文摘
The Pechini synthesis was used to prepare nickel aluminate catalysts with the compositions NiAlb>4b>Ob>7b>, NiAlb>2b>Ob>4b>, and Nib>2b>Alb>2b>Ob>5b>. The samples have been characterized by Nb>2b> physisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). Characterization results indicate unique structural properties and excellent regeneration potential of nickel aluminates. Prepared samples were tested when unreduced and reduced prior to reaction for methane dry reforming and methane steam reforming reactivity. NiAlb>2b>Ob>4b> in the reduced and unreduced state as well as NiAlb>4b>Ob>7b> in the reduced state are active and stable for methane dry reforming due to the presence of 4-fold coordinated oxidized nickel. The limited amount of metallic nickel in these samples minimizes carbon deposition. On the other hand, the presence of metallic nickel is required for methane steam reforming. Nib>2b>Alb>2b>Ob>5b> in the reduced and unreduced states and NiAlb>2b>Ob>4b> in the reduced state are found to be active for methane steam reforming due to the presence of sufficiently small nickel nanoparticles that catalyze the reaction without accumulating carbonaceous deposits.