Structural origin of unusual CO adsorption behavior of a small-pore aluminum bisphosphonate MOF

P.L. Llewellyn, M. Garcia-Rates, L. Gaberová, Stuart R Miller, T. Devic, J.-C. Lavalley, S. Bourrelly, E. Bloch, Y. Filinchuk, P.A. Wright, C. Serre, A. Vimont, G. Maurin

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45 Citations (Scopus)


The adsorption of CO2, CH4, and N2 at 303 K by MIL-91(Al), one of the few porous phosphonate-based-MOFs, has been investigated by combining advanced experimental and computational tools. Whereas CH4 and N2 adsorption isotherms exhibit type I behavior, the reversible CO2 isotherm displays an unusual inflection point at low pressure. In situ X-ray powder diffraction and infrared spectroscopy showed structural changes of this small-pore MOF upon CO2 adsorption. Grand canonical Monte Carlo simulations delivered a detailed picture of the adsorption mechanisms at the microscopic level. The so-predicted arrangements of the confined CO2 molecules were supported by analysis of the in situ diffraction and infrared experiments. It was shown that while adsorbed CH4 and N2 are located mainly in the center of the pores, CO2 molecules interact with the hydrogen-bonded POH–N acid–base pairs. This results in a relatively high adsorption enthalpy for CO2 of ca. −40 kJ mol–1, which suggests that this material might be of interest for CO2 capture at low pressure (postcombustion).

Original languageEnglish
Pages (from-to)4208-4216
Number of pages9
JournalJournal of Physical Chemistry C
Issue number8
Early online date4 Feb 2015
Publication statusPublished - 26 Feb 2015


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