Hydrogen production by ethanol steam reforming on nickel catalysts: Effect of support modification by CeO2 and La2O3

Ethanol steam reforming at low temperatures and high water: ethanol ratios was studied on Ni (8 wt.%) catalysts deposited on CeO2 (6 wt.%) or La2O3 (6 wt.%) promoted alumina and zirconia supports. The catalysts were prepared by successive impregnation: first the rare earth oxide and then the Ni, and characterized by XRD, H-2 chemisorption, TPR and H-2-TPD. Promotion of both alumina and zirconia with CeO2 and La2O3 leads to changes in the Ni - support interaction resulting in much better dispersion and stabilization of the Ni nanoparticles on the catalyst surface. For La2O3 promoted catalysts 100% ethanol conversion was obtained in the experimental conditions used in this work, at temperatures as low as 300 degrees C. The ethanol conversion was improved by the addition of CeO2 to zirconia supported catalyst, but was not significantly influenced by the addition of CeO2 to alumina supported one. A thermodynamic study of ethanol steam reforming was performed (CHEMCAD process simulator and Gibbs reactor with calculations based on free energy minimization), in order to find the thermodynamic equilibrium composition of reaction products in the particular experimental reaction conditions used in this work. The reaction products mixture at 350 degrees C contains higher proportion of hydrogen and lower proportion of methane than the equilibrium concentration predicted by thermodynamic analysis. The best hydrogen yield was obtained for Ni/La2O3-ZrO2 catalyst. All catalysts except Ni/ZrO2 are stable in 24 h time on stream experiments. (C) 2015 Elsevier Ltd. All rights reserved.