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Comparison of traditional and structured adsorbents for CO2 separation by vacuum - swing dsorption / Fateme Rezaei in Industrial & engineering chemistry research, Vol. 49 N° 10 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4832–4841 Titre : Comparison of traditional and structured adsorbents for CO2 separation by vacuum - swing dsorption Type de document : texte imprimé Auteurs : Fateme Rezaei, Auteur ; Alessandra Mosca, Auteur ; Paul Webley, Auteur Année de publication : 2010 Article en page(s) : pp. 4832–4841 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Gas  separation  processes  Adsorbents Résumé : The development of structured adsorbents with attractive characteristics is an important step in the improvement of adsorption-based gas-separation processes. The improved features of structured adsorbents include lower energy consumption, higher throughput, and superior recovery and purity of product because of the even flow distribution, very low mass-transfer resistance, and low pressure drop in combination with a reasonable adsorption capacity. This study examines the vacuum-swing adsorption (VSA) CO2 separation performance of structured adsorbents in the form of thin NaX films grown on the walls of ceramic cordierite monoliths, and the results are compared with NaX pellets. Adsorption equilibrium and dynamic properties are explored experimentally. The CO2 breakthrough front for the NaX film grown on the 400 cells/in.2 (cpsi) monolith was close to ideal and indicated that axial dispersion was very small and that the mass-transfer resistance in the film was very low. The breakthrough front for the structured adsorbent with 400 cpsi was sharper than that for the structured adsorbent with 900 cpsi and only shifted to shorter breakthrough times because of the lower amount of zeolite and higher effective diffusivity of the former sample. In addition, the CO2 breakthrough fronts for the 400 and 900 cpsi structured adsorbents were both sharper than the breakthrough front for NaX beads. This indicates that the flow distribution in the structured adsorbents is more even and that the mass-transfer resistance in the film is very low because of the small film thickness and high effective diffusivity for CO2 in the NaX film. Experimental data were used to obtain overall mass-transfer linear-driving-force constants, which were subsequently used in a numerical simulation program to estimate the performance of the adsorbents for CO2/N2 separation in a VSA process. It was found that the recovery of structured adsorbents was superior to that of a packed bed because of the much shorter mass-transfer zone. The purity, on the other hand, was not as high as that obtained with a packed bed because of excessive voidage in the structured adsorbents. Increased cell density or improved zeolite loading of the structured adsorbents would improve the CO2 purity without sacrificing recovery for the structured adsorbents, and this represents a path forward to improved VSA performance for CO2 capture. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9016545 [article] Comparison of traditional and structured adsorbents for CO2 separation by vacuum - swing dsorption [texte imprimé] / Fateme Rezaei, Auteur ; Alessandra Mosca, Auteur ; Paul Webley, Auteur . - 2010 . - pp. 4832–4841. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4832–4841 Mots-clés : Gas  separation  processes  Adsorbents Résumé : The development of structured adsorbents with attractive characteristics is an important step in the improvement of adsorption-based gas-separation processes. The improved features of structured adsorbents include lower energy consumption, higher throughput, and superior recovery and purity of product because of the even flow distribution, very low mass-transfer resistance, and low pressure drop in combination with a reasonable adsorption capacity. This study examines the vacuum-swing adsorption (VSA) CO2 separation performance of structured adsorbents in the form of thin NaX films grown on the walls of ceramic cordierite monoliths, and the results are compared with NaX pellets. Adsorption equilibrium and dynamic properties are explored experimentally. The CO2 breakthrough front for the NaX film grown on the 400 cells/in.2 (cpsi) monolith was close to ideal and indicated that axial dispersion was very small and that the mass-transfer resistance in the film was very low. The breakthrough front for the structured adsorbent with 400 cpsi was sharper than that for the structured adsorbent with 900 cpsi and only shifted to shorter breakthrough times because of the lower amount of zeolite and higher effective diffusivity of the former sample. In addition, the CO2 breakthrough fronts for the 400 and 900 cpsi structured adsorbents were both sharper than the breakthrough front for NaX beads. This indicates that the flow distribution in the structured adsorbents is more even and that the mass-transfer resistance in the film is very low because of the small film thickness and high effective diffusivity for CO2 in the NaX film. Experimental data were used to obtain overall mass-transfer linear-driving-force constants, which were subsequently used in a numerical simulation program to estimate the performance of the adsorbents for CO2/N2 separation in a VSA process. It was found that the recovery of structured adsorbents was superior to that of a packed bed because of the much shorter mass-transfer zone. The purity, on the other hand, was not as high as that obtained with a packed bed because of excessive voidage in the structured adsorbents. Increased cell density or improved zeolite loading of the structured adsorbents would improve the CO2 purity without sacrificing recovery for the structured adsorbents, and this represents a path forward to improved VSA performance for CO2 capture. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9016545

High surface area vanadium phosphate catalysts for n-butane oxidation / Ali Asghar Rownaghi in Industrial & engineering chemistry research, Vol. 48 N° 16 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 16 (Août 2009) . - pp. 7517–7528 Titre : High surface area vanadium phosphate catalysts for n-butane oxidation Type de document : texte imprimé Auteurs : Ali Asghar Rownaghi, Auteur ; Yun Hin Taufiq-Yap, Auteur ; Fateme Rezaei, Auteur Année de publication : 2009 Article en page(s) : pp. 7517–7528 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Vanadium  phosphorus  oxide  N-butane  Oxidation Résumé : Vanadium phosphorus oxide (VPO) was prepared using the precipitation procedure and tested for potential use in the partial oxidation reaction of n-butane to maleic anhydride. In particular, the effect of reducing agents such as the isobutanol, 1-butanol, and glycol, subsequent water treatment, and microwave heating were investigated in detail. The optimum synthesis conditions were identified with respect to catalyst activity for the oxidation of n-butane. The activity and selectivity of VPO prepared catalysts have been evaluated in a fixed bed microreactor and in situ gas chromatography (GC) was used to evaluate the system efficiency and analyze the product effluent stream. The different catalysts exhibited a range of activities and selectivities under the same reaction conditions. The range in catalyst performance may be attributed to the crystal size as well as particle size of catalyst. The results were interpreted in terms of surface area and catalyst nanostructure, and it has been generally concluded that the catalyst surface area is enhanced by the employment of glycol as the reducing agent, followed refluxing by distilled water and drying by microwave irradiation. The catalyst produced using this method is the most active and selective catalyst for partial oxidation of n-butane to maleic anhydride. The catalyst lifetime was tested under the optimum reaction conditions, and the catalyst was found to be highly stable for more than 70 h. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), Brunauer−Emmer−Teller (BET) surface area measurement, temperature programmed reduction (H2-TPR), and scanning electron microscopy (SEM). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900238a [article] High surface area vanadium phosphate catalysts for n-butane oxidation [texte imprimé] / Ali Asghar Rownaghi, Auteur ; Yun Hin Taufiq-Yap, Auteur ; Fateme Rezaei, Auteur . - 2009 . - pp. 7517–7528. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 16 (Août 2009) . - pp. 7517–7528 Mots-clés : Vanadium  phosphorus  oxide  N-butane  Oxidation Résumé : Vanadium phosphorus oxide (VPO) was prepared using the precipitation procedure and tested for potential use in the partial oxidation reaction of n-butane to maleic anhydride. In particular, the effect of reducing agents such as the isobutanol, 1-butanol, and glycol, subsequent water treatment, and microwave heating were investigated in detail. The optimum synthesis conditions were identified with respect to catalyst activity for the oxidation of n-butane. The activity and selectivity of VPO prepared catalysts have been evaluated in a fixed bed microreactor and in situ gas chromatography (GC) was used to evaluate the system efficiency and analyze the product effluent stream. The different catalysts exhibited a range of activities and selectivities under the same reaction conditions. The range in catalyst performance may be attributed to the crystal size as well as particle size of catalyst. The results were interpreted in terms of surface area and catalyst nanostructure, and it has been generally concluded that the catalyst surface area is enhanced by the employment of glycol as the reducing agent, followed refluxing by distilled water and drying by microwave irradiation. The catalyst produced using this method is the most active and selective catalyst for partial oxidation of n-butane to maleic anhydride. The catalyst lifetime was tested under the optimum reaction conditions, and the catalyst was found to be highly stable for more than 70 h. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), Brunauer−Emmer−Teller (BET) surface area measurement, temperature programmed reduction (H2-TPR), and scanning electron microscopy (SEM). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900238a

Thermal management of structured adsorbents in CO2 capture processes / Fateme Rezaei in Industrial & engineering chemistry research, Vol. 51 N° 10 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 4025–4034 Titre : Thermal management of structured adsorbents in CO2 capture processes Type de document : texte imprimé Auteurs : Fateme Rezaei, Auteur ; Mattias Grahn, Auteur Année de publication : 2012 Article en page(s) : pp. 4025–4034 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Adsorbents  Mass  transfer  Thermal  management Résumé : In order to have an efficient adsorptive separation, structured adsorbents are expected to satisfy not only mass transfer and pressure drop requirements but also thermal management requirements. To what extent the structure of adsorbent affects the thermal behavior of the system is a question which will be addressed in this study. The primary purpose of this study was to assess the performance of alternate adsorbents through development of numerical models for prediction of their thermal behavior under a two-step pressure swing adsorption (PSA) condition. The single-step CO2 breakthrough and temperature profiles confirmed the efficiency of structured adsorbents in managing the thermal effects evolved in the bed under nonisothermal conditions. Two-step PSA results also showed that under real cyclic processes, and especially during rapid cycling, structured adsorbents maintain their superiority and introduce themselves as potential candidates for advanced PSA units. However, the performance of a structured adsorbent is highly dependent on its dimensions and geometrical parameters describing the structures, and these parameters should be optimized for each separation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201057p [article] Thermal management of structured adsorbents in CO2 capture processes [texte imprimé] / Fateme Rezaei, Auteur ; Mattias Grahn, Auteur . - 2012 . - pp. 4025–4034. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 4025–4034 Mots-clés : Adsorbents  Mass  transfer  Thermal  management Résumé : In order to have an efficient adsorptive separation, structured adsorbents are expected to satisfy not only mass transfer and pressure drop requirements but also thermal management requirements. To what extent the structure of adsorbent affects the thermal behavior of the system is a question which will be addressed in this study. The primary purpose of this study was to assess the performance of alternate adsorbents through development of numerical models for prediction of their thermal behavior under a two-step pressure swing adsorption (PSA) condition. The single-step CO2 breakthrough and temperature profiles confirmed the efficiency of structured adsorbents in managing the thermal effects evolved in the bed under nonisothermal conditions. Two-step PSA results also showed that under real cyclic processes, and especially during rapid cycling, structured adsorbents maintain their superiority and introduce themselves as potential candidates for advanced PSA units. However, the performance of a structured adsorbent is highly dependent on its dimensions and geometrical parameters describing the structures, and these parameters should be optimized for each separation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201057p