Quantitative determination of gold active sites by chemisorption and by infrared measurements of adsorbed CO

QuantitativemeasurementsofCOchemisorptionintherange140–180K,supportedbyFTIRdataonadsorbedCO,wereperformedonAu/TiO2, Au/Fe2O3,andAu/CeO2 catalysts. On the first two samples, which had similar particle size distributions, an average Au/CO chemisorption stoichiometryofabout3,referredtostep-edgeAuatoms,wasfound.OnAu/CeO2,whereverysmallclustersandquitelargeparticlesarepresent, the CO-chemisorbed volume was much higher than expected, due to the prevailing contribution of very small Au clusters. On the same sample, a change in the IR absorption coefficient was observedand was reasonably explained. © 2005Elsevier Inc. All rights reserved.