The interaction of CO with alumina-supported ruthenium, reduced at different temperatures, was investigated by following the development of infrared bands due to adsorbed CO. It was concluded that the adsorption of CO on Ru at 170-350 K leads to the oxidative disruption of Ru clusters as indicated by the slow transformation of the band at 2020-2040 cm-1 due to RuxCO to bands at 2140 and 2075 cm-1 attributed to Run+(CO)2 species (n = 1-3). This process occurred more slowly under dry conditions, and in the presence of hydrogen, whereas it was accelerated by H2O addition. Analysis of spectral features suggested the involvement of the isolated OH groups on the alumina support in the oxidative disruption process. It was demonstrated that at higher temperatures, namely at around 500 K, the presence of CO causes the reductive agglomeration of Run+ sites, i.e., the reformation of Rux clusters.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry