Mixed gas adsorption of carbon dioxide and methane on a series of isoreticular microporous metal-organic frameworks based on 2-substituted imidazolate-4-amide-5-imidatesElectronic supplementary information (ESI) available: Indicating spreading pressure diagrams of IFP-1 to IFP-6 at 273 K. See DOI: 10.1039/c2jm15811f

• Main Authors: Debatin, Franziska, Möllmer, Jens, Mondal, Suvendu Sekhar, Behrens, Karsten, Möller, Andreas, Staudt, Reiner, Thomas, Arne, Holdt, Hans-Jürgen
• Format: Article
• Language: English
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/c2jm15811f

In this work the adsorption of CO 2 and CH 4 on a series of isoreticular microporous metal-organic frameworks based on 2-substituted imidazolate-4-amide-5-imidates, IFP-1-IFP-6 ( IFP = Imidazolate Framework Potsdam), is studied firstly by pure gas adsorption at 273 K. All experimental isotherms can be nicely described by using the Tòth isotherm model and show the preferred adsorption of CO 2 over CH 4 . At low pressures the Tòth isotherm equation exhibits a Henry region, wherefore Henry's law constants for CO 2 and CH 4 uptake could be determined and ideal selectivity α CO 2 /CH 4 has been calculated. Secondly, selectivities were calculated from mixture data by using nearly equimolar binary mixtures of both gases by a volumetric-chromatographic method to examine the IFPs . Results showed the reliability of the selectivity calculation. Values of α CO 2 /CH 4 around 7.5 for IFP-5 indicate that this material shows much better selectivities than IFP-1 , IFP-2 , IFP-3 , IFP-4 and IFP-6 with slightly lower selectivity α CO 2 /CH 4 = 4-6. The preferred adsorption of CO 2 over CH 4 especially of IFP-5 and IFP-4 makes these materials suitable for gas separation application. IFP-5 based on Co II and 2-methylimidazolate-4-amide-5-imidate has the highest CO 2 /CH 4 selectivity ( α CO 2 /CH 4 ~7.5) in the series of Imidazolate Frameworks Potsdam.