Unusual chain length dependent adsorption of linear and branched alkanes on UiO-66

Separation properties of the MIL-125(Ti) Metal-Organic Framework in high-performance liquid chromatography revealing cis/trans selectivity

“…1a). This means n-hexane can be adsorbed while conserving its linear conformation in the open tetrahedral cages [24], whereas in the UiO-66 the dibranched molecules are better confined in the closed tetrahedral cages [24][25][26]. MIL-125(Ti) and MIL-125(Ti)-NH 2 have also been proposed by Kim et al [27] for the separation of isoprene from 2methylbutane, a mixture which is typically produced as a mixture in a steam cracker.…”

Adsorption and Diffusion of Light Hydrocarbons in UiO-66(Zr): A Combination of Experimental and Modeling Tools

“…While this Zr-based MOF has been the subject of several adsorption studies, ,,− the literature on the diffusion of confined molecules within its pores is still scarce. Initial studies on pure phases of CO 2 and CH 4 used a fixed framework model, giving a poor agreement with QENS data, leading to the development of a flexible force field for the UiO-66(Zr) framework .…”

Experimental Study of Adsorptive Interactions of Polar and Nonpolar Adsorbates in the Zeolitic Imidazolate Framework ZIF-68 via Pulse Gas Chromatography

“…Branched alkanes, having a shorter main carbon chain, need less space to rotate freely compared to the longer linear alkanes. This effect is more pronounced for dibranched than monobranched alkanes . The entropic advantage of the branched alkanes is canceled out by a lower adsorption enthalpy compared to their linear isomers, resulting in similar Gibbs’ free energies of adsorption and thus comparable Henry adsorption equilibrium constants, with a slight preference for linear alkanes.…”

“…This effect is more pronounced for dibranched than monobranched alkanes. 63 The entropic advantage of the branched alkanes is canceled out by a lower adsorption enthalpy compared to their linear isomers, resulting in similar Gibbs' free energies of adsorption and thus comparable Henry adsorption equilibrium constants, with a slight preference for linear alkanes. Also, cycloalkanes and aromatics have a lower entropic cost compared to their linear aliphatic counterparts (Figure 9c).…”