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Butadiene purification using polar solvents / Paul M. Mathias in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 4996–5004 Titre : Butadiene purification using polar solvents : analysis of solution nonideality using data and estimation methods Type de document : texte imprimé Auteurs : Paul M. Mathias, Auteur ; J. Richard Elliott, Auteur ; Andreas Klamt, Auteur Année de publication : 2008 Article en page(s) : p. 4996–5004 Note générale : Bibliogr. p. 5003-5004 Langues : Anglais (eng) Mots-clés : Butadiene  --  purificationButadiene  --  solventsMolecular  simulation Résumé : The classical problem of 1,3-butadiene recovery from steam cracker C4 hydrocarbons is reconsidered using modern tools of quantum mechanics and molecular simulation. The effectiveness of N,N-dimethylformamide (DMF) and acetonitrile (ACN) to act as extractive-distillation solvents is explored with an emphasis on the predictive capability of various models. The quantum mechanical method of interest is the COSMO-RS method. The chosen molecular simulation method is the SPEADMD model. These methods are compared to conventional methods such as UNIFAC and “thermodynamic intuition”. The COSMO-RS method is found to predict the trends of infinite-dilution activity coefficients quantitatively, but requires a systematic empirical correction to provide accuracy comparable to UNIFAC. It is noted that the COSMO-RS method has a special capability to predict subtle trends. The SPEADMD model is found to provide unique qualitative insights, but requires empirical refinement of the interaction-potential models that is similar to the regression of UNIFAC parameters. This work is intended to serve as an objective framework to evaluate tools—traditional and modern—to predict solution nonideality. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070774p [article] Butadiene purification using polar solvents : analysis of solution nonideality using data and estimation methods [texte imprimé] / Paul M. Mathias, Auteur ; J. Richard Elliott, Auteur ; Andreas Klamt, Auteur . - 2008 . - p. 4996–5004. Bibliogr. p. 5003-5004 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 4996–5004 Mots-clés : Butadiene  --  purificationButadiene  --  solventsMolecular  simulation Résumé : The classical problem of 1,3-butadiene recovery from steam cracker C4 hydrocarbons is reconsidered using modern tools of quantum mechanics and molecular simulation. The effectiveness of N,N-dimethylformamide (DMF) and acetonitrile (ACN) to act as extractive-distillation solvents is explored with an emphasis on the predictive capability of various models. The quantum mechanical method of interest is the COSMO-RS method. The chosen molecular simulation method is the SPEADMD model. These methods are compared to conventional methods such as UNIFAC and “thermodynamic intuition”. The COSMO-RS method is found to predict the trends of infinite-dilution activity coefficients quantitatively, but requires a systematic empirical correction to provide accuracy comparable to UNIFAC. It is noted that the COSMO-RS method has a special capability to predict subtle trends. The SPEADMD model is found to provide unique qualitative insights, but requires empirical refinement of the interaction-potential models that is similar to the regression of UNIFAC parameters. This work is intended to serve as an objective framework to evaluate tools—traditional and modern—to predict solution nonideality. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070774p

Correlation of mixture vapor-liquid equilibria with the SPEADMD model / Amir Vahid in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7955-7964 Titre : Correlation of mixture vapor-liquid equilibria with the SPEADMD model Type de document : texte imprimé Auteurs : Amir Vahid, Auteur ; Amanda D. Sans, Auteur ; J. Richard Elliott, Auteur Année de publication : 2008 Article en page(s) : P. 7955-7964 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Molecular  simulation  SPEADMD  Vapor−Liquid Résumé : The present work examines the accuracy of the SPEADMD molecular simulation methodology in correlating experimental data relative to a standard low-pressure database for testing VLE models. The database contains 104 binary systems categorized according to polarity and ideality. Although the database is somewhat small, it covers a broad range of chemical functionality, including halocarbons and carboxylic acids as well as hydrocarbons and alcohols. Six models were tested and compared for their characterization of these mixtures. Four standard models were evaluated to establish a basis for comparison: the Margules, NRTL, PR, and PRWS models. The SPEADMD model was evaluated in three forms. In its elementary form, the SPEADMD model includes ∼10% deviations in vapor pressure because of the application of transferable potential functions in the molecular model. An alternative model is developed on the basis of SPEADMD combined with corrected vapor pressures and customized self-interaction parameter for pure compounds. This alternative is referred to as the SPEADCI model, in which CI stands for customized interactions. Results show that SPEADCI model provides accuracy similar to the NRTL and PRWS models, even though it includes only one adjustable parameter per binary system, whereas the NRTL model includes two and the PRWS models include three. Deviations in correlated bubble point pressure are roughly 1−2% for these models. The SPEADMD models have the advantage that transferable potentials can be applied for solvation interactions that are similar to the Kamlet-Taft interaction parameters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800374h [article] Correlation of mixture vapor-liquid equilibria with the SPEADMD model [texte imprimé] / Amir Vahid, Auteur ; Amanda D. Sans, Auteur ; J. Richard Elliott, Auteur . - 2008 . - P. 7955-7964. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7955-7964 Mots-clés : Molecular  simulation  SPEADMD  Vapor−Liquid Résumé : The present work examines the accuracy of the SPEADMD molecular simulation methodology in correlating experimental data relative to a standard low-pressure database for testing VLE models. The database contains 104 binary systems categorized according to polarity and ideality. Although the database is somewhat small, it covers a broad range of chemical functionality, including halocarbons and carboxylic acids as well as hydrocarbons and alcohols. Six models were tested and compared for their characterization of these mixtures. Four standard models were evaluated to establish a basis for comparison: the Margules, NRTL, PR, and PRWS models. The SPEADMD model was evaluated in three forms. In its elementary form, the SPEADMD model includes ∼10% deviations in vapor pressure because of the application of transferable potential functions in the molecular model. An alternative model is developed on the basis of SPEADMD combined with corrected vapor pressures and customized self-interaction parameter for pure compounds. This alternative is referred to as the SPEADCI model, in which CI stands for customized interactions. Results show that SPEADCI model provides accuracy similar to the NRTL and PRWS models, even though it includes only one adjustable parameter per binary system, whereas the NRTL model includes two and the PRWS models include three. Deviations in correlated bubble point pressure are roughly 1−2% for these models. The SPEADMD models have the advantage that transferable potentials can be applied for solvation interactions that are similar to the Kamlet-Taft interaction parameters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800374h

Group contribution prediction of vapor pressure with statistical associating fluid theory, perturbed-chain statistical associating fluid theory, and elliott−suresh−donohue equations of state / Fateme Sadat Emami in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8401–8411 Titre : Group contribution prediction of vapor pressure with statistical associating fluid theory, perturbed-chain statistical associating fluid theory, and elliott−suresh−donohue equations of state Type de document : texte imprimé Auteurs : Fateme Sadat Emami, Auteur ; Amir Vahid, Auteur ; J. Richard Elliott, Auteur Année de publication : 2008 Article en page(s) : p. 8401–8411 Note générale : Chemical engineering Langues : Anglais (eng) Résumé : The group contribution methodology developed by Elliott and Natarajan has been extended to the statistical associating fluid theory (SAFT) and perturbed-chain statistical associating fluid theory (PC-SAFT) equations of state (EOS). Thermodynamic properties were correlated and predicted for a database of 878 compounds, including associating compounds. Association contributions were treated with Wertheim’s theory. The database covers 19 chemical families including hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, alcohols, amines, nitriles, thiols, sulfides, aldehydes, ketones, esters, ethers, halocarbons, and silicones. The present group contribution (GC) method was developed in two stages. Initially, pure component parameters of each EOS were obtained by matching their boiling temperatures at 10 or 760 mmHg and available GC estimates of solubility parameter and liquid density, while applying standard hydrogen-bonding parameters. Then, group contributions were regressed for the shape factor parameters of each EOS. Group contributions are presented for 84 first-order functional groups (FOG). Given the GC shape factors, the same GC estimates of solubility parameter and liquid density can be applied to estimate all EOS parameters on a GC basis. The resulting correlation enables three-parameter corresponding states predictions without any experimental data. A byproduct of the correlation for equation of state parameters is the capability to predict vapor pressure only on the basis of chemical structure. This capability was evaluated by computing the vapor pressures at 10, 100, and 760 mmHg. On the basis of the present work, vapor pressure average absolute percent deviations (P AAD%) were 36% for Elliott−Suresh−Donohue (ESD) EOS, 65% for SAFT, 32% PC-SAFT. For comparison, the first- and second-order groups (FOG and SOG) provided by Tihic et al. (for simplified PC-SAFT) have been applied to ∼650 nonassociating compounds. The resulting P AAD% were 53% for Tihic FOG and 42% for Tihic SOG. An alternative characterization of accuracy is the average absolute deviation (|ΔT|) between experimental and calculated saturated temperature. These were 8, 12, 8, 10, and 9 K for ESD, SAFT, PC-SAFT, Tihic FOG, and Tihic SOG equations, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800329r [article] Group contribution prediction of vapor pressure with statistical associating fluid theory, perturbed-chain statistical associating fluid theory, and elliott−suresh−donohue equations of state [texte imprimé] / Fateme Sadat Emami, Auteur ; Amir Vahid, Auteur ; J. Richard Elliott, Auteur . - 2008 . - p. 8401–8411. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8401–8411 Résumé : The group contribution methodology developed by Elliott and Natarajan has been extended to the statistical associating fluid theory (SAFT) and perturbed-chain statistical associating fluid theory (PC-SAFT) equations of state (EOS). Thermodynamic properties were correlated and predicted for a database of 878 compounds, including associating compounds. Association contributions were treated with Wertheim’s theory. The database covers 19 chemical families including hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, alcohols, amines, nitriles, thiols, sulfides, aldehydes, ketones, esters, ethers, halocarbons, and silicones. The present group contribution (GC) method was developed in two stages. Initially, pure component parameters of each EOS were obtained by matching their boiling temperatures at 10 or 760 mmHg and available GC estimates of solubility parameter and liquid density, while applying standard hydrogen-bonding parameters. Then, group contributions were regressed for the shape factor parameters of each EOS. Group contributions are presented for 84 first-order functional groups (FOG). Given the GC shape factors, the same GC estimates of solubility parameter and liquid density can be applied to estimate all EOS parameters on a GC basis. The resulting correlation enables three-parameter corresponding states predictions without any experimental data. A byproduct of the correlation for equation of state parameters is the capability to predict vapor pressure only on the basis of chemical structure. This capability was evaluated by computing the vapor pressures at 10, 100, and 760 mmHg. On the basis of the present work, vapor pressure average absolute percent deviations (P AAD%) were 36% for Elliott−Suresh−Donohue (ESD) EOS, 65% for SAFT, 32% PC-SAFT. For comparison, the first- and second-order groups (FOG and SOG) provided by Tihic et al. (for simplified PC-SAFT) have been applied to ∼650 nonassociating compounds. The resulting P AAD% were 53% for Tihic FOG and 42% for Tihic SOG. An alternative characterization of accuracy is the average absolute deviation (|ΔT|) between experimental and calculated saturated temperature. These were 8, 12, 8, 10, and 9 K for ESD, SAFT, PC-SAFT, Tihic FOG, and Tihic SOG equations, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800329r

Optimization of transferable site – site potentials using a combination of stochastic and gradient search algorithms / Sinan Ucyigitler in Industrial & engineering chemistry research, Vol. 51 N° 17 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 17 (Mai 2012) . - pp. 6219–6231 Titre : Optimization of transferable site – site potentials using a combination of stochastic and gradient search algorithms Type de document : texte imprimé Auteurs : Sinan Ucyigitler, Auteur ; Mehmet C. Camurdan, Auteur ; J. Richard Elliott, Auteur Année de publication : 2012 Article en page(s) : pp. 6219–6231 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Optimization  Stochastic  Algorithms Résumé : Discontinuous molecular dynamics (DMD) simulation and thermodynamic perturbation theory (TPT) have been used to study thermodynamic properties for organic compounds. The aim is to infer transferable intermolecular potential models based on correlating the vapor pressure and liquid density. The combination of DMD/TPT generates a straightforward global optimization problem for the attractive potential, instead of facing an iterative optimization–simulation type problem. This global optimization problem is then formulated as a black-box optimization problem and solved using a combination of random recursive search (RRS) and Levenberg–Marquardt (LM) optimization. RRS is suitable for black-box optimization problems since its algorithm is robust to the effect of random noises in the objective function and is advantageous in optimizing the objective function with negligible parameters. LM is efficient local to an optimum with a smooth response surface. The local response surface is shown to be smooth but very flat along valleys with a high degree of coupling between the potential parameters. The algorithm is demonstrated with discretized versions of the Lennard-Jones (LJ) potential and a linear step potential using a database of 231 hydrocarbons, alcohols, aldehydes, amines, amides, esters, ethers, ketones, phenols, sulfides, and thiols. A correspondence is established between the discretized LJ potential and the TraPPE model, demonstrating the manner of improving density estimates and a way of expediting improvement of continuous transferable potentials. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201186q [article] Optimization of transferable site – site potentials using a combination of stochastic and gradient search algorithms [texte imprimé] / Sinan Ucyigitler, Auteur ; Mehmet C. Camurdan, Auteur ; J. Richard Elliott, Auteur . - 2012 . - pp. 6219–6231. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 17 (Mai 2012) . - pp. 6219–6231 Mots-clés : Optimization  Stochastic  Algorithms Résumé : Discontinuous molecular dynamics (DMD) simulation and thermodynamic perturbation theory (TPT) have been used to study thermodynamic properties for organic compounds. The aim is to infer transferable intermolecular potential models based on correlating the vapor pressure and liquid density. The combination of DMD/TPT generates a straightforward global optimization problem for the attractive potential, instead of facing an iterative optimization–simulation type problem. This global optimization problem is then formulated as a black-box optimization problem and solved using a combination of random recursive search (RRS) and Levenberg–Marquardt (LM) optimization. RRS is suitable for black-box optimization problems since its algorithm is robust to the effect of random noises in the objective function and is advantageous in optimizing the objective function with negligible parameters. LM is efficient local to an optimum with a smooth response surface. The local response surface is shown to be smooth but very flat along valleys with a high degree of coupling between the potential parameters. The algorithm is demonstrated with discretized versions of the Lennard-Jones (LJ) potential and a linear step potential using a database of 231 hydrocarbons, alcohols, aldehydes, amines, amides, esters, ethers, ketones, phenols, sulfides, and thiols. A correspondence is established between the discretized LJ potential and the TraPPE model, demonstrating the manner of improving density estimates and a way of expediting improvement of continuous transferable potentials. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201186q

Self-diffusivity estimation by molecular dynamics / Z. Nevin Gerek in Industrial & engineering chemistry research, Vol. 49 N° 7 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3411–3423 Titre : Self-diffusivity estimation by molecular dynamics Type de document : texte imprimé Auteurs : Z. Nevin Gerek, Auteur ; J. Richard Elliott, Auteur Année de publication : 2010 Article en page(s) : pp. 3411–3423 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Self-Diffusivity  Molecular  Dynamics Résumé : Reference fluid simulations are combined with a mean field correction for attractive effects to achieve a correlation for diffusivity of unentangled species over a wide range of density, temperature, and molecular weight. Reference fluids are composed of hard united atom descriptions including branching, rings, bond angles, and chain length. The molecular model is consistent with the one studied previously by thermodynamic perturbation theory. Molecular simulations of methane through triacontane provide the basis for a diffusivity correlation of reference n-alkanes from zero density to the glass transition. The low density limit is shown to exhibit Rouse scaling, contradicting typical hard sphere models. Experimental data for n-alkanes ranging from methane to hexadecane are used to correlate the correction for attractive forces and for the softness of the potential function. The average deviation is 8.6% for 657 data points. Reference simulations of nonalkanes show that the reference simulations can be interpolated smoothly with the n-alkane correlation by treating the effective chain length as an adjustable parameter. Applying the corresponding alkane mean field correction for attractive forces results in poor predictions for nonalkanes. The attractive energy must be treated as a single adjustable parameter to achieve reasonable accuracy. Existing correlations require two parameters to achieve comparable accuracy, and the physical meaning of the two parameters is difficult to interpret. A correlation between diffusivity and entropy suggested by Rosenfeld is shown to be problematic for chain molecules. Overall, diffusivity data are treated for 35 compounds with 1801 data points with 14% deviation by the correlation developed here. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901247k [article] Self-diffusivity estimation by molecular dynamics [texte imprimé] / Z. Nevin Gerek, Auteur ; J. Richard Elliott, Auteur . - 2010 . - pp. 3411–3423. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3411–3423 Mots-clés : Self-Diffusivity  Molecular  Dynamics Résumé : Reference fluid simulations are combined with a mean field correction for attractive effects to achieve a correlation for diffusivity of unentangled species over a wide range of density, temperature, and molecular weight. Reference fluids are composed of hard united atom descriptions including branching, rings, bond angles, and chain length. The molecular model is consistent with the one studied previously by thermodynamic perturbation theory. Molecular simulations of methane through triacontane provide the basis for a diffusivity correlation of reference n-alkanes from zero density to the glass transition. The low density limit is shown to exhibit Rouse scaling, contradicting typical hard sphere models. Experimental data for n-alkanes ranging from methane to hexadecane are used to correlate the correction for attractive forces and for the softness of the potential function. The average deviation is 8.6% for 657 data points. Reference simulations of nonalkanes show that the reference simulations can be interpolated smoothly with the n-alkane correlation by treating the effective chain length as an adjustable parameter. Applying the corresponding alkane mean field correction for attractive forces results in poor predictions for nonalkanes. The attractive energy must be treated as a single adjustable parameter to achieve reasonable accuracy. Existing correlations require two parameters to achieve comparable accuracy, and the physical meaning of the two parameters is difficult to interpret. A correlation between diffusivity and entropy suggested by Rosenfeld is shown to be problematic for chain molecules. Overall, diffusivity data are treated for 35 compounds with 1801 data points with 14% deviation by the correlation developed here. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901247k