Aqueous Phase Hydrogenation of Toluene over Ru Catalysts Supported on Swellable Organically Modified Silica (SOMS)

Herein, the performance of Ru catalysts supported on swellable organically modified silica (SOMS) for hydrogenation (HYD) of toluene is investigated for the removal of aromatics from contaminated groundwater. SOMS is a hydrophobic material that swells to 3–4 times its original volume when in contact with organic solvents. Catalytic HYD of toluene in the aqueous phase suffers from slow kinetics due to low concentrations of toluene. High absorption capacity for organics and hydrophobicity of SOMS have been shown to allow the preferential concentration of toluene inside its pores, thereby accelerating the HYD kinetics. Comparison of HYD of toluene on SOMS-supported catalysts with commercial Al2O3- and SiO2-supported ones revealed faster kinetics on the former. Characterization using in situ infrared spectroscopy, transmission electron microscopy, X-ray absorption spectroscopy, and N2 physisorption indicates that both swellability and hydrophobicity of SOMS are necessary for its superior HYD performance. An optimal reduction method using NaBH4 for the supported Ru catalyst synthesis is also discussed.