Transferable Potentials for Phase Equilibria. 1. United-Atom Description of <i>n</i>-Alkanes

Martin, Marcus G.; Siepmann, J. Ilja

doi:10.1021/jp972543+

Cited by 2,731 publications

(2,737 citation statements)

References 47 publications

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“…As is shown in Fig. 2, these parameters do not reproduce the experimental isotherm of Cavalcante et al 41 As the Neubauer' 31 gas-phase parameters for the cyclohexane CH 2 groups differ from the gas-phase parameters for the CH 2 groups of linear alkanes from the widely used TraPPE 40 alkane forcefield, we scaled the Vlugt et al parameters for the interaction with the zeolite accordingly (first only e, after that both s and e; see Table 1). The calculated adsorption isotherms using these scaled parameters is also shown in Fig.…”

Section: Resultsmentioning

confidence: 77%

Molecular simulations of the adsorption of cycloalkanes in MFI-type silica

Schenk

Smit

Maesen

et al. 2005

Phys. Chem. Chem. Phys.

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A new force field for the simulation of the adsorption of cycloalkanes in nanoporous silica affords a significant improvement over any previously employed force field. The simulated isotherms reproduce the most salient features in the experimental isotherms extremely well. The study of cyclo-pentane, -hexane, and -heptane adsorption in MFI-type silica indicates an inflection for cyclopentane but not for cyclohexane at intermediate pressure. If corroborated by experiments, such an inflection point would afford an excellent calibration point for further force field developments. At low pressures, mixture isotherms of cyclohexane and n-hexane show a temperature dependence on the selectivity in accordance with recent results by J. P. Fox and S. P. Bates, J. Phys. Chem., 2004, 108, 17136. This dependence is caused by a difference in temperature dependence of the Henry coefficient for both molecules. At high pressures entropy effects due to packing always favor the sorption of n-hexane. Furthermore, the influence of the flexibility of the zeolite framework on the adsorption of these rather bulky molecules is investigated. It is found that this influence of the flexibility on the adsorption of cyclohexane is as small as with n-alkanes.

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Section: Resultsmentioning

confidence: 77%

Molecular simulations of the adsorption of cycloalkanes in MFI-type silica

Schenk

Smit

Maesen

et al. 2005

Phys. Chem. Chem. Phys.

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“…The bond-bending is described by a harmonic potential, and the non-bonded interactions are modeled using Lennard-Jones potentials taken from Ref. [25]. The zeolite is modeled as a rigid crystal [26], consisting exclusively of SiO 2 , so as to make the calculation of the zeolite-alkane interactions efficient.…”

Section: Simulation Techniquementioning

confidence: 99%

Molecular simulations of adsorption isotherms of small alkanes in FER-, TON-, MTW- and DON-type zeolites

Ndjaka

Zwanenburg

Smit

et al. 2004

Microporous and Mesoporous Materials

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Computer simulations are a useful tool in the study of the adsorption of alkanes in zeolites, provided the zeolite-alkane interactions are described in an adequate manner. MFI-type zeolites are among the most frequently studied types of zeolite. Consequently, zeolite specific force fields are often parameterized using experimental data obtained on MFI-type zeolites. In this paper we examine whether these force fields can be used to simulate adsorption in other zeolite types. We find that experimentally obtained isotherms of small alkanes on high silica FER-, TON-, MTW-, and DON-type zeolites can be accurately modeled using a single force field.

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“…18 The parameters for cross interactions between different molecular species (atomic groups) were derived using the standard Lorentz-Berthelot rules. 19 The particle−particle particle−mesh method, 20 as implemented in LAMMPS, 16 with a real space truncation distance of 15 Å and an accuracy of 10 -6 was used to treat the electrostatic interactions.…”

Section: Molecular Modelsmentioning

confidence: 99%

Quantify Water Extraction by TBP/Dodecane via Molecular Dynamics Simulations

Khomami

Cui

Almeida

et al. 2013

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Objective: The purpose of this project is to quantify the interfacial transport of water into the most prevalent nuclear reprocessing solvent extractant mixture, namely tri-butylphosphate (TBP) and dodecane, via massively parallel molecular dynamics simulations on the most powerful machines available for open research. Specifically, we will accomplish this objective by evolving the water/TBP/dodecane system up to 1 ms elapsed time, and validate the simulation results by direct comparison with experimentally measured water solubility in the organic phase. The significance of this effort is to demonstrate for the first time that the combination of emerging simulation tools and state-of-the-art supercomputers can provide quantitative information on par to experimental measurements for solvent extraction systems of relevance to the nuclear fuel cycle.Efforts and Results: To achieve the object described above, initially, the single component, single phase systems were studied to verify existing and develop new molecular models, followed by a single phase mixture, and then finally the complete twophase water extraction system. Specifically, the systems we studied are: (1) pure TB; (2) n-doedecane; (3) TBP/n-dodecane mixture; and (4) the complete extraction system: water-TBP/n-dodecane two phase system to gain deep insight into the water extraction process. We have completely achieved our goal of extracting water molecules into the TBP/n-dodecane mixture to saturation and obtained favorable comparison with experiment. Many insights into fundamental molecular level processes and physics were obtained from the process. Most importantly, we found that the dipole moment of the 2 Bu=C 4 extracting agent is crucially important in affecting the interface roughness and the extraction rate of water molecules into the organic phase. In addition, we have identified shortcomings in the existing OPLS-AA force field potential for long-chain alkanes. The significance of this force field is that it is supposed to be optimized for molecular liquid simulations. We found that it failed for n-dodecane and/or longer chains to correctly predict the liquid state and thus not usable for our water extraction simulation. We have proposed a simple modification to circumvent the artificial crystallization of the long alkane chains applicable at ambient condition.(b) Effort performed and the accomplishments achieved TBP Force Field Model DevelopmentWe conducted force field survey on 4 sets of force field parameters for TBP, a molecule composed of a phosphate head group and three butyl tails as shown in Figure 1. The 4 sets of parameters are based on adoption of Van der Waals parameters for the phosphoryl head group and the butyl tail group of the TBP molecules, from separate force field models already in use. In particular, we used the Amber parameters for the Van der Waals interaction of the phosphoryl group, combined with either the Amber or the OPLS-AA (Optimized Potential for Liiquid Simulation-All Atoms) force field for the butyl tail...

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Transferable Potentials for Phase Equilibria. 1. United-Atom Description of n-Alkanes

Cited by 2,731 publications

References 47 publications

Molecular simulations of the adsorption of cycloalkanes in MFI-type silica

Molecular simulations of the adsorption of cycloalkanes in MFI-type silica

Molecular simulations of adsorption isotherms of small alkanes in FER-, TON-, MTW- and DON-type zeolites

Quantify Water Extraction by TBP/Dodecane via Molecular Dynamics Simulations

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