The Preparation Of Highly Dispersed Ru Catalyst And The Study Of The Catalytic Behavior On Hydrogenation Of N-heterocycles

The highly dispersed supported noble metal catalysts were prepared and their catalytic perfermances in the hydrogenation of pyridine were investigated. Active carbon supported ruthenium catalyst was characterized by HRTEM,XRD and XPS . The active carbon supported ruthenium was reduced to zero valence and the average partical diameter of Ru crystallites was smaller than 5 nm. The results indicated that ruthenium catalyst exhibited the highest activity compared with palladium, platinium and iridium for the hydrogenation of pyridine. The order of catalystic activities is Ru/C > Pd/C > Pt/C > Ir/C. The activities of bimetallic catalysts Ru-Pd/C and Ru-Ir/C were slightly lower than that of Ru/C, but the activity of Ru-Co/C was much lower than that of Ru/C. It suggested that there was no synergetic effect between two metals. The comparing study on hydrogenation of pyridine derivatives showed that the electron factor played an important role in the reaction process. The reactivities of pyridine and its derivateves were pyridine as following : 2-methylpyridine > 2,6-dimethyl- pyridine >3-methylpyridine> 4-methylpyridine > 3,5-dimethylpyridine > 2-methoxy- pyridine. Under the optimum reaction conditions : 100 oC, PH2 = 3.0 MPa, Ru/pyridine = 2.5:1000 (molar ratio), pyridine could be completely converted to piperidine with the selectivity of 100%. The reuse of catalyst showed that the activity and selectivity of Ru/C did not decrease significantly.The catalytic behavior of 5% Ru/C was also investigated in the hydrogenation of quinoline and compared with other bimetallic catalysts (5%Ru-Pd/C, Ru-Ir/C)...