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Effects of Ru addition on the activity and the sustainability of Ni/Mg(Al)O catalysts were investigated in the daily start-up and shutdown (DSS) operation of the steam reforming of CH 4. Mg 2.5 (Ni 0.5)-Al hydrotalcite was prepared by coprecipitation and calcined to form Mg 2.5 (Al,Ni 0.5)O periclase. When the powders of the periclase were dipped in an aqueous solution of Ru(III) nitrate, the hydrotaclite was reconstituted on the surface of Mg 2.5 (Al,Ni 0.5)O particles, resulting in the formation of highly dispersed Ru/Ni bimetal supported catalysts after the calcination, followed by the reduction. The addition of Ru on Ni caused a decrease in the reduction temperature of Ni and an increase in the amount of H 2 uptake on the Ni over the catalyst. Formation of Ru-Ni alloy or strong interaction between Ru and Ni was also suggested. When Ru-Ni 0.5 /Mg 2.5 (Al)O catalysts were tested in the DSS-like operation under steam purging, the deactivation due to the oxidation of Ni metal by steam was effectively suppressed by hydrogen spillover. Moreover, only 0.05 wt% of Ru loading was enough to effectively suppress the deactivation during the DSS-like operation.

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