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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

Simulation of the generation of solution gradients in microfluidic systems using the lattice boltzmann method / Yangxu Hu in Industrial & engineering chemistry research, Vol. 50 N° 24 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 24 (Décembre 2011) . - pp 13932–13939 Titre : Simulation of the generation of solution gradients in microfluidic systems using the lattice boltzmann method Type de document : texte imprimé Auteurs : Yangxu Hu, Auteur ; Xianren Zhang, Auteur ; Wenchuan Wang, Auteur Année de publication : 2012 Article en page(s) : pp 13932–13939 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluid  mechanics  Microfluidics Résumé : In this work, we used the lattice Boltzmann (LB) method to simulate the generation of concentration gradients in microfluidic networks. We first developed a model of microfluidic networks, in which the flow velocity of the laminar flow in the microchannel and the diffusion of solute molecules govern the solute gradients generated, and the obtained results are comparable with experimental data. Our simulation results indicated that the relative positions of the branching plates in different levels, at which a microchannel is split into several daughter microchannels, exert significant effects on the shape of concentration gradients. We also performed extensive simulations to study the dependence of the shape of the concentration gradient on the velocity of the flow u, diffusion coefficients of solutes D, and the length of the microchannel L. A dimensionless parameter, (L/u)/(H2/D), in which H is the hydraulic diameter of the main microchannel, was proposed in this work. It is found that for geometrically similar microfluidic networks, the parameter alone determines the shape of the generated concentration gradient. Therefore, the proposed parameter allows one to perform experiments or simulations with reduced models in microchannels and correlate the data to the other flows or geometry sizes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25299860 [article] Simulation of the generation of solution gradients in microfluidic systems using the lattice boltzmann method [texte imprimé] / Yangxu Hu, Auteur ; Xianren Zhang, Auteur ; Wenchuan Wang, Auteur . - 2012 . - pp 13932–13939. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 24 (Décembre 2011) . - pp 13932–13939 Mots-clés : Fluid  mechanics  Microfluidics Résumé : In this work, we used the lattice Boltzmann (LB) method to simulate the generation of concentration gradients in microfluidic networks. We first developed a model of microfluidic networks, in which the flow velocity of the laminar flow in the microchannel and the diffusion of solute molecules govern the solute gradients generated, and the obtained results are comparable with experimental data. Our simulation results indicated that the relative positions of the branching plates in different levels, at which a microchannel is split into several daughter microchannels, exert significant effects on the shape of concentration gradients. We also performed extensive simulations to study the dependence of the shape of the concentration gradient on the velocity of the flow u, diffusion coefficients of solutes D, and the length of the microchannel L. A dimensionless parameter, (L/u)/(H2/D), in which H is the hydraulic diameter of the main microchannel, was proposed in this work. It is found that for geometrically similar microfluidic networks, the parameter alone determines the shape of the generated concentration gradient. Therefore, the proposed parameter allows one to perform experiments or simulations with reduced models in microchannels and correlate the data to the other flows or geometry sizes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25299860