Modeling adsorption in metal-organic frameworks with open metal sites: propane/propylene separations

Michael Fischer, Jose R. B. Gomes, Michael Froba, Miguel Jorge

Research output: Contribution to journalArticle

57 Citations (Scopus)
230 Downloads (Pure)

Abstract

We present a new approach for modeling adsorption in metal-organic frameworks (MOFs) with unsaturated metal centers and apply it to the challenging propane/propylene separation in copper(II) benzene-1,3,5-tricarboxylate (CuBTC). We obtain information about the specific interactions between olefins and the open metal sites of the MOP using quantum mechanical density functional theory. A proper consideration of all the relevant contributions to the adsorption energy enables us to extract the component that is due to specific attractive interactions between the pi-orbitals of the alkene and the coordinatively unsaturated metal. This component is fitted using a combination of a Morse potential and a power law function and is then included into classical grand canonical Monte Carlo simulations of adsorption. Using this modified potential model, together with a standard Lennard-Jones model, we are able to predict the adsorption of not only propane (where no specific interactions are present), but also of propylene (where specific interactions are dominant). Binary adsorption isotherms for this mixture are in reasonable agreement with ideal adsorbed solution theory predictions. We compare our approach with previous attempts to predict adsorption in MOFs with open metal sites and suggest possible future routes for improving our model.

Original languageEnglish
Pages (from-to)8537-8549
Number of pages13
JournalLangmuir
Volume28
Issue number22
Early online date10 May 2012
DOIs
Publication statusPublished - 5 Jun 2012

Keywords

  • modeling adsorption
  • metal-organic frameworks
  • open metal sites
  • propane/propylene separations

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