Supported Au catalysts for low-temperature CO oxidation were prepared by solvated metal atom impregnation (SMAI) and conventional impregnation (Cl). X-ray photoelectron spectroscopy (XPS) investigations indicated that the elemental gold in all the samples was in the metallic state, XRD measurements showed that the mean diameters of Au particles prepared by SMAI were smaller than those prepared by Cl with the same gold content. Catalytic tests showed that the SMAI catalyst had higher CO oxidation activity than the CI catalyst with the same compositions. Both SMAI and Cl catalysts exhibited high activity in low temperature CO oxidation. Full CO conversion was obtained at 323-383K.
The solvated metal atom impregnation (SMAI) method was used to prepare Co/SiO 2 and Co/La SiO 2 catalyst samples with 5%Co content. The XPS results showed that the cobalt particles both in SiO 2 and in La SiO 2 existed in zero valent state (Co\+0). The CO chemisorption results showed that the cobalt particle size (5 3 nm) of Co/La SiO 2 sample was much smaller than that (8 1 nm) of Co/SiO 2 sample. The turnover frequency (TOF) of CO on Co/La SiO 2 sample was higher than that on Co/SiO 2 sample in F T reaction (CO hydrogenation), which was probably due to the fact that the cobalt particle size in Co/La SiO 2 sample was much smaller than that in Co/SiO 2 sample. The experimental results also showed that the selectivity of Co/La SiO 2 sample for long chain paraffins was higher than that of Co/SiO 2 sample.
