Modelling Slowing-Down Effects in Mixture Diffusion

The efficacy of microporous crystalline materials in separation applications is often influenced to a significant extent by diffusion of guest molecules within the pores of the structural frameworks. The Maxwell–Stefan (M–S) equations provide a fundamental and convenient description of mixture diffusion. In certain classes of materials, such as MFI, and FAU zeolites, slowing-down effects are important. On the other hand, correlation effects are usually of negligible importance for guest diffusion in cage-type zeolites (CHA, DDR, LTA, ERI) that consist of cages separated by narrow 8-ring windows. For background, consult my papers: Krishna, R. Thermodynamic Insights into the Characteristics of Unary and Mixture Permeances in Microporous Membranes. ACS Omega 2019, 4, 9512-9521. https://doi.org/10.1021/acsomega.9b00907. Krishna, R. Using the Maxwell-Stefan formulation for Highlighting the Influence of Interspecies (1-2) Friction on Binary Mixture Permeation across Microporous and Polymeric Membranes. J. Membr. Sci. 2017, 540, 261-276. https://doi.org/10.1016/j.memsci.2017.06.062. Krishna, R. Occupancy Dependency of Maxwell−Stefan Diffusivities in Ordered Crystalline Microporous Materials. ACS Omega 2018, 3, 15743-15753. https://doi.org/10.1021/acsomega.8b02465. Krishna, R. Thermodynamically Consistent Methodology for Estimation of Diffusivities of Mixtures of Guest Molecules in Microporous Materials. ACS Omega 2019, 4, 13520-13529. https://doi.org/10.1021/acsomega.9b01873. Krishna, R.; van Baten, J. M. J. Membr. Sci. 2022, 643, 120049. https://doi.org/10.1016/j.memsci.2021.120049 Watch also Diffusion in Ordered Crystalline Microporous Materials https://www.youtube.com/@rajamanikrishna250/videos