Hydrogen production by steam reforming of LNG over Ni/Al 2O 3–ZrO 2 catalysts: Effect of Al 2O 3–ZrO 2 supports prepared by a grafting method

Abstract

Al 2O 3–ZrO 2 supports with various zirconium contents were prepared by grafting a zirconium precursor onto the surface of γ-Al 2O 3. Ni(20 wt%)/Al 2O 3–ZrO 2 catalysts were then prepared by an impregnation method, and were applied to the hydrogen production by steam reforming of LNG. The effect of Al 2O 3–ZrO 2 supports on the performance of the Ni(20 wt%)/Al 2O 3–ZrO 2 catalysts was investigated. Al 2O 3–ZrO 2 prepared by a grafting method served as an efficient support for the nickel catalyst in the steam reforming of LNG. ZrO 2 inhibited the incorporation of nickel species into the lattice of Al 2O 3 and prevented the growth of metallic nickel particles during the reduction step. The crystalline structures and catalytic activities of the Ni(20 wt%)/ZrO 2–Al 2O 3 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(20 wt%)/ZrO 2–Al 2O 3 (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 ZrO 2–Al 2O 3 (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(20 wt%)/ZrO 2–Al 2O 3 (Zr/Al = 0.17) was also responsible for the enhanced performance of the catalyst.