Dry Reforming of Methane over Mg-Co-Al Mixed-Oxides Catalysts: Effect of Mg Content and Reduction Conditions

Mg-Co-Al mixed oxides were synthesized by the precipitation method and evaluated for dry reforming of methane. The samples were characterized by thermal techniques (TGA/DTA, NH3-TPD, H-2-TPR, and TPO), specific surface area, and X-ray diffraction (XRD). Activity runs were conducted at atmospheric pressure, temperatures between 400 and 550 degrees C, a CH4/CO2 molar ratio of 1, and a space velocity of 6000 NmL CH4/g/h. The partial substitution of Co with Mg increased the surface area and thermal stability and changed the reducibility and acid-base properties of the samples. These modifications led to a higher activity for dry reforming of methane for the catalyst with Mg/Co=0.5, primarily due to its enhanced thermal stability. However, its higher activity was followed by higher amounts of coke. The different activation procedures highlighted Co3O4 as the main active phase rather than the Co-mixed oxides. Therefore, milder activation temperatures are required to properly reduce the Co3O4 phase and avoid sintering.