INFLUENCE OF THERMAL TREATMENT ON THE CATALYTIC ACTIVITY OF SHAPE RUTHENIUM NANOCATALYSTS

Abstract

Ruthenium fabricated as noble metal nanoparticles can be catalytically active for hydrogenation of organic compounds. However, a challenging issue for researchers is that Ru nanocatalysts can be spontaneously deactivated due to some effects, such as sintering or leaching of active components, oxidation of metal particles, inactive metal or metal oxide deposition and impurities in solvents and reagents. Activation of metal nanoparticles is one option for reactivation of shape Ru particles immobilized on SiO2 (0.1 wt% Ru/SiO2) utilized as nanocatalysts in chemical reactions. In fact, the catalytic activity of metal particles is known to be proportional to the active part of the surface area. The effects of thermal treatments on the catalytic activity of “shape Ru/SiO2 for hydrogenation of cyclohexene to cyclohexane were investigated. Optimization of activations by varying temperature and its time proved to be effective on the activity of catalysts retaining the Ru nanocatalysts shapes for the hydrogenation of cyclohexene. Product mixtures were analysed using gas chromatography (GC-FID) to determine conversions. The Ru catalysts showed the highest activity (C%: 100) when the catalysts were activated by activation following protocol No.1 (TPR1) in a furnace under the mildest reduction with more severe conditions (temperature: 200 oC for 1 h, which was the shortest activation time). HRTEM study showed only minimal aggregation and so minor deformation of the shape Ru nanoparticles for this type of Ru activation.