Effect of synthesis procedure on the low-temperature WGS activity of Au/ceria catalysts

摘要

Gold/ceria catalysts were prepared by two different methods (deposition-precipitation and modified deposition-precipitation). Considerable differences in the low-temperature water-gas shift (WGS) activity of both catalysts were observed. The preparation technique strongly influenced catalytic activity due to the large differences in gold particles size and to the availability of active gold sites in close contact with ceria defects on the surface. HRTEM and EDS have shown presence of very highly dispersed gold clusters (d about 1 nm) on the surface of the catalyst prepared by deposition-precipitation. Large gold particles (average d approximate to 15 nm) have been found in gold/ceria catalyst prepared by modified deposition-precipitation. FTIR spectroscopy of adsorbed CO and X-ray photoelectron spectroscopy were employed to obtain information about the surface structure of both catalysts and to explain the differences in catalytic activity. (C) 2004 Elsevier B.V. All rights reserved.