Electronic interaction between supports and ruthenium catalysts for the hydrogenation of carbon monoxide

The effect of oxide supports in hydrogenation of CO was investigated using Ru supported on metal oxides as catalysts. Activity for CO hydrogenation and product distribution depended on the electron affinity of the oxide supports. A support effect was also recognized in the adsorption state of hydrogen and carbon monoxide from temperature-programmed desorption (TPD) experiments. The support effect observed in this study seems to result from electronic interaction between Ru and support oxide, since the binding energy of Ru 3d _{5 2} XPS peaks and the IR absorption frequency of linear-type NO depended on the electron affinity of the oxide support. The extent of charge transfer was represented by the electronegativity of support oxide in this study. The activity and the chain growth probability in CO hydrogenation are enhanced by using Ru on support oxides with high electronegativity because the deficient electron density of Ru weakened the CO adsorption and enhanced the concentration of hydrogen on catalyst surface.