Understanding Hydrocarbon Adsorption in the UiO-66 Metal–Organic Framework: Separation of (Un)saturated Linear, Branched, Cyclic Adsorbates, Including Stereoisomers

Duerinck, Tim; Bueno-Pérez, Rocío; Vermoortele, Frederik; Vos, Dirk De; Calero, Sofı́a; Baron, Gino V.; Denayer, Joeri

doi:10.1021/jp402294h

Cited by 67 publications

(75 citation statements)

References 83 publications

(49 reference statements)

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“…The atomic charges were calculated using the charge equilibrium (QEq) method31, which adjusts atomic charges dynamically to represent the polarization effects. The combination of UFF and QEq has been used successfully to describe many different inorganic materials32. The long-range electrostatic energy was calculated using the Ewald summation, and the VDW interaction was calculated using a 12.5 Å cutoff with a tail correction.…”

Section: Methodsmentioning

confidence: 99%

Origin of the structure-directing effect resulting in identical topological open-framework materials

Liang

Sun

2015

Sci Rep

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In the synthesis of zeolites and related crystalline materials with open-frameworks, a single structure is obtained in the presence of many different templates, known as the “one-structure/multiple-templates” phenomenon. However, the reasons behind this phenomenon have yet to be elucidated. By analyzing the possible starting point of crystallization in several “one-structure/multiple-templates” systems and applying the molecular dynamics simulation to such systems, we found that the template-framework binding free energy level or charge transfer (exchange) degree was the key to the structure-directing effect of a template. This discovery explains why the structure-directing effect of a template can be affected by many variables, such as the nature of the source materials, molar composition of the initial reaction mixture (recipe), mineralizers, type of solvent, and heating temperature. In the synthesis of zeolites and related crystalline materials with open-frameworks, the template or organic additive played a topological structure-directing role instead of a structure-directing role.

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Section: Methodsmentioning

confidence: 99%

Origin of the structure-directing effect resulting in identical topological open-framework materials

Liang

Sun

2015

Sci Rep

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“…This is exclusively attributed to entropy.I ns tructures like UiO-66, the molecules are well separated in small cavities, and intermolecularinteractions for hexane isomers are low.I ng eneral, because there are two types of cavities in UiO-66, molecules of ac ertain type can preferentially adsorb in one of the two types of cage (or transition between them), depending on the temperature and loading. [58] Entropy differences between components in am ixture can be substantial, even at low loading, and mixture separations can be driven by rotational entropy. [43,59] At the start of an adsorption process, DH < TDS and DG < 0, and the process transfers molecules in the direction of lower free energy (which results in adsorption).…”

Section: Adsorptionthermodynamicsmentioning

confidence: 99%

Exploiting Large‐Pore Metal–Organic Frameworks for Separations through Entropic Molecular Mechanisms

Torres‐Knoop

Dubbeldam

2015

ChemPhysChem

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We review the molecular mechanisms behind adsorption and the separations of mixtures in metal-organic frameworks and zeolites. Separation mechanisms can be based on differences in the affinity of the adsorbate with the framework and on entropic effects. To develop next-generation adsorbents, the separation efficiency of the materials needs to be improved. The performance under industrially relevant conditions largely depends on two factors: 1) the separation selectivity and 2) the pore volume capacity of the material. Enthalpic mechanisms can lead to increased selectivities, but these are mostly restricted to the low loading regime, and hence these mechanisms are unable to make use of all of the large-pore volume that a metal-organic framework can provide. Industrial processes routinely operate in the pore saturation regime. In this Review, we focus on entropic molecular separation mechanisms that are effective under these conditions and, in particular, on a recent methodology to obtain high selectivities at high pore loading.

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“…MOFs constitute a family of soft porous crystals, described by Kitagawa and co-workers [11] as 'porous crystals that possess both a highly ordered network and structural transformability'. MOFs have high potential for use in adsorptive separation processes [12][13][14][15][16][17][18][19][20][21] due to the unique characteristics of structural pores which may be adapted to permit adsorption to take place on the basis of molecular shape and size and in particular structural flexibility [22][23][24][25][26][27][28]. In MOFs, metal framework centres and organic units link thereby allowing structural transitions to occur upon gas adsorption [29][30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Statistical mechanics of binary mixture adsorption in metal–organic frameworks in the osmotic ensemble

Dunne

Manos

2018

Phil. Trans. R. Soc. A.

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Although crucial for designing separation processes little is known experimentally about multi-component adsorption isotherms in comparison with pure single components. Very few binary mixture adsorption isotherms are to be found in the literature and information about isotherms over a wide range of gas-phase composition and mechanical pressures and temperature is lacking. Here, we present a quasi-one-dimensional statistical mechanical model of binary mixture adsorption in metal-organic frameworks (MOFs) treated exactly by a transfer matrix method in the osmotic ensemble. The experimental parameter space may be very complex and investigations into multi-component mixture adsorption may be guided by theoretical insights. The approach successfully models breathing structural transitions induced by adsorption giving a good account of the shape of adsorption isotherms of CO and CH adsorption in MIL-53(Al). Binary mixture isotherms and co-adsorption-phase diagrams are also calculated and found to give a good description of the experimental trends in these properties and because of the wide model parameter range which reproduces this behaviour suggests that this is generic to MOFs. Finally, a study is made of the influence of mechanical pressure on the shape of CO and CH adsorption isotherms in MIL-53(Al). Quite modest mechanical pressures can induce significant changes to isotherm shapes in MOFs with implications for binary mixture separation processes.This article is part of the theme issue 'Modern theoretical chemistry'.

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Understanding Hydrocarbon Adsorption in the UiO-66 Metal–Organic Framework: Separation of (Un)saturated Linear, Branched, Cyclic Adsorbates, Including Stereoisomers

Cited by 67 publications

References 83 publications

Origin of the structure-directing effect resulting in identical topological open-framework materials

Origin of the structure-directing effect resulting in identical topological open-framework materials

Exploiting Large‐Pore Metal–Organic Frameworks for Separations through Entropic Molecular Mechanisms

Statistical mechanics of binary mixture adsorption in metal–organic frameworks in the osmotic ensemble

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