Oxidative steam reforming of ethanol on mesoporous silica supported PtNi/CeO2 catalysts

In order to assure good catalyst stability and low carbon deposition rate, in the present work three catalysts having different CeO2 loadings (CeO2/SiO2 ratio ranging between 25 and 40%) were prepared by depositing Pt and Ni over a CeO2/SiO2 mixed support and tested for oxidative steam reforming of ethanol. All the catalysts exhibited total ethanol conversion between 350 and 600 °C; however, the CeO2/SiO2 ratio strongly affected catalyst stability at 500 °C: despite the similar hydrogen yields (almost 40%), the best sample, which displayed the lowest carbon formation rate (1.2×10-6 gcoke/(gcat*gcarbon,fed*h)) and stable behaviour for 135 h, was the 3wt%Pt-10wt%Ni/30CeO2/SiO2. The lower dimension for Ni crystallites was measured over the latter exhausts catalyst and the dependence of carbon formation rate form such parameter was identified. Anyway, the carbon selectivities measured over all the investigated samples were significantly lower than the values reported in the recent literature.