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 Ce0.75−xZr0.25TbxO2 (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, H2-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 CeO2–ZrO2 based materials, and among all the supports studied, Ce0.65Zr0.25Tb0.1O2 (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.
KeywordsSteam reforming of propane Ceria–zirconia Terbium Catalysts Oxygen storage capacity Doping
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