Promotion of Au(en)2Cl3-derived Au/fumed SiO2 by treatment with KMnO4

A new method for the removal of organic ligands used in the synthesis of nanoparticle catalysts via solution-phase chemical oxidation and subsequent pretreatment at moderate temperatures was developed. This synthesis protocol is advantageous for the preparation of highly dispersed gold catalysts with minimum sintering. Highly active Au/SiO2-based catalysts were prepared by treating Au(en)(2)Cl-3-derived Au/fumed SiO2 in strongly oxidative KMnO4 solutions. The low-temperature activity in CO oxidation increased dramatically following the KMnO4 treatment and subsequent thermal activation (including treatment in O-2-He at 300-600 degrees C). The influences of the pH values of KMnO4 solutions and temperatures of activation in O-2-He prior to the reaction testing were investigated, and relevant characterization using XRD, TEM, TG/bTG, SEM, EDX, and ICP-OES was conducted. The catalyst stability in CO oxidation was studied as a function of reaction time on stream. The origin of the promotional effect was discussed.