Jump to main content
Jump to site search

Issue 8, 2003
Previous Article Next Article

FTIR spectroscopic study of CO adsorption on Co–ZSM-5: Evidence of formation of Co+(CO)4 species

Author affiliations


CO adsorption on Co–ZSM-5 results in formation of two kinds of Co2+–CO species characterized by bands at 2217 and 2207 cm−1, respectively. The species are highly resistant towards evacuation at ambient temperature. When CO adsorption is performed at low temperature, new kinds of weakly electrophilic Co2+ sites are evidenced by carbonyl bands at 2197 and 2190 cm−1. The bands detected at ambient temperature are negligibly reduced in intensity, suggesting initial stages of formation of geminal Co2+(CO)2 dicarbonyls (most probably absorbing at 2201 cm−1). Reduction of the sample in a CO atmosphere at temperatures of 423–673 K results in creation of a fraction of Co+ cations. The latter form, with CO, stable Co+(CO)2 dicarbonyl species (bands at 2113 and 2042 cm−1). Coadsorption of 12CO and 13CO allows detection of Co+(12CO)(12CO) (2097 and 2013 cm−1) and Co+(13CO)2 (2065 and 1997 cm−1) species. The dicarbonyls are thermally decomposed without formation of a measurable amount of corresponding monocarbonyls. In the presence of CO in the gas phase the Co+(CO)2 dicarbonyl species are converted into tricarbonyls (2137, 2089 and 2079 cm−1) which are characterized by a disordered C3v symmetry. As a result, a variety of mixed carbonyls are produced after 12CO–13CO coadsorption. Lowering of the temperature in the presence of CO results in coordination of a fourth CO molecule to some of the Co+ sites, the tetracarbonyls formed being characterized by a set of bands at 2130, 2105 and 2075 cm−1. The reasons for the high coordinative unsaturation of the Co+ cations in Co–ZSM-5 and the possible role of Co+ cations in the selective catalytic reduction of nitrogen oxides are discussed.

Back to tab navigation

Publication details

The article was received on 21 Jan 2003, accepted on 25 Feb 2003 and first published on 05 Mar 2003

Article type: Paper
DOI: 10.1039/B300844D
Citation: Phys. Chem. Chem. Phys., 2003,5, 1695-1702
  •   Request permissions

    FTIR spectroscopic study of CO adsorption on Co–ZSM-5: Evidence of formation of Co+(CO)4 species

    K. Hadjiivanov, B. Tsyntsarski, Tz. Venkov, D. Klissurski, M. Daturi, J. Saussey and J.-C. Lavalley, Phys. Chem. Chem. Phys., 2003, 5, 1695
    DOI: 10.1039/B300844D

Search articles by author