Production of hydrogen by oxidative reforming of ethanol over Pt catalysts supported on Al2O3 modified with Ce and La

A series of Pt catalysts supported on alumina modified by Ce and/or La were prepared and tested in the reaction involving the production of hydrogen by oxidative reforming of ethanol. Characterization of the catalysts by N2 adsorption, X-ray diffraction, TPR and X-ray photoelectron spectroscopy (XPS) revealed differences in the interaction between platinum and the supports. These differences have important implications in the behaviour of the catalysts for the ethanol-reforming reaction. Ethanol conversion on the Pt/(La)Al2O3 catalyst was found to be close to that of the Pt/Al2O3 catalyst. However, modification of the Al2O3 substrate by ceria led to a more active Pt/(Ce)Al2O3 catalyst. A lower promotion effect was observed when both ceria and lanthana were present on the support substrate. TPR and XPS analyses of ceria-containing samples revealed the existence of a strong interaction between platinum and ceria. This interaction between Pt crystallites at the ceria surface seemed to be responsible for the better performance of the cerium-containing catalysts. It is suggested that the platinum-ceria interaction affects the adsorption-decomposition of ethanol to CH4 and CO products and their subsequent reforming reactions with steam. When both ceria and lanthana were present on the support substrate the platinum-ceria interaction was diminished, reducing the promoter effect in the production of hydrogen by oxidative reforming of ethanol.