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Integrated modeling of mixture fluid phase equilibrium experiments using SAFT-VR applied to xenon + diborane, xenon + cyclopropane, xenon + boron trifluoride / M. Pollock in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2188–2198 Titre : Integrated modeling of mixture fluid phase equilibrium experiments using SAFT-VR applied to xenon + diborane, xenon + cyclopropane, xenon + boron trifluoride Type de document : texte imprimé Auteurs : M. Pollock, Auteur ; Adjiman, C. S., Auteur ; A. Galindo, Auteur Année de publication : 2009 Article en page(s) : p. 2188–2198 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Vapor−liquid  equilibrium  Integrated  self-consistent  approach  Pure  component  model  SAFT-VR  calculations Résumé : An intermolecular parameter estimation procedure is incorporated into a model of a static cell vapor−liquid equilibrium experiment where only the total pressure and temperature are measured, so that compositions are not available experimentally. The coexistence compositions are often obtained from the raw experimental measurements by data reduction, in which a (mostly empirical) thermodynamic description must be assumed to represent the liquid and vapor phases. The molecular interaction parameters inherent in a more advanced equation of state treatment are then estimated from this pretreated data for the coexistence compositions. This can lead to a bias in the development of the mixture model and does not allow a statistical analysis to be applied to the model. To overcome these limitations, an integrated self-consistent approach is developed in this work. The pure component model parameters are used with an equation of state to calculate the amount of substance in the experimental apparatus, and the mixture parameters are obtained from parameter estimation based on a model of the experimental setup and the representation of the vapor−liquid equilibrium. This type of integrated approach, best achieved by close integration of detailed experimental information and the theoretical treatment, is tested on three well-studied and characterized binary mixtures: xenon + diborane; xenon + cyclopropane; and xenon + boron trifluoride. The statistical associating fluid theory for potentials of variable range (SAFT-VR) is the equation of state used in this work; the molecular models inherent in the approach are associating chain molecules formed from square-well segments. Excellent agreement between SAFT-VR calculations of the fluid phase equilibrium and experimental data is obtained for all three mixtures, without a priori knowledge of the compositions of the coexisting phases. In the case of xenon + boron trifluoride, the region of liquid−liquid immiscibility and the vapor−liquid−liquid three-phase line are accurately predicted. The effect of experimental error is incorporated into the parameter estimation procedure so that the confidence in the optimal parameters can be evaluated providing guidance in choosing which parameters to estimate with confidence. For comparison, SAFT-VR models are also developed using the reduced data for the coexistence compositions. The description of the fluid phase equilibrium and the values of the intermolecular parameters are found to be similar to those obtained from the integrated approach. The integrated approach presented is general and can be modified to specific static cell apparatus or applied to other types of mixtures or with other equations of state. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800928s [article] Integrated modeling of mixture fluid phase equilibrium experiments using SAFT-VR applied to xenon + diborane, xenon + cyclopropane, xenon + boron trifluoride [texte imprimé] / M. Pollock, Auteur ; Adjiman, C. S., Auteur ; A. Galindo, Auteur . - 2009 . - p. 2188–2198. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2188–2198 Mots-clés : Vapor−liquid  equilibrium  Integrated  self-consistent  approach  Pure  component  model  SAFT-VR  calculations Résumé : An intermolecular parameter estimation procedure is incorporated into a model of a static cell vapor−liquid equilibrium experiment where only the total pressure and temperature are measured, so that compositions are not available experimentally. The coexistence compositions are often obtained from the raw experimental measurements by data reduction, in which a (mostly empirical) thermodynamic description must be assumed to represent the liquid and vapor phases. The molecular interaction parameters inherent in a more advanced equation of state treatment are then estimated from this pretreated data for the coexistence compositions. This can lead to a bias in the development of the mixture model and does not allow a statistical analysis to be applied to the model. To overcome these limitations, an integrated self-consistent approach is developed in this work. The pure component model parameters are used with an equation of state to calculate the amount of substance in the experimental apparatus, and the mixture parameters are obtained from parameter estimation based on a model of the experimental setup and the representation of the vapor−liquid equilibrium. This type of integrated approach, best achieved by close integration of detailed experimental information and the theoretical treatment, is tested on three well-studied and characterized binary mixtures: xenon + diborane; xenon + cyclopropane; and xenon + boron trifluoride. The statistical associating fluid theory for potentials of variable range (SAFT-VR) is the equation of state used in this work; the molecular models inherent in the approach are associating chain molecules formed from square-well segments. Excellent agreement between SAFT-VR calculations of the fluid phase equilibrium and experimental data is obtained for all three mixtures, without a priori knowledge of the compositions of the coexisting phases. In the case of xenon + boron trifluoride, the region of liquid−liquid immiscibility and the vapor−liquid−liquid three-phase line are accurately predicted. The effect of experimental error is incorporated into the parameter estimation procedure so that the confidence in the optimal parameters can be evaluated providing guidance in choosing which parameters to estimate with confidence. For comparison, SAFT-VR models are also developed using the reduced data for the coexistence compositions. The description of the fluid phase equilibrium and the values of the intermolecular parameters are found to be similar to those obtained from the integrated approach. The integrated approach presented is general and can be modified to specific static cell apparatus or applied to other types of mixtures or with other equations of state. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800928s

Modeling the fluid phase behavior of carbon dioxide in aqueous solutions of monoethanolamine using transferable parameters with the SAFT-VR approach / Mac Dowell, N. in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1883–1899 Titre : Modeling the fluid phase behavior of carbon dioxide in aqueous solutions of monoethanolamine using transferable parameters with the SAFT-VR approach Type de document : texte imprimé Auteurs : Mac Dowell, N., Auteur ; Llovell, F., Auteur ; Adjiman, C. S., Auteur Année de publication : 2010 Article en page(s) : pp 1883–1899 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Carbon  dioxide  Aqueous  solutions  Fluid  phase. Résumé : The current method of choice for large-scale carbon dioxide (CO2) capture is amine-based chemisorption, typically in packed columns, with the benchmark solvent being aqueous solutions of a primary alkanolamine: monoethanolamine (MEA). In this contribution, we use the statistical associating fluid theory for potentials of variable range (SAFT-VR) to describe the fluid phase behavior of MEA + H2O + CO2 mixtures. The physical chemistry of CO2 in aqueous solutions of amines is highly complex owing to the chemical equilibria between the various species that are formed in solution at ambient conditions. We explicitly consider the multifunctional nature of MEA and, in so doing, are able to represent accurately the thermodynamic properties and phase equilibria of this highly nonideal mixture over a wide range of temperatures, pressures, and compositions. MEA is modeled as an associating chain molecule formed from homonuclear spherical segments with six distinct association sites incorporated to mediate the asymmetric hydrogen bonding interactions exhibited by this molecule. The models for H2O and CO2 are taken from previous work. In order to describe the chemisorption, which is the key to the CO2 capture process, two additional effective sites are incorporated on the otherwise nonassociating CO2 molecule to describe the chemical interaction between the MEA and CO2, so that the correct maximal stoichiometry of two amine molecules per CO2 molecule is retained. The vapor−liquid phase equilibria of the various binary mixtures and of the MEA + H2O + CO2 ternary mixture are accurately described with our approach, including the degree of absorption of CO2 in the solvent for wide ranges of temperature and pressure. This suggests that the underlying complexity of the chemical equilibria associated with this system are correctly captured by the model and provides great promise for the modeling of the overall process of CO2 capture. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901014t [article] Modeling the fluid phase behavior of carbon dioxide in aqueous solutions of monoethanolamine using transferable parameters with the SAFT-VR approach [texte imprimé] / Mac Dowell, N., Auteur ; Llovell, F., Auteur ; Adjiman, C. S., Auteur . - 2010 . - pp 1883–1899. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1883–1899 Mots-clés : Carbon  dioxide  Aqueous  solutions  Fluid  phase. Résumé : The current method of choice for large-scale carbon dioxide (CO2) capture is amine-based chemisorption, typically in packed columns, with the benchmark solvent being aqueous solutions of a primary alkanolamine: monoethanolamine (MEA). In this contribution, we use the statistical associating fluid theory for potentials of variable range (SAFT-VR) to describe the fluid phase behavior of MEA + H2O + CO2 mixtures. The physical chemistry of CO2 in aqueous solutions of amines is highly complex owing to the chemical equilibria between the various species that are formed in solution at ambient conditions. We explicitly consider the multifunctional nature of MEA and, in so doing, are able to represent accurately the thermodynamic properties and phase equilibria of this highly nonideal mixture over a wide range of temperatures, pressures, and compositions. MEA is modeled as an associating chain molecule formed from homonuclear spherical segments with six distinct association sites incorporated to mediate the asymmetric hydrogen bonding interactions exhibited by this molecule. The models for H2O and CO2 are taken from previous work. In order to describe the chemisorption, which is the key to the CO2 capture process, two additional effective sites are incorporated on the otherwise nonassociating CO2 molecule to describe the chemical interaction between the MEA and CO2, so that the correct maximal stoichiometry of two amine molecules per CO2 molecule is retained. The vapor−liquid phase equilibria of the various binary mixtures and of the MEA + H2O + CO2 ternary mixture are accurately described with our approach, including the degree of absorption of CO2 in the solvent for wide ranges of temperature and pressure. This suggests that the underlying complexity of the chemical equilibria associated with this system are correctly captured by the model and provides great promise for the modeling of the overall process of CO2 capture. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901014t