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Interaction of CO with K-FER zeolite was investigated by a combination of variable-temperature IR spectroscopy and computational study. Calculations were performed using öCO/rCO correlation method in combination with a periodic density functional theory model. On the basis of agreement between experimental and calculated results, the following carbonyl complexes were identified: (i) mono- and dicarbonyl C-down complexes on single K+ sites characterized by IR absorption bands at 2163 and 2161 cm-1, respectively; (ii) complexes formed by CO bridging two K+ ions separated by about 7-8 Å (dual sites) characterized by a band at 2148 cm-1; and (iii) isocarbonyl (O-down) complexes characterized by a band at 2116 cm-1. The bridged carbonyl complexes on dual K+ sites are about 5 kJ/mol more stable than monodentate (monocarbonyl) CO complexes. The C-O stretching frequency of monocarbonyl species in K-FER depends on K+ location in the zeolite, and not on K+ coordination to the framework. A combination of theoretical calculations using a periodic density functional model and experimental results showed formation of two types of monocarbonyls. The most abundant type appears at 2163 cm-1, and the less abundant one at 2172 cm-1. These experimentally determined wavenumber values coincide, within (2 cm-1, with those derived from theoretical calculations.

SINGLE AND DUAL CATION SITES IN ZEOLITES – PERIODIC DENSITY FUNCTIONAL AND FTIR SPECTROSCOPIC STUDIES ON CO ADSORPTION ON K-FER / GARRONE E.; R. BULNEK; K. FROLICH; C. OTERO AREN; M. RODRGUEZ DELGADO; G. TURNES PALOMINO; D. NACHTIGALLOV AND P. NACHTIGALL. - In: JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL. - ISSN 1520-6106. - STAMPA. - 110(2006), pp. 22542-22550. [10.1021/jp0631331]

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