Ru/Ni/MgAlO catalysts for steam reforming of methane: effects of Ru content on self-activation property.

The effects of Ru on the self-reducibility of Ru-doped Ni/MgAlO catalysts, which do not need pre-reduction treatment with H, were investigated in the steam reforming of methane (SRM). The Ru-promoted Ni/MgAlO catalysts with various amounts of Ru (0-0.5 wt%) were prepared by stepwise impregnation and co-impregnation methods using hydrotalcite-like MgAlO support. For comparison, Ru/MgAlO catalysts with the same amount of Ru were also prepared by the impregnation method. The catalysts were characterized by the N-sorption, XRD, H-TPR, H-chemisorption, and XPS methods. Ni/MgAlO catalyst in the presence of even the trace amount of Ru (Ru content ≥0.05 wt%) showed higher conversion without pre-reduction as compared to Ru/MgAlO catalysts in SRM under the same conditions. The self-activation of Ru-Ni/MgAlO catalysts is mainly attributed to the spillover of hydrogen, which is produced on Ru at first and then reduces NiO species under reaction conditions. Besides, Ru doping makes the reduction of NiO easier. The stepwise impregnated Ru/Ni/MgAlO catalyst produced superior performance as compared to co-impregnated Ru-Ni/MgAlO catalyst for SRM. [ABSTRACT FROM AUTHOR]