The relationship between the structure and activity of nanometer size gold when supported on Mg(OH)2

In the following paper catalysts of Au supported on Mg(OH)(2) were analyzed by extended X-ray absorption fine structure spectroscopy and Debye function analysis. From these studies only catalysts with Au-size distributions below 1 mm in size were found to be active for CO oxidation. Below 1 Mn in size the gold exists in two forms; icosahedral and fee cuboctahedral. Comparison of turnover frequencies for catalysts prepared with different ratios of the two symmetries suggest that the icosahedral symmetry is the more active form. Above 1 mm in size the gold takes either FCC cuboctahedral or decahedral symmetry. These results suggest that oxidation of CO over the Au/Mg(OH)(2) catalyst is structure-dependent and that care must be taken in comparing results, where no structural information is available. (C) 1998 Academic Press.