Comprehensive Study of Carbon Dioxide Adsorption in the Metal-Organic Frameworks M2(dobdc) (M=Mg, Mn, Fe, Co, Ni, Cu, Zn)

Published

August 28, 2014

Author(s)

Wendy L. Queen, Matthew Ross Hudson, Eric D. Bloch, Jarad A. Mason, Miguel I. Gonzalez, Jason S. Lee, David Gygi, Joshua D. Howe, Kyuho Lee, Tamim A. Darwish, Michael James, Vanessa K. Peterson, Simon J. Teat, Berend Smit, Jeffrey B. Neaton, Jeffrey R. Long, Craig Brown

Abstract

Analysis of the CO₂ adsorption properties of a well-known series of metal-organic frameworks M6d26(dobdc) (dobdc^u4¿6 = 2,5-dioxido-1,4-benzenedicarboxylate; M = Mg, Mn, Fe, Co, Ni, Cu, and Zn) is carried out in tandem with [I]in-situ[/I] structural studies to identify the host-guest interactions that lead to significant differences in isosteric heats of CO₂ adsorption. Neutron and X-ray powder diffraction and single crystal X-ray diffraction experiments are used to unveil the site-specific binding properties of CO₂ within many of these materials while systematically varying both the amount of CO₂ and temperature. Unlike previous studies, we have revealed that CO₂ adsorbed at the metal cations exhibits intramolecular angles with minimal deviations from 180°, a finding that indicates a strongly electrostatic and physisorptive interaction with the framework surface and sheds more light on the ongoing discussion regarding whether CO₂ adsorbs in a linear or nonlinear geometry. For the weaker CO₂ adsorbents, significant elongation of the metal-CO₂ distances are observed and diffraction experiments additionally reveal that secondary CO₂ adsorption sites, while likely stabilized by the population of the primary adsorption sites, significantly contribute to adsorption behavior at ambient temperature. Density functional theory calculations including van der Waals dispersion quantitatively corroborate and rationalize observations regarding intramolecular CO₂ angles and trends in relative geometric properties and heats of adsorption in M₂(dobdc)¿CO₂ adducts.

Citation

Chemical Science

Volume

5

Pub Type

Journals

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Keywords

neutron powder diffraction, carbon dioxide separation, metal-organic frameworks

Citation

Queen, W. , Hudson, M. , Bloch, E. , Mason, J. , Gonzalez, M. , Lee, J. , Gygi, D. , Howe, J. , Lee, K. , Darwish, T. , James, M. , Peterson, V. , Teat, S. , Smit, B. , Neaton, J. , Long, J. and Brown, C. (2014), Comprehensive Study of Carbon Dioxide Adsorption in the Metal-Organic Frameworks M₂(dobdc) (M=Mg, Mn, Fe, Co, Ni, Cu, Zn), Chemical Science, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916344 (Accessed December 26, 2024)