Carbon Nanotubes Supported Cobalt, Ruthenium For Catalysis

Carbon nanotubes (CNTs) supported Co, Ru and Co-Ru bimetallic catalysts were prepared by an impregnation method. The obtained catalysts were characterized by TEM, XRD, TPR, XPS and TG techniques in order to elucidate the dispersion of metal particles, the interaction between cobalt and ruthenium, and the reducibility of catalysts.There are two main parts in catalysts testing. First, the preparation conditions of Co/CNTs were studied. Then the catalytic activities of Co/CNTs catalysts were tested with the hydroformylation of 1-octene as the probe reaction and the reaction conditions were detected. The results show that in co MParison to Co/CNTs catalysts, Co-Ru/CNTs catalysts exhibit good performance in terms of better conversion of 1-octene and higher selectivity to C9-aldehyde. This may be due to the homogenous dispersion of small metal particles and synergic effect of Co and Ru metals in bimetallic catalysts, which can be further attributed to the promoting effect of Ru metal in the catalysts.In the second part, Ru/CNTs was employed for selective oxidation of benzyl alcohol to benzaldehyde in oxygen atmosphere with excellent activity in condition that certain amount of water was added into the reaction system. By co MParing the results of benzyl alcohol oxidation proceeded in solo water solvent, toluene solvent and water-toluene bi-solvent, it is easy to conclude that water plays the essential role for reaction rate acceleration. XRD and XPS examination indicate that ruthenium complex can be reduced to Ru° in our condition. In alcohol oxidation, Ru metal nanoparticles are the active species rather than Ru complexes or Ru cations. Furthermore, Ru/CNTs could be widely used in variety of alcohols oxidation with high activity in water-tolune biphasic system. The catalyst could be reused several times without much loss of catalytic activity and selectivity for benzaldehyde. According to the results, a probable reaction mechanism was proposed.