Liquid-phase hydrogenation of benzene to cyclohexene catalyzed by Ru/SiO2 in the presence of water–organic mixtures

The liquid-phase hydrogenation of benzene to cyclohexene was studied using a Ru/SiO2 catalyst prepared by reduction of ruthenium(III) chloride impregnated in a hydrophilic non-porous silica. In a biphasic water/benzene system at 423 K and 5 MPa of hydrogen pressure, a 14% cyclohexene yield was obtained at 60% benzene conversion. Increased cyclohexene yields and selectivities were observed in the presence of ethylene glycol/water and glycerol/water mixtures, which consist mainly of hydrated organic molecules that can enhance the hydrophilicity around the ruthenium particles favoring the cyclohexene desorption.