(165e) Understanding Mixture Adsorption in Carboxylate Based Metal Organic Frameworks

There is much interest for the potential use of metal organic frameworks in gas adsorption applications including storage and separation. Whilst most experimental gas adsorption studies have been limited to single component adsorption, only a small amount of quite interesting studies have recently been devoted to the adsorption of mixtures [1-3]. Molecular simulation has more extensively been used to predict the behavior of metal organic frameworks with respect to the adsorption of mixtures [1].

The present work combines mixture adsorption experiments with molecular modeling with the aim to follow and further understand the phenomena that occur. The experimental study has used a set-up in which gravimetry is combined with volumetry, densimetry and in some cases chromatography. This combination of the 3 or 4 measurements allows the estimation of the adsorption of the individual components to be made in any mixture. Some of the systems were also studied using calorimetry. Experiments have been undertaken up to 30 bars. From a modeling point of view, both Grand Canonical Monte Carlo and Hybrid Monte Carlo methods using either rigid or fully flexible frameworkswere used. Several metal organic frameworks have been chosen for this study. The materials were all provided by the group of Gerard Férey in Versailles. The flexible MIL53Cr system has been compared with the rigid analogue MIL47V. This work has then been extended to the large pore systems MIL100Cr and MIL101Cr. This range of materials allows several parameters to be explored including structure flexibility, large pore volumes and specific adsorption sites (-OH, free metal sites). Both the low pressure and higher pressure (to 30 bars) regions have been explored enabling different adsorption regimes to be explored.

The study has concentrated on binary mixtures with combinations of CO2 with other gases including CO CH4, N2, C2H6 and C3H8. The combination of the high pressure mixture adsorption experiments, calorimetry with the molecular modeling approach allows the potentiality of such structures for gas separation.

1. Finsy V., Calero S., Garcia-Perez E., Merkling P.J., Vedts G., De Vos D.E., Baron G.V., Denayer J.F.M., Phys. Chem. Chem. Phys, 11(18), (2009), 3515-3521.

2. Finsy V., Ma L., Alaerts L., De Vos D.E., Baron G.V., Denayer J.F.M., Mic. Mes. Mat., 120(3), (2009), 221-227.

3. Finsy V., Verelst H., Alaerts L., De Vos D., Jacobs P.A., Baron G.V., Denayer J.F.M., J. Am. Chem. Soc., 30(22), (2008), 7110-7118.