Steam reforming of methane on reduced non-stoichiometric nickel aluminate catalysts

The steam reforming activity of reduced Nickel aluminate catalysts is reported along with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and hydrogen chemisorption characterization of these catalysts. The nickel content was 33% for a stoichiometric nickel aluminate catalyst and 16% and 49% for two catalysts with non-stoichiometric compositions. The calcined catalysts were completely inactive and did not chemisorb hydrogen. Upon hydrogen reduction, the catalysts exhibited significant catalytic activity, stability to deactivation, and hydrogen uptake capacity which depended on the nickel loading and the pretreatment used. XRD results indicated the existance of NiO and nickel aluminate bulk phases, and XPS results indicated the presence of Ni2+ on the surface. It is speculated that the active nickel sites responsible for the activity, are present in a monodisperse form on special sites provided by the nickel aluminate structure.