Hydrogen production by methanol reforming:: post-reaction characterisation of a Cu/ZnO/Al2O3 catalyst by XPS and TPD

Post-reaction X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) experiments have been carried out after exposure of a commercial Cu/ZnO/Al2O3 catalyst to methanol reforming conditions in the presence Of O-2 and H2O. A dependence of the copper oxidation state on the temperature was observed, with low temperatures favouring a higher oxidation state. In the presence of water, Cu(II) was formed at T less than or equal to 485 K, giving rise to a very low catalytic activity. Under methanol dry partial oxidation conditions at T greater than or equal to 530 K a decrease of the Cu surface concentration was observed. Adsorbed methoxy species were found on the surface after all catalytic treatments, with the amount decreased by the presence of water in the feed. The presence of O-2 favoured the formation of surface formate. (C) 2002 Elsevier Science B.V. All rights reserved.