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Structural Origin of Unusual CO 2 Adsorption Behavior of a Small-Pore Aluminum Bisphosphonate MOF

Abstract : The adsorption of CO2, CH4, and N-2 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 N-2 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 N-2 are located mainly in the center of the pores, CO2 molecules interact with the hydrogen-bonded POHN acidbase 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).
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https://hal-amu.archives-ouvertes.fr/hal-01417308
Contributor : Laurence Tortet <>
Submitted on : Thursday, December 15, 2016 - 3:10:10 PM
Last modification on : Tuesday, October 20, 2020 - 1:04:02 PM

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Philip L. Llewellyn, Miquel Garcia-Rates, Lucia Gaberová, Stuart R. Miller, Thomas Devic, et al.. Structural Origin of Unusual CO 2 Adsorption Behavior of a Small-Pore Aluminum Bisphosphonate MOF. Journal of Physical Chemistry C, American Chemical Society, 2015, 119 (8), pp.4208 - 4216. ⟨10.1021/jp512596u⟩. ⟨hal-01417308⟩

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