Characterisation and activity evaluation of silica supported cobalt and ruthenium catalysts

We prepared Co/SiO2, Co-Ru/SiO2 and Ru/SiO2 catalysts by ion-exchange metho d in an attempt to obtain well dispersed active sites. The catalysts were c haracterised by chemisorption, oxygen titration, TPD and XPS, and their act ivity was evaluated in CO hydrogenation. The results showed that the Co/SiO 2 catalyst exhibited a very low extent of reduction, and consequently its h ydrogen uptake and activity were very low. In case of CoRu/SiO2, the hydrog en and CO uptake was far much higher than for the physical mixture or for t he sum of Co/SiO2 and Ru/SiO2. Evidently, ruthenium acted as a reduction ai d to cobalt in the bimetallic system. Yet, irrespective of the highest upta kes of the CoRu/SiO2 system, the highest activity in CO hydrogenation was o btained with the Ru/SiO2 catalyst. The synergistic performance of the CoRu catalyst was, however, evidenced by the unusually high formation of methano l - a novel finding which indicates that neither of the metals was present as a purr entity in the bimetallic system. (C) 1998 Elsevier Science B.V. A ll rights reserved.