Issue 47, 2006

On the site-specificity of polycarbonyl complexes in Cu/zeolites: combined experimental and DFT study

Abstract

The preferred Cu+ sites and formation of mono-, di-, and tricarbonyl complexes in the Cu-FER were investigated at the periodic density functional theory level and by means of FTIR spectroscopy. The site-specificity of adsorption enthalpies of CO on Cu-FER and of vibrational frequencies of polycarbonyl complexes were investigated for various Cu+ sites in Cu-FER. Large changes in the Cu+ interaction with the zeolite framework were observed upon the formation of carbonyl complexes. The dicarbonyl complexes formed on Cu+ in the main channel or on the intersection of the main and perpendicular channels are stable and both, adsorption enthalpies and CO stretching frequencies are not site-specific. The fraction of Cu+ ions in the FER cage, that cannot form dicarbonyl can be determined from IR spectra (about 7% for the Cu-FER with Si/Al = 27.5 investigated here). The tricarbonyl complexes can be formed at the Cu+ ions located at the 8-member ring window at the intersection of main and perpendicular channel. The stability of tricarbonyl complexes is very low (ΔH°(0 K) ≥ −4 kJ mol−1).

Graphical abstract: On the site-specificity of polycarbonyl complexes in Cu/zeolites: combined experimental and DFT study

Article information

Article type
Paper
Submitted
22 sep 2006
Accepted
20 okt 2006
First published
07 nov 2006

Phys. Chem. Chem. Phys., 2006,8, 5535-5542

On the site-specificity of polycarbonyl complexes in Cu/zeolites: combined experimental and DFT study

R. Bulánek, H. Drobná, P. Nachtigall, M. Rubeš and O. Bludský, Phys. Chem. Chem. Phys., 2006, 8, 5535 DOI: 10.1039/B613805E

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