DRIFT AND MASS SPECTROSCOPIC STUDIES ON THE REACTIVITY OF RHODIUM CLUSTERS AT THE SURFACE OF POLYCRYSTALLINE OXIDES

This work presents the results of a systematic experimental study on the chemistry of rhodium clusters on the surfaces of polycrystalline MgO, Al2O3, and CeO2. The reactions were induced by temperature and by reductive and oxidizing treatments followed by interactions with gaseous CO- or CO2-containing atmospheres. Eight reactivity experiments were performed on each sample in a high-pressure micro-plug-flow reactor and the reactions were followed by DRIFT and mass spectrometry. New findings were made on (a) the formation and reactivity of carbon-containing and oxygen-containing species and of hydridocarbonyl clusters; (b) the influence of the support in determining the chemistry of the rhodium complexes; (c) the differences between the carbonyl surface clusters formed during the CO and the CO2 hydrogenation reactions; and (d) the balance between temperature and ligand effects in determining the formation of rhodium clusters.