Partial oxidation of ethanol on supported Pt catalysts

This work studied the effect of the nature of the support on the performance of Pt/Al2O3, Pt/ZrO2, Pt/CeO2 and Pt/Ce0.50Zr0.50O2 catalysts on partial oxidation of ethanol. The reducibility and oxygen transfer capacity were evaluated by temperature-programmed reduction (TPR) and oxygen storage capacity (OSC) experiments. The results showed that the support plays an important role on the products distribution of the partial oxidation of ethanol. Acetic acid was the main product on Pt/Al2O3 catalyst whereas methane and acetaldehyde were the only products detected on Pt/ZrO2, Pt/CeO2 and Pt/Ce0.50Zr0.50O2 catalysts. The products distribution obtained on Pt/ZrO2, Pt/CeO2 and Pt/Ce0.50Zr0.50O2 catalysts was related to their redox properties. The OSC experiments showed that the oxygen exchange capacity was higher on Pt/CeO2 and Pt/Ce0.50Zr0.50O2 catalysts. A high oxygen storage capacity favored the formation of acetate species, which could be decomposed to CH4 and/or oxidized to CO2 via carbonate species. On the other hand, the lower oxygen exchange capacity of Pt/ZrO2 catalyst led to a higher ethoxy species formation. These species can be dehydrogenated and desorb as acetaldehyde. Then, the higher selectivity to acetaldehyde observed on Pt/ZrO2 catalyst could be assigned to its low oxygen storage/release capacity. In the case of Pt/Al2O3 catalyst, the production of acetic acid could be related to its acidic properties, since this material did not show redox properties, as revealed by OSC analysis.