Adsorption and reactions of ethanol and ethanol-water mixture on alumina-supported Pt catalysts

The formation of surface species in the ethanol-water interaction and the reforming of ethanol have been investigated on Pt/Al2O3 catalysts and for comparison on the support. By means of infrared spectroscopy it was found that on Pt/Al2O3 not only adsorbed ethanol, different types of ethoxy species but also traces of acetaldehyde and a significant amount of acetate groups were detectable on the surface. The latter species were stable even at 700 K. The gas phase analysis of the ethanol-dosed surface showed at higher temperature considerable amount of ethylene in the case of Al2O3 and hydrogen in the case of Pt/Al2O3. In the ethanol + water reaction the selectivity of H-2 and CO2 formation at 723 K decreased in time, while that of ethylene increased. This trend was attenuated by increasing the following parameters: water concentration, metal loading and reaction temperature. It was assumed that this behavior of Pt/Al2O3 in the ethanol + water reaction can be attributed to the formation of surface acetate groups which hindered the reaction on the metal, although these species were located rather on the support. (c) 2006 Elsevier B.V. All rights reserved.