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Computational study on purification of CO2 from natural gas by C60 intercalated graphite / Xuan Peng in Industrial & engineering chemistry research, Vol. 49 N° 18 (Septembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8787–8796 Titre : Computational study on purification of CO2 from natural gas by C60 intercalated graphite Type de document : texte imprimé Auteurs : Xuan Peng, Auteur ; Dapeng Cao, Auteur ; Wenchuan Wang, Auteur Année de publication : 2010 Article en page(s) : pp. 8787–8796 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Natural  Gas Résumé : By combining grand canonical Monte Carlo (GCMC) simulations with adsorption theory, we perform a computational study on adsorption of CH4 and CO2 gases and purification of CO2 from the CH4−CO2 and N2−CO2 binary mixtures by the C60 intercalated graphite. The adsorption isotherms, isosteric heats and snapshots of pure gases have been examined extensively. It is found that the maximum excess uptakes at 298 K are relatively low, only giving 4.04 and 4.96 mmol/g for CH4 and CO2, respectively, due to a low porosity of 0.45 and a large crystal density of 1.57 g/cm3 of this material. It indicates that the pristine material is not suitable for gas storage. However, this material provides excellent selectivity for CO2, and the selectivity at ambient condition can reach 8 and 50 for the CH4−CO2 and N2−CO2 mixture, respectively. Furthermore, the selectivity of CO2 is almost independent of the bulk gas composition for P > 0.1 MPa. The dual-site Langmuir−Freundlich (DSLF) equation is used to fit the adsorption isotherms of pure gases from GCMC simulations, and the corresponding parameters are obtained. Moreover, we further predicted the adsorption behavior of binary mixtures by the DSLF-based ideal adsorption solution theory (IAST). Although the IAST theory slightly overestimates the selectivity, compared to GCMC results, the uptakes and selectivity from both methods are basically consistent. To improve the adsorption capacities, we further tailor the structural parameter “g” of the C60 intercalated graphite by GCMC simulations. For equimolar gas composition, at the condition of g = 1.4 nm and 6 MPa, the CO2 uptakes could be raised by 200%, approaching 12 mmol/g for both mixtures, without loss of the selectivity for CO2. In summary, this work demonstrates that the C60 intercalated graphite is an excellent material for CO2 purification, especially for N2−CO2 system at room temperature. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1010433 [article] Computational study on purification of CO2 from natural gas by C60 intercalated graphite [texte imprimé] / Xuan Peng, Auteur ; Dapeng Cao, Auteur ; Wenchuan Wang, Auteur . - 2010 . - pp. 8787–8796. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8787–8796 Mots-clés : Natural  Gas Résumé : By combining grand canonical Monte Carlo (GCMC) simulations with adsorption theory, we perform a computational study on adsorption of CH4 and CO2 gases and purification of CO2 from the CH4−CO2 and N2−CO2 binary mixtures by the C60 intercalated graphite. The adsorption isotherms, isosteric heats and snapshots of pure gases have been examined extensively. It is found that the maximum excess uptakes at 298 K are relatively low, only giving 4.04 and 4.96 mmol/g for CH4 and CO2, respectively, due to a low porosity of 0.45 and a large crystal density of 1.57 g/cm3 of this material. It indicates that the pristine material is not suitable for gas storage. However, this material provides excellent selectivity for CO2, and the selectivity at ambient condition can reach 8 and 50 for the CH4−CO2 and N2−CO2 mixture, respectively. Furthermore, the selectivity of CO2 is almost independent of the bulk gas composition for P > 0.1 MPa. The dual-site Langmuir−Freundlich (DSLF) equation is used to fit the adsorption isotherms of pure gases from GCMC simulations, and the corresponding parameters are obtained. Moreover, we further predicted the adsorption behavior of binary mixtures by the DSLF-based ideal adsorption solution theory (IAST). Although the IAST theory slightly overestimates the selectivity, compared to GCMC results, the uptakes and selectivity from both methods are basically consistent. To improve the adsorption capacities, we further tailor the structural parameter “g” of the C60 intercalated graphite by GCMC simulations. For equimolar gas composition, at the condition of g = 1.4 nm and 6 MPa, the CO2 uptakes could be raised by 200%, approaching 12 mmol/g for both mixtures, without loss of the selectivity for CO2. In summary, this work demonstrates that the C60 intercalated graphite is an excellent material for CO2 purification, especially for N2−CO2 system at room temperature. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1010433

Synthesis of gold nanoparticles coated with polystyrene-block-poly(n-isopropylacrylamide) and their thermoresponsive ultraviolet−visible absorbance / Yunxia Liu in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2707–2715 Titre : Synthesis of gold nanoparticles coated with polystyrene-block-poly(n-isopropylacrylamide) and their thermoresponsive ultraviolet−visible absorbance Type de document : texte imprimé Auteurs : Yunxia Liu, Auteur ; Weixia Tu, Auteur ; Dapeng Cao, Auteur Année de publication : 2010 Article en page(s) : pp. 2707–2715 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Gold  nanoparticles;  Polystyrene;  Poly;  N-isopropylacrylamide;  Thermoresponsive;  Ultraviolet;  Visible;  Absorbance Résumé : Poly(styrene-b-N-isopropylacrylamide) (PSt-b-PNIPAM) with a narrow molecular weight distribution is prepared by reversible addition−fragmentation transfer radical polymerization. The dithioester group at the chain end of PSt-b-PNIPAM is converted into thiol terminal group by LiB(C2H5)3H. Gold nanoparticles and the PSt-b-PNIPAM interact via the terminal thiol group (-SH). The size of the gold nanoparticles coated with copolymers can be easily manipulated by adjusting the molar ratio of HAuCl4/PSt-b-PNIPAM. Interestingly, the thermosensitive gold nanoparticles exhibit a sharp and reversible transparent−opaque transition between 25 and 40 °C. Moreover, the transition change is sensitive to the size of the gold nanoparticles and the macromolecular weight of the copolymer. The maximum wavelength of the surface plasmon band and the hydrodynamic size of the PSt-b-PNIPAM-Au micelles are sensitive to temperature, pH, and salt concentration. A considerable red shift from 524 to 534 nm in the plasmon band is observed in 0.9% NaCl aqueous solution, but no appreciable change in the band is observed in pure water when the temperature increases from 25 to 40 °C. With a decrease of the pH of the solution, the maximum wavelength of the surface plasmon band exhibits a red shift (from 520 to 534 nm). In addition, dynamic light scatting (DLS) reveals that the hydrodynamic size of coated gold nanoparticles exhibits a small change under alkaline and neutral (pH = 7) conditions, but it gives a pronounced change in the acidic condition (from 350 to 280 nm) when the temperature increases from 25 to 40 °C. Furthermore, the UV−vis absorption spectrum clearly shows that the red shift of the thermosensitive gold nanoparticles is reversible. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901143p [article] Synthesis of gold nanoparticles coated with polystyrene-block-poly(n-isopropylacrylamide) and their thermoresponsive ultraviolet−visible absorbance [texte imprimé] / Yunxia Liu, Auteur ; Weixia Tu, Auteur ; Dapeng Cao, Auteur . - 2010 . - pp. 2707–2715. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2707–2715 Mots-clés : Gold  nanoparticles;  Polystyrene;  Poly;  N-isopropylacrylamide;  Thermoresponsive;  Ultraviolet;  Visible;  Absorbance Résumé : Poly(styrene-b-N-isopropylacrylamide) (PSt-b-PNIPAM) with a narrow molecular weight distribution is prepared by reversible addition−fragmentation transfer radical polymerization. The dithioester group at the chain end of PSt-b-PNIPAM is converted into thiol terminal group by LiB(C2H5)3H. Gold nanoparticles and the PSt-b-PNIPAM interact via the terminal thiol group (-SH). The size of the gold nanoparticles coated with copolymers can be easily manipulated by adjusting the molar ratio of HAuCl4/PSt-b-PNIPAM. Interestingly, the thermosensitive gold nanoparticles exhibit a sharp and reversible transparent−opaque transition between 25 and 40 °C. Moreover, the transition change is sensitive to the size of the gold nanoparticles and the macromolecular weight of the copolymer. The maximum wavelength of the surface plasmon band and the hydrodynamic size of the PSt-b-PNIPAM-Au micelles are sensitive to temperature, pH, and salt concentration. A considerable red shift from 524 to 534 nm in the plasmon band is observed in 0.9% NaCl aqueous solution, but no appreciable change in the band is observed in pure water when the temperature increases from 25 to 40 °C. With a decrease of the pH of the solution, the maximum wavelength of the surface plasmon band exhibits a red shift (from 520 to 534 nm). In addition, dynamic light scatting (DLS) reveals that the hydrodynamic size of coated gold nanoparticles exhibits a small change under alkaline and neutral (pH = 7) conditions, but it gives a pronounced change in the acidic condition (from 350 to 280 nm) when the temperature increases from 25 to 40 °C. Furthermore, the UV−vis absorption spectrum clearly shows that the red shift of the thermosensitive gold nanoparticles is reversible. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901143p