NiAl2O4 as a beneficial precursor for Ni/Al2O3 catalysts for the dry reforming of methane

Abstract

We have studied the catalytic behavior of different Ni/Al2O3 catalysts for the dry reforming of methane which originate from different Ni metal sources: NiO and also non-stoichiometric and stoichiometric NiAl2O4. After complete reduction of the stoichiometric NiAl2O4 precursor at high temperatures, the resulting Ni/Al2O3 catalyst had more dispersed Ni particles of smaller size and with stronger interactions with alumina. Accordingly, this catalyst was more active and stable, developing only a moderate amount of carbon deposits which were less graphitized. On the other hand, the catalyst formed from NiO showed low initial activity and notable deactivation resulting from the encapsulation and separation of Ni metal particles from the support by more graphitic carbons, which was facilitated by the weaker metal-support interactions. In contrast to what is frequently reported, here we provide evidence which suggests that the NiAl2O4 species should be considered the most beneficial precursor for Ni metal in a Ni/Al2O3 catalyst for the dry reforming of methane even though a high reduction temperature (>950 °C) is needed to activate it.