The influence of the nature of the metal on the performance of cerium oxide supported catalysts in the partial oxidation of ethanol

Instituto Nacional de Tecnologia-INT, Av. Venezuela 82, CEP 20081-312 Rio de Janeiro, Brazil, 2005.This work studied the effect of the nature of the metal on the performance of Co/CeO₂, Pd/CeO₂ and Pt/CeO₂ catalysts in the partial oxidation of ethanol. Infrared spectroscopy of adsorbed ethanol and temperature programmed desorption of ethanol were performed in order to establish the reaction mechanism. Catalytic experiments revealed that the product distribution is strongly affected by the nature of the metal. Acetaldehyde was practically the only product formed on a Co/CeO₂ catalyst while methane was also produced on Pt/CeO₂ and Pd/CeO₂ catalysts. These results were explained through a reaction mechanism proposed by the characterization techniques. Co/CeO₂ and Pt/CeO₂ catalysts show mainly ethoxy species at room temperature whereas acetate species is mainly formed on the Pd/CeO₂ catalyst. The ethoxy species can undergo further dehydrogenation and desorb as acetaldehyde. This effect is more significant with the Co/CeO₂ catalyst and could explain the higher selectivity to acetaldehyde observed on supported Co and Pt catalysts.