Active states of gold in small and big metal particles in CO and methanol selective oxidation

[Display omitted] ► Catalytic properties of gold catalysts in the CO conversion. ► Catalytic properties of gold catalysts in methanol partial oxidation. ► Cationic Au species as active sites in the oxidation processes. ► Role of big gold particles in catalytic oxidation processes at high temperatures. Role of small and big gold particles in CO oxidation and methanol selective oxidation to formaldehyde has been studied by the methods of diffuse reflectance electron spectroscopy, XRD, XPS, HRTEM and catalytic testing. By comparison of catalytic and spectroscopic data it was concluded that states Auδ+ with certain effective charge (δ