Catalytic hydrogenation of aromatic ring over ruthenium nanoparticles supported on α-Al2O3 at room temperature

Selective hydrogenation of aromatic ring represents an essential process for the valorization of lignin in the chemical industry but achieving this process at low temperature is still a challenge. Herein, a series of Ru-based catalysts were investigated. It is found that Ru/γ-Al2O3 with small Ru metal particle size shows the low activity in this system. A unique and strong metal-support interaction for Ru/γ-Al2O3 indicates that the strongly bounded Ru-O-Al sites lead to the positive charge of Ru species. In contrast, Ru/α-Al2O3 with well-dispersed Ru nanoparticles supported on α-Al2O3 can successfully catalyze the selective hydrogenation of lignin-derived aromatic compounds at room temperature. Ru/α-Al2O3 has the excellent recyclability, air stability and the highest activity. The selective hydrogenation of aromatic ring for Ru/α-Al2O3 results from the fast dissociation of H2 and the high adsorption energy of aromatic ring as revealed by X-ray absorption spectra, X-ray photoelectron spectroscopy and density functional theory calculations.