Revealing the Transient Concentration of CO2 in a Mixed-Matrix Membrane by IR Microimaging and Molecular Modeling
Seungtaik Hwang (University of Leipzig)
Rocio Semino (Université de Montpellier, École Polytechnique Fédérale de Lausanne)
Beatriz Seoane (Debye Institute, TU Delft - Applied Sciences)
Marufa Zahan (University of Leipzig)
Christian Chmelik (University of Leipzig)
Rustem Valiullin (University of Leipzig)
Marko Bertmer (University of Leipzig)
Jürgen Haase (University of Leipzig)
Freek Kapteijn (TU Delft - Applied Sciences)
Jorge Gascon (King Abdullah University of Science and Technology, TU Delft - Applied Sciences)
Guillaume Maurin (Université de Montpellier)
Jörg Kärger (University of Leipzig)
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Abstract
Through IR microimaging the spatially and temporally resolved development of the CO2 concentration in a ZIF-8 at 6FDA-DAM mixed matrix membrane (MMM) was visualized during transient adsorption. By recording the evolution of the CO2 concentration, it is observed that the CO2 molecules propagate from the ZIF-8 filler, which acts as a transport "highway", towards the surrounding polymer. A high-CO2-concentration layer is formed at the MOF/polymer interface, which becomes more pronounced at higher CO2 gas pressures. A microscopic explanation of the origins of this phenomenon is suggested by means of molecular modeling. By applying a computational methodology combining quantum and force-field based calculations, the formation of microvoids at the MOF/polymer interface is predicted. Grand canonical MonteCarlo simulations further demonstrate that CO2 tends to preferentially reside in these microvoids, which is expected to facilitate CO2 accumulation at the interface.