Trace amounts of Pt- and Ru-doped Ni/Mg(Al)O catalysts were prepared by a citrate method and tested in the oxidative reforming of C3H8 under daily start-up and shut-down (DSS) operation. The activity and the sustainability of the catalysts were compared with those of the Pt- and Ru-doped Ni/Mg(Al)O catalysts derived from hydrotalcite (HT) precursor. The DSS operation of C3H8 reforming was carried Out with O-2 gas or O-2/H2O mixed gas between 200 degrees C and 600 degrees C or 700 degrees C under air purging conditions. The catalysts underwent steaming treatment with H-2/H2O mixed gas at 900 degrees C for 10 h. This allowed us to test the effect of Ni sintering on the catalyst deactivation. Coking was significantly suppressed on both HT- and citrate-derived Ni catalysts. Although both preparations produced highly dispersed Ni particles on the catalysts, the HT-derived catalysts exhibited more finely dispersed Ni particles, resulting in higher activity values than those of the citrate-derived catalysts, The regenerative activity due to redispersion of sintered Ni particles was enhanced over the HT-derived catalysts compared with the activity over citrate-derived catalysts. Although a clear redispersion of Ni particles was not observed in the oxidative reforming, i.e., in the absence of steam, the size decrease in Ni particles was more significant over the HT-derived catalysts than over the citrate-derived catalysts. The Mg(Al)O periclase structure derived from Mg-Al HT likely plays an important role in the regenerative activity of Pt- and Ru-Ni/Mg(Al)O catalysts. Pt-doping was more effective than Ru for the catalyst sustainability in the oxidative reforming of C3H8. (C) 2009 Elsevier B.V. All rights reserved.