Hydrogen production by steam reforming of LNG over Ni/Al2O3-ZrO2 catalysts:: Effect of Al2O3-ZrO2 supports prepared by a grafting method

Al2O3-ZrO2 supports with various zirconium contents were prepared by grafting a zirconium precursor onto the surface of gamma-Al2O3. Ni(20wt%)/Al2O3-ZrO2 catalysts were then prepared by an impregnation method, and were applied to the hydrogen production by steam reforming of LNG. The effect of Al2O3-ZrO2 supports on the performance of the Ni(20 wt%)/Al2O3-ZrO2 catalysts was investigated. Al2O3-ZrO2 prepared by a grafting method served as an efficient support for the nickel catalyst in the steam reforming of LNG. ZrO2 inhibited the incorporation of nickel species into the lattice of Al2O3 and prevented the growth of metallic nickel particles during the reduction step. The crystalline structures and catalytic activities of the Ni(20 wt%)/ZrO2-Al2O3 catalysts were strongly influenced by the amount of zirconium grafted. LNG conversion and hydrogen yield showed volcano-shaped curves with respect to zirconium content. Among the catalysts tested, the Ni(20wt%)/ZrO2-Al2O3 (Zr/Al =0.17) catalyst showed the best catalytic performance in terms of both LNG conversion and hydrogen yield. The well-developed and pure tetragonal phase of ZrO2-Al2O3 (Zr/Al =0.17) played an important role in the adsorption of steam and the subsequent spillover of steam from the support to the active nickel. The high reducibility of Ni(20wt%)/ZrO2-Al2O3 (Zr/Al =0.17) was also responsible for the enhanced performance of the catalyst. (c) 2006 Elsevier B.V. All rights reserved.