Abstract:

The promoting effect of La2O3 on Ni/γ-Al2O3 methanation catalyst was investigated by XPS, TPR and TPD methods. Results indicated that La2O3 can be partially reduced to LaOx (x＜3/2) during H2 reduction of the Ni catalysts with La2O3.The excess charge associated with the LaOx can be transfered to Ni. It weakened C-O bond strength, accelerated CO dissociation, proportionation and methanation reaction. The interaction between NiO and Al2O3 can be suppressed and the formation of NiAl2O4-like species can be reduced by adding La2O3. With the increase of La2O3 contents the fraction of NiO which is easier to be reduced becomes larger. The fact that there was more residual H2 on the catalyst with La2O3 means that it is able to retain some H2. Besides, the distribution of CO adsorption sites of the Ni catalyst was shifted by adding La2O3.

Key words: Ni/γ-Al₂O₃, La₂O₃, Promotion effect, Methanation catalyst