Abstract: Activated carbon (AC) was modified by supercritical methanol (scCH₃OH) treatment, HNO₃ oxidation, and HNO₃ oxidation in combination with scCH₃OH treatment. The pristine and modified AC samples were characterized by N₂ physisorption, Boehm titration, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and transmission electron microscopy (TEM). These modifications did not significantly change the surface area and the pore size distribution of the AC. scCH₃OH treatment decreased the density of surface acidic groups, especially carboxylic groups. However, HNO₃ oxidation increased the density of surface acidic groups. ICP analysis revealed that the ScCH₃OH modified sample had a similar adsorptive capacity for ruthenium as the original AC, while the AC oxidized with HNO₃ had the highest adsorptive capacity of all samples tested. Ru/AC catalysts were prepared with RuCl₃ solution impregnation on the four aforementioned AC supports. The as-prepared catalysts were characterized by TEM, XPS and examined for their effectiveness in D-glucose hydrogenation as well. The modifications drastically affected the properties of the activated carbons and the catalysts loaded on them. The dispersion of ruthenium after impregnation was highly dependent on the density of surface acidic groups. The AC sample treated by scCH₃OH, which contained a lower amount of surface acidic complexes, showed the highest dispersion of ruthenium. The XPS results showed that the scCH₃OH modification enhanced the interaction between AC and Ru. The Ru/AC-scCH₃OH catalyst showed the highest activity for hydrogenation of D-glucose; producing a reaction rate 1.56 times higher than that produced by Ru/AC.

Key words: Surface modification, Activated carbon, Ruthenium catalyst, Surface oxygen containing group, Hydrogenation