Carbon dioxide reforming of methane over Ni/CaO/Al₂O₃

Ni catalysts supported on CaO-precoated Al₂O₃ were prepared and characterized by BET, XRD and TPR techniques. The Ni/CaO/Al ₂O₃ catalysts with various CaO loadings were applied to carbon dioxide reforming of CH₄. All the catalysts showed a fairly good stability but the activity of Ni/CaO/Al₂O₃ depended upon the amount of CaO. Among the catalysts tested, the Ni/CaO/Al ₂O₃ catalyst with a Ca/Al ratio of 0.04 exhibited the highest activity and stability. The interaction between Ni and the support was changed with the addition of CaO and the variation of Ca/Al ratio. Based on the characterization results, the promotional effect of CaO on Ni/-Al ₂O₃ resulted from (1) the interaction between Ni and CaO, (2) the stabilization of CaO on Al₂O₃ and (3) the strong basicity of CaO. It was suggested that the highly dispersed CaO species are effective to obtain active and stable Ni/CaO/Al₂O₃ catalysts in carbon dioxide reforming of methane.