EXAFS STUDY OF THE CO-ADSORPTION-INDUCED MORPHOLOGY CHANGE IN RUTHENIUM CLUSTERS SUPPORTED ON ALUMINA

Highly dispersed Ru/Al2O3 catalysts were prepared from Ru3(CO)12. EXAFS (extended X-ray absorption fine structure) studies show that all the Ru atoms in the catalyst are in small metal clusters. The Ru clusters are so small that the oxygen atoms at the cluster-support interface have a significant contribution to the EXAFS signal. Adsorption of CO completely changes the structure of this small metal cluster as is evidenced from EXAFS oscillation; Ru-Ru bonds are disrupted and Al-O-Ru-(CO)n (n = 1-2) is formed. When the temperature is raised, Ru atoms agglomerate and small metal clusters are recovered. Infrared spectroscopic observation supports the conclusions obtained from EXAFS. © 1990 American Chemical Society.