IR spectra of the CO molecules adsorbed on Pt/NaY and Pt-ColNaY bimetallic catalysts prepared by ion exchange (IE) and impregnation (IM) methods, have been measured at different temperatures. On different samples the absorption frequencies of the linearly bound CO molecules shift towards lower wavenumbers in the sequence of Pt/NaY(IE) > Pt-Co/NaY(IE) > Pt/NaY(IM). This red shift is attributed to the interaction between Pt and Co and to the influence of the particle size and locations of metals, e. g. inside the cages or on the external surface of the zeolite. Upon heating the samples in CO gas the absorption bands for the linearly bound CO on Pt/NaY(IE), Pt-Co/NaY(IE) and Pt/NaY(IM) shift to the lower wavenumbers due to re-dispersion of the adsorbed CO layer, which diminishes the dipole-dipole interaction between the adsorbed CO molecules. Upon adsorption and heating the Pt-Co/NaY(IM) in CO a new band for linear CO appears due to formation of the Co sub-carbonyl species.
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry