Estimation of Parameters for the NRTL Equation for Excess Gibbs Energies of Strongly Nonideal Liquid Mixtures

Renon, H.; Prausnitz, J. M.

doi:10.1021/i260031a019

Cited by 533 publications

(441 citation statements)

References 6 publications

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“…The NRTL-based models use the standard nonrandomness parameter values (Sørensen andArlt, 1979-1980;Renon and Prausnitz, 1969) of α ij = α ji = 0.2 for immiscible binaries, and α ij = α ji = 0.3 for completely miscible binaries (Renon and Prausnitz, 1968), unless excess enthalpy data is used for fitting the interaction parameters, in which case the larger value of α ij = α ji = 0.8 is used (Simoni et al, 2009b). The symmetric eNRTL and asymmetric NRTL/eNRTL models contain parameters that are related to the distance of closest ionic approach (ρ and σ).…”

Section: Modelingmentioning

confidence: 99%

Extraction of biofuels and biofeedstocks from aqueous solutions using ionic liquids

Simoni

Chapeaux

Brennecke

et al. 2010

Computers & Chemical Engineering

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The production from biomass of chemicals and fuels by fermentation, biocatalysis, and related techniques implies energy-intensive separations of organics from relatively dilute aqueous solutions, and may require use of hazardous materials as entrainers to break azeotropes.We consider the design feasibility of using ionic liquids as solvents in liquid-liquid extractions for separating organic compounds from dilute aqueous solutions. As an example, we focus on the extraction of 1-butanol from a dilute aqueous solution. We have recently shown (Chapeaux et al., 2008) that 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide shows significant promise as a solvent for extracting 1-butanol from water. We will consider here two additional ionic liquids, 1-(6-hydroxyhexyl)-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, as extraction solvents for 1-butanol. Preliminary design feasibility calculations will be used to compare the three ionic liquid extraction solvents considered. The ability to predict the observed ternary liquid-liquid equilibrium behavior using selected excess Gibbs energy models, with parameters estimated solely using binary data and pure component properties, will also be explored.

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Section: Modelingmentioning

confidence: 99%

Extraction of biofuels and biofeedstocks from aqueous solutions using ionic liquids

Simoni

Chapeaux

Brennecke

et al. 2010

Computers & Chemical Engineering

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“…(3) to obtain the system of equations to be solved for the NRTL interaction parameters θ 12 = ∆g 12 and θ 21 = ∆g 21 . This equation system is usually solved [2,3,9] using standard local methods, such as Newton's method, but is well known to frequently have multiple solutions [9]. Multiple solutions can be found using local methods and trying multiple starting points; however, this approach is not guaranteed to find all the solutions, and can lead to incorrect solutions, as shown in Section 4.2.…”

Section: Nrtlmentioning

confidence: 99%

“…There are a wide variety of such two-parameter models, including the UNIQUAC, NRTL (with fixed nonrandomness parameter), electrolyte-NRTL (eNRTL), van Laar and Margules (three suffix) models. Values of the binary parameters can be determined directly from mutual solubility data at a given temperature [1,2]. The equal activity conditions for liquid-liquid equilibrium provide two equations that, given the experimental phase compositions, can be solved directly for the two binary parameter values needed to fit the mutual solubility data, thereby providing an exact fit to the experimental results.…”

Section: Introductionmentioning

confidence: 99%

Reliable computation of binary parameters in activity coefficient models for liquid–liquid equilibrium

Simoni

Lin

Brennecke

et al. 2007

Fluid Phase Equilibria

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A method based on interval analysis is presented for determining parameter values from mutual solubility data in two-parameter activity coefficient models for liquid-liquid equilibrium. The method is mathematically and computationally guaranteed to locate all sets of parameter values corresponding to stable phase equilibria. The technique is demonstrated with examples using the NRTL and electrolyte-NRTL (eNRTL) models. In two of the NRTL examples, results are found that contradict previous work. In the eNRTL examples, binary systems of an ionic liquid and an alcohol are considered. This appears to be the first time that a method for parameter estimation in the eNRTL model from binary LLE data (mutual solubility) has been presented.

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“…The model is considered to be especially valuable for highly nonideal solutions that lead to phase splitting. Renon and Prausnitz (1969) provide graphs for determination of NRTL parameters from immiscibility data and from infinite dilution activity coefficients. Here we provide essentially the opposite result: given a set of NRTL parameters will one see phase splitting, homogeneous azeotropes, plus extrema and inflections points for ln ␥ i ?…”

Section: Nrtl Modelmentioning

confidence: 99%

Characteristics of activity coefficient models for liquid solutions

Eubank

Wang

2004

AIChE Journal

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Liquid-phase activity coefficient models (or excess Gibbs energy models) with three or fewer adjustable parameters are often sufficient to model the liquid solutions present for the vapor-liquid equilibria (VLE) or the vapor-liquid-liquid equilibria (VLLE) calculations of phase equilibria. Our purpose here is to show the flexibility of three such equations in the correlation and prediction of (1) extrema and inflection points on the popular ln ␥ i vs. x 1 diagram for binary solutions, (2) liquid-liquid phase splitting, and (3) homogeneous azeotropes. The empirical equations investigated here are (a) the twoconstant Margules model, (b) the van Laar model, and (c) the three-constant NRTL model. New mathematical procedures lead to new graphs and equations, which allow the reader to identify the presence of any of the above three phenomena by inspection withoutperforming detailed calculations such as a Gibbs energy minimization for liquid phase splitting.

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Estimation of Parameters for the NRTL Equation for Excess Gibbs Energies of Strongly Nonideal Liquid Mixtures

Cited by 533 publications

References 6 publications

Extraction of biofuels and biofeedstocks from aqueous solutions using ionic liquids

Extraction of biofuels and biofeedstocks from aqueous solutions using ionic liquids

Reliable computation of binary parameters in activity coefficient models for liquid–liquid equilibrium

Characteristics of activity coefficient models for liquid solutions

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