Adsorption of CO 2 in metal organic frameworks of different metal centres: Grand Canonical Monte Carlo simulations compa
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Adsorption of CO2 in metal organic frameworks of different metal centres: Grand Canonical Monte Carlo simulations compared to experiments Naseem A. Ramsahye · Guillaume Maurin · Sandrine Bourrelly · Philip L. Llewellyn · Thomas Devic · Christian Serre · Thierry Loiseau · Gerard Ferey Received: 30 April 2007 / Revised: 10 July 2007 / Accepted: 13 July 2007 / Published online: 29 September 2007 © Springer Science+Business Media, LLC 2007
Abstract A Grand Canonical Monte Carlo study has been performed in order to compare the different CO2 adsorption mechanisms between two members of the MIL-n family of hybrid metal-organic framework materials. The MIL-53 (Al) and MIL-47 (V) systems were considered. The results obtained confirm that there is a structural interchange between a large pore and narrow pore forms of MIL-53 (Al), not seen with the MIL-47 (V) material, which is a consequence of the presence of μ2 -OH groups. The interactions between the CO2 molecules and these μ2 OH groups mainly govern the adsorption mechanism in this MIL-53 (Al) material. The subsequent breaking of these adsorption geometries after the adsorbate loading increases past the point where no more preferred adsorption sites are available, are proposed as key features of the breathing phenomenon. After this, any new adsorbates introduced into the MIL-53 (Al) large pore structure experience a homogeneous adsorption environment with no preferential adsorption sites in a similar way to what occurs in MIL-47 (V). Keywords CO2 , adsorption · Metal-organic frameworks · Grand Canonical Monte Carlo · Microcalorimetry · N.A. Ramsahye · G. Maurin () Institut Charles Gerhardt Montpellier, UMR CNRS 5253, UM2, ENSCM, Université Montpellier 2, 34095 Montpellier cedex 05, France e-mail: [email protected] S. Bourrelly · P.L. Llewellyn Laboratoire MADIREL UMR CNRS 6121, Université de Provence, 13397 Marseille cedex 20, France T. Devic · C. Serre · T. Loiseau · G. Ferey Institut Lavoisier, UMR CNRS 8637, Université de Versailles Saint-Quentin-en-Yvelines, 78035 Versailles cedex, France
Isotherm · Differential adsorption enthalpy, adsorption mechanism, breathing effect
1 Introduction Carbon dioxide is a necessary intermediate in existing hydrogen production processes, and a greenhouse gas implicated in the current opinion of global warming (Kikkinides et al. 1993). In addition, recent commitments to the Kyoto Agreement means that efforts must be concentrated to reduce CO2 emissions, opening up the need for materials to efficiently capture and store this gas. Promising candidates for this application include the nanoporous “Metal-Organic Framework” materials (Férey et al. 2005; Yaghi et al. 2003), which are built up from metal-oxygen polyhedra containing either divalent (Zn2+ , Cu2+ ) or trivalent (Al3+ , Cr3+ ) cations interconnected by variable organic groups such as carboxylates or phosphonates. The number of different structures of these materials is large and some of these new organic-inorganic hybrid porous solids show the unusual feature of being s
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