Citrate or hydrotalcite?

Abstract

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 C 3 H 8 under daily start-up and shutdown (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 C 3 H 8 reforming was carried out with O 2 gas or O 2 /H 2 O mixed gas between 200 ºC and 600 or 700 ºC under air purging conditions. The catalysts underwent steaming treatment with H 2 /H 2 O mixed gas at 900 ºC 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 C 3 H 8 .

Hydrogen Production by Catalytic Reforming of Liquid Hydrocarbons

“…Takehira et al [44] reported that Pt or Ru doped Nibased catalyst prepared from Mg-Al hydrotalcite-like anionic clay with citrate method showed high and stable activity for steam reforming of propane. Dreyer et al [45] studied autotherrmal steam reforming of higher hydrocarbons such as n-decane, n-hexadecane and JP-8 over Rh-coated monolith.…”