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

Abstract

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 m²g^-1) and TiO₂ (33 m²g^-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.