Hydrogenation of Quinoline over Ru/ZrO_2·xH_2O

The highly dispersed supported catalyst (Ru/ZrO2·xH2O) was prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microsocpy. The results showed that ruthenium was reduced to low oxidation state and the average partical diameter of Ru particles was about 3.8 nm. The catalyst exhibited high activity in hydrogenation of quinoline under the mild reaction conditions, 40 ℃, 2 MPa, quinoline/Ru molar ratio of 250/1 and H2O as solvent. The conversion of quinoline was 98.2% and the selectity of 1,2,3,4-tetrahydroquinoline was 98.0%. The catalyst can be reused for several times. The mechanism of quinoline hydrogenation over Ru/ZrO2·xH2O catalyst was discussed. The coordination of nitrogen atom of quinoline on the surface of ruthenium nanoparticles and the effect of hydrogen bond between OH groups on ZrO2 surface and nitrogen in quinoline were favourable for the desorption of the substrate and products from the surface of catalyst.