Abstract
An anodic alumina supported nickel catalyst (Ni/Al2O3/Alloy) was synthesized using a double impregnation method with a high temperature calcination in between, to investigate reactivity performance thereof during steam reforming of methane (SRM) reactions in continuous and daily start-up and shut-down (DSS)-like operations. The catalyst was structurally characterized using X-ray diffraction (XRD), BET and temperature programmed reduction (TPR) technologies. The TPR results showed that almost all nickel content from the first impregnation was transformed into nickel aluminate, whereas nickel from the second impregnation predominantly existed in the more reducible forms of NiO and xNiO·Al2O3 (x < 1). The existence of these NiO and NiAl2O4 phases was identified by XRD.
The catalyst provided high and stable SRM reactivity near the equilibrium value, while no deactivation was observed in continuous durability testing for 200 h at 800°C and 130 h at 700°C, and in DSS-like mode operation at 700°C. The investigation of the influence of methane and/or steam treatments on the reactivity of Ni/Al2O3/Alloy showed the catalyst is not disturbed by the methane treatment, whereas it is remarkably deactivated by the steam treatment. In addition, no differences in the reduction effect were found when using hydrogen or methane to regenerate a steamed catalyst.
