Preparation of supported gold catalysts from gold complexes and their catalytic activities for CO oxidation

A phosphine-stabilized mononuclear gold complex Au(PPh(3))(NO3) (1) and a phosphine-stabilized gold cluster [An(9)(PPh(3))(8)](NO3)(3) (2) were used as precursors for preparation of supported gold catalysts. Both complexes 1 and 2 supported on inorganic oxides such as alpha-Fe2O3, TiO2, and SiO2 were inactive for CO oxidation, whereas the 1 or 2/oxides treated under air or CO or 5% H-2/Ar atmosphere were found to be active for CO oxidation. The catalytic activity depended on not only the treatment conditions but also the kinds of the precursor and the supports used. The catalysts derived from 1 showed higher activity than those derived from 2. alpha-Fe2O3 and TiO2 were much more efficient supports than SiO2 for the gold particles which were characterized by XRD and EXAFS.