Abstract: The influence of the addition of n-type semiconductor oxide CeO₂ to Ni-based catalyst on carbon deposition from CH₄ and carbon elimination by CO₂ was studied by using a pulse microreaction technique. The catalysts were characterized by TPR, XPS and hydrogen chemisorption. It was found that there was an interaction between active metal Ni and semiconductor oxide CeO₂. The XPS data indicated that the addition of CeO₂ could increase the d-electron density of active atom Ni, which would inhibit the migration of C-H σ-electron from CH₄ molecule to d-orbital of Ni atom, therefore, the carbon deposition activity of CH₄ decreases. Meanwhile, the migration of d-electron from Ni atom to empty antibond π-orbital of CO₂ could be strengthened due to the addition of n-type semiconductor CeO₂, thereby, carbon elimination activity of CO₂ increases. As a result, the Ni/CeO₂-Al₂O ₃ catalyst has an excellent resistance to carbon deposition. In addition, the influence of the synergetic effect between SMSI and MScI on the resistance to carbon deposition of the catalysts calcined at various temperatures was investigated. It was discovered that, only in the presence of relatively weak metal-support interaction, it could exhibit the metal-semiconductor interaction(MScI).

Key words: Ni/CeO₂-Al₂O₃ catalyst, Metal-semiconductor interaction, Metal-support interaction, Carbon deposition from CH₄, Carbon elimination from CO₂