Influence of terbium doping on oxygen storage capacity of Ceria-zirconia supports: Enhanced durability of ni catalysts for propane steam reforming

Systematic studies were conducted to understand the influence of Tb doping on durability of Ni-based catalysts supported onto Ce_0.75-xZr _0.25Tb_xO₂ (CZT _x, x = 0.0-0.2), prepared by glycine-nitrate process. Ni metals were deposited onto the as-synthesized supports using a solvothermal method. The prepared supports and catalysts were characterized by a number of ex-situ techniques including X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, H ₂-temperature-programmed reduction and Brunauer-Emmett-Teller analyses. These studies along with soot oxidation experiments confirmed that the existence of Tb³⁺ and/or Ce³⁺ ions made significant contribution to enhancing oxygen storage capacity (OSC) of the Tb doped CeO ₂-ZrO₂ based materials, and among all the supports studied, Ce_0.65Zr_0.25Tb_0.1O₂ (x = 0.1, CZT _0.1 ) showed the highest OSC. To assess the performance of these catalysts, steam reforming reactions of propane were further carried out on the Ni supported catalysts (Ni/CZT _x ) at a steam-to-carbon ratio of 1.5, a gas hourly spaced velocity of 45,000 h^-1, and a reaction temperature of 700 C. Consistent with the determined OSC of the catalysts, the durabilities of the Ni/CZT _x catalysts were found to be increased in the order of Ni/CZT _0.1 > Ni/CZT _0.15 > Ni/CZT _0.2 > Ni/CZT _0.05 > Ni/CZ. In particular, the activity of Ni/CZT _0.1 was maintained to be >99 % of propane conversion at least for 200 h without significant deactivation. Graphical Abstract: [Figure not available: see fulltext.]