Steam Reforming of Biogas over CeO2-Coated Ni–Al Plate Catalysts

Abstract

Hydrogen production via steam reforming of a simulated biogas was achieved in a temperature range of 500–800 °C over a plate-type Ni–Al catalyst. To enhance the catalytic activity of the Ni–Al catalyst, a pretreatment process involving pre-oxidation with sequential reduction was employed prior to the reforming reactions. The activated Ni–Al catalyst exhibited increased methane conversion depending on the pre-oxidation temperature. Studies using X-ray diffraction and scanning electron microscopy suggested that the catalyst surface was restructured upon pretreatment, ultimately improving the catalytic activity. To increase its catalytic stability, CeO2 was employed additionally as a structural promoter to prevent both Ni sintering and carbon deposition. The durability of the CeO2-coated Ni–Al catalyst was improved significantly, particularly upon addition of ≥2.8 wt% of CeO2, with ca. 75 % of CH4 conversions being achieved without deactivation over 100 h at 700 °C. The influence of the pre-oxidation temperature, reforming temperature, and steam/CH4 ratio on reforming over a CeO2–Ni–Al catalyst was also elucidated. In addition, the potential roles of CeO2 in the enhancement of activity and stability were discussed.