Adsorption of Acetone Vapor by Cu-BTC: An Experimental and Computational Study

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–1. 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.