UiO-66 (Zr) MOF as a Promising Material for Butane Isomers Separation: Evidence Based on the Analysis of the Adsorbed Alkanes Mobility by <sup>2</sup>H NMR and Molecular Dynamics Simulation
Alexander E. Khudozhitkov, Sergei S. Arzumanov, Daniil I. Kolokolov, Alexander G. Stepanov
Abstract
UiO-66 (Zr) is a thermally and chemically stable Zr-based metal–organic framework (MOF) that has proved to be promising for different hydrocarbon separation applications including membrane-based processes. Here, we present a combined experimental (2H NMR) and computational (molecular dynamics simulation) study of the molecular mobility and transport of n-butane and isobutane in the dehydroxylated UiO-66 (Zr) MOF. We show that the microscopic diffusivity Dn for n-butane is significantly higher than Diso for isobutane, Dn/Diso = 1000 at 300 K with a large difference in diffusion barriers, En = 25 kJ mol–1 for n-butane and Eiso = 50 kJ mol–1 for isobutane. High selectivity for kinetic-driven separation of the n-butane/isobutane mixture in UiO-66 (Zr)-based materials or membranes is expected based on this result.