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Competitive adsorption of C20 − C36 linear paraffins on the amorphous microporous silica − alumina ERS-8 in vapor phase and liquid phase / Ben Li in Industrial & engineering chemistry research, Vol. 49 N° 16 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 16 (Août 2010) . - pp. 7541–7549 Titre : Competitive adsorption of C20 − C36 linear paraffins on the amorphous microporous silica − alumina ERS-8 in vapor phase and liquid phase Type de document : texte imprimé Auteurs : Ben Li, Auteur ; Vincenzo Calemma, Auteur ; Chiara Gambaro, Auteur Année de publication : 2010 Article en page(s) : pp. 7541–7549 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Microporous Résumé : Adsorption of C20−C36 linear paraffins on the amorphous microporous silica−alumina ERS-8 was studied at vapor phase and liquid phase conditions. Henry adsorption constants and low coverage adsorption enthalpies were determined using the pulse chromatographic method at temperatures between 90 and 370 °C in gas phase. The low coverage adsorption enthalpy increases linearly with carbon number with 5.5 kJ/mol per additional methyl group. Competitive adsorption in liquid and dense vapor phase conditions was studied by performing column breakthrough experiments with various binary C20−C36 n-paraffin mixtures diluted in short chain length alkane solvents or undiluted as bulk mixture, at temperatures ranging from 25 to 300 °C and pressures from 3 to 110 bar. Both the adsorption capacity and the selectivity are strongly temperature and pressure dependent. At low temperature and high pressure, all n-paraffins are adsorbed equally and no separation is possible. With increasing temperature and decreasing pressure, the density of the bulk phase decreases, and a transition from a pure liquid paraffin stream to a dense vapor stream occurs. In such conditions, longer n-paraffins are adsorbed preferentially compared to the shorter n-paraffins. The selectivity increases with increasing difference in chain length between the adsorbing n-paraffins. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100728h [article] Competitive adsorption of C20 − C36 linear paraffins on the amorphous microporous silica − alumina ERS-8 in vapor phase and liquid phase [texte imprimé] / Ben Li, Auteur ; Vincenzo Calemma, Auteur ; Chiara Gambaro, Auteur . - 2010 . - pp. 7541–7549. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 16 (Août 2010) . - pp. 7541–7549 Mots-clés : Microporous Résumé : Adsorption of C20−C36 linear paraffins on the amorphous microporous silica−alumina ERS-8 was studied at vapor phase and liquid phase conditions. Henry adsorption constants and low coverage adsorption enthalpies were determined using the pulse chromatographic method at temperatures between 90 and 370 °C in gas phase. The low coverage adsorption enthalpy increases linearly with carbon number with 5.5 kJ/mol per additional methyl group. Competitive adsorption in liquid and dense vapor phase conditions was studied by performing column breakthrough experiments with various binary C20−C36 n-paraffin mixtures diluted in short chain length alkane solvents or undiluted as bulk mixture, at temperatures ranging from 25 to 300 °C and pressures from 3 to 110 bar. Both the adsorption capacity and the selectivity are strongly temperature and pressure dependent. At low temperature and high pressure, all n-paraffins are adsorbed equally and no separation is possible. With increasing temperature and decreasing pressure, the density of the bulk phase decreases, and a transition from a pure liquid paraffin stream to a dense vapor stream occurs. In such conditions, longer n-paraffins are adsorbed preferentially compared to the shorter n-paraffins. The selectivity increases with increasing difference in chain length between the adsorbing n-paraffins. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100728h

Molecular dynamics simulation of diffusion behavior of benzene/water in PDMS-calix[4]arene hybrid pervaporation membranes / Ben Li in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4440–4447 Titre : Molecular dynamics simulation of diffusion behavior of benzene/water in PDMS-calix[4]arene hybrid pervaporation membranes Type de document : texte imprimé Auteurs : Ben Li, Auteur ; Fusheng Pan, Auteur ; Zhiping Fang, Auteur ; Liang Liu, Auteur Année de publication : 2008 Article en page(s) : p. 4440–4447 Note générale : Bibliogr. p. 4446-4447 Langues : Anglais (eng) Mots-clés : Benzene/water  --  diffusion  behavior;  Molecular  dynamics  simulation;  PDMS  membranes;  CA; Résumé : Molecular dynamics (MD) simulation was employed to investigate diffusion behavior of small penetrants in rubbery-polymer-based hybrid membranes, using pervaporative removal of benzene from its dilute solution by poly(dimethylsiloxane) (PDMS) membranes filled with calix[4]arene (CA) as the model system. In our previous experimental investigation, the normalized permeation rate of benzene (NPRb) and separation factor (benzene/water) through PDMS−CA hybrid membranes did not follow the usual monotonous or single peak/valley change, but accompanied minimum and maximum values instead. In the present study, nonbonding interaction energy between PDMS and CA, mean-square displacement (MSD), free volume characteristics, and diffusion coefficients of benzene and water in pure PDMS and hybrid membranes were analyzed by molecular dynamics simulation. The simulation results revealed that MSD and fractional free volume (FFV) values were closely dependent on interaction energy. Diffusion coefficients of benzene and water at “infinite dilution” and saturated condition displayed the same changing tendency, although the values at saturated condition were a bit larger. Moreover, it was observed that diffusion coefficients were not only related to FFV but also affected by the interaction between CA and the penetrants. Overall, the MD results agreed well with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0708935 [article] Molecular dynamics simulation of diffusion behavior of benzene/water in PDMS-calix[4]arene hybrid pervaporation membranes [texte imprimé] / Ben Li, Auteur ; Fusheng Pan, Auteur ; Zhiping Fang, Auteur ; Liang Liu, Auteur . - 2008 . - p. 4440–4447. Bibliogr. p. 4446-4447 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4440–4447 Mots-clés : Benzene/water  --  diffusion  behavior;  Molecular  dynamics  simulation;  PDMS  membranes;  CA; Résumé : Molecular dynamics (MD) simulation was employed to investigate diffusion behavior of small penetrants in rubbery-polymer-based hybrid membranes, using pervaporative removal of benzene from its dilute solution by poly(dimethylsiloxane) (PDMS) membranes filled with calix[4]arene (CA) as the model system. In our previous experimental investigation, the normalized permeation rate of benzene (NPRb) and separation factor (benzene/water) through PDMS−CA hybrid membranes did not follow the usual monotonous or single peak/valley change, but accompanied minimum and maximum values instead. In the present study, nonbonding interaction energy between PDMS and CA, mean-square displacement (MSD), free volume characteristics, and diffusion coefficients of benzene and water in pure PDMS and hybrid membranes were analyzed by molecular dynamics simulation. The simulation results revealed that MSD and fractional free volume (FFV) values were closely dependent on interaction energy. Diffusion coefficients of benzene and water at “infinite dilution” and saturated condition displayed the same changing tendency, although the values at saturated condition were a bit larger. Moreover, it was observed that diffusion coefficients were not only related to FFV but also affected by the interaction between CA and the penetrants. Overall, the MD results agreed well with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0708935

Rubbery polymer − inorganic nanocomposite membranes / Ben Li in Industrial & engineering chemistry research, Vol. 49 N° 24 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12444–12451 Titre : Rubbery polymer − inorganic nanocomposite membranes : free volume characteristics on separation property Type de document : texte imprimé Auteurs : Ben Li, Auteur ; Dan Xu, Auteur ; Xiongfei Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 12444–12451 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nanocomposite  Polymer  inorganic Résumé : The rational design of polymer−inorganic nanocomposite membranes relies heavily on the precise insight and elaborate control of the interface. Presently, the direct exploration of the hierarchical structure of nanocomposite membranes still remains elusive. In the present study, we propose a facile and generic methodology to quantitatively probe the interfacial structure by complementary positron annihilation lifetime spectroscopy (PALS) and molecular dynamics simulation (MDS) techniques. MDS is used to acquire the molecular level information such as the polymer−inorganic interface interaction energy, chain mobility within the nanocomposite membranes, whereas PALS is used to acquire the free volume characteristics of the nanocomposite membranes. As proof-of-principle, we choose anisotropic inorganic nanotube embedded rubbery polymer membrane as a model, which generates the interface between soft polymer and rigid inorganic. PALS reveals that incorporation of titanate nanotubes (TNTs) narrows the free volume pore radius distribution of the membranes. MDS indicates that the segmental chain mobility in the vicinity of the polymer−inorganic interface is substantially restrained, which creates numerous nanosized voids for molecular transport, and dramatically enhances the fractional free volume (FFV) of the membranes. Quite interestingly, it was found that the rubbery membranes can also exhibit simultaneously increased permeability and membrane selectivity, and this unusual phenomenon was tentatively elucidated by relating the separation properties to the free volume characteristics of the membranes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101142b [article] Rubbery polymer − inorganic nanocomposite membranes : free volume characteristics on separation property [texte imprimé] / Ben Li, Auteur ; Dan Xu, Auteur ; Xiongfei Zhang, Auteur . - 2011 . - pp. 12444–12451. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12444–12451 Mots-clés : Nanocomposite  Polymer  inorganic Résumé : The rational design of polymer−inorganic nanocomposite membranes relies heavily on the precise insight and elaborate control of the interface. Presently, the direct exploration of the hierarchical structure of nanocomposite membranes still remains elusive. In the present study, we propose a facile and generic methodology to quantitatively probe the interfacial structure by complementary positron annihilation lifetime spectroscopy (PALS) and molecular dynamics simulation (MDS) techniques. MDS is used to acquire the molecular level information such as the polymer−inorganic interface interaction energy, chain mobility within the nanocomposite membranes, whereas PALS is used to acquire the free volume characteristics of the nanocomposite membranes. As proof-of-principle, we choose anisotropic inorganic nanotube embedded rubbery polymer membrane as a model, which generates the interface between soft polymer and rigid inorganic. PALS reveals that incorporation of titanate nanotubes (TNTs) narrows the free volume pore radius distribution of the membranes. MDS indicates that the segmental chain mobility in the vicinity of the polymer−inorganic interface is substantially restrained, which creates numerous nanosized voids for molecular transport, and dramatically enhances the fractional free volume (FFV) of the membranes. Quite interestingly, it was found that the rubbery membranes can also exhibit simultaneously increased permeability and membrane selectivity, and this unusual phenomenon was tentatively elucidated by relating the separation properties to the free volume characteristics of the membranes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101142b