Characterization of CO₂ methanation catalysts prepared from amorphous Ni-Zr and Ni-Zr-rare earth element alloys

Nano-grained Ni/ZrO₂ and Ni/ZrO₂-Sm₂O₃ catalysts were prepared from amorphous Ni-Zr and Ni-Zr-Sm alloys by oxidation-reduction treatment. Their catalytic activity for methanation of carbon dioxide was examined as a function of precursor alloy composition and temperature. The addition of samarium is effective in enhancing the activity of the nickel-rich catalysts, but not effective for the zirconium-rich catalysts. The surface area and hydrogen uptake of the nickel-rich catalysts are increased by the samarium addition. In addition, tetragonal zirconia, the formation of which is beneficial to the catalytic activity, is stabilized and formed predominantly by the addition of samarium to the nickel-rich catalysts, although monoclinic zirconia is also formed in the zirconium-rich catalysts. As a consequence, the higher conversion of carbon dioxide is obtained on the Ni-Zr-Sm catalysts with relatively high nickel contents.