iso-Octane partial oxidation over Ni-Sn/Ce0.75Zr0.25O2 catalysts

In this study, Ni/Ce0.75Zr0.25O2 catalyst was doped with different amounts of Sn by co-impregnation method. The catalysts were characterized by BET, H2 chemisorption, XRD, TPR, TEM, XPS and tested for iso-octane partial oxidation (iC8POX) to H2 in the temperature range of 400–800 °C at atmospheric pressure. The results showed that most of Sn species were present on the surface of Ni particles and did not modify the reducibility of the support. Addition of a small amount of Sn (<0.5 wt.%) lowered the catalytic activity for iso-octane partial oxidation by less than 5% while the extent of carbon deposition was decreased by more than 50%. However, Sn loadings higher than 1 wt.% caused a massive drop in catalytic activity. This indicates that as long as the Ni surface is only partially covered with Sn species, the active sites for the partial oxidation of iso-octane remain intact, while the surface site ensembles required for carbon formation are blocked.