Influence of support on ruthenium-dispersion and hydrogenation activity of supported ruthenium catalysts: Ru/ZrO2 and Ru/TiO2 systems

Ru/ZrO2 and Ru/TiO2 (Rutile) catalysts with varying Ru loadings from 0.50 to 5.00 wt% are prepared by the incipient wetness method and characterised by hydrogen chemisorption and benzene hydrogenation. It is observed that Ru dispersions and metal areas of Ru/TiO2 catalysts are more than double those of Ru/ZrO2 catalysts contrary to the expectation from the consideration of BET surface areas of the supports, ZrO2 (66 m(2)g(-1)) and TiO2 (33 m(2)g(-1)). Benzene hydrogenation rates over Ru/TiO2 are also about twice the rates over Ru/ZrO2 catalysts. The higher dispersion of Ru on TiO2 is attributed to the intensely pronounced interaction of ruthenium with TiO2 surface. The abnormally high reversible hydrogen uptakes on Ru/TiO2 catalysts at ambient temperature are considered to comprise hydrogen chemisorbed through multiple bonds on fine particles of Ru and split over hydrogen on the support. The split over hydrogen is also considered to be partly responsible for the higher activities of Ru/TiO2 catalysts.