CO2 reforming of methane over Ni/Mg/Al/Ce mixed oxides

Ni/Mg/Al/Ce mixed oxides were synthesized by thermal decomposition of layered double hydroxide-type compounds, which were obtained by the coprecipitation method at constant pH. The effect of the Ni2+ and Ce3+ incorporation methods in the hydrotalcite-type structure was studied. The solids were characterized using chemical analysis by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTG), diffuse reflectance infrared spectroscopy (DRIFT), temperature programmed reduction (TPR-H-2), BET surface areas and scanning electron microscopy (SEM). The methane reforming reaction was carried out at 700 degrees C. The results demonstrate the formation of solids with mixed crystalline phases of NiO-MgO (periclase) type and CeO2 (fluorite) as well as other types of reducible species. Catalysts with CH4 conversions of 50-80%, CO2 conversions of 80-90%, CO selectivities of 20-40% and H-2 of 18-30% and high stability under the reaction conditions were obtained. Cerium promotes the catalytic activity of this type of solids. The catalyst with the best activity was obtained by coprecipitation of Ni2+ Mg2+, Al3+ and Ce3+. (c) 2007 Elsevier B.V. All rights reserved.