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

Abstract

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, H₂-TPR, and TPO), specific surface area, and X-ray diffraction (XRD). Activity runs were conducted at atmospheric pressure, temperatures between 400 and 550°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.

Keywords:

• Cobalt catalyst
• Coke
• Dry reforming of methane
• Magnesium
• Mixed oxides
• Precipitation method