INFLUENCE OF METAL LOADING AND TEMPERATURE ON HYDROGEN CHEMISORPTION AND HYDROGENATION ACTIVITY OF RY GAMMA-AL2O3 CATALYSTS/

Ru/gamma-Al2O3 Catalysts with Ru loadings from 0.5% to 5.0% prepared b y the incipient wetness method are characterized by hydrogen chemisorp tion, and benzene hydrogenation in the temperature range from 85-degre es-C to 200-degrees-C under differential conditions with the objective of studying the influence of metal loading on the physico-chemical ch aracteristics of the catalysts. Ru surface area calculated from irreve rsible H-2 uptake is found to increase steadily with Ru loading upto 2 .5% above which the increase is minimal, while Ru particle size increa ses upto 7.1 nm and Ru dispersion decreases with Ruy loading. Effect o f temperature is studied on hydrogen chemisorption on 5.0% Ru catalyst and on benzene hydrogenation on all the catalysts. Hydrogen chemisorp tion as well as the activity of the catalysts increase with temperatur e upto 12-degrees-C and decrease above this temperature signifying the important role played by the reversibly adsorbed hydrogen in enhancin g the activity of the catalysts. Hydrogenation activity of the catalys t is observed to increase proportionately with metal area while the tu rnover frequency of the reaction remains fairly constant over the rang e of Ru particle size from 2.7 nm to 7.1 nm.