Packing sticky hard spheres into rigid zeolite frameworks

Treacy, M.M.J.; Foster, Martin D.

doi:10.1016/j.micromeso.2008.08.039

Cited by 42 publications

(40 citation statements)

References 25 publications

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“…Defined as the number of spheres with a diameter of 2.8 Å that can be packed into zeolite framework, the occupiable volume has been calculated through computational methods for 176 different zeolite frameworks. 40 When the occupiable volume is smaller, the degree of confinement is greater. From Table 1 , we observe that a trend exists between the loss in rotational entropy and the occupiable volume.…”

Section: Resultsmentioning

confidence: 99%

A Universal Descriptor for the Entropy of Adsorbed Molecules in Confined Spaces

Dauenhauer

Abdelrahman

2018

ACS Cent. Sci.

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Confinement of hydrocarbons in nanoscale pockets and pores provides tunable capability for controlling molecules in catalysts, sorbents, and membranes for reaction and separation applications. While computation of the enthalpic interactions of hydrocarbons in confined spaces has improved, understanding and predicting the entropy of confined molecules remains a challenge. Here we show, using a set of nine aluminosilicate zeolite frameworks with broad variation in pore and cavity structure, that the entropy of adsorption can be predicted as a linear combination of rotational and translational entropy. The extent of entropy lost upon adsorption is predicted using only a single material descriptor, the occupiable volume (Vocc). Predictive capability of confined molecular entropy permits an understanding of the relation with adsorption enthalpy, the ability to computationally screen microporous materials, and an understanding of the role of confinement on the kinetics of molecules in confined spaces.

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Section: Resultsmentioning

confidence: 99%

A Universal Descriptor for the Entropy of Adsorbed Molecules in Confined Spaces

Dauenhauer

Abdelrahman

2018

ACS Cent. Sci.

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“…To date, the database of the International Zeolite Association (IZA) [60] contains 235 zeolite structures (each identified by a three-letter code) which may be classified according to the size of the pore openings (i. e., the number of T atoms), or the number of dimensions defined by the pores. [58,194] Other structural descriptors provide information on the geometry of the pores, [195] the building blocks of the framework, [196] or the environment of a T atom, [197] as nicely documented by a themed review. [198] The high number of zeolite framework types (or "topologies") implies a wide variety of cages and channels, with different geometry and size.…”

Section: Structural Aspectsmentioning

confidence: 99%

Supramolecular Organization in Confined Nanospaces

Tabacchi

2018

ChemPhysChem

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Empty spaces are abhorred by nature, which immediately rushes in to fill the void. Humans have learnt pretty well how to make ordered empty nanocontainers, and to get useful products out of them. When such an order is imparted to molecules, new properties may appear, often yielding advanced applications. This review illustrates how the organized void space inherently present in various materials: zeolites, clathrates, mesoporous silica/organosilica, and metal organic frameworks (MOF), for example, can be exploited to create confined, organized, and self-assembled supramolecular structures of low dimensionality. Features of the confining matrices relevant to organization are presented with special focus on molecular-level aspects. Selected examples of confined supramolecular assemblies - from small molecules to quantum dots or luminescent species - are aimed to show the complexity and potential of this approach. Natural confinement (minerals) and hyperconfinement (high pressure) provide further opportunities to understand and master the atomistic-level interactions governing supramolecular organization under nanospace restrictions.

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“…In the present paper, special attention is paid to these algorithms. In 2009, Treacy and Foster [ 64 ] established a procedure for estimating the packing of hard spheres in the rigid zeolite frameworks, achieving a packing density corresponding to the inert gases and water for 176 known zeolite framework types. The authors noted the great diversity of the pore shapes in zeolites: Spherical, cylindrical, ellipses as well as irregular ones.…”

Section: Packing Of Spheres Into a Channel Of An Irregular Shapementioning

confidence: 99%

Filling of Irregular Channels with Round Cross-Section: Modeling Aspects to Study the Properties of Porous Materials

et al. 2018

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The filling of channels in porous media with particles of a material can be interpreted in a first approximation as a packing of spheres in cylindrical recipients. Numerous studies on micro- and nanoscopic scales show that they are, as a rule, not ideal cylinders. In this paper, the channels, which have an irregular shape and a circular cross-section, as well as the packing algorithms are investigated. Five patterns of channel shapes are detected to represent any irregular porous structures. A novel heuristic packing algorithm for monosized spheres and different irregularities is proposed. It begins with an initial configuration based on an fcc unit cell and the subsequent densification of the obtained structure by shaking and gravity procedures. A verification of the algorithm was carried out for nine sinusoidal axisymmetric channels with different Dmin/Dmax ratio by MATLAB® simulations, reaching a packing fraction of at least 0.67 (for sphere diameters of 5%Dmin or less), superior to a random close packing density. The maximum packing fraction was 73.01% for a channel with a ratio of Dmin/Dmax = 0.1 and a sphere size of 5%Dmin. For sphere diameters of 50%Dmin or larger, it was possible to increase the packing factor after applying shaking and gravity movements.

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Packing sticky hard spheres into rigid zeolite frameworks

Cited by 42 publications

References 25 publications

A Universal Descriptor for the Entropy of Adsorbed Molecules in Confined Spaces

A Universal Descriptor for the Entropy of Adsorbed Molecules in Confined Spaces

Supramolecular Organization in Confined Nanospaces

Filling of Irregular Channels with Round Cross-Section: Modeling Aspects to Study the Properties of Porous Materials

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