New opportunities for the identification of oxide clusters in supported Ru/MgO catalysts

The Ru/MgO systems were studied using XPS, transmission electron microscopy, and X-ray diffraction analysis. It was found that from 25 to 75% of the supported metal can occur in an X-ray amorphous form with a particle size of smaller than 3 nm. The insertion of supported metal ions into the support structure was absent. A comparison between the valence band XPS spectra and the corresponding densities of states calculated by quantum-chemical methods indicated that the X-ray amorphous portion of the metal can occur as both metal and oxide clusters depending on the precursor of ruthenium.