This work is focused on a group of metal-organic frameworks (MOFs) that contain the unsaturated metal centers. These materials are practically important due to their strong ability of separating alkenes from alkanes. Applications of various MOFs for hydrocarbon separation were recently reviewed by Long et al. [1]. Here, ethylene and ethane are used to quantify the contribution of p bond interactions with open metal sites (OMS).Adsorption isotherms of ethylene and ethane were measured at 200, 215 and 230 K using a high-resolution Micromeritics 3Flex adsorption instrument equipped with high-vacuum system that was coupled with a cryostat (Cold Edge Technologies) maintaining cryogenic temperatures with a stability of +/_0.001 K from the target.Selected isotherms measured on Cu2(btc)3at 200 K (Figure 1) demonstrate the effect of the OMS-p bond interactions by much higher uptake of ethylene versus ethane at low pressure range. This effect is also reflected by the elevated isosteric heat of adsorption (Qst) obtained for ethylene in the range of low amount adsorbed (Figure 2). The Qst was calculated from isotherms at three temperatures.   Presented results obtained for Cu2(btc)3illustrate our approach that is used to compare the OMS-p bond interactions for various MOF samples.References[1] Z. R. Herm, E. D. Bloch, and J. R. Long, Chem. Mater. 2014, 26, 323-338.

Thermodynamic assessment of the ethylene ? bond interactions with open metal sites of MOF materials

248th National Meeting (2014)

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