Ni/M-Al₂O₃ (M=Sm, Ce or Mg) for combined steam and CO₂ reforming of CH₄ from coke oven gas

Effects of structural promoters such as Sm, Ce, Mg metal oxides on the Ni/M-Al₂O₃ catalysts (where M = Sm, Ce, or Mg) were verified to elucidate different catalytic activity for a combined steam and CO₂ reforming reaction with CH₄ (CSCR) using H₂-rich coke oven gases generated from steel industry. The enhanced catalytic performance and stability were explained in terms of the variations of surface basic sites with different aggregation phenomena of active nickel crystallites and resistances for a coke formation. The most efficient Sm promoter having a high electronegativity and basic property on the Ni/M-Al₂O₃ was found to largely suppress a coke deposition and less aggregation of active nickel crystallites by forming the strongly interacted nickel nanoparticles with an enhanced basic sites on the Sm-modified Al₂O₃. In addition, a larger amount of basic sites on the Ni/Sm-Al₂O₃ were responsible for a less coke deposition and best catalytic performances in terms of the conversions of CH₄ and CO₂. These positive effects of Sm promoter were also attributed to a relatively easy activation of CO₂ and the formation of the strongly interacted smaller nickel crystallites on the newly formed basic perovskite-like SmAlO₃ structures or segregated Sm₂O₃ species.