NMR Study of the Host Structure and Guest Dynamics Investigated with Alkane/Alkene Mixtures in Metal Organic Frameworks ZIF-8

Within the family of metal organic frameworks, the zeolite-imidazolate framework (ZIF) of type ZIF-8 is among the most promising materials with potential application for hydrocarbon separation, notably of alkanes and alkenes. We have applied NMR spectroscopy for exploring the interaction of representative alkane/alkene mixtures with the host framework as well as the mobility of the various components in their mixture. Deviating from, for example, the separation patterns known for MFI-based membranes, the mobility of the faster molecules (alkenes) is found to remain essentially unaffected by the presence of more slowly diffusing molecules (alkanes). In addition, H-2 and Zn-67 magic-angle spinning NMR contributes to the characterization of ZIF-8 in search for guest-induced changes in the lattice structure.