Adsorption
of Acetone Vapor by Cu-BTC: An Experimental
and Computational Study
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Abstract
We report an experimental and theoretical
study of acetone adsorption
in the metal–organic framework (MOF) compound Cu-BTC. The isosteric
heat of adsorption could be derived experimentally and was found to
be −60 kJ mol<sup>–1</sup>. This value matches the theoretical
data obtained by DFT-based methods at zero coverage. In situ DRIFT
measurements allowed us to precisely describe the adsorption steps
from zero coverage to saturation. Two main adsorption sites were determined
for the adsorption of acetone. The small cavities were found to interact
through van der Waals interaction with acetone, while the Cu(II) site
was found to interact with the carbonyl function of acetone. On the
basis of the in situ infrared experiments, it was demonstrated that
the small cavities were first in interaction with acetone. DFT proved
consistent with these findings by giving the energy of interaction
in the different sites explored but also by providing calculated infrared
spectra of adsorbed acetone in Cu-BTC. Using acetone as a probe allowed
showing that dispersive interactions with the pore sites of the Cu-BTC
can be dominant among all other interactions. Additionally, the adsorption
of acetone in Cu-BTC proved not fully reversible unless exposed to
atmospheric moisture