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

Abstract

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/ZrO 2 and Ni/V 2O 5 catalysts exhibited higher activities than the Ni catalysts supported on CeO 2, Al 2O 3, SiO 2–Al 2O 3 and MgO and a reduced catalyst. The cesium-doped Ni/ZrO 2 promoted more hydrogen formation than the Li-, K-, La- and Ce-doped catalysts. From the XRD measurement, crystals of ZrO 2, Ni carbide and Ni metal were formed during the carburization of the Ni/ZrO 2 catalyst at 823 K. No Ni carbide was observed on the MgO, CeO 2 Al 2O 3, and V 2O 5 carburized catalysts. The Cs 0.2Ni/ZrO 2 and Cs 0.5Ni 0.5/Zr exhibited no carbon deposition at 7 h. The carburized and cesium-doped Ni/ZrO 2 was more effective in decreasing the carbon deposition. From the IR study, the formed carbonated species were attributed to the formation of CO 3 − from the formed CO 2 (CO 2 + O 2 − → CO 3 −). In the pulse experiment of H 2 18O, Cs 0.2Ni/ZrO 2 helped to facilitate the dissociation of H 2O to 2H and O and the decomposition of CH 3CHO to hydrogen and CO 2 through the CH 3CO species. The TPD after ethanol adsorption on Ni/ZrO 2 with and without Cs-doping showed that the Cs-doped Ni/ZrO 2 catalyst promoted the C–H breaking through the CH 3CO species more than the Ni/ZrO 2 catalyst.