Documents disponibles écrits par cet auteur

Precipitation of piperazine in aqueous piperazine solutions with and without CO2 loadings / Xiaoguang Ma in Industrial & engineering chemistry research, Vol. 51 N° 37 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 37 (Septembre 2012) . - pp. 12126–12134 Titre : Precipitation of piperazine in aqueous piperazine solutions with and without CO2 loadings Type de document : texte imprimé Auteurs : Xiaoguang Ma, Auteur ; Inna Kim, Auteur ; Ralf Beck, Auteur Année de publication : 2012 Article en page(s) : pp. 12126–12134 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Piperazine  Crystallization Résumé : The crystallization of piperazine in water as well as in systems loaded with CO2 has been studied for piperazine concentrations of 30–70 wt %, representing conditions relevant for CO2 capture. The use of a LabMax reactor system equipped with probes for in situ focused beam reflectance measurement (FBRM) and particle vision measurement (PVM) made it possible to determine solid–liquid transitions, crystal habit, and chord length distributions in these highly concentrated systems without disturbing the solid–liquid–gas equilibrium during crystallization. As shown by powder X-ray diffraction analysis, three phases including piperazine hemihydrate, piperazine hexahydrate, and anhydrous crystals were precipitated from the aqueous piperazine solutions at different concentrations and temperatures, as also supported by findings from FBRM and PVM. It was found that the metastable zone widths of the piperazine–H2O system were substantial even at the lower cooling rates, which could allow for a higher tolerance with respect to cooling prior to a new carbon dioxide absorption cycle. However, the eutectic composition exhibits a smaller metastable zone width than the other concentrations, which is believed to be caused by the precursor needle-shaped crystals, assisting the precipitation of the final product. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301101q [article] Precipitation of piperazine in aqueous piperazine solutions with and without CO2 loadings [texte imprimé] / Xiaoguang Ma, Auteur ; Inna Kim, Auteur ; Ralf Beck, Auteur . - 2012 . - pp. 12126–12134. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 37 (Septembre 2012) . - pp. 12126–12134 Mots-clés : Piperazine  Crystallization Résumé : The crystallization of piperazine in water as well as in systems loaded with CO2 has been studied for piperazine concentrations of 30–70 wt %, representing conditions relevant for CO2 capture. The use of a LabMax reactor system equipped with probes for in situ focused beam reflectance measurement (FBRM) and particle vision measurement (PVM) made it possible to determine solid–liquid transitions, crystal habit, and chord length distributions in these highly concentrated systems without disturbing the solid–liquid–gas equilibrium during crystallization. As shown by powder X-ray diffraction analysis, three phases including piperazine hemihydrate, piperazine hexahydrate, and anhydrous crystals were precipitated from the aqueous piperazine solutions at different concentrations and temperatures, as also supported by findings from FBRM and PVM. It was found that the metastable zone widths of the piperazine–H2O system were substantial even at the lower cooling rates, which could allow for a higher tolerance with respect to cooling prior to a new carbon dioxide absorption cycle. However, the eutectic composition exhibits a smaller metastable zone width than the other concentrations, which is believed to be caused by the precursor needle-shaped crystals, assisting the precipitation of the final product. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301101q

Study of the heat of absorption of CO2 in aqueous ammonia / Feng Qin in Industrial & engineering chemistry research, Vol. 49 N° 8 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3776–3784 Titre : Study of the heat of absorption of CO2 in aqueous ammonia : comparison between experimental data and model predictions Type de document : texte imprimé Auteurs : Feng Qin, Auteur ; Shujuan Wang, Auteur ; Inna Kim, Auteur Année de publication : 2010 Article en page(s) : pp. 3776–3784 Langues : Anglais (eng) Mots-clés : Heat  Absorption  CO2  Aqueous  Ammonia  Experimental  Data  Model Résumé : Differential enthalpies of absorption of CO2 in aqueous ammonia were predicted based on reaction equilibrium constants using the Gibbs−Helmholtz equation. The reaction equilibrium constants were selected from the literature and integrated into an electrolyte-NRTL model and the model proposed by Edwards, in which the interaction parameters were previously and solely fitted from the NH3−CO2−H2O vapor−liquid equilibrium (VLE) data. The heat contributions of the individual reactions were taken into account in the total heat of absorption in both of the models. The heat of absorption was presented as a function of the CO2 loading and temperature. The predicted heats of absorption were compared with experimental data for temperatures ranging from 35 to 80 °C obtained in this work and also some other modeling results. The predicted results fit the experimental data well at lower temperatures, and also well at lower loadings when the temperature was higher, but the model was not good at high loadings and high temperature. The paper suggested that the heat of absorption data should also be included when parameters were fit together with VLE data in order to predict the heat of absorption well over a wide range of temperatures and loadings. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901869j [article] Study of the heat of absorption of CO2 in aqueous ammonia : comparison between experimental data and model predictions [texte imprimé] / Feng Qin, Auteur ; Shujuan Wang, Auteur ; Inna Kim, Auteur . - 2010 . - pp. 3776–3784. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3776–3784 Mots-clés : Heat  Absorption  CO2  Aqueous  Ammonia  Experimental  Data  Model Résumé : Differential enthalpies of absorption of CO2 in aqueous ammonia were predicted based on reaction equilibrium constants using the Gibbs−Helmholtz equation. The reaction equilibrium constants were selected from the literature and integrated into an electrolyte-NRTL model and the model proposed by Edwards, in which the interaction parameters were previously and solely fitted from the NH3−CO2−H2O vapor−liquid equilibrium (VLE) data. The heat contributions of the individual reactions were taken into account in the total heat of absorption in both of the models. The heat of absorption was presented as a function of the CO2 loading and temperature. The predicted heats of absorption were compared with experimental data for temperatures ranging from 35 to 80 °C obtained in this work and also some other modeling results. The predicted results fit the experimental data well at lower temperatures, and also well at lower loadings when the temperature was higher, but the model was not good at high loadings and high temperature. The paper suggested that the heat of absorption data should also be included when parameters were fit together with VLE data in order to predict the heat of absorption well over a wide range of temperatures and loadings. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901869j