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Vol. 49 N° 15 - Août 2010 [texte imprimé] . - 2010 . - p. 6683–7112 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierHybrid TiO2−SiMgOX composite for combined chemisorption and photocatalytic elimination of gaseous H2S / Søren Birk Rasmussen in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010)
Titre : Hybrid TiO2−SiMgOX composite for combined chemisorption and photocatalytic elimination of gaseous H2S Type de document : texte imprimé Auteurs : Søren Birk Rasmussen, Auteur ; Raquel Portela, Auteur ; Silvia Suarez, Auteur Année de publication : 2010 Article en page(s) : pp 6685–6690 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hybrid TiO2− SiMgOX Photocatalytic. Résumé : Cheap natural sepiolite clay and TiO2 in the anatase form can easily be converted into an efficient hybrid adsorbent/photocatalytic material, usable for H2S and SO2 capture and odor elimination. This can be achieved by extrusion of powder mixtures combined with coating of photocatalytically active titania. By means of the sorption capacity of the sepiolite, it is possible to fixate gaseous sulfur species and by subsequent or simultaneous use of sunlight or artificial light sources, photocatalytic oxidation into oxidized sulfur compounds can be achieved without SO2 release. The formation of such compounds as final products makes it possible to regenerate the composite material after saturation by washing with normal water. This technology constitutes an economically promising, sustainable, nontoxic, future method for H2S elimination from the gas phase in sewage and wastewater treatment plants. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901733p
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6685–6690[article] Hybrid TiO2−SiMgOX composite for combined chemisorption and photocatalytic elimination of gaseous H2S [texte imprimé] / Søren Birk Rasmussen, Auteur ; Raquel Portela, Auteur ; Silvia Suarez, Auteur . - 2010 . - pp 6685–6690.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6685–6690
Mots-clés : Hybrid TiO2− SiMgOX Photocatalytic. Résumé : Cheap natural sepiolite clay and TiO2 in the anatase form can easily be converted into an efficient hybrid adsorbent/photocatalytic material, usable for H2S and SO2 capture and odor elimination. This can be achieved by extrusion of powder mixtures combined with coating of photocatalytically active titania. By means of the sorption capacity of the sepiolite, it is possible to fixate gaseous sulfur species and by subsequent or simultaneous use of sunlight or artificial light sources, photocatalytic oxidation into oxidized sulfur compounds can be achieved without SO2 release. The formation of such compounds as final products makes it possible to regenerate the composite material after saturation by washing with normal water. This technology constitutes an economically promising, sustainable, nontoxic, future method for H2S elimination from the gas phase in sewage and wastewater treatment plants. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901733p Exemplaires
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Titre : Measurement and correlation of the solubility of carbohydrates in subcritical water Type de document : texte imprimé Auteurs : Dongfang Zhang, Auteur ; Fernando Montanés, Auteur ; Keerthi Srinivas, Auteur Année de publication : 2010 Article en page(s) : pp 6691–6698 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Carbohydrates Aqueous solubilities Measurement Correlation. Résumé : The measurement and correlation of the high-temperature aqueous solubilities of three different carbohydrates (glucose, maltose, xylose, etc.) between 293 and 453 K are reported in this study. Sugar solubilities were measured by a continuous-flow technique in which the sugar is saturated at various temperatures in a stream of flowing hot water. Sugar solubilities were measured on the diluted samples taken in the “saturation plateau” region of the solubility measurement technique. Because of a large increase in the sugar solubility with temperature, particularly above the boiling point of water, adjustments in the size and amount of solute in the saturation cell as well as an adjustment of the dilution water rate were necessary. The determined sugar solubility values compare favorably with existing data below the boiling point of water and provide nonexisting data over the above temperature range above the boiling point of water. The resultant sugar solubility trends were modeled empirically or by use of a modified Apelblat equation or the A-UNIFAC model. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901845b
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6691–6698[article] Measurement and correlation of the solubility of carbohydrates in subcritical water [texte imprimé] / Dongfang Zhang, Auteur ; Fernando Montanés, Auteur ; Keerthi Srinivas, Auteur . - 2010 . - pp 6691–6698.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6691–6698
Mots-clés : Carbohydrates Aqueous solubilities Measurement Correlation. Résumé : The measurement and correlation of the high-temperature aqueous solubilities of three different carbohydrates (glucose, maltose, xylose, etc.) between 293 and 453 K are reported in this study. Sugar solubilities were measured by a continuous-flow technique in which the sugar is saturated at various temperatures in a stream of flowing hot water. Sugar solubilities were measured on the diluted samples taken in the “saturation plateau” region of the solubility measurement technique. Because of a large increase in the sugar solubility with temperature, particularly above the boiling point of water, adjustments in the size and amount of solute in the saturation cell as well as an adjustment of the dilution water rate were necessary. The determined sugar solubility values compare favorably with existing data below the boiling point of water and provide nonexisting data over the above temperature range above the boiling point of water. The resultant sugar solubility trends were modeled empirically or by use of a modified Apelblat equation or the A-UNIFAC model. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901845b Exemplaires
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Titre : Kinetics of 4-methoxybenzyl alcohol oxidation in aqueous solution in a fixed bed photocatalytic reactor Type de document : texte imprimé Auteurs : Sedat Yurdakal, Auteur ; Vittorio Loddo, Auteur ; Giovanni Palmisano, Auteur Année de publication : 2010 Article en page(s) : pp 6699–6708 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Kinetics Photocatalytic reactor Aqueous solution. Résumé : The photocatalytic oxidation of 4-methoxybenzyl alcohol in water was performed in a fixed bed continuous annular reactor by using a home-prepared TiO2 catalyst supported on Pyrex glass beads. The investigation was aimed to modeling the complex kinetics of the photoprocess which occurs through two parallel pathways: (i) partial oxidation to the corresponding aldehyde and (ii) total oxidation to CO2 and H2O. On these grounds, the influence of liquid flow rate, inlet concentrations of alcohol and oxygen, catalyst amount, and irradiation power on the photoreactivity were studied. A kinetic model like that of Langmuir−Hinshelwood satisfactorily fitted the experimental results and allowed determination of the values of model parameters. It was found that all these parameters are positively affected by an increase of radiant energy absorbed by the catalyst. All the reactivity results indicate that the partial oxidation pathway is favored by the low flux of absorbed photons and by low oxygen coverage on the TiO2 surface; opposite conditions favor the mineralization pathway. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9008056
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6699–6708[article] Kinetics of 4-methoxybenzyl alcohol oxidation in aqueous solution in a fixed bed photocatalytic reactor [texte imprimé] / Sedat Yurdakal, Auteur ; Vittorio Loddo, Auteur ; Giovanni Palmisano, Auteur . - 2010 . - pp 6699–6708.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6699–6708
Mots-clés : Kinetics Photocatalytic reactor Aqueous solution. Résumé : The photocatalytic oxidation of 4-methoxybenzyl alcohol in water was performed in a fixed bed continuous annular reactor by using a home-prepared TiO2 catalyst supported on Pyrex glass beads. The investigation was aimed to modeling the complex kinetics of the photoprocess which occurs through two parallel pathways: (i) partial oxidation to the corresponding aldehyde and (ii) total oxidation to CO2 and H2O. On these grounds, the influence of liquid flow rate, inlet concentrations of alcohol and oxygen, catalyst amount, and irradiation power on the photoreactivity were studied. A kinetic model like that of Langmuir−Hinshelwood satisfactorily fitted the experimental results and allowed determination of the values of model parameters. It was found that all these parameters are positively affected by an increase of radiant energy absorbed by the catalyst. All the reactivity results indicate that the partial oxidation pathway is favored by the low flux of absorbed photons and by low oxygen coverage on the TiO2 surface; opposite conditions favor the mineralization pathway. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9008056 Exemplaires
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Titre : Gas−liquid two-phase flow in minichannels with liquid side introduction Type de document : texte imprimé Auteurs : Wei Du, Auteur ; Lifeng Zhang, Auteur ; Xiaotao T. Bi, Auteur Année de publication : 2010 Article en page(s) : pp 6709–6721 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas liquid Minichannels Liquid side. Résumé : In the present work, computational fluid dynamics (CFD) modeling with a volume of fluid (VOF) method was used to understand gas−liquid two-phase flow in PEM fuel cell flow channels under typical fuel cell flow conditions. Simulations with different liquid water introduction manners to flow channels were discussed to resemble liquid water transport in flow channels in active fuel cells. Those introduction methods included side liquid introduction through a number of ports, continuous liquid introduction along the channel with uniform and nonuniform flow rates, and liquid water introduction from the inlet together with the gas phase. The simulated results showed that the side introduction of water increases the water accumulation near the end of the channel and the gas slugs are significantly elongated, compared to the cases with water introduction from the inlet. When water was introduced nonuniformly along the channel with more near the outlet of the channel, there appears to be less probability of slug formation in the channel. With low liquid to gas volumetric flow ratios as encountered in fuel cells, the flow pattern changed between slug flow and stratified flow, depending on different liquid introduction manners. When water was introduced into the channel from ports on the bottom wall, it emerged and accumulated near the port region before slugs formed, detached, and purged out of the channel, causing high pressure drop and pressure drop fluctuations. When the wettability, or contact angle, of the channel walls varied, liquid water tended to attach to the wall surface with low contact angles, namely, more hydrophilic surface. In addition, the change in surface contact angle can also lead to the change in flow patterns. The slug frequency decreased with an increase in the port size. With increasing of the port number, more liquid tended to accumulate in the channel. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901120n#cor1
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6709–6721[article] Gas−liquid two-phase flow in minichannels with liquid side introduction [texte imprimé] / Wei Du, Auteur ; Lifeng Zhang, Auteur ; Xiaotao T. Bi, Auteur . - 2010 . - pp 6709–6721.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6709–6721
Mots-clés : Gas liquid Minichannels Liquid side. Résumé : In the present work, computational fluid dynamics (CFD) modeling with a volume of fluid (VOF) method was used to understand gas−liquid two-phase flow in PEM fuel cell flow channels under typical fuel cell flow conditions. Simulations with different liquid water introduction manners to flow channels were discussed to resemble liquid water transport in flow channels in active fuel cells. Those introduction methods included side liquid introduction through a number of ports, continuous liquid introduction along the channel with uniform and nonuniform flow rates, and liquid water introduction from the inlet together with the gas phase. The simulated results showed that the side introduction of water increases the water accumulation near the end of the channel and the gas slugs are significantly elongated, compared to the cases with water introduction from the inlet. When water was introduced nonuniformly along the channel with more near the outlet of the channel, there appears to be less probability of slug formation in the channel. With low liquid to gas volumetric flow ratios as encountered in fuel cells, the flow pattern changed between slug flow and stratified flow, depending on different liquid introduction manners. When water was introduced into the channel from ports on the bottom wall, it emerged and accumulated near the port region before slugs formed, detached, and purged out of the channel, causing high pressure drop and pressure drop fluctuations. When the wettability, or contact angle, of the channel walls varied, liquid water tended to attach to the wall surface with low contact angles, namely, more hydrophilic surface. In addition, the change in surface contact angle can also lead to the change in flow patterns. The slug frequency decreased with an increase in the port size. With increasing of the port number, more liquid tended to accumulate in the channel. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901120n#cor1 Exemplaires
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Titre : Oxidative photomineralization of dichloroacetic acid in an externally-irradiated rectangular bubble tank reactor: computational fluid dynamics modeling and experimental verification studies Type de document : texte imprimé Auteurs : Francisco J. Trujillo, Auteur ; Tomasz Safinski, Auteur ; Adesoji A. Adesina, Auteur Année de publication : 2010 Article en page(s) : pp 6722–6734 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Oxidative photomineralization Fluid dynamics. Résumé : The effect of antecedent factors on the performance of an aerated tank photoreactor containing externally irradiated suspended titania particles has been carried out using the oxidative photomineralisation of dichloroacetic acid (DCA) as the model reaction. The phase hold-up contours, velocity distribution profiles, and the spatial variation of the incident radiative flux as well as the local volumetric rate of photon absorption (LVPRA) inside the reactor were obtained from computational fluid dynamics (CFD) simulation based on the simultaneous solution of the Navier−Stokes equation (NSE) and radiation transport equation (RTE). The species modeling equation (SME) for the oxidative decomposition of DCA to HCl and CO2 was then coupled to the NSE and RTE to determine the influence of catalyst loading, air superficial velocity, pollutant concentration, and radiation intensity on the reactor performance. The SME utilized the intrinsic kinetic expression provided by Zalazar et al. [Chem. Eng. Sci. 2005, 60, 5240−5254] with rate parameters secured from a preliminary fit of our experimental data. The good agreement between numerical results and empirical data for practically all predictor variables suggest that CFD modeling is a reliable and valid tool for the design and evaluation of the new photoreactor system and may in fact be used as a surrogate for subsequent optimization studies. Within the range of variables examined, it is evident that although reaction rate initially increased with air flow rate, a “plateau” was attained after about 30 L min−1. The rate also exhibited a maximum at a catalyst loading of about 2.5 g L−1 while a characteristic Langmuir-type dependency on DCA concentration was observed. However, reaction rate varied only linearly with light intensity indicating the absence of deleterious hole−electron recombination at the relatively low values (20−80 W m−2) employed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901364z
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6722–6734[article] Oxidative photomineralization of dichloroacetic acid in an externally-irradiated rectangular bubble tank reactor: computational fluid dynamics modeling and experimental verification studies [texte imprimé] / Francisco J. Trujillo, Auteur ; Tomasz Safinski, Auteur ; Adesoji A. Adesina, Auteur . - 2010 . - pp 6722–6734.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6722–6734
Mots-clés : Oxidative photomineralization Fluid dynamics. Résumé : The effect of antecedent factors on the performance of an aerated tank photoreactor containing externally irradiated suspended titania particles has been carried out using the oxidative photomineralisation of dichloroacetic acid (DCA) as the model reaction. The phase hold-up contours, velocity distribution profiles, and the spatial variation of the incident radiative flux as well as the local volumetric rate of photon absorption (LVPRA) inside the reactor were obtained from computational fluid dynamics (CFD) simulation based on the simultaneous solution of the Navier−Stokes equation (NSE) and radiation transport equation (RTE). The species modeling equation (SME) for the oxidative decomposition of DCA to HCl and CO2 was then coupled to the NSE and RTE to determine the influence of catalyst loading, air superficial velocity, pollutant concentration, and radiation intensity on the reactor performance. The SME utilized the intrinsic kinetic expression provided by Zalazar et al. [Chem. Eng. Sci. 2005, 60, 5240−5254] with rate parameters secured from a preliminary fit of our experimental data. The good agreement between numerical results and empirical data for practically all predictor variables suggest that CFD modeling is a reliable and valid tool for the design and evaluation of the new photoreactor system and may in fact be used as a surrogate for subsequent optimization studies. Within the range of variables examined, it is evident that although reaction rate initially increased with air flow rate, a “plateau” was attained after about 30 L min−1. The rate also exhibited a maximum at a catalyst loading of about 2.5 g L−1 while a characteristic Langmuir-type dependency on DCA concentration was observed. However, reaction rate varied only linearly with light intensity indicating the absence of deleterious hole−electron recombination at the relatively low values (20−80 W m−2) employed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901364z Exemplaires
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Titre : Slip velocity in downer reactors: drag coefficient and the influence of operational variables Type de document : texte imprimé Auteurs : Mohammad Ashraful Islam, Auteur ; Stefan Krol, Auteur ; Hugo I. De Lasa, Auteur Année de publication : 2010 Article en page(s) : pp 6735–6744 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Slip velocity Operational variables. Résumé : Cluster formation in downer reactors is considered a most important factor influencing slip velocity between the flowing phases. This study investigates the formation of clusters using CREC-GS-Optiprobes. This probe is a nonintrusive device that records information from a well-defined optical measuring volume. This probe can provide accurate measurements tracking closely gas−solid flows in downer units. This study shows that cluster drag coefficients can be correlated as function of both Reynolds number and number of particles contained in agglomerates. This yields a close to linear relationship between cluster size and average slip velocity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901466p
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6735–6744[article] Slip velocity in downer reactors: drag coefficient and the influence of operational variables [texte imprimé] / Mohammad Ashraful Islam, Auteur ; Stefan Krol, Auteur ; Hugo I. De Lasa, Auteur . - 2010 . - pp 6735–6744.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6735–6744
Mots-clés : Slip velocity Operational variables. Résumé : Cluster formation in downer reactors is considered a most important factor influencing slip velocity between the flowing phases. This study investigates the formation of clusters using CREC-GS-Optiprobes. This probe is a nonintrusive device that records information from a well-defined optical measuring volume. This probe can provide accurate measurements tracking closely gas−solid flows in downer units. This study shows that cluster drag coefficients can be correlated as function of both Reynolds number and number of particles contained in agglomerates. This yields a close to linear relationship between cluster size and average slip velocity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901466p Exemplaires
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Titre : Horseradish peroxidase and hematin as biocatalysts for alizarin degradation using hydrogen peroxide Type de document : texte imprimé Auteurs : Silvina Pirillo, Auteur ; Fernando Sebastian Garcia Einschlag, Auteur ; Elsa H. Rueda, Auteur Année de publication : 2010 Article en page(s) : pp 6745–6752 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Peroxidase Hematin Biocatalysts. Résumé : Degradation of organic dyes from the textile industry is a matter of enormous environmental concern. The horseradish peroxidase enzyme is known for its capacity to remove phenolic compounds and aromatic amines from aqueous solutions and also to decolorize textile effluents. This study evaluates the potential of the both enzyme horseradish peroxidase (HRP) and its biomimetic hematin in the decolorization of alizarin. We describe an UV−visible study of alizarin elimination from aqueous solutions by polymerization using HRP or hematin as catalysts, hydrogen peroxide as oxidant, and HCl as coagulant. The effects of the initial dye concentration and the temperature on the decolorization efficiencies, attained with each catalyst after 2 h of reaction time, are reported. Alizarin removal with HRP/H2O2 achieved the highest elimination level (88%) when the dye concentration was 50 mg/L. At the same dye concentration a degradation of 97% was obtained using hematin as biocatalyst. A comparative analysis of time-resolved spectra and dissolved oxygen profiles is presented. The oxygen profiles found for hematin/H2O2/alizarin and HRP/H2O2/alizarin systems are clearly different, pointing to oxygen consumption for hematin and oxygen production for peroxidase. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901528y
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6745–6752[article] Horseradish peroxidase and hematin as biocatalysts for alizarin degradation using hydrogen peroxide [texte imprimé] / Silvina Pirillo, Auteur ; Fernando Sebastian Garcia Einschlag, Auteur ; Elsa H. Rueda, Auteur . - 2010 . - pp 6745–6752.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6745–6752
Mots-clés : Peroxidase Hematin Biocatalysts. Résumé : Degradation of organic dyes from the textile industry is a matter of enormous environmental concern. The horseradish peroxidase enzyme is known for its capacity to remove phenolic compounds and aromatic amines from aqueous solutions and also to decolorize textile effluents. This study evaluates the potential of the both enzyme horseradish peroxidase (HRP) and its biomimetic hematin in the decolorization of alizarin. We describe an UV−visible study of alizarin elimination from aqueous solutions by polymerization using HRP or hematin as catalysts, hydrogen peroxide as oxidant, and HCl as coagulant. The effects of the initial dye concentration and the temperature on the decolorization efficiencies, attained with each catalyst after 2 h of reaction time, are reported. Alizarin removal with HRP/H2O2 achieved the highest elimination level (88%) when the dye concentration was 50 mg/L. At the same dye concentration a degradation of 97% was obtained using hematin as biocatalyst. A comparative analysis of time-resolved spectra and dissolved oxygen profiles is presented. The oxygen profiles found for hematin/H2O2/alizarin and HRP/H2O2/alizarin systems are clearly different, pointing to oxygen consumption for hematin and oxygen production for peroxidase. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901528y Exemplaires
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Titre : Nafion-incorporated silicate structured nanocomposite mesoporous catalysts for dimethyl ether synthesis Type de document : texte imprimé Auteurs : Aysegul Ciftci, Auteur ; Naime Asli Sezgi, Auteur ; Timur Dogu, Auteur Année de publication : 2010 Article en page(s) : pp 6753–6762 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Mesoporous Catalysts Ether synthesis. Résumé : Being chemically and thermally stable, Nafion resin is considered to be an attractive solid acid catalyst. Although it has high acid strength and the ability to catalyze a wide range of reactions, the catalytic activity of Nafion is limited, because of its very low specific surface area. In this study, mesoporous Nafion−silica nanocomposites were developed by following a one-pot acidic hydrothermal synthesis procedure. Synthesized catalysts were determined to have well-dispersed structures with high surface area values (595−792 m2/g) and strong Brønsted, as well as Lewis, acid sites. The activities of these novel catalysts were tested in dimethyl ether synthesis from methanol in a flow system. The effects of modifications in the synthesis procedure and Nafion loading showed that the material synthesized from a solution containing a Nafion/silica weight ratio of 0.15 and refluxed with a 2 M sulfuric acid−ethanol (SAE) mixture for surfactant removal was the best catalyst for this reaction. Production of the green transportation fuel alternate dimethyl ether (DME) was achieved with this catalyst at very high yields with almost 100% DME selectivity at >180 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9015667
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6753–6762[article] Nafion-incorporated silicate structured nanocomposite mesoporous catalysts for dimethyl ether synthesis [texte imprimé] / Aysegul Ciftci, Auteur ; Naime Asli Sezgi, Auteur ; Timur Dogu, Auteur . - 2010 . - pp 6753–6762.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6753–6762
Mots-clés : Mesoporous Catalysts Ether synthesis. Résumé : Being chemically and thermally stable, Nafion resin is considered to be an attractive solid acid catalyst. Although it has high acid strength and the ability to catalyze a wide range of reactions, the catalytic activity of Nafion is limited, because of its very low specific surface area. In this study, mesoporous Nafion−silica nanocomposites were developed by following a one-pot acidic hydrothermal synthesis procedure. Synthesized catalysts were determined to have well-dispersed structures with high surface area values (595−792 m2/g) and strong Brønsted, as well as Lewis, acid sites. The activities of these novel catalysts were tested in dimethyl ether synthesis from methanol in a flow system. The effects of modifications in the synthesis procedure and Nafion loading showed that the material synthesized from a solution containing a Nafion/silica weight ratio of 0.15 and refluxed with a 2 M sulfuric acid−ethanol (SAE) mixture for surfactant removal was the best catalyst for this reaction. Production of the green transportation fuel alternate dimethyl ether (DME) was achieved with this catalyst at very high yields with almost 100% DME selectivity at >180 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9015667 Exemplaires
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Titre : Oxygenated biofuels from butanol for diesel blends: synthesis of the acetal 1,1-dibutoxyethane catalyzed by amberlyst-15 Ion-exchange resin Type de document : texte imprimé Auteurs : Nuno S. Graça, Auteur ; Luis S. Pais, Auteur ; Viviana M. T. M. Silva, Auteur Année de publication : 2010 Article en page(s) : pp 6763–6771 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Biofuels butanol Dibutoxyethane. Résumé : The synthesis of 1,1-dibutoxyethane or acetaldehyde dibutylacetal was studied in a batch reactor by reacting butanol and acetaldehyde in a liquid phase, using Amberlyst-15 as the catalyst. The reaction equilibrium constant was experimentally determined in the temperature range 20−40 °C at 6 atm, where Ka = 0.00959 exp[1755.3/T (K)]. The standard properties of the reaction at 298.15 K were estimated: ΔH° = −14.59 kJ mol−1, ΔG° = −3.07 kJ mol−1, and ΔS° = −38.64 J mol−1 K−1. Kinetic experiments were performed in the temperature range 10−50 °C at 6 atm. A two-parameter kinetic law based on a Langmuir−Hinshelwood rate expression, using activity coefficients from the UNIFAC method, was used. The kinetic parameters are kc = 2.39 × 109 exp[−6200.9/T (K)] (mol gcat−1 min−1) and ks,D = 2.25 × 10−4 exp[3303.1/T (K)]. The activation energy of the reaction is 51.55 kJ mol−1. This work is an important step for further implementation of an integrated reaction−separation process, such as a simulated moving-bed reactor. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901635j
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6763–6771[article] Oxygenated biofuels from butanol for diesel blends: synthesis of the acetal 1,1-dibutoxyethane catalyzed by amberlyst-15 Ion-exchange resin [texte imprimé] / Nuno S. Graça, Auteur ; Luis S. Pais, Auteur ; Viviana M. T. M. Silva, Auteur . - 2010 . - pp 6763–6771.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6763–6771
Mots-clés : Biofuels butanol Dibutoxyethane. Résumé : The synthesis of 1,1-dibutoxyethane or acetaldehyde dibutylacetal was studied in a batch reactor by reacting butanol and acetaldehyde in a liquid phase, using Amberlyst-15 as the catalyst. The reaction equilibrium constant was experimentally determined in the temperature range 20−40 °C at 6 atm, where Ka = 0.00959 exp[1755.3/T (K)]. The standard properties of the reaction at 298.15 K were estimated: ΔH° = −14.59 kJ mol−1, ΔG° = −3.07 kJ mol−1, and ΔS° = −38.64 J mol−1 K−1. Kinetic experiments were performed in the temperature range 10−50 °C at 6 atm. A two-parameter kinetic law based on a Langmuir−Hinshelwood rate expression, using activity coefficients from the UNIFAC method, was used. The kinetic parameters are kc = 2.39 × 109 exp[−6200.9/T (K)] (mol gcat−1 min−1) and ks,D = 2.25 × 10−4 exp[3303.1/T (K)]. The activation energy of the reaction is 51.55 kJ mol−1. This work is an important step for further implementation of an integrated reaction−separation process, such as a simulated moving-bed reactor. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901635j Exemplaires
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Titre : Effect of ethanol, dimethylether, and oxygen, when mixed with acetylene, on the formation of soot and gas products Type de document : texte imprimé Auteurs : Claudia Esarte, Auteur ; Angela Millera, Auteur ; Rafael Bilbao, Auteur Année de publication : 2010 Article en page(s) : pp 6772–6779 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Ethanol Dimethylether Oxygen. Résumé : The purpose of this research work is to analyze the effect of ethanol, dimethylether (DME), and oxygen on the formation of gas and soot products when mixed with acetylene and reacted under different conditions, the influence of the oxygenated compounds’ molecular structure, and the impact of the origin of the carbon and oxygen in the different reacting compounds. Experiments have been carried out in a quartz flow reactor in the temperature interval of 975−1475 K, and gas and soot products have been identified and quantified. Experimental data have been interpreted in terms of a literature detailed gas phase kinetic model. Results show that the presence of ethanol and DME in the reacting mixtures results in a diminution of the production of soot compared to the pyrolysis of pure acetylene; less soot is produced in the pyrolysis of acetylene−DME mixtures. The source of C and O is a key factor, being directly related to the soot-forming tendency of the molecules and the different bonds in the molecules. The concentrations of CO, CO2, and the rest of the gaseous compounds found in the outlet stream are related to the different reaction pathways which occur depending on either the presence of the oxygenated compounds or O2. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901663g
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6772–6779[article] Effect of ethanol, dimethylether, and oxygen, when mixed with acetylene, on the formation of soot and gas products [texte imprimé] / Claudia Esarte, Auteur ; Angela Millera, Auteur ; Rafael Bilbao, Auteur . - 2010 . - pp 6772–6779.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6772–6779
Mots-clés : Ethanol Dimethylether Oxygen. Résumé : The purpose of this research work is to analyze the effect of ethanol, dimethylether (DME), and oxygen on the formation of gas and soot products when mixed with acetylene and reacted under different conditions, the influence of the oxygenated compounds’ molecular structure, and the impact of the origin of the carbon and oxygen in the different reacting compounds. Experiments have been carried out in a quartz flow reactor in the temperature interval of 975−1475 K, and gas and soot products have been identified and quantified. Experimental data have been interpreted in terms of a literature detailed gas phase kinetic model. Results show that the presence of ethanol and DME in the reacting mixtures results in a diminution of the production of soot compared to the pyrolysis of pure acetylene; less soot is produced in the pyrolysis of acetylene−DME mixtures. The source of C and O is a key factor, being directly related to the soot-forming tendency of the molecules and the different bonds in the molecules. The concentrations of CO, CO2, and the rest of the gaseous compounds found in the outlet stream are related to the different reaction pathways which occur depending on either the presence of the oxygenated compounds or O2. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901663g Exemplaires
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Titre : Computational fluid dynamic investigation of change of volumetric flow in fluidized-bed reactors Type de document : texte imprimé Auteurs : Tingwen Li, Auteur ; Andrés Mahecha-Botero, Auteur ; John R. Grace, Auteur Année de publication : 2010 Article en page(s) : pp 6780–6789 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluid Dynamic Volumetric flow. Résumé : The modeling and characterization of fluidized-bed reactors is challenging due to the variety of interrelated phenomena during the fluidization process. A key feature affecting gas−solid fluidized-bed reactors is the distribution of gas flow between phases. To address this flow distribution, conventional reactor modeling and computational fluid dynamics have been proposed in the literature. However, very little attention has been given to cases where the fluid volume changes due to factors such as variation in the total molar flow due to reaction, change of phase, utilization of membranes, and changes in temperature and pressure. This article investigates change in volumetric flow based on computational fluid dynamics. It is shown that a decrease in volumetric flow can profoundly influence the hydrodynamics, especially for smaller particles, whereas an increase in volumetric flow is accommodated with limited consequences, especially for larger particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901676d
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6780–6789[article] Computational fluid dynamic investigation of change of volumetric flow in fluidized-bed reactors [texte imprimé] / Tingwen Li, Auteur ; Andrés Mahecha-Botero, Auteur ; John R. Grace, Auteur . - 2010 . - pp 6780–6789.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6780–6789
Mots-clés : Fluid Dynamic Volumetric flow. Résumé : The modeling and characterization of fluidized-bed reactors is challenging due to the variety of interrelated phenomena during the fluidization process. A key feature affecting gas−solid fluidized-bed reactors is the distribution of gas flow between phases. To address this flow distribution, conventional reactor modeling and computational fluid dynamics have been proposed in the literature. However, very little attention has been given to cases where the fluid volume changes due to factors such as variation in the total molar flow due to reaction, change of phase, utilization of membranes, and changes in temperature and pressure. This article investigates change in volumetric flow based on computational fluid dynamics. It is shown that a decrease in volumetric flow can profoundly influence the hydrodynamics, especially for smaller particles, whereas an increase in volumetric flow is accommodated with limited consequences, especially for larger particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901676d Exemplaires
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Titre : Effect of synthesis conditions on the structure and catalytic performance of V- and Ce-incorporated SBA-15-like materials in propane selective oxidation Type de document : texte imprimé Auteurs : Ozge Aktas, Auteur ; Sena Yasyerli, Auteur ; Gulsen Dogu, Auteur Année de publication : 2010 Article en page(s) : pp 6790–6802 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst Selective Oxidation. Résumé : Vanadia- and/or ceria-incorporated SBA-15-like materials were prepared by impregnation and one-pot hydrothermal synthesis procedures at different solution pH values. The pH of the synthesis solution was found to have a very strong effect on the pore structure, chemical composition, and morphology of the synthesized materials. Materials synthesized by impregnation of V and/or Ce and by the one-pot hydrothermal route at pH 1.0 showed the characteristic ordered pore structure of SBA-15. However, the materials prepared by the one-pot synthesis route at pH 1.5 gave complex pore structures with bottleneck-shaped and/or slit-like interconnected pores. Activity tests in the selective oxidation of propane showed higher activities for the V-incorporated materials than for the materials containing Ce and V−Ce. Catalysts synthesized by impregnation gave higher propane conversions. However, the propylene selectivity values were higher with the catalysts prepared by the one-pot route. An increase in the temperature from 550 to 600 °C led to increases in both the conversion and the propylene selectivity with the V- and V−Ce-incorporated materials prepared by the one-pot procedure at pH 1.5. For the V-incorporated catalyst prepared by this route, the propane conversion and propylene selectivity were obtained as 40% and 62%, respectively, at a space time of 0.4 s·g·cm−3 and a temperature of 600 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901672b
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6790–6802[article] Effect of synthesis conditions on the structure and catalytic performance of V- and Ce-incorporated SBA-15-like materials in propane selective oxidation [texte imprimé] / Ozge Aktas, Auteur ; Sena Yasyerli, Auteur ; Gulsen Dogu, Auteur . - 2010 . - pp 6790–6802.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6790–6802
Mots-clés : Catalyst Selective Oxidation. Résumé : Vanadia- and/or ceria-incorporated SBA-15-like materials were prepared by impregnation and one-pot hydrothermal synthesis procedures at different solution pH values. The pH of the synthesis solution was found to have a very strong effect on the pore structure, chemical composition, and morphology of the synthesized materials. Materials synthesized by impregnation of V and/or Ce and by the one-pot hydrothermal route at pH 1.0 showed the characteristic ordered pore structure of SBA-15. However, the materials prepared by the one-pot synthesis route at pH 1.5 gave complex pore structures with bottleneck-shaped and/or slit-like interconnected pores. Activity tests in the selective oxidation of propane showed higher activities for the V-incorporated materials than for the materials containing Ce and V−Ce. Catalysts synthesized by impregnation gave higher propane conversions. However, the propylene selectivity values were higher with the catalysts prepared by the one-pot route. An increase in the temperature from 550 to 600 °C led to increases in both the conversion and the propylene selectivity with the V- and V−Ce-incorporated materials prepared by the one-pot procedure at pH 1.5. For the V-incorporated catalyst prepared by this route, the propane conversion and propylene selectivity were obtained as 40% and 62%, respectively, at a space time of 0.4 s·g·cm−3 and a temperature of 600 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901672b Exemplaires
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Titre : Modeling study on the performance of an integrated APU fed with hydrocarbon fuels Type de document : texte imprimé Auteurs : Stefania Specchia, Auteur ; Vito Specchia, Auteur Année de publication : 2010 Article en page(s) : pp 6803–6809 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrocarbon fuels Modeling. Résumé : The employment of H2 in fuel cell (FCs) technologies could ensure significant advantages in terms of efficiency and environmental impact, representing thus an important alternative to the conventional energy production systems. As far as the actual lack of infrastructure for H2 production, storage, and distribution is concerned, FCs fed with H2, produced by fossil fuel reforming to generate on-board vehicles at least auxiliary power, represent a valid and interesting alternative to overcome the actual unfavorable situation, waiting for further development of infrastructures. The present work deals with the analysis of a 5 kWe auxiliary power unit (APU) integrated with a fuel processor unit (FPU), based on oxidative steam reforming (OSR, with bleed air, BA) and related CO clean-up technologies, for the production of H2-rich fuel gas, which is fed to a PEM-FC stack. Using the results of a series of steady-state system simulations with Matlab/Simulink, the APU performance was analyzed in terms of FP and APU efficiency, specific power produced by the stack, and water balance, by considering different liquid hydrocarbon fuels (gasoline, light and heavy diesel) and compressed natural gas (CNG) as feed. A parametric sensitivity analysis concerning the effects of the variation of steam to carbon ratio (SCR) and the BA rate to OSR was also carried out. As the main obtained results, the APU performance in transforming the primary fuel in H2-rich gas was more efficient according to the higher H2 to carbon ratio HCR of the feedstock. In fact, the APU net efficiency decreased with the following order: methane (27.8%) > gasoline (27.0%) > light diesel (26.5%) > heavy diesel (26.0%). The parametric sensitivity analysis revealed that with small SCR decrease and bleed air rate increase it was possible to improve the APU performance. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901696j
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6803–6809[article] Modeling study on the performance of an integrated APU fed with hydrocarbon fuels [texte imprimé] / Stefania Specchia, Auteur ; Vito Specchia, Auteur . - 2010 . - pp 6803–6809.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6803–6809
Mots-clés : Hydrocarbon fuels Modeling. Résumé : The employment of H2 in fuel cell (FCs) technologies could ensure significant advantages in terms of efficiency and environmental impact, representing thus an important alternative to the conventional energy production systems. As far as the actual lack of infrastructure for H2 production, storage, and distribution is concerned, FCs fed with H2, produced by fossil fuel reforming to generate on-board vehicles at least auxiliary power, represent a valid and interesting alternative to overcome the actual unfavorable situation, waiting for further development of infrastructures. The present work deals with the analysis of a 5 kWe auxiliary power unit (APU) integrated with a fuel processor unit (FPU), based on oxidative steam reforming (OSR, with bleed air, BA) and related CO clean-up technologies, for the production of H2-rich fuel gas, which is fed to a PEM-FC stack. Using the results of a series of steady-state system simulations with Matlab/Simulink, the APU performance was analyzed in terms of FP and APU efficiency, specific power produced by the stack, and water balance, by considering different liquid hydrocarbon fuels (gasoline, light and heavy diesel) and compressed natural gas (CNG) as feed. A parametric sensitivity analysis concerning the effects of the variation of steam to carbon ratio (SCR) and the BA rate to OSR was also carried out. As the main obtained results, the APU performance in transforming the primary fuel in H2-rich gas was more efficient according to the higher H2 to carbon ratio HCR of the feedstock. In fact, the APU net efficiency decreased with the following order: methane (27.8%) > gasoline (27.0%) > light diesel (26.5%) > heavy diesel (26.0%). The parametric sensitivity analysis revealed that with small SCR decrease and bleed air rate increase it was possible to improve the APU performance. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901696j Exemplaires
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Titre : Use of fluidized bed reactors for direct gas phase oxidation of benzene to phenol Type de document : texte imprimé Auteurs : Maria. P. Gimeno, Auteur ; Jaime Soler, Auteur ; Javier Herguido, Auteur Année de publication : 2010 Article en page(s) : pp 6810–6814 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas phase Oxidation Benzene Phenol. Résumé : A study on the direct gas phase oxidation of benzene to phenol over a Pt-VOx/SiO2 catalyst was carried out in both a conventional fluidized bed reactor (FBR) and a two-zone fluidized bed reactor (TZFBR). For this purpose, Pt-VOx/SiO2 catalyst was synthesized by a method based on two consecutive impregnations. In the FBR, the effect of the main operating variables was studied: temperature, H2/O2 ratio, and relative gas velocity (u/umf) in order to obtain the optimal conditions. Furthermore, two configurations in a TZFBR were tested feeding the reactants separately: benzene and hydrogen or oxygen at the middle of the bed, and oxygen or hydrogen at the bottom, respectively. Depending on the TZFBR configuration, the selectivity was tailored to obtain different products. The use of TZFBR allowed the production of phenol, cyclohexanone, or cyclohexane in the same reactor simply by changing the point where every reactant was introduced. Phenol selectivity near 100% was obtained in one of the configurations studied. Continuous operation without catalyst deactivation was observed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901706y
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6810–6814[article] Use of fluidized bed reactors for direct gas phase oxidation of benzene to phenol [texte imprimé] / Maria. P. Gimeno, Auteur ; Jaime Soler, Auteur ; Javier Herguido, Auteur . - 2010 . - pp 6810–6814.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6810–6814
Mots-clés : Gas phase Oxidation Benzene Phenol. Résumé : A study on the direct gas phase oxidation of benzene to phenol over a Pt-VOx/SiO2 catalyst was carried out in both a conventional fluidized bed reactor (FBR) and a two-zone fluidized bed reactor (TZFBR). For this purpose, Pt-VOx/SiO2 catalyst was synthesized by a method based on two consecutive impregnations. In the FBR, the effect of the main operating variables was studied: temperature, H2/O2 ratio, and relative gas velocity (u/umf) in order to obtain the optimal conditions. Furthermore, two configurations in a TZFBR were tested feeding the reactants separately: benzene and hydrogen or oxygen at the middle of the bed, and oxygen or hydrogen at the bottom, respectively. Depending on the TZFBR configuration, the selectivity was tailored to obtain different products. The use of TZFBR allowed the production of phenol, cyclohexanone, or cyclohexane in the same reactor simply by changing the point where every reactant was introduced. Phenol selectivity near 100% was obtained in one of the configurations studied. Continuous operation without catalyst deactivation was observed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901706y Exemplaires
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Titre : Catalytic cracking of 2,2,4-trimethylpentane on FAU, MFI, and bimodal porous materials: influence of acid properties and pore topology Type de document : texte imprimé Auteurs : Rhona Van Borm, Auteur ; Alexander Aerts, Auteur ; Marie-Françoise Reyniers, Auteur Année de publication : 2010 Article en page(s) : pp 6815–6823 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalytic Bimodal porous materials. Résumé : Cracking experiments using 2,2,4-trimethylpentane as a model component have been performed on five FAU and three MFI zeolites. In addition to these eight commercially available catalysts, two newly developed zeotype materials with bimodal pore structure, BIPOMs, have been investigated. Both BIPOMs possess an MFI ultramicropore ( DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901708m
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6815–6823[article] Catalytic cracking of 2,2,4-trimethylpentane on FAU, MFI, and bimodal porous materials: influence of acid properties and pore topology [texte imprimé] / Rhona Van Borm, Auteur ; Alexander Aerts, Auteur ; Marie-Françoise Reyniers, Auteur . - 2010 . - pp 6815–6823.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6815–6823
Mots-clés : Catalytic Bimodal porous materials. Résumé : Cracking experiments using 2,2,4-trimethylpentane as a model component have been performed on five FAU and three MFI zeolites. In addition to these eight commercially available catalysts, two newly developed zeotype materials with bimodal pore structure, BIPOMs, have been investigated. Both BIPOMs possess an MFI ultramicropore ( DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901708m Exemplaires
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Titre : Photocatalytic thermodynamic efficiency factors. practical limits in photocatalytic reactors Type de document : texte imprimé Auteurs : Benito Serrano, Auteur ; Aaron Ortiz, Auteur ; Jesus Moreira, Auteur Année de publication : 2010 Article en page(s) : pp 6824–6833 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photocatalytic reactors Thermodynamic. Résumé : The photocatalytic thermodynamic efficiency factor (PTEF) is a parameter that can be used in photocatalytic reactors to establish photon energy utilization as the ratio of the energy used to generate OH• free radicals and the energy absorbed by the TiO2 photocatalyst. The PTEF evaluation requires the assessment of the total rate of OH• free radicals at any given time during the photoconversion of organic species. A key parameter in this assessment is the availability of the complete spectrum of measurable chemical species including various intermediates. Quantification of different chemical species and their evolution with irradiation time allow via stoichiometric relationships the calculation of the OH• radicals consumed in the photocatalytic reactor. PTEFs and quantum yields (QY) were reported recently for phenol photocatalytic conversion in water media (free of iron ions) displaying 71% and 19% maximum QYs and PTEFs, respectively.19 In the present study, the QY and PTEF are reviewed further, considering the photoconversion of phenol in water media enhanced by iron ions. It is shown using the more realistic RN2 model that the maximum QYs and PTEFs reach up to 85% and 23% levels, respectively. These encouraging efficiency factors demonstrate the favorable prospects of photocatalysis and Photo-CREC Water reactors operated under optimum photocatalyst loading conditions (0.14 g/L), with only a small fraction of the total absorbed photons potentially lost in photon recombination. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017034
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6824–6833[article] Photocatalytic thermodynamic efficiency factors. practical limits in photocatalytic reactors [texte imprimé] / Benito Serrano, Auteur ; Aaron Ortiz, Auteur ; Jesus Moreira, Auteur . - 2010 . - pp 6824–6833.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6824–6833
Mots-clés : Photocatalytic reactors Thermodynamic. Résumé : The photocatalytic thermodynamic efficiency factor (PTEF) is a parameter that can be used in photocatalytic reactors to establish photon energy utilization as the ratio of the energy used to generate OH• free radicals and the energy absorbed by the TiO2 photocatalyst. The PTEF evaluation requires the assessment of the total rate of OH• free radicals at any given time during the photoconversion of organic species. A key parameter in this assessment is the availability of the complete spectrum of measurable chemical species including various intermediates. Quantification of different chemical species and their evolution with irradiation time allow via stoichiometric relationships the calculation of the OH• radicals consumed in the photocatalytic reactor. PTEFs and quantum yields (QY) were reported recently for phenol photocatalytic conversion in water media (free of iron ions) displaying 71% and 19% maximum QYs and PTEFs, respectively.19 In the present study, the QY and PTEF are reviewed further, considering the photoconversion of phenol in water media enhanced by iron ions. It is shown using the more realistic RN2 model that the maximum QYs and PTEFs reach up to 85% and 23% levels, respectively. These encouraging efficiency factors demonstrate the favorable prospects of photocatalysis and Photo-CREC Water reactors operated under optimum photocatalyst loading conditions (0.14 g/L), with only a small fraction of the total absorbed photons potentially lost in photon recombination. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017034 Exemplaires
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Titre : Biomass catalytic steam gasification thermodynamics analysis and reaction experiments in a CREC riser simulator Type de document : texte imprimé Auteurs : Enrique Salaices, Auteur ; Benito Serrano, Auteur ; Hugo De Lasa, Auteur Année de publication : 2010 Article en page(s) : pp 6834–6844 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalytic Thermodynamics Gasification. Résumé : A thermodynamic equilibrium model based on evaluations involving C, H, and O element balances and various product species up to C6 hydrocarbons is reported in this study. This model establishes the effects of biomass composition, temperature, and steam on the various gas product molar fractions. On this basis, most significant parameters determining the chemical interconversions and distribution of chemical species are identified. On the basis of the proposed equilibrium model and using glucose as a model biomass species [C6H12O6], an optimum gasification temperature close to 800 °C and a steam/biomass ratio between 0.5 and 0.7 g/g is established. This study has the special value of comparing thermodynamic equilibrium predictions with experimental data obtained in a CREC riser simulator using a fluidizable Ni−Al2O3 catalyst. Results are relevant for scaled-up gasifiers. They show that for reaction times longer than 30 s chemical species are essentially equilibrated and that the proposed model does provide adequate description of various product fractions. Data obtained also demonstrate the shortcomings of equilibrium models for gasifiers with reaction times shorter than 10 s and the need for nonequilibrium models to describe gasifier performance at such conditions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901710n
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6834–6844[article] Biomass catalytic steam gasification thermodynamics analysis and reaction experiments in a CREC riser simulator [texte imprimé] / Enrique Salaices, Auteur ; Benito Serrano, Auteur ; Hugo De Lasa, Auteur . - 2010 . - pp 6834–6844.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6834–6844
Mots-clés : Catalytic Thermodynamics Gasification. Résumé : A thermodynamic equilibrium model based on evaluations involving C, H, and O element balances and various product species up to C6 hydrocarbons is reported in this study. This model establishes the effects of biomass composition, temperature, and steam on the various gas product molar fractions. On this basis, most significant parameters determining the chemical interconversions and distribution of chemical species are identified. On the basis of the proposed equilibrium model and using glucose as a model biomass species [C6H12O6], an optimum gasification temperature close to 800 °C and a steam/biomass ratio between 0.5 and 0.7 g/g is established. This study has the special value of comparing thermodynamic equilibrium predictions with experimental data obtained in a CREC riser simulator using a fluidizable Ni−Al2O3 catalyst. Results are relevant for scaled-up gasifiers. They show that for reaction times longer than 30 s chemical species are essentially equilibrated and that the proposed model does provide adequate description of various product fractions. Data obtained also demonstrate the shortcomings of equilibrium models for gasifiers with reaction times shorter than 10 s and the need for nonequilibrium models to describe gasifier performance at such conditions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901710n Exemplaires
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Titre : Modeling the partial oxidation of o-xylene in an industrial packed-bed catalytic reactor: the role of hydrodynamics and catalyst activity in the heat transport Type de document : texte imprimé Auteurs : C. O. Castillo-Araiza, Auteur ; F. Lopez-Isunza, Auteur Année de publication : 2010 Article en page(s) : pp 6845–6853 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Partial oxidation Catalytic reactor Hydrodynamics Heat transport. Résumé : In this work, the role of hydrodynamics in an industrial-scale packed-bed catalytic reactor with a low tube/particle diameter ratio (dt/dp 3) and the role of redox dynamics of the catalyst surface together with the use of a catalyst activity profile are assessed on the heat transport during the partial oxidation of o-xylene on a V2O5/TiO2 catalyst. Temperature and concentration observations at different steady-state conditions are used to test the modeling approach, and reasonably good predictions are obtained when (1) the information contained in the heat-transport parameters, estimated from a boundary layer approximation to the hydrodynamics in the absence of chemical reactions [Ind. Eng. Chem. Res. 2007, 46 (23), 7426−7435], is used in the reactor model and (2) the redox catalyst dynamics, included in the reaction kinetics, is used, together with an empirical catalyst activity profile. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901720z
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6845–6853[article] Modeling the partial oxidation of o-xylene in an industrial packed-bed catalytic reactor: the role of hydrodynamics and catalyst activity in the heat transport [texte imprimé] / C. O. Castillo-Araiza, Auteur ; F. Lopez-Isunza, Auteur . - 2010 . - pp 6845–6853.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6845–6853
Mots-clés : Partial oxidation Catalytic reactor Hydrodynamics Heat transport. Résumé : In this work, the role of hydrodynamics in an industrial-scale packed-bed catalytic reactor with a low tube/particle diameter ratio (dt/dp 3) and the role of redox dynamics of the catalyst surface together with the use of a catalyst activity profile are assessed on the heat transport during the partial oxidation of o-xylene on a V2O5/TiO2 catalyst. Temperature and concentration observations at different steady-state conditions are used to test the modeling approach, and reasonably good predictions are obtained when (1) the information contained in the heat-transport parameters, estimated from a boundary layer approximation to the hydrodynamics in the absence of chemical reactions [Ind. Eng. Chem. Res. 2007, 46 (23), 7426−7435], is used in the reactor model and (2) the redox catalyst dynamics, included in the reaction kinetics, is used, together with an empirical catalyst activity profile. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901720z Exemplaires
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Titre : Photocatalytic hydrogen production on Cd1−xZnxS solid solutions under visible light: influence of thermal treatment Type de document : texte imprimé Auteurs : J. A. Villoria, Auteur ; Rufino M. Navarro Yerga, Auteur ; S. M. Al-Zahrani, Auteur Année de publication : 2010 Article en page(s) : pp 6854–6861 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrogen production Photocatalytic Thermal treatment. Résumé : Cd1−xZnxS solid solutions have been prepared by employing different thermal treatments (He flow from 773 to 1073 K and static vacuum at 1073 K). The photocatalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), N2 adsorption isotherms, X-ray diffraction (XRD), UV−vis absorption spectra, and X-ray photoelectron spectroscopy (XPS) techniques and tested in the production of hydrogen from aqueous solutions containing S2−/SO32− as sacrificial agents under visible light irradiation. Structure, morphology, composition, and visible light absorption capacity of the Cd1−xZnxS solid solutions were found to be strongly dependent on the postsynthesis thermal treatments. The samples treated under He flow presented Cd loss with the temperature rise that implies formation of defects in the crystalline structure of the solid solutions. The increase in the extent of the structural defects of the Cd1−xZnxS solid solutions with the annealing temperature rise is related with a progressive decrease in their capacity to produce hydrogen. A significant improvement of the photoactivity was obtained for the solid solution derived from the treatment under static vacuum. The improvement in activity is related to the formation of Cd1−xZnxS solid solutions with higher crystallinity and less thermal Cd sublimation that inhibits the formation of structural defects and thus improves the effective utilization of the e−/hole energy carriers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901718r
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6854–6861[article] Photocatalytic hydrogen production on Cd1−xZnxS solid solutions under visible light: influence of thermal treatment [texte imprimé] / J. A. Villoria, Auteur ; Rufino M. Navarro Yerga, Auteur ; S. M. Al-Zahrani, Auteur . - 2010 . - pp 6854–6861.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6854–6861
Mots-clés : Hydrogen production Photocatalytic Thermal treatment. Résumé : Cd1−xZnxS solid solutions have been prepared by employing different thermal treatments (He flow from 773 to 1073 K and static vacuum at 1073 K). The photocatalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), N2 adsorption isotherms, X-ray diffraction (XRD), UV−vis absorption spectra, and X-ray photoelectron spectroscopy (XPS) techniques and tested in the production of hydrogen from aqueous solutions containing S2−/SO32− as sacrificial agents under visible light irradiation. Structure, morphology, composition, and visible light absorption capacity of the Cd1−xZnxS solid solutions were found to be strongly dependent on the postsynthesis thermal treatments. The samples treated under He flow presented Cd loss with the temperature rise that implies formation of defects in the crystalline structure of the solid solutions. The increase in the extent of the structural defects of the Cd1−xZnxS solid solutions with the annealing temperature rise is related with a progressive decrease in their capacity to produce hydrogen. A significant improvement of the photoactivity was obtained for the solid solution derived from the treatment under static vacuum. The improvement in activity is related to the formation of Cd1−xZnxS solid solutions with higher crystallinity and less thermal Cd sublimation that inhibits the formation of structural defects and thus improves the effective utilization of the e−/hole energy carriers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901718r Exemplaires
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Titre : Study on void behavior in a turbulent fluidized bed with catalyst powders Type de document : texte imprimé Auteurs : Xiaoping Zhang, Auteur ; Hsiaotao T. Bi, Auteur Année de publication : 2010 Article en page(s) : pp 6862–6869 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidized bed Turbulent Catalyst powders. Résumé : Turbulent fluidized beds have been recognized as very effective gas−solids contacting devices because of their outstanding performance in gas−solids contact, heat transfer, and mass transfer. To characterize the void behavior, which governs the hydrodynamics and the efficiency of operation of turbulent fluidized beds, an optical fiber probe with a separation distance of 5 mm between the two measuring tips has been used to measure the axial and radial profiles of the bubble/void parameters in a turbulent fluidized bed over a gas velocity range of 0.4−1.0 m/s. Experiments were carried out in a Plexiglas column with an inner diameter of 0.19 m and a height of 5.5 m. Fluid cracking catalyst (FCC) powders with a mean size of 78 μm were used as bed particles, and air was used as the fluidizing gas. Signals from the optical fiber probe were used to obtain the rise velocity and the chord length of voids at various spatial positions and superficial gas velocities. The results show that, in the turbulent fluidization regime, the void size and the void rise velocity have a relatively uniform distribution along the radial direction in the bed. Based on the assumption that bubble splitting is dominant over bubble coalescence at high superficial gas velocities, a modified bubble coalescence−splitting balance model was found to give reasonable agreement with the measured void size profiles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901715z
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6862–6869[article] Study on void behavior in a turbulent fluidized bed with catalyst powders [texte imprimé] / Xiaoping Zhang, Auteur ; Hsiaotao T. Bi, Auteur . - 2010 . - pp 6862–6869.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6862–6869
Mots-clés : Fluidized bed Turbulent Catalyst powders. Résumé : Turbulent fluidized beds have been recognized as very effective gas−solids contacting devices because of their outstanding performance in gas−solids contact, heat transfer, and mass transfer. To characterize the void behavior, which governs the hydrodynamics and the efficiency of operation of turbulent fluidized beds, an optical fiber probe with a separation distance of 5 mm between the two measuring tips has been used to measure the axial and radial profiles of the bubble/void parameters in a turbulent fluidized bed over a gas velocity range of 0.4−1.0 m/s. Experiments were carried out in a Plexiglas column with an inner diameter of 0.19 m and a height of 5.5 m. Fluid cracking catalyst (FCC) powders with a mean size of 78 μm were used as bed particles, and air was used as the fluidizing gas. Signals from the optical fiber probe were used to obtain the rise velocity and the chord length of voids at various spatial positions and superficial gas velocities. The results show that, in the turbulent fluidization regime, the void size and the void rise velocity have a relatively uniform distribution along the radial direction in the bed. Based on the assumption that bubble splitting is dominant over bubble coalescence at high superficial gas velocities, a modified bubble coalescence−splitting balance model was found to give reasonable agreement with the measured void size profiles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901715z Exemplaires
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Titre : Dimethyl ether synthesis with in situ H2O removal in fixed-bed membrane reactor: model and simulations Type de document : texte imprimé Auteurs : I. Iliuta, Auteur ; F. Larachi, Auteur ; P. Fongarland, Auteur Année de publication : 2010 Article en page(s) : pp 6870–6877 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Dimethyl ether Membrane reactor. Résumé : The potential and limits of in situ removal of water under dimethyl ether (DME) synthesis conditions in a fixed-bed membrane reactor were studied numerically. The motivation for in situ H2O removal during DME synthesis by means of hydrophilic membranes is to displace the water−gas shift equilibrium to enhance conversion of CO2 into methanol to improve DME productivity. In CO-rich feeds, methanol yield/selectivity increases/decreases slowly with increasing H2O permeance because only small amounts of water are removed from the system. Methanol dehydration is not inhibited by water, and DME selectivity is not improved significantly with increasing H2O permeance. When CO is gradually replaced with CO2, with the increase of H2O membrane permeance and H2O removal, methanol yield and DME selectivity are favored and the fraction of unconverted methanol is reduced as the dehydration reaction is accelerated due to reduced kinetic inhibition by H2O. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901726u
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6870–6877[article] Dimethyl ether synthesis with in situ H2O removal in fixed-bed membrane reactor: model and simulations [texte imprimé] / I. Iliuta, Auteur ; F. Larachi, Auteur ; P. Fongarland, Auteur . - 2010 . - pp 6870–6877.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6870–6877
Mots-clés : Dimethyl ether Membrane reactor. Résumé : The potential and limits of in situ removal of water under dimethyl ether (DME) synthesis conditions in a fixed-bed membrane reactor were studied numerically. The motivation for in situ H2O removal during DME synthesis by means of hydrophilic membranes is to displace the water−gas shift equilibrium to enhance conversion of CO2 into methanol to improve DME productivity. In CO-rich feeds, methanol yield/selectivity increases/decreases slowly with increasing H2O permeance because only small amounts of water are removed from the system. Methanol dehydration is not inhibited by water, and DME selectivity is not improved significantly with increasing H2O permeance. When CO is gradually replaced with CO2, with the increase of H2O membrane permeance and H2O removal, methanol yield and DME selectivity are favored and the fraction of unconverted methanol is reduced as the dehydration reaction is accelerated due to reduced kinetic inhibition by H2O. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901726u Exemplaires
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Titre : Chemocatalytic oxidation of lactose to lactobionic acid over Pd−Bi/SBA-15: reaction kinetics and modeling Type de document : texte imprimé Auteurs : Khaled Belkacemi, Auteur ; Safia Hamoudi, Auteur Année de publication : 2010 Article en page(s) : pp 6878–6889 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Chemocatalytic oxidation Reaction kinetics. Résumé : Lactobionic acid (LBA) was synthesized from the direct aerobic oxidation of lactose under a very low O2 concentration with high conversion (96%) and 100% selectivity over low loadings (1.02−0.64%) of bimetallic Pd−Bi supported on mesoporous SBA-15 silica material. Under alkaline conditions (pH 9), the catalyst exhibited enhanced activity and stability with unprecedented complete selectivity toward LBA formation. Furthermore, it exhibited pretty good stability toward metal leaching. It was observed that, with a selective deposition of bismuth on palladium, as well as adequate alkaline pH processing, the redox reaction chain performed efficiently and maintained the continuous dehydrogenation of lactose, while avoiding poisoning of the Pd−Bi bimetallic catalyst. Using the Langmuir−Hinshelwood−Hougen−Watson approach, a kinetic model was developed to predict the fates of the lactose and LBA. The rate equation of lactose consumption contains Langmuir adsorption terms, which accounts for the competitive reversible dissociative chemisorption of oxygen and for the reversible associative adsorption of lactose. The kinetic model was verified by comparing the experimental results with those foreseen in the simulation for different experimental conditions. The assessment of the determined Arrhenius parameters led to physically meaningful estimates of activation energy. The Langmuir adsorption isotherms are physically meaningful, where the standard entropy and enthalpy of adsorption were shown to fulfill established guidelines, which assesses the physical sense of their values. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901724j
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6878–6889[article] Chemocatalytic oxidation of lactose to lactobionic acid over Pd−Bi/SBA-15: reaction kinetics and modeling [texte imprimé] / Khaled Belkacemi, Auteur ; Safia Hamoudi, Auteur . - 2010 . - pp 6878–6889.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6878–6889
Mots-clés : Chemocatalytic oxidation Reaction kinetics. Résumé : Lactobionic acid (LBA) was synthesized from the direct aerobic oxidation of lactose under a very low O2 concentration with high conversion (96%) and 100% selectivity over low loadings (1.02−0.64%) of bimetallic Pd−Bi supported on mesoporous SBA-15 silica material. Under alkaline conditions (pH 9), the catalyst exhibited enhanced activity and stability with unprecedented complete selectivity toward LBA formation. Furthermore, it exhibited pretty good stability toward metal leaching. It was observed that, with a selective deposition of bismuth on palladium, as well as adequate alkaline pH processing, the redox reaction chain performed efficiently and maintained the continuous dehydrogenation of lactose, while avoiding poisoning of the Pd−Bi bimetallic catalyst. Using the Langmuir−Hinshelwood−Hougen−Watson approach, a kinetic model was developed to predict the fates of the lactose and LBA. The rate equation of lactose consumption contains Langmuir adsorption terms, which accounts for the competitive reversible dissociative chemisorption of oxygen and for the reversible associative adsorption of lactose. The kinetic model was verified by comparing the experimental results with those foreseen in the simulation for different experimental conditions. The assessment of the determined Arrhenius parameters led to physically meaningful estimates of activation energy. The Langmuir adsorption isotherms are physically meaningful, where the standard entropy and enthalpy of adsorption were shown to fulfill established guidelines, which assesses the physical sense of their values. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901724j Exemplaires
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Titre : Kinetic study of acetaldehyde photocatalytic oxidation with a thin film of TiO2 coated on stainless steel and CFD modeling approach Type de document : texte imprimé Auteurs : Amélie Queffeulou, Auteur ; Laurent Geron, Auteur ; Catherine Archambeau, Auteur Année de publication : 2010 Article en page(s) : pp 6890–6897 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Kinetic Photocatalytic oxidation Stainless steel. Résumé : Removal of low-ppm concentrations of acetaldehyde, a common indoor air pollutant, by photocatalysis is investigated in an annular photoreactor with a thin film of TiO2 coated on a stainless steel plate. Numerical residence time distribution is performed by CFD and characterized with the dispersion model. No byproducts are detected, and complete carbon balance is achieved, allowing the assumption that all of the eventually formed byproducts are converted into carbon dioxide and water. The dependence of the reaction rate on light intensity is studied, showing a first-order tendency in the experimental conditions. Modeling of fluid dynamics and photocatalytic reaction is realized with a CFD approach, considering that intrinsic kinetics is independent of reactor geometry, radiation field, and fluid dynamics. Kinetic parameters determined in a batch reactor are used to calculate the concentration distribution in the annular reactor. In terms of conversion yield, model prediction and experimental results are found in good agreement. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017308
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6890–6897[article] Kinetic study of acetaldehyde photocatalytic oxidation with a thin film of TiO2 coated on stainless steel and CFD modeling approach [texte imprimé] / Amélie Queffeulou, Auteur ; Laurent Geron, Auteur ; Catherine Archambeau, Auteur . - 2010 . - pp 6890–6897.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6890–6897
Mots-clés : Kinetic Photocatalytic oxidation Stainless steel. Résumé : Removal of low-ppm concentrations of acetaldehyde, a common indoor air pollutant, by photocatalysis is investigated in an annular photoreactor with a thin film of TiO2 coated on a stainless steel plate. Numerical residence time distribution is performed by CFD and characterized with the dispersion model. No byproducts are detected, and complete carbon balance is achieved, allowing the assumption that all of the eventually formed byproducts are converted into carbon dioxide and water. The dependence of the reaction rate on light intensity is studied, showing a first-order tendency in the experimental conditions. Modeling of fluid dynamics and photocatalytic reaction is realized with a CFD approach, considering that intrinsic kinetics is independent of reactor geometry, radiation field, and fluid dynamics. Kinetic parameters determined in a batch reactor are used to calculate the concentration distribution in the annular reactor. In terms of conversion yield, model prediction and experimental results are found in good agreement. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017308 Exemplaires
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Titre : Analysis of photocatalytic reactors employing the photonic efficiency and the removal efficiency parameters: degradation of radiation absorbing and nonabsorbing pollutants Type de document : texte imprimé Auteurs : Gerd Sagawe, Auteur ; Maria L. Satuf, Auteur ; Rodolfo J. Brandi, Auteur Année de publication : 2010 Article en page(s) : pp 6898–6908 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photocatalytic reactors Photonic Nonabsorbing pollutants. Résumé : The photocatalytic degradation of radiation absorbing and nonabsorbing pollutants in slurry reactors is analyzed in terms of two performance parameters: the observed photonic efficiency (OPE) and the removal efficiency (RE) [Sagawe et al. Chem. Eng. Sci. 2003, 58, 2587]. The OPE proposal permits a simple approach to analyze complex reacting systems. Conversely, to calculate the RE, the modeling of radiation absorption and scattering inside the reactors is necessary, which requires the determination of the optical properties of the catalyst and the modeling of the optical effects of the reactor walls. The degradation of dichloroacetic acid, phenol, and 4-nitrophenol was studied employing aeroxide TiO2 P25 from Evonik-Degussa in well-mixed batch reactors irradiated by UV lamps. 4-Nitrophenol has the particular characteristic to compete with titania for the absorption of photons in the employed wavelength range of irradiation. Two reaction kinetics proposals were considered to interpret experimental data: a “photocatalytic” Langmuir−Hinshelwood model (the L-HPh model) and a “photocatalytic” Langmuir−Hinshelwood linear model (the L-HPh/1 model). The good agreement observed between experimental results and model simulations confirms the usefulness of the proposed OPE approximation and the more accurate information provided by the RE performance parameter. The inclusion of 4-nitrophenol allowed inference of the situation that would be encountered when treating real samples contaminated with strong radiation absorbing compounds. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901753k
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6898–6908[article] Analysis of photocatalytic reactors employing the photonic efficiency and the removal efficiency parameters: degradation of radiation absorbing and nonabsorbing pollutants [texte imprimé] / Gerd Sagawe, Auteur ; Maria L. Satuf, Auteur ; Rodolfo J. Brandi, Auteur . - 2010 . - pp 6898–6908.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6898–6908
Mots-clés : Photocatalytic reactors Photonic Nonabsorbing pollutants. Résumé : The photocatalytic degradation of radiation absorbing and nonabsorbing pollutants in slurry reactors is analyzed in terms of two performance parameters: the observed photonic efficiency (OPE) and the removal efficiency (RE) [Sagawe et al. Chem. Eng. Sci. 2003, 58, 2587]. The OPE proposal permits a simple approach to analyze complex reacting systems. Conversely, to calculate the RE, the modeling of radiation absorption and scattering inside the reactors is necessary, which requires the determination of the optical properties of the catalyst and the modeling of the optical effects of the reactor walls. The degradation of dichloroacetic acid, phenol, and 4-nitrophenol was studied employing aeroxide TiO2 P25 from Evonik-Degussa in well-mixed batch reactors irradiated by UV lamps. 4-Nitrophenol has the particular characteristic to compete with titania for the absorption of photons in the employed wavelength range of irradiation. Two reaction kinetics proposals were considered to interpret experimental data: a “photocatalytic” Langmuir−Hinshelwood model (the L-HPh model) and a “photocatalytic” Langmuir−Hinshelwood linear model (the L-HPh/1 model). The good agreement observed between experimental results and model simulations confirms the usefulness of the proposed OPE approximation and the more accurate information provided by the RE performance parameter. The inclusion of 4-nitrophenol allowed inference of the situation that would be encountered when treating real samples contaminated with strong radiation absorbing compounds. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901753k Exemplaires
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Titre : Degradation of nonylphenol ethoxylate-9 (NPE-9) by photochemical advanced oxidation technologies Type de document : texte imprimé Auteurs : Luciana De la Fuente, Auteur ; Tatiana Acosta, Auteur ; Paola Babay, Auteur Année de publication : 2010 Article en page(s) : pp 6909–6915 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nonylphenol Ethoxylate Photochemical Oxidation. Résumé : The applicability of different photochemical advanced oxidation technologies (PAOTs), namely, direct UV-C photolysis, UV-C/H2O2 and UV-A/TiO2 heterogeneous photocatalysis (HP), and photo-Fenton reactions (UV-A/H2O2/Fe2+, PF), for the degradation of 300 mg L−1 nonylphenol ethoxylate-9 (NPE-9) in water is described. Different kinetic regimes for each PAOT were found, and as a result, comparative efficiencies could be obtained only from final parameters such as NPE-9 conversion, TOC decrease, and aldehyde production after 3 h of treatment. The initial photonic efficiencies indicate, however, that UV-A processes make better use of photons than UV-C processes. Preliminary optimization of PF systems showed that the most efficient NPE-9/H2O2/Fe2+ molar ratio was 1:1:0.5. Degradation products were partially investigated. Fortunately, toxic 4-nonylphenol was never found as a byproduct of the degradation after any of the treatments. Aldehydes were formed in all of the processes, but they appeared at a low extent in PF reactions. Therefore, PF treatments were considered to be the best degradation processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901785j
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6909–6915[article] Degradation of nonylphenol ethoxylate-9 (NPE-9) by photochemical advanced oxidation technologies [texte imprimé] / Luciana De la Fuente, Auteur ; Tatiana Acosta, Auteur ; Paola Babay, Auteur . - 2010 . - pp 6909–6915.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6909–6915
Mots-clés : Nonylphenol Ethoxylate Photochemical Oxidation. Résumé : The applicability of different photochemical advanced oxidation technologies (PAOTs), namely, direct UV-C photolysis, UV-C/H2O2 and UV-A/TiO2 heterogeneous photocatalysis (HP), and photo-Fenton reactions (UV-A/H2O2/Fe2+, PF), for the degradation of 300 mg L−1 nonylphenol ethoxylate-9 (NPE-9) in water is described. Different kinetic regimes for each PAOT were found, and as a result, comparative efficiencies could be obtained only from final parameters such as NPE-9 conversion, TOC decrease, and aldehyde production after 3 h of treatment. The initial photonic efficiencies indicate, however, that UV-A processes make better use of photons than UV-C processes. Preliminary optimization of PF systems showed that the most efficient NPE-9/H2O2/Fe2+ molar ratio was 1:1:0.5. Degradation products were partially investigated. Fortunately, toxic 4-nonylphenol was never found as a byproduct of the degradation after any of the treatments. Aldehydes were formed in all of the processes, but they appeared at a low extent in PF reactions. Therefore, PF treatments were considered to be the best degradation processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901785j Exemplaires
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Titre : CO2 carrying behavior of calcium aluminate pellets under high-temperature/high-CO2 concentration calcination conditions Type de document : texte imprimé Auteurs : Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur Année de publication : 2010 Article en page(s) : pp 6916–6922 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Calcium aluminate High-CO2. Résumé : Sintering and a resulting loss of activity during calcination/carbonation can introduce substantial economic penalties for a CO2 looping cycle using CaO-based sorbents. In a real system, sorbent regeneration must be done at a high temperature to produce an almost pure CO2 stream, and this will increase both sintering and loss of sorbent activity. The influence of severe calcination conditions on the CO2 carrying behavior of calcium aluminate pellets is investigated here. Up to 30 calcination/carbonation cycles were performed using a thermogravimetric analyzer apparatus. The maximum temperature during the calcination stage in pure CO2 was 950 °C, using different heating/cooling rates between two carbonation stages (700 °C, 20% CO2). For comparison, cycles were also done using N2 during the calcination stages. In addition, the original Cadomin limestone, used for pelletization, was also examined in its original form and the results obtained were compared with those for the aluminate pellets. As expected, high temperature during calcination strongly reduced CO2 carrying capacities of both sorbents. However, aluminate pellets showed better resistance to these severe conditions. The conversion profiles obtained are significantly different to those obtained under milder conditions, with significant increased activity during the slower, diffusion-controlled, carbonation stage. Moreover, scanning electron microscopy analysis of samples after prolonged carbonation showed that pore filling occurred at the sorbent particle surfaces preventing diffusion of CO2 toward the particle interior. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901795e
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6916–6922[article] CO2 carrying behavior of calcium aluminate pellets under high-temperature/high-CO2 concentration calcination conditions [texte imprimé] / Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur . - 2010 . - pp 6916–6922.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6916–6922
Mots-clés : Calcium aluminate High-CO2. Résumé : Sintering and a resulting loss of activity during calcination/carbonation can introduce substantial economic penalties for a CO2 looping cycle using CaO-based sorbents. In a real system, sorbent regeneration must be done at a high temperature to produce an almost pure CO2 stream, and this will increase both sintering and loss of sorbent activity. The influence of severe calcination conditions on the CO2 carrying behavior of calcium aluminate pellets is investigated here. Up to 30 calcination/carbonation cycles were performed using a thermogravimetric analyzer apparatus. The maximum temperature during the calcination stage in pure CO2 was 950 °C, using different heating/cooling rates between two carbonation stages (700 °C, 20% CO2). For comparison, cycles were also done using N2 during the calcination stages. In addition, the original Cadomin limestone, used for pelletization, was also examined in its original form and the results obtained were compared with those for the aluminate pellets. As expected, high temperature during calcination strongly reduced CO2 carrying capacities of both sorbents. However, aluminate pellets showed better resistance to these severe conditions. The conversion profiles obtained are significantly different to those obtained under milder conditions, with significant increased activity during the slower, diffusion-controlled, carbonation stage. Moreover, scanning electron microscopy analysis of samples after prolonged carbonation showed that pore filling occurred at the sorbent particle surfaces preventing diffusion of CO2 toward the particle interior. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901795e Exemplaires
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Titre : Photodegradation of estrone in solar irradiation Type de document : texte imprimé Auteurs : Rajib Roy Chowdhury, Auteur ; Paul Charpentier, Auteur ; Madhumita B. Ray, Auteur Année de publication : 2010 Article en page(s) : pp 6923–6930 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photodegradation Solar Irradiation. Résumé : The photodegradation of the steroid estrone (E1), an endocrine disrupting hormone which is commonly released into aquatic environments, was investigated in aqueous solution using natural sunlight (290−700 nm) produced using a solar simulator. The degradation of E1 was found to follow pseudo-first-order kinetics, with the rate constant decreasing slightly with increasing initial concentration and varying linearly with solar intensity in the region of 25−100 mW cm−2. The half-life of E1 using 1 Sun (100 mW cm−2) was measured to be 52.50 min in natural conditions. The rate of mineralization based on total organic carbon (TOC) reduction was lower than E1 degradation, while the TOC of the solution decreased steadily with increased irradiation time. In the presence of humic acid, the photodegradation rate increased significantly, attributed to photosensitization by the reactive species. The solution pH also had a considerable effect on the rate with maximum degradation occurring around neutral pH of 7. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901796x
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6923–6930[article] Photodegradation of estrone in solar irradiation [texte imprimé] / Rajib Roy Chowdhury, Auteur ; Paul Charpentier, Auteur ; Madhumita B. Ray, Auteur . - 2010 . - pp 6923–6930.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6923–6930
Mots-clés : Photodegradation Solar Irradiation. Résumé : The photodegradation of the steroid estrone (E1), an endocrine disrupting hormone which is commonly released into aquatic environments, was investigated in aqueous solution using natural sunlight (290−700 nm) produced using a solar simulator. The degradation of E1 was found to follow pseudo-first-order kinetics, with the rate constant decreasing slightly with increasing initial concentration and varying linearly with solar intensity in the region of 25−100 mW cm−2. The half-life of E1 using 1 Sun (100 mW cm−2) was measured to be 52.50 min in natural conditions. The rate of mineralization based on total organic carbon (TOC) reduction was lower than E1 degradation, while the TOC of the solution decreased steadily with increased irradiation time. In the presence of humic acid, the photodegradation rate increased significantly, attributed to photosensitization by the reactive species. The solution pH also had a considerable effect on the rate with maximum degradation occurring around neutral pH of 7. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901796x Exemplaires
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Titre : Kinetics and modeling of the flexible fuel reformer: n-hexadecane steam reforming and combustion Type de document : texte imprimé Auteurs : Preshit V. Gawade, Auteur ; Dhaval Patel, Auteur ; G. Glenn Lipscomb, Auteur Année de publication : 2010 Article en page(s) : pp 6931–6940 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Kinetics Flexible fuel. Résumé : Steam reforming of liquid hydrocarbon fuels provides one possible solution for the production of hydrogen for solid oxide fuel cells (SOFCs). However, the design of the reformer is dependent on the kinetics of the catalytic reaction, which is not widely reported. Because reforming is highly endothermic, we have investigated the use of a heat exchange device, designated the flexible fuel reformer (FFR), as a reactor in which combustion and reforming can be simultaneously accomplished. In the present study, we evaluated the reforming and combustion kinetics of n-hexadecane (used as an analog for diesel) over the rhodium/nickel catalyst supported on alumina. Reforming data obtained over the temperature range of 500−750 °C was compared against three different mechanistic models: Eley−Rideal, Langmuir−Hinshelwood bimolecular adsorption, and Langmuir−Hinshelwood dual site. Among all, Eley−Rideal produced good data fitting and fulfilled the thermodynamic criteria in every case. Combustion kinetics of hexadecane was also studied, since our proposed reactor configuration uses the heat from the exothermic combustion reaction as a driver for the endothermic reforming reaction. It was found that power-law model produced the best fit among all the models and this result was further corroborated using statistical analysis. The kinetic results can be combined with the reactor design model to predict the performance and demonstrate the benefit obtained from simultaneous reforming and combustion. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901819x
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6931–6940[article] Kinetics and modeling of the flexible fuel reformer: n-hexadecane steam reforming and combustion [texte imprimé] / Preshit V. Gawade, Auteur ; Dhaval Patel, Auteur ; G. Glenn Lipscomb, Auteur . - 2010 . - pp 6931–6940.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6931–6940
Mots-clés : Kinetics Flexible fuel. Résumé : Steam reforming of liquid hydrocarbon fuels provides one possible solution for the production of hydrogen for solid oxide fuel cells (SOFCs). However, the design of the reformer is dependent on the kinetics of the catalytic reaction, which is not widely reported. Because reforming is highly endothermic, we have investigated the use of a heat exchange device, designated the flexible fuel reformer (FFR), as a reactor in which combustion and reforming can be simultaneously accomplished. In the present study, we evaluated the reforming and combustion kinetics of n-hexadecane (used as an analog for diesel) over the rhodium/nickel catalyst supported on alumina. Reforming data obtained over the temperature range of 500−750 °C was compared against three different mechanistic models: Eley−Rideal, Langmuir−Hinshelwood bimolecular adsorption, and Langmuir−Hinshelwood dual site. Among all, Eley−Rideal produced good data fitting and fulfilled the thermodynamic criteria in every case. Combustion kinetics of hexadecane was also studied, since our proposed reactor configuration uses the heat from the exothermic combustion reaction as a driver for the endothermic reforming reaction. It was found that power-law model produced the best fit among all the models and this result was further corroborated using statistical analysis. The kinetic results can be combined with the reactor design model to predict the performance and demonstrate the benefit obtained from simultaneous reforming and combustion. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901819x Exemplaires
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Titre : Combustion of volatile organic compounds at trace concentration levels in zeolite-coated microreactors Type de document : texte imprimé Auteurs : Nuria Navascués, Auteur ; Miguel Escuin, Auteur ; Yolanda Rodas, Auteur Année de publication : 2010 Article en page(s) : pp 6941–6947 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Combustion Microréacteurs Zeolite coated. Résumé : A study is presented of the preparation of zeolite films (Pt/ZSM5 and Pt/Zeolite Y) on microreactor channels with a diameter of 500 μm. The catalysts were prepared and fully characterized as powders and then incorporated into the microreactors by a seeded hydrothermal synthesis procedure. The performance of the zeolite-coated microreactors were tested in the combustion of n-hexane, alone, and in mixtures with acetone at concentrations of 100 and 200 ppmV. The microreactors outperformed the fixed-bed reactor, giving light-off temperatures in the 150−190 °C range. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901843t
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6941–6947[article] Combustion of volatile organic compounds at trace concentration levels in zeolite-coated microreactors [texte imprimé] / Nuria Navascués, Auteur ; Miguel Escuin, Auteur ; Yolanda Rodas, Auteur . - 2010 . - pp 6941–6947.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6941–6947
Mots-clés : Combustion Microréacteurs Zeolite coated. Résumé : A study is presented of the preparation of zeolite films (Pt/ZSM5 and Pt/Zeolite Y) on microreactor channels with a diameter of 500 μm. The catalysts were prepared and fully characterized as powders and then incorporated into the microreactors by a seeded hydrothermal synthesis procedure. The performance of the zeolite-coated microreactors were tested in the combustion of n-hexane, alone, and in mixtures with acetone at concentrations of 100 and 200 ppmV. The microreactors outperformed the fixed-bed reactor, giving light-off temperatures in the 150−190 °C range. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901843t Exemplaires
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Titre : Fischer−tropsch synthesis in a slurry reactor using a nanoiron carbide catalyst produced by a plasma spray technique Type de document : texte imprimé Auteurs : Jasmin Blanchard, Auteur ; Nicolas Abatzoglou, Auteur ; Roham Eslahpazir-Esfandabadi, Auteur Année de publication : 2010 Article en page(s) : pp 6948–6955 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst Nanoiron Slurry reactor. Résumé : A new catalyst, composed of iron carbide nanoparticles (FeCNPs) and synthesized by plasma-spraying technology, was tested for Fischer−Tropsch synthesis (FTS) in a continuously stirred slurry reactor. The plasma-produced FeCNPs were core−matrix structures (FeC-rich core inside a graphitic carbon matrix) which protected air-sensitive carbides, preventing oxidation during their handling. The reactant used for FTS testing was simulated syngas with a composition similar to that obtained from air gasification of urban waste. This work reports the optimization of a new nanocatalyst reduction/activation protocol aimed at maximizing catalyst activity and a 100-h-long test performed to examine the catalyst’s behavior over time. The catalyst was compared with Nanocat commercial nanoiron powder, and the results showed that its activity and robustness were higher. Conversion with the Nanocat catalyst was slightly but not statistically significantly lower than with the plasma-produced catalyst. However, 6% CH4 selectivity with the plasma-produced catalyst was significantly lower than the 10% obtained with Nanocat. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901861y
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6948–6955[article] Fischer−tropsch synthesis in a slurry reactor using a nanoiron carbide catalyst produced by a plasma spray technique [texte imprimé] / Jasmin Blanchard, Auteur ; Nicolas Abatzoglou, Auteur ; Roham Eslahpazir-Esfandabadi, Auteur . - 2010 . - pp 6948–6955.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6948–6955
Mots-clés : Catalyst Nanoiron Slurry reactor. Résumé : A new catalyst, composed of iron carbide nanoparticles (FeCNPs) and synthesized by plasma-spraying technology, was tested for Fischer−Tropsch synthesis (FTS) in a continuously stirred slurry reactor. The plasma-produced FeCNPs were core−matrix structures (FeC-rich core inside a graphitic carbon matrix) which protected air-sensitive carbides, preventing oxidation during their handling. The reactant used for FTS testing was simulated syngas with a composition similar to that obtained from air gasification of urban waste. This work reports the optimization of a new nanocatalyst reduction/activation protocol aimed at maximizing catalyst activity and a 100-h-long test performed to examine the catalyst’s behavior over time. The catalyst was compared with Nanocat commercial nanoiron powder, and the results showed that its activity and robustness were higher. Conversion with the Nanocat catalyst was slightly but not statistically significantly lower than with the plasma-produced catalyst. However, 6% CH4 selectivity with the plasma-produced catalyst was significantly lower than the 10% obtained with Nanocat. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901861y Exemplaires
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Titre : Alkali-promoted trimetallic Co−Rh−Mo sulfide catalysts for higher alcohols synthesis from synthesis gas: comparison of MWCNT and activated carbon supports Type de document : texte imprimé Auteurs : Venkateswara Rao Surisetty, Auteur ; Ajay Kumar Dalai, Auteur ; Janusz Kozinski, Auteur Année de publication : 2010 Article en page(s) : pp 6956–6963 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalysts Trimetallic Gas. Résumé : Multiwalled carbon nanotubes (MWCNTs) and activated carbon were used as supports for the Co (4.5 and 6 wt %) promoted K (9 wt %) modified Rh−Mo catalysts (1.5 wt % Rh and 15 wt % Mo). The catalysts were extensively characterized in both oxide and sulfide phases. A drastic fall in surface area over the activated carbon-supported catalysts was observed after impregnating with metal species. Diffraction peaks were observed in the X-ray diffraction (XRD) patterns of the sulfided alkali-modified trimetallic catalysts, due to the characteristic reflections of the K−Mo−S mixed phase. H2-temperature programmed reduction (TPR) profiles showed that the reduction behavior of metal species was improved with the addition of Co. The activated carbon-supported trimetallic catalysts showed less activity and selectivity compared to the MWCNT-supported catalyst, and metal dispersions were higher on the MWCNT-supported catalysts. The MWCNT-supported, alkali-promoted trimetallic catalyst with 4.5 wt % Co showed the highest total alcohols yield of 0.244 g/(g cat h), ethanol selectivity of 20.1%, and higher alcohols selectivity of 31.4% at 320 °C and 8.28 MPa using a gas hourly space velocity (GHSV) of 3.6 m3 (STP)/(kg catalyst h). A maximum total alcohol yield of 0.261 g/(g cat h) and a selectivity of 42.9% were obtained on the 4.5 wt % Co−Rh−Mo−K/MWCNT catalyst, at a temperature of 330 °C. The total alcohol yield increased from 0.163 to 0.256 g/(g cat h) with increased pressure from 5.52 MPa (800 psig) to 9.65 MPa (1400 psig) over the 4.5 wt % Co−Rh−Mo−K/MWCNT catalyst. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100427j
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6956–6963[article] Alkali-promoted trimetallic Co−Rh−Mo sulfide catalysts for higher alcohols synthesis from synthesis gas: comparison of MWCNT and activated carbon supports [texte imprimé] / Venkateswara Rao Surisetty, Auteur ; Ajay Kumar Dalai, Auteur ; Janusz Kozinski, Auteur . - 2010 . - pp 6956–6963.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6956–6963
Mots-clés : Catalysts Trimetallic Gas. Résumé : Multiwalled carbon nanotubes (MWCNTs) and activated carbon were used as supports for the Co (4.5 and 6 wt %) promoted K (9 wt %) modified Rh−Mo catalysts (1.5 wt % Rh and 15 wt % Mo). The catalysts were extensively characterized in both oxide and sulfide phases. A drastic fall in surface area over the activated carbon-supported catalysts was observed after impregnating with metal species. Diffraction peaks were observed in the X-ray diffraction (XRD) patterns of the sulfided alkali-modified trimetallic catalysts, due to the characteristic reflections of the K−Mo−S mixed phase. H2-temperature programmed reduction (TPR) profiles showed that the reduction behavior of metal species was improved with the addition of Co. The activated carbon-supported trimetallic catalysts showed less activity and selectivity compared to the MWCNT-supported catalyst, and metal dispersions were higher on the MWCNT-supported catalysts. The MWCNT-supported, alkali-promoted trimetallic catalyst with 4.5 wt % Co showed the highest total alcohols yield of 0.244 g/(g cat h), ethanol selectivity of 20.1%, and higher alcohols selectivity of 31.4% at 320 °C and 8.28 MPa using a gas hourly space velocity (GHSV) of 3.6 m3 (STP)/(kg catalyst h). A maximum total alcohol yield of 0.261 g/(g cat h) and a selectivity of 42.9% were obtained on the 4.5 wt % Co−Rh−Mo−K/MWCNT catalyst, at a temperature of 330 °C. The total alcohol yield increased from 0.163 to 0.256 g/(g cat h) with increased pressure from 5.52 MPa (800 psig) to 9.65 MPa (1400 psig) over the 4.5 wt % Co−Rh−Mo−K/MWCNT catalyst. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100427j Exemplaires
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Titre : Synthesis of photoactive magnetic nanoparticles with atomic layer deposition Type de document : texte imprimé Auteurs : Yun Zhou, Auteur ; David M. King, Auteur ; Jianhua Li, Auteur Année de publication : 2010 Article en page(s) : pp 6964–6971 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photoactive Magnetic Nanoparticles. Résumé : Iron-based magnetic nanoparticles have been produced by decomposition of iron oxalate powder. The micrometer-size iron oxalate powder was first ground by use of a cryogenic milling process. A titanium dioxide (TiO2) thin film was then deposited on the synthesized iron nanoparticles with an in situ atomic layer deposition (ALD) process at 100 °C with TiCl4 and H2O2 as precursors. However, because of the high surface area, the iron nanoparticles were unstable and spontaneously oxidized when exposed to H2O2 during the TiO2 ALD process, thus reducing the magnetic moment of the core particles. As an improvement in the process, prior to the TiO2 deposition, an aluminum nitride (AlN) film was deposited in situ to coat and passivate the iron core particles. The AlN ALD was performed at 250 °C with trimethylaluminium (TMA) and ammonia (NH3) as precursors. This passivation provided a significant decrease in the iron oxidation as determined by X-ray diffraction and magnetization measurements. Photoactivity of the TiO2 film was demonstrated by decomposition of methylene blue solution under ultraviolet irradiation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901712q
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6964–6971[article] Synthesis of photoactive magnetic nanoparticles with atomic layer deposition [texte imprimé] / Yun Zhou, Auteur ; David M. King, Auteur ; Jianhua Li, Auteur . - 2010 . - pp 6964–6971.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6964–6971
Mots-clés : Photoactive Magnetic Nanoparticles. Résumé : Iron-based magnetic nanoparticles have been produced by decomposition of iron oxalate powder. The micrometer-size iron oxalate powder was first ground by use of a cryogenic milling process. A titanium dioxide (TiO2) thin film was then deposited on the synthesized iron nanoparticles with an in situ atomic layer deposition (ALD) process at 100 °C with TiCl4 and H2O2 as precursors. However, because of the high surface area, the iron nanoparticles were unstable and spontaneously oxidized when exposed to H2O2 during the TiO2 ALD process, thus reducing the magnetic moment of the core particles. As an improvement in the process, prior to the TiO2 deposition, an aluminum nitride (AlN) film was deposited in situ to coat and passivate the iron core particles. The AlN ALD was performed at 250 °C with trimethylaluminium (TMA) and ammonia (NH3) as precursors. This passivation provided a significant decrease in the iron oxidation as determined by X-ray diffraction and magnetization measurements. Photoactivity of the TiO2 film was demonstrated by decomposition of methylene blue solution under ultraviolet irradiation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901712q Exemplaires
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Titre : Characterization and control strategies of an integrated chemical−biological system for the temediation of toxic pollutants in wastewater: a case of study Type de document : texte imprimé Auteurs : Jordi Bacardit, Auteur ; Carmen Sans, Auteur ; Ramon Seminago, Auteur Année de publication : 2010 Article en page(s) : pp 6972–6976 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Chemical biological Toxic pollutants. Résumé : In a previous work, a hybrid system consisting of an advanced oxidation process (AOP) named Photo-Fenton (Ph-F) and a fixed bed biological treatment operating as a sequencing batch biofilm reactor (SBBR) was started-up and optimized to treat 200 mg·L−1 of 4-chlorophenol (4-CP) as a model compound. In this work, studies of reactor stability and control as well as microbial population determination by molecular biology techniques were carried out to further characterize and control the biological reactor. Results revealed that the integrated system was flexible and even able to overcome toxic shock loads. Oxygen uptake rate (OUR) in situ was shown to be a valid tool to control the SBBR operation, to detect toxic conditions to the biomass, and to assess the recovery of performance. A microbial characterization by 16S rDNA sequence analysis reveals that the biological population was varied, although about 30% of the bacteria belonged to the Wautersia genus. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901642u
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6972–6976[article] Characterization and control strategies of an integrated chemical−biological system for the temediation of toxic pollutants in wastewater: a case of study [texte imprimé] / Jordi Bacardit, Auteur ; Carmen Sans, Auteur ; Ramon Seminago, Auteur . - 2010 . - pp 6972–6976.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6972–6976
Mots-clés : Chemical biological Toxic pollutants. Résumé : In a previous work, a hybrid system consisting of an advanced oxidation process (AOP) named Photo-Fenton (Ph-F) and a fixed bed biological treatment operating as a sequencing batch biofilm reactor (SBBR) was started-up and optimized to treat 200 mg·L−1 of 4-chlorophenol (4-CP) as a model compound. In this work, studies of reactor stability and control as well as microbial population determination by molecular biology techniques were carried out to further characterize and control the biological reactor. Results revealed that the integrated system was flexible and even able to overcome toxic shock loads. Oxygen uptake rate (OUR) in situ was shown to be a valid tool to control the SBBR operation, to detect toxic conditions to the biomass, and to assess the recovery of performance. A microbial characterization by 16S rDNA sequence analysis reveals that the biological population was varied, although about 30% of the bacteria belonged to the Wautersia genus. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901642u Exemplaires
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Titre : Optimizing silica synthesis for the preparation of mesoporous Ti-SBA-15 epoxidation catalysts Type de document : texte imprimé Auteurs : François Bérubé, Auteur ; Abdelkarim Khadhraoui, Auteur ; Michael T. Janicke, Auteur Année de publication : 2010 Article en page(s) : pp 6977–6985 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalysts Mesoporous Epoxidation. Résumé : The influence of the synthesis conditions of SBA-15 silica support in the development of Ti-SBA-15 epoxidation catalysts has been studied in detail. In this study, efficient and stable Ti-SBA-15 epoxidation catalysts were prepared using a recently developed postgrafting method based on the insertion of a chelated titanium alkoxide precursor inside the SBA-15 silica mesophase. First, the nature of the SBA-15 supports was analyzed as a function of different synthesis parameters, such as hydrothermal aging temperature and calcination temperature, by solid-state NMR spectroscopy, thermal analysis, and nitrogen physisorption at −196 °C. Subsequently, titanium-substituted SBA-15 materials were characterized by DR UV−vis spectroscopy, elemental analysis, and nitrogen physisorption. As a catalytic test reaction, the activity, selectivity, and catalyst regenerability were studied in the epoxidation of cyclohexene. Our findings show that the density of silanol groups on the support greatly influences the retention and coordination number of the grafted titanium species. This characteristic of the mesoporous silica supports also has an influence on the catalytic activity of the resulting titanosilicate materials. The conversion of cyclohexene obtained with Ti-SBA-15 catalysts synthesized using noncalcined mesoporous silica was found to increase with the hydrothermal aging temperature of the support. Furthermore, the results showed that higher conversions of cyclohexene were obtained with catalysts prepared using SBA-15 calcined at 550 °C prior to the Ti grafting step, although lower dispersion of the titanium species was usually observed for these materials. A higher accessibility of the substrates to the active sites on the surface of these materials can explain these results. However, a dramatic deactivation of the catalysts was observed upon recycling of these active materials. In contrast, the grafted catalysts prepared using uncalcined mesoporous silica supports showed a substantially lower catalytic deactivation upon different reaction cycles as compared to those grafted after calcination. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901659k
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6977–6985[article] Optimizing silica synthesis for the preparation of mesoporous Ti-SBA-15 epoxidation catalysts [texte imprimé] / François Bérubé, Auteur ; Abdelkarim Khadhraoui, Auteur ; Michael T. Janicke, Auteur . - 2010 . - pp 6977–6985.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6977–6985
Mots-clés : Catalysts Mesoporous Epoxidation. Résumé : The influence of the synthesis conditions of SBA-15 silica support in the development of Ti-SBA-15 epoxidation catalysts has been studied in detail. In this study, efficient and stable Ti-SBA-15 epoxidation catalysts were prepared using a recently developed postgrafting method based on the insertion of a chelated titanium alkoxide precursor inside the SBA-15 silica mesophase. First, the nature of the SBA-15 supports was analyzed as a function of different synthesis parameters, such as hydrothermal aging temperature and calcination temperature, by solid-state NMR spectroscopy, thermal analysis, and nitrogen physisorption at −196 °C. Subsequently, titanium-substituted SBA-15 materials were characterized by DR UV−vis spectroscopy, elemental analysis, and nitrogen physisorption. As a catalytic test reaction, the activity, selectivity, and catalyst regenerability were studied in the epoxidation of cyclohexene. Our findings show that the density of silanol groups on the support greatly influences the retention and coordination number of the grafted titanium species. This characteristic of the mesoporous silica supports also has an influence on the catalytic activity of the resulting titanosilicate materials. The conversion of cyclohexene obtained with Ti-SBA-15 catalysts synthesized using noncalcined mesoporous silica was found to increase with the hydrothermal aging temperature of the support. Furthermore, the results showed that higher conversions of cyclohexene were obtained with catalysts prepared using SBA-15 calcined at 550 °C prior to the Ti grafting step, although lower dispersion of the titanium species was usually observed for these materials. A higher accessibility of the substrates to the active sites on the surface of these materials can explain these results. However, a dramatic deactivation of the catalysts was observed upon recycling of these active materials. In contrast, the grafted catalysts prepared using uncalcined mesoporous silica supports showed a substantially lower catalytic deactivation upon different reaction cycles as compared to those grafted after calcination. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901659k Exemplaires
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Titre : Solids transport modeling in a fluidized drum granulator Type de document : texte imprimé Auteurs : Rodrigo Rojas, Auteur ; Juliana Pina, Auteur ; Verónica Bucalá, Auteur Année de publication : 2010 Article en page(s) : pp 6986–6997 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Solids transport Granulator. Résumé :
The fluidized-bed granulator (FDG) involves the use of a fluidized bed in a drum granulator, which is a horizontal cylinder fitted with internal flights. Despite its demonstrated success on an industrial scale, there are few published fundamental studies of this granulation process. In this work, a mathematical model to represent the solids flow pattern within the different active and passive zones of the rotating FDGs is developed. The fluidization table geometry as well as the angular velocity, drum inclination angle, and flights number strongly affect the mass holdups. Relatively high rotational speeds, inclination angles, and number of flights allow increasing the active mass holdups, reducing the passive mass, and eliminating the kilning flow.
The model presented in this work, which accounts for the solids mass flows and holdups in the different zones of a FDG, provides a firm foundation for integration with energy and population balances.DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901691v
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6986–6997[article] Solids transport modeling in a fluidized drum granulator [texte imprimé] / Rodrigo Rojas, Auteur ; Juliana Pina, Auteur ; Verónica Bucalá, Auteur . - 2010 . - pp 6986–6997.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6986–6997
Mots-clés : Solids transport Granulator. Résumé :
The fluidized-bed granulator (FDG) involves the use of a fluidized bed in a drum granulator, which is a horizontal cylinder fitted with internal flights. Despite its demonstrated success on an industrial scale, there are few published fundamental studies of this granulation process. In this work, a mathematical model to represent the solids flow pattern within the different active and passive zones of the rotating FDGs is developed. The fluidization table geometry as well as the angular velocity, drum inclination angle, and flights number strongly affect the mass holdups. Relatively high rotational speeds, inclination angles, and number of flights allow increasing the active mass holdups, reducing the passive mass, and eliminating the kilning flow.
The model presented in this work, which accounts for the solids mass flows and holdups in the different zones of a FDG, provides a firm foundation for integration with energy and population balances.DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901691v Exemplaires
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Titre : Effects of particle shape, density, and size on a distribution of phase holdups in a gas−liquid−solid circulating fluidized bed riser Type de document : texte imprimé Auteurs : S. A. Razzak, Auteur ; J.-X. Zhu, Auteur ; S. Barghi, Auteur Année de publication : 2010 Article en page(s) : pp 6998–7007 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidized bed Gas liquid solid. Résumé : Electrical resistance tomography and optical fiber probe were employed to study the effects of particle shape, size, and density on the distribution of phase holdups in the riser section (5.97 m tall) of a gas−liquid−solid circulating fluidized bed (GLSCFB) at four axial locations. Saline water was used as conductive liquid phase while air was the gas phase. Two different sizes of spherical shape glass beads and two different sizes of irregular shape lava rock particles were used as the solid nonconductive phase. Because of the tendency of gas bubbles to move in the central region of the riser, gas holdup was higher in this region and decreased gradually toward the wall region for all four types of particles. Consequently, liquid and solid holdups were lower in the central region compared to the wall region. Under the same auxiliary fluidization rate, larger particles had low solids circulation rate (low particle velocity) compared to smaller size particles due to less fluidization in the distribution region. Gas and solids holdups for the smaller particles were found higher compared to larger particles. Shape (sphericity) appeared to have minimum influence on the phase holdups. The decreasing hydrostatic pressure on rising gas bubbles resulted in gas bubble expansion leading to higher concentration of solid particles in wall regions at higher axial locations. The particle size and shape appeared to have a direct impact on gas bubble breakage and coalescence, and in turn also on phase holdup distributions at different heights along the riser. Solids holdup decreased with increasing liquid velocity at all axial locations for all types of particles. The nonuniformity of solids holdup in the central region decreased as the flow structure was developing along the riser. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901704d
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6998–7007[article] Effects of particle shape, density, and size on a distribution of phase holdups in a gas−liquid−solid circulating fluidized bed riser [texte imprimé] / S. A. Razzak, Auteur ; J.-X. Zhu, Auteur ; S. Barghi, Auteur . - 2010 . - pp 6998–7007.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6998–7007
Mots-clés : Fluidized bed Gas liquid solid. Résumé : Electrical resistance tomography and optical fiber probe were employed to study the effects of particle shape, size, and density on the distribution of phase holdups in the riser section (5.97 m tall) of a gas−liquid−solid circulating fluidized bed (GLSCFB) at four axial locations. Saline water was used as conductive liquid phase while air was the gas phase. Two different sizes of spherical shape glass beads and two different sizes of irregular shape lava rock particles were used as the solid nonconductive phase. Because of the tendency of gas bubbles to move in the central region of the riser, gas holdup was higher in this region and decreased gradually toward the wall region for all four types of particles. Consequently, liquid and solid holdups were lower in the central region compared to the wall region. Under the same auxiliary fluidization rate, larger particles had low solids circulation rate (low particle velocity) compared to smaller size particles due to less fluidization in the distribution region. Gas and solids holdups for the smaller particles were found higher compared to larger particles. Shape (sphericity) appeared to have minimum influence on the phase holdups. The decreasing hydrostatic pressure on rising gas bubbles resulted in gas bubble expansion leading to higher concentration of solid particles in wall regions at higher axial locations. The particle size and shape appeared to have a direct impact on gas bubble breakage and coalescence, and in turn also on phase holdup distributions at different heights along the riser. Solids holdup decreased with increasing liquid velocity at all axial locations for all types of particles. The nonuniformity of solids holdup in the central region decreased as the flow structure was developing along the riser. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901704d Exemplaires
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Titre : Thermodynamic model of liquid−liquid phase equilibrium in solutions of alkanethiol-coated nanoparticles Type de document : texte imprimé Auteurs : Ezequiel R. Soulé, Auteur ; Cristina E. Hoppe, Auteur ; Julio Borrajo, Auteur Année de publication : 2010 Article en page(s) : pp 7008–7016 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Thermodynamic Liquid Phase Equilibrium. Résumé : A thermodynamic model for a mixture of alkanethiol-coated nanoparticles (NPs) and low-molecular-weight (nonpolymeric) solvent is developed, and calculations of liquid−liquid phase equilibria for different values of NP core radius, alkanethiol chain length, solvent molar volume, and alkanethiol−solvent interaction parameter, are presented. The model takes into account the swelling of the organic coronas and the dispersion of particles with swollen coronas in the solvent. The energetic interaction between alkyl chains and solvent is considered, both within the corona and between the outer alkyl segments and free solvent. Swelling involves mixing of alkanethiol chains and solvent in the corona and stretching of the organic chains. Dispersion considers an entropic contribution based on the Carnahan−Starling equation of state and an enthalpic term calculated considering the surface contacts between alkyl segments placed in the external boundary of the corona and the molecules of free solvent. Two different kinds of phase equilibrium are found. One of them, observed at high values of the interaction parameter, is the typical liquid−liquid equilibrium for compact NPs in a poor solvent where a complete phase separation is observed when cooling (increasing the interaction parameter). The second liquid−liquid equilibrium is observed at low values of the interaction parameter, where swelling of coronas is favored. In this region two different phases coexist: one more concentrated in NPs that exhibit relatively compact coronas and the other one more diluted in NPs with extended coronas. In diluted solutions of NPs the deswelling of the fully extended coronas takes place abruptly in a very small temperature range, leading to a solution of compact NPs. This critical transition might find practical applications similar to those found for the abrupt shrinkage of hydrogels at a critical temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901784r
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7008–7016[article] Thermodynamic model of liquid−liquid phase equilibrium in solutions of alkanethiol-coated nanoparticles [texte imprimé] / Ezequiel R. Soulé, Auteur ; Cristina E. Hoppe, Auteur ; Julio Borrajo, Auteur . - 2010 . - pp 7008–7016.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7008–7016
Mots-clés : Thermodynamic Liquid Phase Equilibrium. Résumé : A thermodynamic model for a mixture of alkanethiol-coated nanoparticles (NPs) and low-molecular-weight (nonpolymeric) solvent is developed, and calculations of liquid−liquid phase equilibria for different values of NP core radius, alkanethiol chain length, solvent molar volume, and alkanethiol−solvent interaction parameter, are presented. The model takes into account the swelling of the organic coronas and the dispersion of particles with swollen coronas in the solvent. The energetic interaction between alkyl chains and solvent is considered, both within the corona and between the outer alkyl segments and free solvent. Swelling involves mixing of alkanethiol chains and solvent in the corona and stretching of the organic chains. Dispersion considers an entropic contribution based on the Carnahan−Starling equation of state and an enthalpic term calculated considering the surface contacts between alkyl segments placed in the external boundary of the corona and the molecules of free solvent. Two different kinds of phase equilibrium are found. One of them, observed at high values of the interaction parameter, is the typical liquid−liquid equilibrium for compact NPs in a poor solvent where a complete phase separation is observed when cooling (increasing the interaction parameter). The second liquid−liquid equilibrium is observed at low values of the interaction parameter, where swelling of coronas is favored. In this region two different phases coexist: one more concentrated in NPs that exhibit relatively compact coronas and the other one more diluted in NPs with extended coronas. In diluted solutions of NPs the deswelling of the fully extended coronas takes place abruptly in a very small temperature range, leading to a solution of compact NPs. This critical transition might find practical applications similar to those found for the abrupt shrinkage of hydrogels at a critical temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901784r Exemplaires
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Titre : The breadth and intensity of supercritical particle formation research with an emphasis on publication and patent disclosures Type de document : texte imprimé Auteurs : Ozlem Yesil-Celiktas, Auteur ; Deniz Senyay, Auteur Année de publication : 2010 Article en page(s) : pp 7017–7026 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Supercritical particle Patent disclosures. Résumé : The drawbacks of the conventional mechanical treatments for particle micronization often resulting in product damage or performance degradation have highlighted the need for alternative particle formation processes. The aim of this study was to shed light on the trends of the scientific studies and innovations in the field of particle formation using supercritical fluids (SCF) in order to observe the progress of science and technology and to satisfy the need for a global view of research activities. The publications in the ISI Web and the patents in a patent database were screened using nine different keywords in title or topics. A total of 939 journal publication and 206 patent disclosures between 1980−2009, with the contributions of 3588 authors and 604 innovators, were found to focus on particle formation using SCF. The results showed that the majority of the publication (59.2%) and patent (40.3%) disclosures were related to antisolvent precipitation and rapid expansion of SCF (18.3, 16%). Patents originating from United States (56.8%) were dominating, followed by those from the European Union (30.1%) and Japan (9.2%). The analysis revealed the appetite of the companies for commercialization (73.8%), which can be interpreted as an indicator of upcoming industrial applications. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100115x
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7017–7026[article] The breadth and intensity of supercritical particle formation research with an emphasis on publication and patent disclosures [texte imprimé] / Ozlem Yesil-Celiktas, Auteur ; Deniz Senyay, Auteur . - 2010 . - pp 7017–7026.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7017–7026
Mots-clés : Supercritical particle Patent disclosures. Résumé : The drawbacks of the conventional mechanical treatments for particle micronization often resulting in product damage or performance degradation have highlighted the need for alternative particle formation processes. The aim of this study was to shed light on the trends of the scientific studies and innovations in the field of particle formation using supercritical fluids (SCF) in order to observe the progress of science and technology and to satisfy the need for a global view of research activities. The publications in the ISI Web and the patents in a patent database were screened using nine different keywords in title or topics. A total of 939 journal publication and 206 patent disclosures between 1980−2009, with the contributions of 3588 authors and 604 innovators, were found to focus on particle formation using SCF. The results showed that the majority of the publication (59.2%) and patent (40.3%) disclosures were related to antisolvent precipitation and rapid expansion of SCF (18.3, 16%). Patents originating from United States (56.8%) were dominating, followed by those from the European Union (30.1%) and Japan (9.2%). The analysis revealed the appetite of the companies for commercialization (73.8%), which can be interpreted as an indicator of upcoming industrial applications. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100115x Exemplaires
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Titre : Efficient methanolytic cleavage of phosphate, phosphonate, and phosphonothioate esters promoted by solid supported lanthanide ions Type de document : texte imprimé Auteurs : Tamer Andrea, Auteur ; Alexei A. Neverov, Auteur ; R. Stan Brown, Auteur Année de publication : 2010 Article en page(s) : pp 7027–7033 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Methanolytic Phosphate Ions. Résumé : The methanolyses of three neutral organophosphorus esters, namely paraoxon (O,O-diethyl O-p-nitrophenyl phosphate (12), O-ethyl O-p-nitrophenyl methylphosphonate (13), O-ethyl S-3,5-dichlorophenyl methylphosphonothioate (14, a model for VX), and an anionic phosphonate ester, O-hydrogen S-3,5-dichlorophenyl methylphosphonothioate (15, a model for a toxic hydrolytic decomposition product of VX known as EA2192)), promoted by solid supported lanthanide ion catalysts (La3+, Sm3+, Eu3+, Yb3+) were investigated at 25 °C under sspH controlled conditions in methanol. The supports were derived from commercially available chlorobenzylated silica and chloromethylated polystyrene functionalized with two chelating ligands, iminodiacetic acid (IDA) and ethylenediamine-N,N′-diacetic acid (EDDA), followed by exposure to Ln3+ ions. The catalysts showed good activity at two investigated sspH values of 8.8 and 11 (in methanol). Despite the fact that the methoxide promoted reactions for the four substrates span a range of 20000-fold, the apparent second order rate constants (k2app) for methanolysis of these promoted by the solid supported lanthanide catalysts were rather insensitive to the nature of the support (Si or polystyrene), Ln3+ ion, substrate, and sspH. The Yb3+ complex of IDA on silica (Si/IDA/Yb) gave the highest k2app values of 6.6 and 14.4 M−1 s−1 for 12 and 13, 48.8 M−1 s−1 for 14, and 2.6 M−1 s−1 for 15 at sspH 11. The acceleration of cleavage of 13 at sspH 8.8 by the Si/IDA/Yb catalyst at an apparent concentration of 4.8 mM (50 mg suspended in 2.5 mL of methanol) is about 8.5 × 105 faster than the methoxide reaction at that sspH. The acceleration of the cleavage of 14 and 15 by 50 mg of Si/IDA/Yb at sspH 11 is 6.3 × 105- and 5 × 108-fold relative to the methoxide promoted reaction at that sspH. The matrixes containing the smaller lanthanide ions like Eu and Yb could be recycled at least eight times without loss of activity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008458
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7027–7033[article] Efficient methanolytic cleavage of phosphate, phosphonate, and phosphonothioate esters promoted by solid supported lanthanide ions [texte imprimé] / Tamer Andrea, Auteur ; Alexei A. Neverov, Auteur ; R. Stan Brown, Auteur . - 2010 . - pp 7027–7033.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7027–7033
Mots-clés : Methanolytic Phosphate Ions. Résumé : The methanolyses of three neutral organophosphorus esters, namely paraoxon (O,O-diethyl O-p-nitrophenyl phosphate (12), O-ethyl O-p-nitrophenyl methylphosphonate (13), O-ethyl S-3,5-dichlorophenyl methylphosphonothioate (14, a model for VX), and an anionic phosphonate ester, O-hydrogen S-3,5-dichlorophenyl methylphosphonothioate (15, a model for a toxic hydrolytic decomposition product of VX known as EA2192)), promoted by solid supported lanthanide ion catalysts (La3+, Sm3+, Eu3+, Yb3+) were investigated at 25 °C under sspH controlled conditions in methanol. The supports were derived from commercially available chlorobenzylated silica and chloromethylated polystyrene functionalized with two chelating ligands, iminodiacetic acid (IDA) and ethylenediamine-N,N′-diacetic acid (EDDA), followed by exposure to Ln3+ ions. The catalysts showed good activity at two investigated sspH values of 8.8 and 11 (in methanol). Despite the fact that the methoxide promoted reactions for the four substrates span a range of 20000-fold, the apparent second order rate constants (k2app) for methanolysis of these promoted by the solid supported lanthanide catalysts were rather insensitive to the nature of the support (Si or polystyrene), Ln3+ ion, substrate, and sspH. The Yb3+ complex of IDA on silica (Si/IDA/Yb) gave the highest k2app values of 6.6 and 14.4 M−1 s−1 for 12 and 13, 48.8 M−1 s−1 for 14, and 2.6 M−1 s−1 for 15 at sspH 11. The acceleration of cleavage of 13 at sspH 8.8 by the Si/IDA/Yb catalyst at an apparent concentration of 4.8 mM (50 mg suspended in 2.5 mL of methanol) is about 8.5 × 105 faster than the methoxide reaction at that sspH. The acceleration of the cleavage of 14 and 15 by 50 mg of Si/IDA/Yb at sspH 11 is 6.3 × 105- and 5 × 108-fold relative to the methoxide promoted reaction at that sspH. The matrixes containing the smaller lanthanide ions like Eu and Yb could be recycled at least eight times without loss of activity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008458 Exemplaires
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Titre : Fluidized bed methanation of wood-derived producer gas for the production of synthetic natural gas Type de document : texte imprimé Auteurs : Martin C. Seemann, Auteur ; Tilman J. Schildhauer, Auteur ; Serge M. A. Biollaz, Auteur Année de publication : 2010 Article en page(s) : pp 7034–7038 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidized bed Wood derived Natural gas. Résumé : For proving the concept of SNG production from wood gasification derived producer gas under real conditions, a mobile bench-scale fluidized bed reactor setup was fed with producer gas of the Fast Internally Circulating Bed (FICFB) wood gasifier in Gssing, Austria. In long-term experiments, it could be shown that the fluidized methanation catalyst allows for constantly high CO-conversion (about 98%) and CH4 concentration (about 40%) in the outlet. A similar experiment was conducted in a bench-scale reactor that allows for the measurement of axial gas phase concentration profiles by means of a movable sampling tube. It could be shown that under the chosen operation conditions, all three important reactions (methanation, water gas shift, and reforming of olefins) take place very rapidly in a region close to the reactor inlet. In the rest of the bed, the reaction of reactants transferred from the bubbles to the catalyst containing dense phase of the fluidized bed reactor is dominant. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100510m
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7034–7038[article] Fluidized bed methanation of wood-derived producer gas for the production of synthetic natural gas [texte imprimé] / Martin C. Seemann, Auteur ; Tilman J. Schildhauer, Auteur ; Serge M. A. Biollaz, Auteur . - 2010 . - pp 7034–7038.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7034–7038
Mots-clés : Fluidized bed Wood derived Natural gas. Résumé : For proving the concept of SNG production from wood gasification derived producer gas under real conditions, a mobile bench-scale fluidized bed reactor setup was fed with producer gas of the Fast Internally Circulating Bed (FICFB) wood gasifier in Gssing, Austria. In long-term experiments, it could be shown that the fluidized methanation catalyst allows for constantly high CO-conversion (about 98%) and CH4 concentration (about 40%) in the outlet. A similar experiment was conducted in a bench-scale reactor that allows for the measurement of axial gas phase concentration profiles by means of a movable sampling tube. It could be shown that under the chosen operation conditions, all three important reactions (methanation, water gas shift, and reforming of olefins) take place very rapidly in a region close to the reactor inlet. In the rest of the bed, the reaction of reactants transferred from the bubbles to the catalyst containing dense phase of the fluidized bed reactor is dominant. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100510m Exemplaires
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Titre : Simulation of a nonisothermal modern three-way catalyst converter Type de document : texte imprimé Auteurs : Hyuk Jae Kwon, Auteur ; Joon Hyun Baik, Auteur ; Sung Bong Kang, Auteur Année de publication : 2010 Article en page(s) : pp 7039–7051 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nonisothermal Catalyst converter. Résumé : A two-dimensional (2D) nonisothermal monolith reactor model based upon intrinsic detailed reaction kinetics has been developed to simulate the performance of a commercial modern three-way catalytic converter. The model directly employed the reliable kinetic parameters estimated from the detailed reaction kinetics determined over the powder-type three-way catalysts (TWCs). The TWC activity of the monolith reactor containing each Pd and Pt/Rh/Ce catalyst with respect to the catalyst mileages, 4k miles (stabilized) and 100k miles (aged) equivalent aged by engine-dynamometer, has been examined in a molten-salt bath under the steady-state condition. To simulate the commercial performance of a modern TWC converter, both reactor models specifically developed for the Pd (front) and Pt/Rh/Ce (rear) monoliths have been sequentially integrated on the basis of the commercial configuration of the monolith reactors in a dual-bed mode. The 2D nonisothermal monolith reactor model developed in the present study well predicts the TWC performance, including the gas compositions and the temperature distribution with respect to both axial and radial positions of the single-bed containing each individual catalyst monolith as well as of the dual-bed monolith reactor system including both Pd (front) and Pt/Rh/Ce (rear) monolith bricks. The reactor model was further validated by predicting the TWC performance of the dual-bed reactor under the steady-state sweep test (st-ST) condition varying the A/F ratios from 14.23 to 15.03 with respect to the reaction temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1007486
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7039–7051[article] Simulation of a nonisothermal modern three-way catalyst converter [texte imprimé] / Hyuk Jae Kwon, Auteur ; Joon Hyun Baik, Auteur ; Sung Bong Kang, Auteur . - 2010 . - pp 7039–7051.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7039–7051
Mots-clés : Nonisothermal Catalyst converter. Résumé : A two-dimensional (2D) nonisothermal monolith reactor model based upon intrinsic detailed reaction kinetics has been developed to simulate the performance of a commercial modern three-way catalytic converter. The model directly employed the reliable kinetic parameters estimated from the detailed reaction kinetics determined over the powder-type three-way catalysts (TWCs). The TWC activity of the monolith reactor containing each Pd and Pt/Rh/Ce catalyst with respect to the catalyst mileages, 4k miles (stabilized) and 100k miles (aged) equivalent aged by engine-dynamometer, has been examined in a molten-salt bath under the steady-state condition. To simulate the commercial performance of a modern TWC converter, both reactor models specifically developed for the Pd (front) and Pt/Rh/Ce (rear) monoliths have been sequentially integrated on the basis of the commercial configuration of the monolith reactors in a dual-bed mode. The 2D nonisothermal monolith reactor model developed in the present study well predicts the TWC performance, including the gas compositions and the temperature distribution with respect to both axial and radial positions of the single-bed containing each individual catalyst monolith as well as of the dual-bed monolith reactor system including both Pd (front) and Pt/Rh/Ce (rear) monolith bricks. The reactor model was further validated by predicting the TWC performance of the dual-bed reactor under the steady-state sweep test (st-ST) condition varying the A/F ratios from 14.23 to 15.03 with respect to the reaction temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1007486 Exemplaires
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Titre : Novel inherently flame-retardant poly(trimethylene terephthalate) copolyester with the phosphorus-containing linking pendent group Type de document : texte imprimé Auteurs : Hong-Bing Chen, Auteur ; Yi Zhang, Auteur ; Chen, Li, Auteur Année de publication : 2010 Article en page(s) : pp 7052–7059 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Copolyester Phosphorus. Résumé : A novel phosphorus-containing copolyester, poly(trimethylene terephthalate)-co-poly(trimethylene DDP)s (PTTP), was synthesized through esterification and polycondensation of terephthalic acid (TPA), 1,3-propane diol (PDO), and 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP). The analysis of phosphorus content and the test of intrinsic viscosity indicated that DDP was successfully introduced to the poly(trimethylene terephthalate) (PTT) chain. The chemical structure of the resulting copolyesters was further confirmed by 1H NMR and 31P NMR. The thermal behaviors were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and it was shown that the introduction of DDP lowered the melting temperature and crystallization because of its bulky pendent groups and decreased the initial decomposition temperature in the nitrogen atmosphere due to its weak P−C bond. The flame retardant properties of the resulting copolyesters were characterized by limiting oxygen index (LOI) and cone calorimeter, and it was shown that the copolyesters had good inherent flame retardancy. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1006917
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7052–7059[article] Novel inherently flame-retardant poly(trimethylene terephthalate) copolyester with the phosphorus-containing linking pendent group [texte imprimé] / Hong-Bing Chen, Auteur ; Yi Zhang, Auteur ; Chen, Li, Auteur . - 2010 . - pp 7052–7059.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7052–7059
Mots-clés : Copolyester Phosphorus. Résumé : A novel phosphorus-containing copolyester, poly(trimethylene terephthalate)-co-poly(trimethylene DDP)s (PTTP), was synthesized through esterification and polycondensation of terephthalic acid (TPA), 1,3-propane diol (PDO), and 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP). The analysis of phosphorus content and the test of intrinsic viscosity indicated that DDP was successfully introduced to the poly(trimethylene terephthalate) (PTT) chain. The chemical structure of the resulting copolyesters was further confirmed by 1H NMR and 31P NMR. The thermal behaviors were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and it was shown that the introduction of DDP lowered the melting temperature and crystallization because of its bulky pendent groups and decreased the initial decomposition temperature in the nitrogen atmosphere due to its weak P−C bond. The flame retardant properties of the resulting copolyesters were characterized by limiting oxygen index (LOI) and cone calorimeter, and it was shown that the copolyesters had good inherent flame retardancy. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1006917 Exemplaires
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Titre : Effect of electrolyte solutions on the adsorption of surfactants at PTFE−water interface Type de document : texte imprimé Auteurs : Nihar Ranjan Biswal, Auteur ; Santanu Paria, Auteur Année de publication : 2010 Article en page(s) : pp 7060–7067 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Electrolyte Adsorption ionic PTFE water. Résumé : Adsorption of ionic and nonionic surfactants on low surface energy hydrophobic PTFE−water interfaces in the absence and presence of electrolytes have been studied here. The objective of this study is to see the surfactant adsorption behavior in the presence of electrolytes that may reduce the consumption of surfactants. The kinetics of adsorption fits well pseudo-second-order kinetic model for the three surfactants studied here. Adsorption isotherms of TX-100 follow Langmuir type, whereas sodium dodecylbenzene sulfonate (SDBS) and cetylpyridinium bromide (CPB) follow Freundlich type. However, in the presence of electrolytes both the ionic surfactants show better fitting with Langmuir type isotherm. The effect of electrolytes on the surfactant concentration far below the CMC shows there is a linear increase in amount adsorbed with the increase in ionic strength of the electrolyte mainly due to reduction in headgroup repulsion and finally reaches a plateau level when the equilibrium concentration reaches CMC at that electrolyte concentration. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100812k
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7060–7067[article] Effect of electrolyte solutions on the adsorption of surfactants at PTFE−water interface [texte imprimé] / Nihar Ranjan Biswal, Auteur ; Santanu Paria, Auteur . - 2010 . - pp 7060–7067.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7060–7067
Mots-clés : Electrolyte Adsorption ionic PTFE water. Résumé : Adsorption of ionic and nonionic surfactants on low surface energy hydrophobic PTFE−water interfaces in the absence and presence of electrolytes have been studied here. The objective of this study is to see the surfactant adsorption behavior in the presence of electrolytes that may reduce the consumption of surfactants. The kinetics of adsorption fits well pseudo-second-order kinetic model for the three surfactants studied here. Adsorption isotherms of TX-100 follow Langmuir type, whereas sodium dodecylbenzene sulfonate (SDBS) and cetylpyridinium bromide (CPB) follow Freundlich type. However, in the presence of electrolytes both the ionic surfactants show better fitting with Langmuir type isotherm. The effect of electrolytes on the surfactant concentration far below the CMC shows there is a linear increase in amount adsorbed with the increase in ionic strength of the electrolyte mainly due to reduction in headgroup repulsion and finally reaches a plateau level when the equilibrium concentration reaches CMC at that electrolyte concentration. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100812k Exemplaires
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Titre : Coalescence extraction system for rapid efficient and selective separation of zirconium and hafnium Type de document : texte imprimé Auteurs : Majid Haji Hosseini, Auteur ; Naader Alizadeh, Auteur Année de publication : 2010 Article en page(s) : pp 7068–7073 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Coalescence Zirconium Hafnium. Résumé : The coalescence extraction system was developed for rapid, efficient, and selective separation of zirconium and hafnium from an aqueous solution containing alkali, alkaline earth, and transition metal ions. Extraction was based on the coalescence properties of glutaronitrile in combination with the aqueous solution at elevated temperature from a homogeneous solution. In the next step, a significant temperature reduction (temperature-induced phase separation) was used to enter the spinodal to form the two phase’s regions. The particle-size distribution at coalescence temperature was measured by a laser particle-size analyzer. Metal separation could be completed in a single operation lasting only 2 min with the extraction efficiency of more than 90%. The extractability in the coalescence extraction was comparable to that of traditional methods and was feasible for rapid separation of zirconium and hafnium. The mechanism of extraction was proposed depending on the hydrolysis and polymerization of these ions and the temperature of extraction. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901729e
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7068–7073[article] Coalescence extraction system for rapid efficient and selective separation of zirconium and hafnium [texte imprimé] / Majid Haji Hosseini, Auteur ; Naader Alizadeh, Auteur . - 2010 . - pp 7068–7073.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7068–7073
Mots-clés : Coalescence Zirconium Hafnium. Résumé : The coalescence extraction system was developed for rapid, efficient, and selective separation of zirconium and hafnium from an aqueous solution containing alkali, alkaline earth, and transition metal ions. Extraction was based on the coalescence properties of glutaronitrile in combination with the aqueous solution at elevated temperature from a homogeneous solution. In the next step, a significant temperature reduction (temperature-induced phase separation) was used to enter the spinodal to form the two phase’s regions. The particle-size distribution at coalescence temperature was measured by a laser particle-size analyzer. Metal separation could be completed in a single operation lasting only 2 min with the extraction efficiency of more than 90%. The extractability in the coalescence extraction was comparable to that of traditional methods and was feasible for rapid separation of zirconium and hafnium. The mechanism of extraction was proposed depending on the hydrolysis and polymerization of these ions and the temperature of extraction. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901729e Exemplaires
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Titre : Fe-grown carbon nanofibers for removal of arsenic(V) in wastewater Type de document : texte imprimé Auteurs : Amit Kumar Gupta, Auteur ; Dinesh Deva, Auteur ; Ashutosh Sharma, Auteur Année de publication : 2010 Article en page(s) : pp 7074–7084 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Carbon Nanofibers Wastewater. Résumé : An Fe-impregnated hierarchal web of carbon fibers was synthesized and evaluated as an adsorbent for arsenic(V) removal from wastewater. The web was prepared by growing carbon nanofibers (CNFs) on the activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Fe as a catalyst. Fe was found to play a bifunctional role in the development of the micro-/nanoweb of carbon fibers: (1) as a catalyst for growing CNFs and (2) as an adsorbent for removing arsenic(V) from water. The method of preparation consisted of impregnation of substrate ACFs with ferric chloride, calcinations followed by reduction to convert oxides of Fe to the metallic state, growth of CNFs by CVD, and subsequent mild sonication of the web to open its pore spaces. The Fe-impregnated adsorbent was tested for the removal of arsenic(V) over the concentration range of 1−50 mg/L in water under both batch and flow conditions. The results showed comparable or greater removal of arsenic(V) compared to that obtained with commercial adsorbents. The prepared adsorbent was characterized by various analytical techniques such as BET area and pore size distribution (PSD), elemental analysis, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100392q
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7074–7084[article] Fe-grown carbon nanofibers for removal of arsenic(V) in wastewater [texte imprimé] / Amit Kumar Gupta, Auteur ; Dinesh Deva, Auteur ; Ashutosh Sharma, Auteur . - 2010 . - pp 7074–7084.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7074–7084
Mots-clés : Carbon Nanofibers Wastewater. Résumé : An Fe-impregnated hierarchal web of carbon fibers was synthesized and evaluated as an adsorbent for arsenic(V) removal from wastewater. The web was prepared by growing carbon nanofibers (CNFs) on the activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Fe as a catalyst. Fe was found to play a bifunctional role in the development of the micro-/nanoweb of carbon fibers: (1) as a catalyst for growing CNFs and (2) as an adsorbent for removing arsenic(V) from water. The method of preparation consisted of impregnation of substrate ACFs with ferric chloride, calcinations followed by reduction to convert oxides of Fe to the metallic state, growth of CNFs by CVD, and subsequent mild sonication of the web to open its pore spaces. The Fe-impregnated adsorbent was tested for the removal of arsenic(V) over the concentration range of 1−50 mg/L in water under both batch and flow conditions. The results showed comparable or greater removal of arsenic(V) compared to that obtained with commercial adsorbents. The prepared adsorbent was characterized by various analytical techniques such as BET area and pore size distribution (PSD), elemental analysis, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100392q Exemplaires
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Titre : Phase behavior modeling of alkyl−amine+water mixtures and prediction of alkane solubilities in alkanolamine aqueous solutions with group contribution with association equation of state Type de document : texte imprimé Auteurs : Francisco A. Sanchez, Auteur ; Ticiana M. Soria, Auteur ; Selva Pereda, Auteur Année de publication : 2010 Article en page(s) : pp 7085–7092 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Alkyl amine Water Alkane solubilities Aqueous solutions. Résumé : Precise knowledge of phase behavior of natural gas+aqueous alkanolamine solutions is of interest to design and optimize amine absorption units. In this work, we extend a group contribution with association equation of state to the modeling of phase behavior of mixtures containing water, alkanolamine, and light hydrocarbons (HC). The model parameters were estimated on the basis of binary vapor−liquid equilibrium and liquid−liquid equilibrium data of the following binary systems: HC + amines, HC + alcohol, water + amine, water + alcohol. The group contribution approach allows the use of an extended databank of experimental data which gives a solid foundation for predicting hydrocarbon solubility in aqueous alkanolamine solutions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100421m
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7085–7092[article] Phase behavior modeling of alkyl−amine+water mixtures and prediction of alkane solubilities in alkanolamine aqueous solutions with group contribution with association equation of state [texte imprimé] / Francisco A. Sanchez, Auteur ; Ticiana M. Soria, Auteur ; Selva Pereda, Auteur . - 2010 . - pp 7085–7092.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7085–7092
Mots-clés : Alkyl amine Water Alkane solubilities Aqueous solutions. Résumé : Precise knowledge of phase behavior of natural gas+aqueous alkanolamine solutions is of interest to design and optimize amine absorption units. In this work, we extend a group contribution with association equation of state to the modeling of phase behavior of mixtures containing water, alkanolamine, and light hydrocarbons (HC). The model parameters were estimated on the basis of binary vapor−liquid equilibrium and liquid−liquid equilibrium data of the following binary systems: HC + amines, HC + alcohol, water + amine, water + alcohol. The group contribution approach allows the use of an extended databank of experimental data which gives a solid foundation for predicting hydrocarbon solubility in aqueous alkanolamine solutions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100421m Exemplaires
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Titre : Effects of temperature on aerobic treatment of anaerobically digested palm oil mill effluent (POME) Type de document : texte imprimé Auteurs : Yi Jing Chan, Auteur ; Mei Fong Chong, Auteur ; Chung Lim Law, Auteur Année de publication : 2010 Article en page(s) : pp 7093–7101 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Aerobic treatment thermophilic anaerobic. Résumé : Aerobic treatment of wastewater under thermophilic conditions has received growing interest in recent years. Because of the high discharge temperature (75 to 85 °C) of palm oil mill effluent (POME), it would be more economical if POME were treated thermophilically, as then cooling facilities prior to biological treatment can be eliminated. In the present investigation, the feasibility of thermophilic aerobic biological treatment as a suitable post-treatment system for anaerobically treated POME was examined. Also, the effects of temperature on the treated effluent quality were investigated by using sequencing batch reactors (SBRs) under mesophilic (28 °C) and thermophilic (45, 50, and 55 °C) conditions. The average total COD (TCOD) removal efficiencies varied from 55 to 98% at organic loading rates (OLR) of 2.6 to 4.5 kg COD/m3·day, dissolved oxygen (DO) concentrations of 2.9−4.5 mg/L, and mixed-liquor suspended solids (MLSS) concentrations of 22500−24200 mg/L. The results show that the thermophilic aerobic treatment was capable of achieving promising treatment efficiencies in terms of TCOD and biochemical oxygen demand (BOD) removals, which exceeded 72% and 76%, respectively, at an OLR of 2.8 ± 0.3 kg COD/m3·day. The thermophilic sludge also showed good settling characteristics, as reflected by the low sludge volume index (SVI) values ( DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901952m
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7093–7101[article] Effects of temperature on aerobic treatment of anaerobically digested palm oil mill effluent (POME) [texte imprimé] / Yi Jing Chan, Auteur ; Mei Fong Chong, Auteur ; Chung Lim Law, Auteur . - 2010 . - pp 7093–7101.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7093–7101
Mots-clés : Aerobic treatment thermophilic anaerobic. Résumé : Aerobic treatment of wastewater under thermophilic conditions has received growing interest in recent years. Because of the high discharge temperature (75 to 85 °C) of palm oil mill effluent (POME), it would be more economical if POME were treated thermophilically, as then cooling facilities prior to biological treatment can be eliminated. In the present investigation, the feasibility of thermophilic aerobic biological treatment as a suitable post-treatment system for anaerobically treated POME was examined. Also, the effects of temperature on the treated effluent quality were investigated by using sequencing batch reactors (SBRs) under mesophilic (28 °C) and thermophilic (45, 50, and 55 °C) conditions. The average total COD (TCOD) removal efficiencies varied from 55 to 98% at organic loading rates (OLR) of 2.6 to 4.5 kg COD/m3·day, dissolved oxygen (DO) concentrations of 2.9−4.5 mg/L, and mixed-liquor suspended solids (MLSS) concentrations of 22500−24200 mg/L. The results show that the thermophilic aerobic treatment was capable of achieving promising treatment efficiencies in terms of TCOD and biochemical oxygen demand (BOD) removals, which exceeded 72% and 76%, respectively, at an OLR of 2.8 ± 0.3 kg COD/m3·day. The thermophilic sludge also showed good settling characteristics, as reflected by the low sludge volume index (SVI) values ( DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901952m Exemplaires
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Titre : Correlation of hydrate-film growth rate at the guest/liquid-water interface to mass transfer resistance Type de document : texte imprimé Auteurs : Kota Saito, Auteur ; Amadeu K. Sum, Auteur ; Ryo Ohmura, Auteur Année de publication : 2010 Article en page(s) : pp 7102–7103 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Correlation hydrate film Mass transfer Heat transfer. Résumé : The correlation of hydrate-film growth rate at the guest/liquid-water interface to mass transfer limitations is considered. Most of the hydrate-film growth rate data from the literature are compiled based on the system subcooling (ΔT), suggesting predominant heat transfer limitations. In this communication, we investigate how existing data on hydrate-film growth is better correlated to solubility differences of the guest species in equilibrium with bulk fluid and hydrate. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1000696
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7102–7103[article] Correlation of hydrate-film growth rate at the guest/liquid-water interface to mass transfer resistance [texte imprimé] / Kota Saito, Auteur ; Amadeu K. Sum, Auteur ; Ryo Ohmura, Auteur . - 2010 . - pp 7102–7103.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7102–7103
Mots-clés : Correlation hydrate film Mass transfer Heat transfer. Résumé : The correlation of hydrate-film growth rate at the guest/liquid-water interface to mass transfer limitations is considered. Most of the hydrate-film growth rate data from the literature are compiled based on the system subcooling (ΔT), suggesting predominant heat transfer limitations. In this communication, we investigate how existing data on hydrate-film growth is better correlated to solubility differences of the guest species in equilibrium with bulk fluid and hydrate. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1000696 Exemplaires
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Titre : Predicting vapor pressure of heavy hydrocarbons from molar refraction and Its applications to petroleum mixtures Type de document : texte imprimé Auteurs : M. R. Riazi, Auteur ; Y. S. AlQaheem, Auteur Année de publication : 2010 Article en page(s) : pp 7104–7112 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Vapor pressure Hydrocarbons Petroleum mixtures. Résumé : In this paper a generalized relation based on the corresponding states approach and use of molar refraction is proposed for the estimation of vapor pressure of pure hydrocarbons from C1 to C100. The hydrocarbons are divided into three groups of n-alkanes, n-alkylcyclohexanes, and n-alkylbenzenes from the paraffinic, naphthenic, and aromatic families. The method is also extended to undefined petroleum mixtures using bulk measurable properties, and unified methods are proposed for the calculation of input parameters from measurable properties of the mixture. The AAD for the proposed method for pure hydrocarbons (C1−C100) and for temperature range of Tr = 0.4 to the critical point (ca. 91−968 K) for 1300 data points is 1.85% while from other available methods in the literature this error is about 24%. When evaluated against petroleum fractions the proposed method produces data slightly more accurate than the existing methods recommended specifically for petroleum mixtures. Application of the proposed method to vapor pressure of crude oil is also demonstrated. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100861c
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7104–7112[article] Predicting vapor pressure of heavy hydrocarbons from molar refraction and Its applications to petroleum mixtures [texte imprimé] / M. R. Riazi, Auteur ; Y. S. AlQaheem, Auteur . - 2010 . - pp 7104–7112.
Chimie industrielle
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7104–7112
Mots-clés : Vapor pressure Hydrocarbons Petroleum mixtures. Résumé : In this paper a generalized relation based on the corresponding states approach and use of molar refraction is proposed for the estimation of vapor pressure of pure hydrocarbons from C1 to C100. The hydrocarbons are divided into three groups of n-alkanes, n-alkylcyclohexanes, and n-alkylbenzenes from the paraffinic, naphthenic, and aromatic families. The method is also extended to undefined petroleum mixtures using bulk measurable properties, and unified methods are proposed for the calculation of input parameters from measurable properties of the mixture. The AAD for the proposed method for pure hydrocarbons (C1−C100) and for temperature range of Tr = 0.4 to the critical point (ca. 91−968 K) for 1300 data points is 1.85% while from other available methods in the literature this error is about 24%. When evaluated against petroleum fractions the proposed method produces data slightly more accurate than the existing methods recommended specifically for petroleum mixtures. Application of the proposed method to vapor pressure of crude oil is also demonstrated. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100861c Exemplaires
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