FTIR study of 12C16O and 13C18O coadsorption on Cu–ZSM-5

Adsorption of 12C16O–13C18O isotopic mixtures was used to establish polycarbonyl structures formed with Cu+ ions in Cu–ZSM-5. The principal Cu+(12C16O)2 dicarbonyls are characterized by νs at 2178 cm−1 and νas at 2151 cm−1. In excellent agreement with theory, Cu+(12C16O)(13C18O) mixed-ligand species were found to absorb at 2168 and 2065 cm−1. Another kind of dicarbonyls, characterized by νs at 2183 cm−1, was also unambiguously detected. Tricarbonyls are characterized by two IR modes, at 2191 and 2166 cm−1. Different bands of Cu+(12C16O)x(13C18O)y (x + y = 3) species were established. The use of isotopic mixtures also helped in the assignment of a shoulder at 2194 cm−1 to Cu2+–CO adducts.

Adsorption of 12C16O–13C18O isotopic mixtures on Cu–ZSM-5 was used to establish polycarbonyl structures.Figure optionsDownload high-quality image (145 K)Download as PowerPoint slideHighlights
► 12C16O–13C18O isotopic mixtures are useful for establishing of polycarbonyl structures.
► Two kinds of Cu+(CO)2 species are formed on Cu–ZSM-5.
► Bands of tricarbonyls with one or two 13C18O ligands are determined.