Rhodium Supported on Faujasites: Effects of Cluster Size and CO Ligands on Catalytic Activity for Toluene Hydrogenation

摘要: NaY zeolite-supported rhodium carbonyls, with the predominant species being [Rh6(CO)16], were prepared by carbonylation of adsorbed [Rh(CO)2(acac)] at 125°C. The carbonyl clusters treated in He or H2at 200, 250, 300°C to remove ligands. When decarbonylation took place He, resultant had Rh–Rh coordination numbers (determined extended X-ray absorption fine structure spectroscopy) between 3.5 and 3.9, hardly any evidence Rh–C contributions, indicating that cluster frames nearly intact was complete. In contrast, when treatment H2, partially decarbonylated aggregates formed, having 3.8 6.7; aggregation increased increasing temperature. formed all similar catalytic activities for toluene hydrogenation. (partially temperatures <300°C) presence H2showed a strong dependence on temperature, which is explained inhibition remaining CO ligands aggregate size effects, more active than smaller clusters. Comparison data those reported separately NaX zeolite shows zeolites equivalent as supports. indicates are approximately same activity iridium zeolite.