Alkali (earth)-doped Au/Al2O3 catalysts for the total oxidation of propene

The addition of alkali (earth) metal oxides (MOx with M = Li, Rb, Mg, or Ba) is beneficial for the performance of Au/Al2O3 catalysts in the total oxidation of propene (C3H6). The effect of the MOx additives on the microstructure and nature of Au/Al2O3 catalyst was investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), total surface area (BET), and diffuse reflectance ultraviolet visible spectroscopy (DR-UV/vis). It is found that MOx induces a decrease in the size of gold particles and stabilizes them against sintering. In turn, a direct dependence of the catalytic performance on the size of the gold particles is found. The role of the additives is that of a structural promoter and not a chemical promoter. (c) 2005 Elsevier Inc. All rights reserved.