NMR studies of carbon dioxide and methane self-diffusion in ZIF-8 at elevated gas pressures

作者：Pusch Anne Kristin; Splith Tobias; Moschkowitz Lutz; Karmakar Shilpi; Biniwale Rajesh; Sant Marco; Suffritti Giuseppe B; Demontis Pierfranco; Cravillon Janosch; Pantatosaki Evangelia; Stallmach Frank^*

来源：Adsorption, 2012, 18(5-6): 359-366.

DOI：10.1007/s10450-012-9414-2

• ZIF-8
• Self-diffusion
• Carbon dioxide
• Methane
• NMR
• Molecular dynamic simulation

Self-diffusion measurements with methane and carbon dioxide adsorbed in the Zeolitic Imidazolate Framework-8 (ZIF-8) were performed by H-1 and C-13 pulsed field gradient nuclear magnetic resonance (PFG NMR). The experiments were conducted at 298 K and variable pressures of 7 to 15 bar in the gas phase above the ZIF-8 bed. Via known adsorption isotherms these pressures were converted to loadings of the adsorbed molecules. The self-diffusion coefficients of carbon dioxide measured by PFG NMR are found to be independent of loading. They are in good agreement with results from molecular dynamic (MD) simulations and resume the trend previously found by IR microscopy at lower loadings. Methane diffuses in ZIF-8 only slightly slower than carbon dioxide. Its experimentally obtained self-diffusion coefficients are about a factor of two smaller than the corresponding values determined by MD simulations using flexible frameworks.

• 出版日期2012-12