FTIR study of carbon monoxide adsorption on ceria: CO 2? 2 carbonite dianion adsorbed species

CO has been adsorbed in doses at room temperature by ceria which had been reduced with CO and then evacuated at 873 K, or only evacuated at this temperature, as well as by a Pd/CeO2 catalyst, H2-reduced and evacuated at 823 K. From comparison of the observed IR spectra with literature results concerning matrix-isolated Cs2CO2 species, the formation of two carbonite CO2–2 species adsorbed over reduced ceria may be inferred. One of these species, with C2v geometry and with IR bands at around 1300 and 1160 cm–1, was formed before the other one, with a Cs structure and characterized by IR bands at 1270, 1071 and 771 cm–1. A band at 1465 cm–1 was only tentatively assigned to a third carbonite species. CO2–2 species ultimately lead to CO2–3 species when they are heated in vacuum.