Effects of TiO₂ promoter on the catalytic performance of Ni/Al₂O₃ in CO methanation

A series of TiO₂-Al₂O₃ composite supports with different TiO₂ contents were prepared by sol-gel method and then supported nickel catalysts (NiO/TiO₂-Al₂O₃) were obtained by impregnation with NiO/TiO₂-Al₂O₃ as the supports. The effects of TiO₂ promoter content and reaction temperature on the performance of TiO₂-Al₂O₃ catalysts in CO methanation were investigated. The results showed that the nickel catalyst supported on the TiO₂-Al₂O₃ composite containing 30% TiO₂ exhibits the highest activity for CO methanation under a temperature from 350 to 450 ℃. BET, XRD and H₂-TPR characterization results indicated that the addition of TiO₂ promoter can restrain the formation of Ni/Al₂O₄, improve the dispersion of NiO, avoid the formation of large NiO granules, and make NiO reduction easier, which can then enhance the activity of the nickel catalysts in CO methanation.