Ultra-low-gold loading Au/CeO2 catalysts for ambient temperature CO oxidation: Effect of preparation conditions on surface composition and activity

A series of 0.06–0.09 wt% Au/CeO2 catalysts for CO oxidation at ambient temperature were prepared under different preparation conditions and characterized by BET, XRD, XPS, HRTEM and FT-IR techniques. Experiment results showed that with acid material as support, the catalyst prepared by raising the pH of the acid support suspension before introduction of the HAuCl4 solution exhibits the highest activity because of the higher Au0/Auδ+ ratio existing on the surface. The optimum calcination temperature of the support CeO2 and the drying temperature of the catalyst, which affect strongly the amount of water-derived species and the activity, were found to be 873 and 333 K, respectively. Base pretreatment for acid CeO2 support leads to the decrease in Auδ+ and favors the preparation of an excellent catalyst with the specific rate raised from 2.92 to 10.06 mol image. Possible active center model and its formation process were proposed.