Effect of promoter on Ni/MgO catalyst in C8H18 autothermal reforming in solid oxide fuel cell system

Autothermal reforming, which is a combined process of steam reforming and partial oxidation reforming, has excellent coke resistance and high efficiency in reforming reactions. Octane autothermal reforming was carried out over Ni-supported catalysts. The catalysts were prepared by normal precipitation and promoters were added by impregnation. The formation of NiO–MgO solid solution was accomplished during calcination of the Ni/MgO catalyst at 900 °C, resulting in loss of the active Ni metal and very low catalytic activity. Therefore, all catalysts were treated by a reduction process without calcination in order to prevent the formation of NiO–MgO solid solution. Among Ni/MgO catalysts combined with various promoters such as Ag, Cr, and Cu, Ni–Cr/MgO catalyst showed the most desirable characteristics in the aspects of its activity, stability, and resistance to carbon deposition. We found an optimal condition for octane autothermal reforming when steam-to-carbon ratio and oxygen-to-carbon ratio were 1.5 and 0.5, respectively.

. In Ni/MgO catalysts combined with various promoters such as Ag, Cr, and Cu, Cr which did not make an alloy with Ni acted as a blocker for Ni sintering and then gave good dispersion of Ni. For this reason, Ni–Cr/MgO catalyst showed the most desirable characteristics in the aspects of its activity, stability, and resistance to carbon deposition.Figure optionsDownload high-quality image (25 K)Download as PowerPoint slideResearch highlights▶ The formation of NiO–MgO solid solution resulted in loss of active Ni metal. ▶ Among Ag, Cr, and Cu promoters for Ni/MgO catalysts, Cr acted as a blocker for Ni sintering not forming an alloy with Ni unlike Ag and Cu. ▶ Cr-promoted Ni/MgO catalyst, Ni–Cr/MgO, showed stably the highest activity. ▶ An optimal condition of octane ATR was 1.5 and 0.5 for steam-to-carbon ratio and oxygen-to-carbon ratio, respectively.