Issue 24, 2010

Experimental and theoretical determination of adsorption heats of CO2 over alkali metal exchanged ferrierites with different Si/Al ratio

Abstract

The adsorption of CO2 in Li-, Na-, and K-FER was investigated by a combination of volumetric adsorption experiments, FTIR spectroscopy, and density functional theory. Experimental isosteric heats of CO2, Qst, depend significantly on the cation size, cation concentration, and on the amount of adsorbed CO2. The differences observed in experimentally determined isosteric heats were interpreted at the molecular level based on good agreement between experimental and calculated characteristics. The highest interaction energies were found for CO2 adsorbed on so-called “dual cation sites” in which CO2 is bridged between two alkali metal cations. The formation of CO2 adsorption complexes on dual cation sites is particularly important on Na-FER and K-FER samples with higher cation concentration. On the contrary, the differences in Qst observed for Li-FER samples are due to the changes in the Li+ coordination with the framework. The DFT/CC calculations show that the dispersion interactions between CO2 and the zeolites framework are rather large (about −20 kJ mol−1).

Graphical abstract: Experimental and theoretical determination of adsorption heats of CO2 over alkali metal exchanged ferrierites with different Si/Al ratio

Supplementary files

Article information

Article type
Paper
Submitted
28 1月 2010
Accepted
12 3月 2010
First published
30 3月 2010

Phys. Chem. Chem. Phys., 2010,12, 6413-6422

Experimental and theoretical determination of adsorption heats of CO2 over alkali metal exchanged ferrierites with different Si/Al ratio

A. Zukal, A. Pulido, B. Gil, P. Nachtigall, O. Bludský, M. Rubeš and J. Čejka, Phys. Chem. Chem. Phys., 2010, 12, 6413 DOI: 10.1039/C001950J

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