Rare-earth oxides promoted nickel based catalysts for steam reforming

The effect of the oxides of cerium, samarium and praseodymium as promoters for nickel based catalysts for the steam reforming of methane has been studied. The catalysts, prepared by a two-step impregnation method, showed significant enhancement of activity for methane steam reforming. The activity increased linearly with increased loading of the rare-earth oxides. The positive effect of the rare-earth oxides on the steam reforming activity decreased as CeO2 > PrO2 > Sm2O3 The cerium oxide-containing catalysts exhibited excellent anti-coking ability comparable to that of advanced commercial catalysts. This was explained in terms of the larger adsorption of water on the surface of cerium oxide and the resulting relatively high rates of carbon gasification. The selectivity of the nickel-cerium oxide catalysts to hydrogen and carbon dioxide production during methane steam reforming was also significantly improved due to the increase of importance of the water gas shift reaction.