Supported nanoscale gold particles are among the most active catalysts reported to date for the catalytic oxidation of carbon monoxide by various oxidants, such as oxygen in low- temperature dry CO oxidation, the PROX reaction in the presence of large amounts of hydrogen and water; and water in low- temperature WGS reaction, all of which are used to upgrade hydrogen-rich gas streams for use in PEM fuel cells. In this work, fundamental studies of the interactions of gold supported on different carriers, such as cerium oxide, iron oxide, and lanthanum oxide, with CO are reported to elucidate the activity/stability of various structures in the WGS reaction. We used different methods to prepare the desired gold structure (clusters, nanoparticles) on the oxide supports and examined the reactivity of each. Activation of –OH groups from the support appears to involve the strongly bound CO on the gold clusters. On the other hand, weakly bound CO on metallic gold nanoparticles is not important for the WGS reaction. Various characterization techniques including TEM, XPS, XRD, TPR, and in situ XANES/EXAFS were used to identify the reaction-relevant gold structures.

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