Relationship between mixed and pure gas self-diffusion for ethane and ethene in ZIF-8/6FDA-DAM mixed-matrix membrane by pulsed field gradient NMR

摘要: Abstract Pulsed field gradient (PFG) NMR was applied to study self-diffusion of an ethane/ethene mixture and the corresponding pure gases in a mixed-matrix membrane (MMM) formed by dispersing ZIF-8 particles 6FDA-DAM polymer. In addition MMM, diffusion measurements were also carried out for constituents, i.e. particle bed polymer film. PFG studies performed at high magnetic 17.6 T using large gradients up 30 T/m. The former allowed achieving sufficiently signal-to-noise ratios, while latter enabled diffusivity be molecular displacements smaller than size particles. As result, gas self-diffusivities inside dispersed MMM surrounding matrix could obtained separately. For each gas, diffusivities phases found neat This observation is explained reduced framework flexibility chain rigidification MMM. ethane ethene loaded with compared single gas. It that presence another component does not change self-diffusivity both gases. At same time, faster-diffusing sorbate (ethene) phase co-adsorption slower-diffusing (ethane) analytical expression proposed our previous work long-range MMMs validated mixtures based on experimental data reported this work.