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Study of the CO2/sorbent interaction in sorbents prepared with mesoporous supports and calcium compounds / Josefa Fernandez 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. 2986–2991 Titre : Study of the CO2/sorbent interaction in sorbents prepared with mesoporous supports and calcium compounds Type de document : texte imprimé Auteurs : Josefa Fernandez, Auteur ; Fernando González, Auteur ; Carmen Pesquera, Auteur Année de publication : 2010 Article en page(s) : pp. 2986–2991 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Interaction--CO2/Sorbent--Sorbents--Mesoporous--Calcium  Compounds Résumé : CO2 chemisorption experiments were used to study the behavior of sorbents prepared from MCM-41 and SBA-15 mesoporous supports and Ca(OH)2 at different ratios in two main aspects: to determine the capacity of the sorbents to capture CO2 and to identify the products synthesized in the process. Two different ways of preparation of the sorbents were used: Type I sorbents were prepared by mixing CaO, water, and the support at room temperature, and Type II were prepared by impregnation of the support with calcium nitrate followed by calcination and hydration to form Ca(OH)2. Static chemisorption experiments at low temperature (323 K) and low CO2 pressure showed that Type I yielded higher values of CO2 retention than Type II. MCM-41 support, with a higher specific surface area than SBA-15, achieved the more effective sorbent, 10% Ca(OH)2/MCM-41. The moles of CO2 per mole of calcium retained by this sorbent was approximately five times that obtained with unsupported commercial Ca(OH)2. To determine the form in which CO2 was retained at this low temperature dynamic chemisorption experiments with CO2 were performed with commercial Ca(OH)2 and with 10% Ca(OH)2/MCM-41 sorbent. The results showed that CO2 was chemisorbed on both solids as a complex CaO·CO2, which was reversibly desorbed at 473 K, and as CaCO3. The 10% Ca(OH)2/MCM-41 sorbent can be used as a regenerable sorbent at temperatures up to 823 K. At those conditions, only the CO2 retained as CaO·CO2 is desorbed, with no relevant loss of capture in the five cycles tested. Experiments varying the adsorption time proved that, in a first step, the CO2 retention is fast and probably kinetically controlled, making the further uptake much slower in a process controlled by diffusion; the maximum amount of CO2 retained (56.6% mol CO2/mol Ca) was obtained at 18 h of exposure with the sorbent prepared at the lowest Ca(OH)2/MCM-41 ratio tested (2.5%), showing that the reaction at low temperature is favored with a good calcium distribution. Note de contenu : Bibiogr. ISSN : 0885-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901815u [article] Study of the CO2/sorbent interaction in sorbents prepared with mesoporous supports and calcium compounds [texte imprimé] / Josefa Fernandez, Auteur ; Fernando González, Auteur ; Carmen Pesquera, Auteur . - 2010 . - pp. 2986–2991. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2986–2991 Mots-clés : Interaction--CO2/Sorbent--Sorbents--Mesoporous--Calcium  Compounds Résumé : CO2 chemisorption experiments were used to study the behavior of sorbents prepared from MCM-41 and SBA-15 mesoporous supports and Ca(OH)2 at different ratios in two main aspects: to determine the capacity of the sorbents to capture CO2 and to identify the products synthesized in the process. Two different ways of preparation of the sorbents were used: Type I sorbents were prepared by mixing CaO, water, and the support at room temperature, and Type II were prepared by impregnation of the support with calcium nitrate followed by calcination and hydration to form Ca(OH)2. Static chemisorption experiments at low temperature (323 K) and low CO2 pressure showed that Type I yielded higher values of CO2 retention than Type II. MCM-41 support, with a higher specific surface area than SBA-15, achieved the more effective sorbent, 10% Ca(OH)2/MCM-41. The moles of CO2 per mole of calcium retained by this sorbent was approximately five times that obtained with unsupported commercial Ca(OH)2. To determine the form in which CO2 was retained at this low temperature dynamic chemisorption experiments with CO2 were performed with commercial Ca(OH)2 and with 10% Ca(OH)2/MCM-41 sorbent. The results showed that CO2 was chemisorbed on both solids as a complex CaO·CO2, which was reversibly desorbed at 473 K, and as CaCO3. The 10% Ca(OH)2/MCM-41 sorbent can be used as a regenerable sorbent at temperatures up to 823 K. At those conditions, only the CO2 retained as CaO·CO2 is desorbed, with no relevant loss of capture in the five cycles tested. Experiments varying the adsorption time proved that, in a first step, the CO2 retention is fast and probably kinetically controlled, making the further uptake much slower in a process controlled by diffusion; the maximum amount of CO2 retained (56.6% mol CO2/mol Ca) was obtained at 18 h of exposure with the sorbent prepared at the lowest Ca(OH)2/MCM-41 ratio tested (2.5%), showing that the reaction at low temperature is favored with a good calcium distribution. Note de contenu : Bibiogr. ISSN : 0885-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901815u

Vapor-pressure measurements and modeling of dipentaerythritol ester lubricants / Josefa Garcia in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4231–4237 Titre : Vapor-pressure measurements and modeling of dipentaerythritol ester lubricants Type de document : texte imprimé Auteurs : Josefa Garcia, Auteur ; Ramy Abou Naccoul, Auteur ; Josefa Fernandez, Auteur Année de publication : 2011 Article en page(s) : pp. 4231–4237 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Lubricants  Vapor  pressure  measurements Résumé : The aim of this work is to present new vapor-pressure measurements and provide a good description of the volumetric and phase behavior of dipentaerythritol ester (DiPEs) lubricants, using the Statistical Associating Fluid Theory (SAFT) model (PC-SAFT and SAFT-VR versions). Characteristic parameters of these versions were optimized for dipentaerythritol hexapentanoate (DiPEC5), dipentaerythritol hexaheptanoate (DiPEC7), and dipentaerythritol isononanoate (DiPEiC9), using experimental vapor pressures and densities. With these parameters, compressed densities were predicted. Experimental vapor pressures, determined by a gas saturation apparatus, range between 2 × 10−5 Pa and 16 Pa, whereas the absolute deviations obtained in the correlations for both versions of the model (PC-SAFT and SAFT-VR) are between 10−6 Pa and 1 Pa. In the case of saturated densities, the average absolute deviation (AAD) values, for both models, range from 0.2% to 1.3%, except for DiPEC7, where the AAD is 4.4% when using the SAFT-VR model. The SAFT-VR version gives slightly better correlations, although we must note that this version has four parameters, whereas the PC-SAFT version has three. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102166r [article] Vapor-pressure measurements and modeling of dipentaerythritol ester lubricants [texte imprimé] / Josefa Garcia, Auteur ; Ramy Abou Naccoul, Auteur ; Josefa Fernandez, Auteur . - 2011 . - pp. 4231–4237. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4231–4237 Mots-clés : Lubricants  Vapor  pressure  measurements Résumé : The aim of this work is to present new vapor-pressure measurements and provide a good description of the volumetric and phase behavior of dipentaerythritol ester (DiPEs) lubricants, using the Statistical Associating Fluid Theory (SAFT) model (PC-SAFT and SAFT-VR versions). Characteristic parameters of these versions were optimized for dipentaerythritol hexapentanoate (DiPEC5), dipentaerythritol hexaheptanoate (DiPEC7), and dipentaerythritol isononanoate (DiPEiC9), using experimental vapor pressures and densities. With these parameters, compressed densities were predicted. Experimental vapor pressures, determined by a gas saturation apparatus, range between 2 × 10−5 Pa and 16 Pa, whereas the absolute deviations obtained in the correlations for both versions of the model (PC-SAFT and SAFT-VR) are between 10−6 Pa and 1 Pa. In the case of saturated densities, the average absolute deviation (AAD) values, for both models, range from 0.2% to 1.3%, except for DiPEC7, where the AAD is 4.4% when using the SAFT-VR model. The SAFT-VR version gives slightly better correlations, although we must note that this version has four parameters, whereas the PC-SAFT version has three. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102166r