Abstract: Methanation of carbon dioxide by hydrogenating over Ni/Al₂O₃ and Ni-CeO₂/Al₂O₃ catalysts was investigated by methods of reaction and in-situ diffuse reflectance FTIR(in-situ DRFTIR). The results showed that carbon monooxide was not the product over those catalysts whether CeO₂ was added or not, but the yield of methane was increased with CeO₂ addition. At 300 ℃, the yield of methane over Ni-CeO₂/Al₂O₃ catalysts was two times higher than that over Ni/Al₂O₃ catalysts. The DRFTIR results showed that methane came from two processes, which were hydrogenation of CO₂^- species and formate species over the catalysts. The more effective species was formate on the surface of catalyst. The reason why the activity of Ni/Al₂O₃ catalyst was promoted by addition CeO₂ was that a large amount of formate forms over Ni-CeO₂/Al₂O₃ catalyst.

Key words: Ni/Al₂O₃, CeO₂, Catalysts, Hydrogenation of carbon dioxide, Methane