparticles are considered as the most favorable for liquid-phase alcohol oxidation. Our previous studies showed that MgAl2O4 spinel can be an effective support for gold catalysts in liquid-phase alcohol oxidation. Objective: The aim of the present paper a comparative study of gold supported on different metal oxides (Al2O3, MgO, MgAl2O4 spinel) in liquid phase oxidation of glycerol. Also we highlighted the influence of the precursor protective layer in mediating the support effect on catalytic activity and comparing MgAl2O4 spinel with individual oxide supports. Method: Catalytic tests in glycerol liquid-phase oxidation at 50 °C. Catalyst characterization by Transmission electron microscopy, X-ray diffraction, adsorption measurements, plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy. Results and Conclusion: It was shown that, depending on the preparation method, the activity of Au supported on oxide supports can become reversed. For deposition-precipitation method Au/Al2O3 is more active than Au/MgO while for sol immobilization, the contrary occurs and Au/MgO is more active than Au/Al2O3. Activities of Au catalysts supported on MgAl2O4 spinel are high and close to each other for catalysts prepared by both methods. It is suggested that Au particle size and interaction of Au with support are activity determining parameters, while gold content do not play a significant role. This study gets an insight on the importance of the direct contact between the support and the gold particle.