United Atom Force Field for Alkanes in Nanoporous Materials

Dubbeldam, David; Calero, Sofı́a; Vlugt, Thijs J. H.; Krishna, Rajamani; Maesen, Theo L. M.; Smit, Berend

doi:10.1021/jp0376727

Cited by 322 publications

(485 citation statements)

References 69 publications

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“…͑8͒-͑10͒, linear relations can also be derived for ⌬H 0 , ⌬U 0 , and ⌬A 0 . Such linear relations were previously found in the q st 0 for the adsorption of linear alkanes on Carbopack C and C-HT, 8 in the q st 0 and K H for the adsorption of linear alkanes on silicalite, 22,26,29,31,39,40 and in the q st 0 for the adsorption of linear and branched alkanes on silicalite. 9,41 From these relations, we can estimate the limiting adsorption properties of longer linear alkanes.…”

Section: Simulation Methodssupporting

confidence: 77%

“…Also, force fields have been reported for alkane adsorption by calibrating simulation results with reliable experimental data. Dubbeldam et al 39 generated a united-atom force field for linear and branched alkanes on MFI and other zeolites. Calero et al 40 constructed a united-atom force field for linear alkanes on sodium-exchanged FAU-type zeolites.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption and separation of linear and branched alkanes on carbon nanotube bundles from configurational-bias Monte Carlo simulation

et al. 2005

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The adsorption and separation of linear ͑C 1 -nC 5 ͒ and branched ͑C 5 isomers͒ alkanes on single-walled carbon nanotube bundles at 300 K have been studied using configurational-bias Monte Carlo simulation. For pure linear alkanes, the limiting adsorption properties at zero coverage exhibit a linear relation with the alkane carbon number; the long alkane is more adsorbed at low pressures, but the reverse is found for the short alkane at high pressures. For pure branched alkanes, the linear isomer adsorbs to a greater extent than its branched counterpart. For a five-component mixture of C 1 -nC 5 linear alkanes, the long alkane adsorption first increases and then decreases with increasing pressure, but the short alkane adsorption continues increasing and progressively replaces the long alkane at high pressures due to the size entropy effect. All the linear alkanes adsorb into the internal annular sites with preferred alignment parallel to the nanotube axis on a bundle with a gap of 3.2 Å, and also intercalate the interstitial channels in a bundle with a gap of 4.2 Å. For a three-component mixture of C 5 isomers, the adsorption of each isomer increases with increasing pressure until saturation, though nC 5 increases more rapidly with pressure and is preferentially adsorbed due to the configurational entropy effect. All the C 5 isomers adsorb into the internal annular sites on a bundle with a gap of 3.2 Å, but only nC 5 also intercalates the interstitial channels on a bundle with a gap of 4.2 Å. This work suggests the possibility of separating alkane mixtures based on differences in either size or configuration, as a consequence of competitive adsorption on the carbon nanotube bundles.

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Section: Simulation Methodssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Adsorption and separation of linear and branched alkanes on carbon nanotube bundles from configurational-bias Monte Carlo simulation

et al. 2005

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“…The potential parameters are optimized to reproduce adsorption properties in pure silica confinements. 50,51 A. Molecular Dynamics. The diffusion was calculated using molecular dynamics (MD) calculations.…”

Section: Methodsmentioning

confidence: 99%

Loading Dependence of the Diffusion Coefficient of Methane in Nanoporous Materials

2006

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In this work, we use molecular simulations to study the loading dependence of the self-and collective diffusion coefficients of methane in various zeolite structures. To arrive at a microscopic interpretation of the loading dependence, we interpret the diffusion behavior in terms of hopping rates over a free-energy barrier. These free-energy barriers are computed directly from a molecular simulation. We show that these free-energy profiles are a convenient starting point to explain a particular loading dependence of the diffusion coefficient. On the basis of these observations, we present a classification of zeolite structures for the diffusion of methane as a function of loading: three-dimensional cagelike structures, one-dimensional channels, and intersecting channels. Structures in each of these classes have their loading dependence of the free-energy profiles in common. An important conclusion of this work is that diffusion in nanoporous materials can never be described by one single effect so that we need to distinguish different loading regimes to describe the diffusion over the entire loading range.

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“…The difficulties in obtaining reliable data have been emphasized by Dubbeldam et al; 94 an illustration of this point is given in Figure 14; although the experimental data are at relatively low pressures, a comparison with the results of molecular simulations shows that the experiments are not in the Henry regime. 90 The crossing of the lines gives the parameters for which both the Henry coefficient and heat of adsorption agree with the experimental results.…”

Section: Zeolite-adsorbate Interactionsmentioning

confidence: 97%