Abstract: ZIF-8 is a metal-organic framework (MOF) renowned for its outstanding thermal and chemical stability [1]. This material is comprised of large spherical cavities with 11.4 A diameter connected by narrow windows with a size 3.4 A. Due to the dynamics of the linkers the effective size of the window increases allowing adsorption of the molecules larger than 3.4 A. Moreover, the flexible nature of the window leads to the high separation selectivity of light hydrocarbons. In particular, there are several reports showing the efficiency of ZIF-8 in propane/propylene separation. There have been several attempts to rationalize the ability of ZIF-8 to separate propane and propylene using adsorption methods and various computational techniques [2-5]. However, the diffusivity and the diffusional activation barrier of guest molecules obtained by different methods vary from 9.7 to 22 kJ/mol for propylene and from 26.8 to 74 kJ/mol for propane. In present work we clarified the mechanism of molecular transport inside ZIF-8 and determined the correct value of diffusivity by means of 2H NMR method. Spin relaxation analysis allowed characterization of the intracavity mobility as well as the transport properties between cavities. The reported study was funded by RFBR according to the research project 18-33-00048.

Cite: Khudozhitkov A.E. , Kolokolov D.I. , Stepanov A.G.
2H NMR Study of Propane and Propylene Mobility in ZIF-8
In compilation MR 2020. The 16th National MR Meeting, January 7th - 8th, 2020, Oslo : Book of Abstracts. 2020. – C.32.

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