Phase Equilibria Calculations with a Modified SAFT Equation of State. 2. Binary Mixtures of <i>n</i>-Alkanes, 1-Alkanols, and Water

Kraska, Thomas; Gubbins, Keith E.

doi:10.1021/ie960233s

Cited by 136 publications

(97 citation statements)

References 35 publications

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“…In subsequent work with the SAFT-LJ EOS [166,167], and in the closely related soft-SAFT EOS [168][169][170], the constraint of a fixed geometry was relaxed in an implicit manner by treating the effective bonding volume K LJ ab as an adjustable parameter; one should point out, however, that when one employs this type of empirical approach the direct correspondence with the geometry of the association site is lost. A very good description of the thermodynamic properties and fluid-phase equilibria of water and other associating fluids can nevertheless be obtained in this way, making this type of approach particularly versatile.…”

Section: Correlation Of Simulation Data For Associating Lennard-jonesmentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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(2015) The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids, Molecular Physics, 113:9-10, 948-984, DOI: 10.1080/00268976.2015 An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values of the Mie repulsive exponent. The resulting SAFT-VR Mie EOS allows for a much improved description of the vapour-liquid equilibria and single-phase properties of associating fluids such as water, methanol, ammonia, hydrogen sulphide, and their mixtures. A comparison is also made between the theoretical predictions of the degree of association for water and the extent of hydrogen bonding obtained from molecular simulations of the SPC/E and TIP4P/2005 atomistic models.

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Section: Correlation Of Simulation Data For Associating Lennard-jonesmentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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“…The Lennard-Jones SAFT (LJ-SAFT), exhibited better agreement with experimental data than the original version, however it can only be applied to a limited range of density [23]. Grenner et al, employed the simplified perturbed chain SAFT model (PC-SAFT) using a different set of water pure component parameters based on some physically justified arguments to predict very satisfactorily the solubilities in the hydrocarbon rich phase but the obtained solubility of the hydrocarbon in water was higher than the experimental values [24].…”

Section: Introductionmentioning

confidence: 99%

Mutual solubilities of hydrocarbons and water with the CPA EoS

Oliveira

Coutinho

Queimada

2007

Fluid Phase Equilibria

142

103

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The knowledge of hydrocarbon/water phase equilibria is important in the design and operation of equipment for petroleum transport and refining and petrochemical plants. The presence of water in a hydrocarbon mixture can affect the product quality and damage the operation equipment due to corrosion and formation of gas hydrates. Tracing the concentration of hydrocarbons in aqueous media is also important for technical purposes like preventing oil spills and for ecological concerns such as predicting the fate of these organic pollutants in the environment.In spite of its huge interest there was no model able for a qualitative description of the mutual solubility of water and hydrocarbons for a broad range of systems in a wide range of thermodynamic conditions. In this work it is shown that an equation of state incorporating association known as the CPA EoS is able to produce an excellent description of the mutual solubilities of water and several aliphatic and aromatic hydrocarbons in a broad range of pressures and temperatures.

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“…(21) through eq. (24), a number of interactions in the chain system are now determined as: (25) Eq. (25) represents that N r-r depends on both the segment number and the system density.…”

Section: Square-well Based Equation For the Attractive Termmentioning

confidence: 99%

“…Most of the models are developed in analytical form and shows high accuracy, however, the obtained expressions are too lengthy and difficult to handle. 7,[17][18][19][20][21][22][23][24][25][26] In this study, we developed three hard-sphere-chain equations of state based on the well-known Carnahan-Starling hard-sphere equation 27 differing in the perturbation terms, that have more simplified form than those of the models mentioned above. Each model is directly extended from the Carnahan-Starling equation by introducing a bonding term which accounts for the chain connectivity.…”

Section: Introductionmentioning

confidence: 99%

Equations of state for hard-sphere chains: effect of attractive contribution

Kim

2006

Macromol. Res.

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Several equations of state for hard-sphere chains with various perturbation terms are reviewed. For each model, three characteristic parameters are required to represent phase equilibria of normal fluids and obtained from thermodynamic properties of pure saturated liquids. The models are then compared with computer simulation data to show the effect of attractive contribution forms employed. Calculated values of vapor-liquid equilibria (VLE) of hydrocarbons that can be reproduced for each model are also compared with experimental results. An additional parameter, ζ KB , is required to represent the VLE of pure water, which is ascertained to have a strong influence on the theoretical coexistence curve.

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Phase Equilibria Calculations with a Modified SAFT Equation of State. 2. Binary Mixtures of n-Alkanes, 1-Alkanols, and Water

Cited by 136 publications

References 35 publications

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

Mutual solubilities of hydrocarbons and water with the CPA EoS

Equations of state for hard-sphere chains: effect of attractive contribution

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