Steam reforming of ethanol over carburized alkali-doped nickel on zirconia and various supports for hydrogen production

The steam reforming of ethanol over carburized alkali-, La-and Ce-doped nickels on zirconia and various supports was studied to determine the support effects, alkali addition and carburization. The 823 K-carburized Ni/ZrO2 and Ni/V2O5 catalysts exhibited higher activities than the Ni catalysts supported on CeO2, Al2O3, SiO2-Al2O3 and MgO and a reduced catalyst. The cesium-doped Ni/ZrO2 promoted more hydrogen formation than the Li-, K-, La-and Ce-doped catalysts. From the XRD measurement, crystals of ZrO2, Ni carbide and Ni metal were formed during the carburization of the Ni/ZrO2 catalyst at 823 K. No Ni carbide was observed on the MgO, CeO2 Al2O3, and V2O5 carburized catalysts. The Cs0.2Ni/ZrO2 and Cs0.5Ni0.5/Zr exhibited no carbon deposition at 7 h. The carburized and cesium-doped Ni/ZrO2 was more effective in decreasing the carbon deposition. From the IR study, the formed carbonated species were attributed to the formation of CO3- from the formed CO2 (CO2 + O-2(-) -> CO3-). In the pulse experiment of H-2 O-18, Cs0.2Ni/ZrO2 helped to facilitate the dissociation of H2O to 2H and O and the decomposition of CH3CHO to hydrogen and CO2 through the CH3CO species. The TPD after ethanol adsorption on Ni/ZrO2 with and without Cs-doping showed that the Cs-doped Ni/ZrO2 catalyst promoted the C-H breaking through the CH3CO species more than the Ni/ZrO2 catalyst. (C) 2011 Elsevier B.V. All rights reserved.