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Vol. 51 N° 22 - Juin 2012 [texte imprimé] . - 2012 . - p. 7457-7844 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierImpact of sulfur poisoning on the catalytic partial oxidation of methane on rhodium - based catalysts / Stefano Cimino in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012)
Titre : Impact of sulfur poisoning on the catalytic partial oxidation of methane on rhodium - based catalysts Type de document : texte imprimé Auteurs : Stefano Cimino, Auteur ; Luciana Lisi, Auteur Année de publication : 2012 Article en page(s) : pp. 7459–7466 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalytic partial oxidation Natural gas Résumé : Catalytic partial oxidation (CPO) of natural gas into syngas (CO and H2) at short contact time over precious-metal-structured reactors has received increasing attention in industrial applications. However, only recently, sulfur poisoning of the best-performing and costly rhodium catalysts has been recognized as a serious issue of this technology. This work critically reviews and integrates recent experimental results obtained from our group and others, both at steady state and during transient operation of the CPO reactor, particularly with regard to poisoning/regeneration cycles and low-temperature light-off phase. Furthermore, the origin of sulfur poisoning of Rh active sites during the CPO of methane has been studied via in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, using CO as a probe molecule, and an attempt is made to identify sites responsible for the loss in the catalytic activity by comparing the results with the activity data. The effect of the type of alumina support and the partial substitution of Rh with either Pt or Pd were investigated to enhance the sulfur tolerance of the catalyst. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201648e
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7459–7466[article] Impact of sulfur poisoning on the catalytic partial oxidation of methane on rhodium - based catalysts [texte imprimé] / Stefano Cimino, Auteur ; Luciana Lisi, Auteur . - 2012 . - pp. 7459–7466.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7459–7466
Mots-clés : Catalytic partial oxidation Natural gas Résumé : Catalytic partial oxidation (CPO) of natural gas into syngas (CO and H2) at short contact time over precious-metal-structured reactors has received increasing attention in industrial applications. However, only recently, sulfur poisoning of the best-performing and costly rhodium catalysts has been recognized as a serious issue of this technology. This work critically reviews and integrates recent experimental results obtained from our group and others, both at steady state and during transient operation of the CPO reactor, particularly with regard to poisoning/regeneration cycles and low-temperature light-off phase. Furthermore, the origin of sulfur poisoning of Rh active sites during the CPO of methane has been studied via in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, using CO as a probe molecule, and an attempt is made to identify sites responsible for the loss in the catalytic activity by comparing the results with the activity data. The effect of the type of alumina support and the partial substitution of Rh with either Pt or Pd were investigated to enhance the sulfur tolerance of the catalyst. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201648e Exemplaires
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Titre : NOx abatement by HC - assisted SCR over combustion synthesized - supported Ag catalysts Type de document : texte imprimé Auteurs : Murid Hussain, Auteur ; Nunzio Russo, Auteur ; Guido Saracco, Auteur Année de publication : 2012 Article en page(s) : pp. 7467-7474 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst Combustion Selective catalytic reduction Pollution abatement Résumé : In this work, catalysts containing 2% by weight of silver particles dispersed on different oxide supports (CeO2, La2O3, ZrO2,Al2O3), and oxides without silver particles were prepared by means of the combustion synthesis method. This cheap and quick technique has been developed to produce very fine, homogeneous, crystalline powders without the intermediate decomposition and/or calcining steps which other conventional synthesis routes require. These features are also interesting for the cosynthesis of supported Ag catalysts; it has in fact been possible in one-shot to achieve values of the Ag clusters (estimated size 5―10 nm) that are comparable with those obtained by means of the more complex methods reported in literature. The catalysts were characterized via XRD, BET, TEM, FESEM-EDS, and XPS analysis. The catalytic performances of the prepared catalysts were evaluated in a TPR apparatus for the selective reduction of NO with benzene in the presence of oxygen. A noticeable enhancement in activity was achieved when the selected oxides were doped with Ag. Lantana and ceria-supported Ag catalysts with good hydrothermal stability were found to perform comparatively well, as a significant NOx to N2 conversion was obtained at temperatures slightly above 250 °C. As far as the results concerning the catalysts are concerned, a synergic effect of the supports with the Ag clusters has been highlighted. Some conclusions may be drawn concerning the reaction mechanism. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968298
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7467-7474[article] NOx abatement by HC - assisted SCR over combustion synthesized - supported Ag catalysts [texte imprimé] / Murid Hussain, Auteur ; Nunzio Russo, Auteur ; Guido Saracco, Auteur . - 2012 . - pp. 7467-7474.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7467-7474
Mots-clés : Catalyst Combustion Selective catalytic reduction Pollution abatement Résumé : In this work, catalysts containing 2% by weight of silver particles dispersed on different oxide supports (CeO2, La2O3, ZrO2,Al2O3), and oxides without silver particles were prepared by means of the combustion synthesis method. This cheap and quick technique has been developed to produce very fine, homogeneous, crystalline powders without the intermediate decomposition and/or calcining steps which other conventional synthesis routes require. These features are also interesting for the cosynthesis of supported Ag catalysts; it has in fact been possible in one-shot to achieve values of the Ag clusters (estimated size 5―10 nm) that are comparable with those obtained by means of the more complex methods reported in literature. The catalysts were characterized via XRD, BET, TEM, FESEM-EDS, and XPS analysis. The catalytic performances of the prepared catalysts were evaluated in a TPR apparatus for the selective reduction of NO with benzene in the presence of oxygen. A noticeable enhancement in activity was achieved when the selected oxides were doped with Ag. Lantana and ceria-supported Ag catalysts with good hydrothermal stability were found to perform comparatively well, as a significant NOx to N2 conversion was obtained at temperatures slightly above 250 °C. As far as the results concerning the catalysts are concerned, a synergic effect of the supports with the Ag clusters has been highlighted. Some conclusions may be drawn concerning the reaction mechanism. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968298 Exemplaires
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Titre : Thermochemical stability of alumina - supported Rh - LaCoO3 catalysts for Tar conversion Type de document : texte imprimé Auteurs : Paola Ammendola, Auteur ; Elena Cammisa, Auteur ; Luciana Lisi, Auteur Année de publication : 2012 Article en page(s) : pp. 7475–7481 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalysts thermal chemical stability Résumé : The thermal and chemical stability of alumina-supported catalysts (Rh/Al2O3, LaCoO3/Al2O3, Rh-LaCoO3/Al2O3) have been investigated by performing cycles of tar conversion at 700 °C followed by regeneration of the catalyst by oxidation of coke deposited on the surface up to 800 °C. Structural and chemical modifications underwent by the catalysts upon conversion/regeneration cycles have been studied by BET, TPR/TPO, and DRIFT analyses. The catalysts containing rhodium are highly stable maintaining the original performance and chemical properties of the fresh sample also after several cycles, dispersion of rhodium on Al2O3 surface being sufficiently preserved also at 800 °C. On the contrary, LaCoO3/Al2O3 catalyst undergoes a partial deactivation after the first cycles related to the irreversible migration of cobalt into the alumina lattice. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016448
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7475–7481[article] Thermochemical stability of alumina - supported Rh - LaCoO3 catalysts for Tar conversion [texte imprimé] / Paola Ammendola, Auteur ; Elena Cammisa, Auteur ; Luciana Lisi, Auteur . - 2012 . - pp. 7475–7481.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7475–7481
Mots-clés : Catalysts thermal chemical stability Résumé : The thermal and chemical stability of alumina-supported catalysts (Rh/Al2O3, LaCoO3/Al2O3, Rh-LaCoO3/Al2O3) have been investigated by performing cycles of tar conversion at 700 °C followed by regeneration of the catalyst by oxidation of coke deposited on the surface up to 800 °C. Structural and chemical modifications underwent by the catalysts upon conversion/regeneration cycles have been studied by BET, TPR/TPO, and DRIFT analyses. The catalysts containing rhodium are highly stable maintaining the original performance and chemical properties of the fresh sample also after several cycles, dispersion of rhodium on Al2O3 surface being sufficiently preserved also at 800 °C. On the contrary, LaCoO3/Al2O3 catalyst undergoes a partial deactivation after the first cycles related to the irreversible migration of cobalt into the alumina lattice. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016448 Exemplaires
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Titre : Experimental and theoretical investigation of controlling regimes during lean oxidation of methane and propylene on Pt /Al2O3 monolithic reactors Type de document : texte imprimé Auteurs : Saurabh Y. Joshi, Auteur ; Yongjie Ren, Auteur ; Michael P. Harold, Auteur Année de publication : 2012 Article en page(s) : pp. 7482–7492 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Controlling regimes Oxidation methane Résumé : The performance of a catalytic reactor is bounded by the kinetic regime at low temperature (or before light-off) and the mass-transfer-controlled regime at high temperature. Pore diffusion may also be significant at intermediate temperature. We utilize the recently developed criteria (Joshi, S. Y.; Harold, M. P.; Balakotaiah, V. Chem. Eng. Sci.2010, 65, 1729–1747) to characterize the controlling regimes during lean oxidation of CH4 and C3H6 in Pt/Al2O3 monolithic reactors. First, we determine the global kinetics of lean oxidation of CH4 and C3H6 in a Pt/Al2O3 monolithic catalyst. We also present a method for estimation of the effective diffusivity of the limiting reactant and the external mass-transfer coefficient under reacting conditions. Further, we characterize the relative contributions of chemical kinetics, washcoat diffusion, and external mass transfer as a function of the various catalyst design and operating parameters. The analysis reveals that methane oxidation is kinetically controlled over a wide range of temperatures (350–600 °C) whereas propylene oxidation has a more classical transition between the kinetic and mass-transfer-controlled regimes. We use the bench-scale results to analyze the impact of various design and operating variables on transitions between the controlling regimes. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201653e
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7482–7492[article] Experimental and theoretical investigation of controlling regimes during lean oxidation of methane and propylene on Pt /Al2O3 monolithic reactors [texte imprimé] / Saurabh Y. Joshi, Auteur ; Yongjie Ren, Auteur ; Michael P. Harold, Auteur . - 2012 . - pp. 7482–7492.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7482–7492
Mots-clés : Controlling regimes Oxidation methane Résumé : The performance of a catalytic reactor is bounded by the kinetic regime at low temperature (or before light-off) and the mass-transfer-controlled regime at high temperature. Pore diffusion may also be significant at intermediate temperature. We utilize the recently developed criteria (Joshi, S. Y.; Harold, M. P.; Balakotaiah, V. Chem. Eng. Sci.2010, 65, 1729–1747) to characterize the controlling regimes during lean oxidation of CH4 and C3H6 in Pt/Al2O3 monolithic reactors. First, we determine the global kinetics of lean oxidation of CH4 and C3H6 in a Pt/Al2O3 monolithic catalyst. We also present a method for estimation of the effective diffusivity of the limiting reactant and the external mass-transfer coefficient under reacting conditions. Further, we characterize the relative contributions of chemical kinetics, washcoat diffusion, and external mass transfer as a function of the various catalyst design and operating parameters. The analysis reveals that methane oxidation is kinetically controlled over a wide range of temperatures (350–600 °C) whereas propylene oxidation has a more classical transition between the kinetic and mass-transfer-controlled regimes. We use the bench-scale results to analyze the impact of various design and operating variables on transitions between the controlling regimes. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201653e Exemplaires
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Titre : Dicumyl peroxide thermal decomposition in cumene : Development of a kinetic model Type de document : texte imprimé Auteurs : Ilaria Di Somma, Auteur ; Raffaele Marotta, Auteur ; Roberto Andreozzi, Auteur Année de publication : 2012 Article en page(s) : pp. 7493-7499 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Modeling Kinetic model Thermal decomposition Résumé : A kinetic model is developed to simulate the thermal decomposition of dicumyl peroxide (DCP) in cumene with and without oxygen in the reacting system, based on a reaction network that is comprised of a set of 51 reactions. An optimization procedure is adopted to obtain the best estimates for most of the related kinetic parameters, few of which are available in the literature. The model is successfully validated by simulating the concentration profiles of all the species participating in the decomposition of DCP in cumene, under varying initial conditions, using previously best-estimated values of the kinetic parameters. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968301
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7493-7499[article] Dicumyl peroxide thermal decomposition in cumene : Development of a kinetic model [texte imprimé] / Ilaria Di Somma, Auteur ; Raffaele Marotta, Auteur ; Roberto Andreozzi, Auteur . - 2012 . - pp. 7493-7499.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7493-7499
Mots-clés : Modeling Kinetic model Thermal decomposition Résumé : A kinetic model is developed to simulate the thermal decomposition of dicumyl peroxide (DCP) in cumene with and without oxygen in the reacting system, based on a reaction network that is comprised of a set of 51 reactions. An optimization procedure is adopted to obtain the best estimates for most of the related kinetic parameters, few of which are available in the literature. The model is successfully validated by simulating the concentration profiles of all the species participating in the decomposition of DCP in cumene, under varying initial conditions, using previously best-estimated values of the kinetic parameters. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968301 Exemplaires
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Titre : Electrochemical performance of Pt - based catalysts supported on different ordered mesoporous carbons (Pt / OMCs) for oxygen reduction reaction Type de document : texte imprimé Auteurs : Juqin Zeng, Auteur ; Carlotta Francia, Auteur ; Mihaela A. Dumitrescu, Auteur Année de publication : 2012 Article en page(s) : pp. 7500–7509 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalysts Mesoporous Carbons Résumé : The present work aims to compare and evaluate the behavior of platinum catalysts supported on different ordered mesoporous carbons (Pt/OMCs). OMCs were templated from two kinds of ordered mesoporous silicas (2-D SBA-15 and 3-D SBA-16), with sucrose as carbon precursor and boric acid as a pore expanding agent. Structural characterizations revealed that all OMCs inherited the structure from silica templates. OMC synthesized from a mixture of sucrose and boric acid exhibited a larger pore size. According to XRD, TEM, and XPS analysis, particle size and distribution of Pt were influenced by the porosity of OMC supports. In single PEMFC tests, catalysts supported on OMC with a 3-D pore structure (Pt/C16sucr: 0.57 W cm–2 at 0.45 V) or with 2-D larger pores (Pt/C15sucr+B: 0.44 W cm–2 at 0.45 V) significantly enhanced the FC performance compared to Pt/C15sucr (0.29 W cm–2 at 0.45 V), which may be attributed to a better mass transfer and a higher catalytic activity. In particular, it was found that Pt/C16sucr had a catalytic behavior superior to that of the Pt/Vulcan commercial catalyst in the high potential region, suggesting that C16sucr is a promising catalyst support for PEMFC application. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016619
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7500–7509[article] Electrochemical performance of Pt - based catalysts supported on different ordered mesoporous carbons (Pt / OMCs) for oxygen reduction reaction [texte imprimé] / Juqin Zeng, Auteur ; Carlotta Francia, Auteur ; Mihaela A. Dumitrescu, Auteur . - 2012 . - pp. 7500–7509.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7500–7509
Mots-clés : Catalysts Mesoporous Carbons Résumé : The present work aims to compare and evaluate the behavior of platinum catalysts supported on different ordered mesoporous carbons (Pt/OMCs). OMCs were templated from two kinds of ordered mesoporous silicas (2-D SBA-15 and 3-D SBA-16), with sucrose as carbon precursor and boric acid as a pore expanding agent. Structural characterizations revealed that all OMCs inherited the structure from silica templates. OMC synthesized from a mixture of sucrose and boric acid exhibited a larger pore size. According to XRD, TEM, and XPS analysis, particle size and distribution of Pt were influenced by the porosity of OMC supports. In single PEMFC tests, catalysts supported on OMC with a 3-D pore structure (Pt/C16sucr: 0.57 W cm–2 at 0.45 V) or with 2-D larger pores (Pt/C15sucr+B: 0.44 W cm–2 at 0.45 V) significantly enhanced the FC performance compared to Pt/C15sucr (0.29 W cm–2 at 0.45 V), which may be attributed to a better mass transfer and a higher catalytic activity. In particular, it was found that Pt/C16sucr had a catalytic behavior superior to that of the Pt/Vulcan commercial catalyst in the high potential region, suggesting that C16sucr is a promising catalyst support for PEMFC application. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016619 Exemplaires
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Titre : Catalytic performance of solution combustion synthesized alumina - and ceria - supported Pt and Pd nanoparticles for the combustion of propane and dimethyl ether (DME) Type de document : texte imprimé Auteurs : Sara Colussi, Auteur ; Arup Gayen, Auteur ; Jordi Llorca, Auteur Année de publication : 2012 Article en page(s) : pp. 7510–7517 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalytic Combustion Nanoparticles Résumé : Pd- and Pt-based catalysts supported on CeO2 and Al2O3 have been prepared by traditional incipient wetness impregnation and by solution combustion synthesis, and their catalytic activities have been compared for propane and DME combustion. Kinetic measurements carried out in a laboratory-scale recycle reactor apparatus indicate that combustion synthesized Pd-based materials are much more active than the corresponding impregnated ones, whereas for Pt-based catalysts no significant difference is observed. On the basis of high-resolution transmission electron microscopy (HRTEM) results, the enhanced catalytic activity is tentatively ascribed to the coexistence of highly active palladium centers (PdII species) that form upon solution combustion synthesis and nanosized metallic Pd particles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016625
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7510–7517[article] Catalytic performance of solution combustion synthesized alumina - and ceria - supported Pt and Pd nanoparticles for the combustion of propane and dimethyl ether (DME) [texte imprimé] / Sara Colussi, Auteur ; Arup Gayen, Auteur ; Jordi Llorca, Auteur . - 2012 . - pp. 7510–7517.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7510–7517
Mots-clés : Catalytic Combustion Nanoparticles Résumé : Pd- and Pt-based catalysts supported on CeO2 and Al2O3 have been prepared by traditional incipient wetness impregnation and by solution combustion synthesis, and their catalytic activities have been compared for propane and DME combustion. Kinetic measurements carried out in a laboratory-scale recycle reactor apparatus indicate that combustion synthesized Pd-based materials are much more active than the corresponding impregnated ones, whereas for Pt-based catalysts no significant difference is observed. On the basis of high-resolution transmission electron microscopy (HRTEM) results, the enhanced catalytic activity is tentatively ascribed to the coexistence of highly active palladium centers (PdII species) that form upon solution combustion synthesis and nanosized metallic Pd particles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016625 Exemplaires
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Titre : Enzymatic hydrolysis of lignocellulosic biomasses via CFD and experiments Type de document : texte imprimé Auteurs : Danilo Carvajal, Auteur ; Daniele L. Marchisio, Auteur ; Samir Bensaid, Auteur Année de publication : 2012 Article en page(s) : pp. 7518–7525 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Enzymatic Hydrolysis Biomasses Résumé : The time evolution of the rheological properties of pretreated Arundo slurries has been estimated, during enzymatic hydrolysis for bioethanol production, by computational fluid dynamics simulations in conjunction with experimental tests on a laboratory scale anchor reactor with different solid concentrations (18.5 and 27.5% w/w) and stirring velocities (50–200 rpm). The simulations were carried out with Fluent 6.2 using the moving reference frame approach and the Herschel–Bulkley rheological model. Great care was taken in the development of the computational grid and in the solution of the numerical issues. The identification of the rheological parameters was successful and the results are consistent with other works published in the literature on similar systems. The next steps of this work will involve the use of these results to design new continuous reactors for enzymatic hydrolysis and their scale up to a pilot and industrial level. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201673t
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7518–7525[article] Enzymatic hydrolysis of lignocellulosic biomasses via CFD and experiments [texte imprimé] / Danilo Carvajal, Auteur ; Daniele L. Marchisio, Auteur ; Samir Bensaid, Auteur . - 2012 . - pp. 7518–7525.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7518–7525
Mots-clés : Enzymatic Hydrolysis Biomasses Résumé : The time evolution of the rheological properties of pretreated Arundo slurries has been estimated, during enzymatic hydrolysis for bioethanol production, by computational fluid dynamics simulations in conjunction with experimental tests on a laboratory scale anchor reactor with different solid concentrations (18.5 and 27.5% w/w) and stirring velocities (50–200 rpm). The simulations were carried out with Fluent 6.2 using the moving reference frame approach and the Herschel–Bulkley rheological model. Great care was taken in the development of the computational grid and in the solution of the numerical issues. The identification of the rheological parameters was successful and the results are consistent with other works published in the literature on similar systems. The next steps of this work will involve the use of these results to design new continuous reactors for enzymatic hydrolysis and their scale up to a pilot and industrial level. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201673t Exemplaires
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Titre : Screening analysis for hazard assessment of peroxides decomposition Type de document : texte imprimé Auteurs : V. Casson, Auteur ; G. Maschio, Auteur Année de publication : 2012 Article en page(s) : pp.7526–7535 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Analysis hazard assessment Peroxides Résumé : In this study, the analysis of the decomposition of four different peroxides (including hydrogen peroxide) by screening calorimetry is proposed. The objective is to analyze the decomposition reactions and evaluate the consequences in particular when the process undergoes to thermal explosion and may be the cause of incidents. Screening calorimetry data allow us to define the conditions and ranges of temperature and pressure evolved during the reaction. In the experimental apparatus used (a screening calorimeter), the experiments have been carried out safely, even when there is a rapid and large increase in temperature and pressure. Scanning and isothermal conditions has been investigated. An Early Warning Detection System (EWDS) for thermal runaway, based on the divergence criterion, has also been applied off-line to the experimental isothermal data, in order to evaluate the sensitivity of the method applied to both temperature and pressure profiles. The results of the application of the EWDS have been compared to those obtained using the Hub and Jones criterion. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201690n
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7526–7535[article] Screening analysis for hazard assessment of peroxides decomposition [texte imprimé] / V. Casson, Auteur ; G. Maschio, Auteur . - 2012 . - pp.7526–7535.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7526–7535
Mots-clés : Analysis hazard assessment Peroxides Résumé : In this study, the analysis of the decomposition of four different peroxides (including hydrogen peroxide) by screening calorimetry is proposed. The objective is to analyze the decomposition reactions and evaluate the consequences in particular when the process undergoes to thermal explosion and may be the cause of incidents. Screening calorimetry data allow us to define the conditions and ranges of temperature and pressure evolved during the reaction. In the experimental apparatus used (a screening calorimeter), the experiments have been carried out safely, even when there is a rapid and large increase in temperature and pressure. Scanning and isothermal conditions has been investigated. An Early Warning Detection System (EWDS) for thermal runaway, based on the divergence criterion, has also been applied off-line to the experimental isothermal data, in order to evaluate the sensitivity of the method applied to both temperature and pressure profiles. The results of the application of the EWDS have been compared to those obtained using the Hub and Jones criterion. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201690n Exemplaires
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Titre : Catalytic partial oxidation of isooctane to hydrogen on rhodium catalysts : Effect of tail - gas recycling Type de document : texte imprimé Auteurs : Torsten Kaltschmitt, Auteur ; Claudia Diehm, Auteur ; Olaf Deutschmann, Auteur Année de publication : 2012 Article en page(s) : pp. 7536-7546 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Recycling Catalyst Isooctane Partial oxidation Catalytic reaction Résumé : Catalytic partial oxidation (CPOX) is a promising technology for reforming of liquid hydrocarbon fuels to hydrogen or synthesis gas for use in fuel cells. The addition of a certain amount of the tail gas of the fuel cell stack to the reformer inlet feed can increase overall efficiency and lead to higher H2 and CO selectivities and reduce coke formation. The effect of carbon dioxide or steam addition (1, 5, 10, 20, and 30 vol% of the total flow) on the performance of a CPOX reformer operated with isooctane as fuel surrogate is systematically studied over a wide range of C/O feed ratios (0.72―1.79) using a Rh/alumina honeycomb catalyst. The specific impact of the coreactants H2O and CO2 on reformer behavior can be interpreted by the water gas shift (WGS) chemistry. Production of H2 and CO2 increases with H2O addition at the expense of CO and H2O. Opposite trends are observed in case of CO2 addition. Tail gas recycling reduces formation of soot precursors up to 50% compared to the corresponding fuel feed without coreactants. However, tail-gas recycling shifts the formation of soot precursors toward lower C/O ratios. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968306
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7536-7546[article] Catalytic partial oxidation of isooctane to hydrogen on rhodium catalysts : Effect of tail - gas recycling [texte imprimé] / Torsten Kaltschmitt, Auteur ; Claudia Diehm, Auteur ; Olaf Deutschmann, Auteur . - 2012 . - pp. 7536-7546.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7536-7546
Mots-clés : Recycling Catalyst Isooctane Partial oxidation Catalytic reaction Résumé : Catalytic partial oxidation (CPOX) is a promising technology for reforming of liquid hydrocarbon fuels to hydrogen or synthesis gas for use in fuel cells. The addition of a certain amount of the tail gas of the fuel cell stack to the reformer inlet feed can increase overall efficiency and lead to higher H2 and CO selectivities and reduce coke formation. The effect of carbon dioxide or steam addition (1, 5, 10, 20, and 30 vol% of the total flow) on the performance of a CPOX reformer operated with isooctane as fuel surrogate is systematically studied over a wide range of C/O feed ratios (0.72―1.79) using a Rh/alumina honeycomb catalyst. The specific impact of the coreactants H2O and CO2 on reformer behavior can be interpreted by the water gas shift (WGS) chemistry. Production of H2 and CO2 increases with H2O addition at the expense of CO and H2O. Opposite trends are observed in case of CO2 addition. Tail gas recycling reduces formation of soot precursors up to 50% compared to the corresponding fuel feed without coreactants. However, tail-gas recycling shifts the formation of soot precursors toward lower C/O ratios. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968306 Exemplaires
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Titre : High - pressure methane combustion over a perovskyte catalyst Type de document : texte imprimé Auteurs : Paola S. Barbato, Auteur ; Almerinda Di Benedetto, Auteur ; Valeria Di Sarli, Auteur Année de publication : 2012 Article en page(s) : pp. 7547–7558 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Combustion Catalyst Résumé : Catalytic combustion has been extensively studied as an alternative route to homogeneous combustion for power generation systems, in particular for gas turbines. Despite the great interest, very little work has been devoted to high-pressure catalytic combustion, i.e., under conditions more relevant for gas turbines. In this work, the effect of pressure on the catalytic combustion of methane on a perovskite-based monolith is investigated both experimentally and numerically. Results show that methane can be ignited by increasing the operating pressure, and this behavior can be reproduced qualitatively and quantitatively by simulating the monolith using simple overall homogeneous and heterogeneous reaction rates. Moreover, numerical results show that only the coupling between catalytic and homogeneous reactions allows correct prediction of methane conversion. As the operating pressure increases, the catalytic reaction is activated, thus behaving as a pilot for sustaining the homogeneous reaction that allows it to overcome the mass transport limitations at the catalytic surface. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201736p
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7547–7558[article] High - pressure methane combustion over a perovskyte catalyst [texte imprimé] / Paola S. Barbato, Auteur ; Almerinda Di Benedetto, Auteur ; Valeria Di Sarli, Auteur . - 2012 . - pp. 7547–7558.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7547–7558
Mots-clés : Combustion Catalyst Résumé : Catalytic combustion has been extensively studied as an alternative route to homogeneous combustion for power generation systems, in particular for gas turbines. Despite the great interest, very little work has been devoted to high-pressure catalytic combustion, i.e., under conditions more relevant for gas turbines. In this work, the effect of pressure on the catalytic combustion of methane on a perovskite-based monolith is investigated both experimentally and numerically. Results show that methane can be ignited by increasing the operating pressure, and this behavior can be reproduced qualitatively and quantitatively by simulating the monolith using simple overall homogeneous and heterogeneous reaction rates. Moreover, numerical results show that only the coupling between catalytic and homogeneous reactions allows correct prediction of methane conversion. As the operating pressure increases, the catalytic reaction is activated, thus behaving as a pilot for sustaining the homogeneous reaction that allows it to overcome the mass transport limitations at the catalytic surface. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201736p Exemplaires
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Titre : Influence of diesel fuel characteristics on soot oxidation properties Type de document : texte imprimé Auteurs : Harrie Jansma, Auteur ; Debora Fino, Auteur ; Renate Uitz, Auteur Année de publication : 2012 Article en page(s) : pp. 7559-7564 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Oxidation Soot Diesel fuel Résumé : This study provides an overview on the impact of fuels on certain soot characteristics, such as oxidation behavior and morphology. The aim is to understand how fuel parameters affect the ease at which soot can be oxidized. The oxidation behavior of soot samples obtained from different types of diesel fuel was determined by means of Temperature Programmed Oxidation in a Thermo-Gravimetric Analyzer and a six-flow reactor; the structural morphology of soot was examined via Transmission Electron Microscopy. The soot oxidation temperature was found to be dependent to a great extent on the type of the diesel fuel, when oxygen is the only oxidant with or without a Pt-catalyst upstream. Soot oxidation in the presence of NO and a Pt-catalyst upstream resulted in a reduction in the oxidation temperature; this environment also led to smaller differentiation between the soot samples compared with the pure oxygen conditions. The amount of sulfur in the fuel had only a minor impact on the soot oxidation temperature, whereas the aromatic compound content affected this temperature significantly. A low-aromatic fuel results in a soot with a significantly higher oxidation temperature than a fuel with a large amount of aromatics (particularly diaromatics). This may have an impact on induced diesel soot abatement and regeneration strategies in automotive Diesel Particulate Filters as well as on the design of a new class of diesel fuels. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968308
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7559-7564[article] Influence of diesel fuel characteristics on soot oxidation properties [texte imprimé] / Harrie Jansma, Auteur ; Debora Fino, Auteur ; Renate Uitz, Auteur . - 2012 . - pp. 7559-7564.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7559-7564
Mots-clés : Oxidation Soot Diesel fuel Résumé : This study provides an overview on the impact of fuels on certain soot characteristics, such as oxidation behavior and morphology. The aim is to understand how fuel parameters affect the ease at which soot can be oxidized. The oxidation behavior of soot samples obtained from different types of diesel fuel was determined by means of Temperature Programmed Oxidation in a Thermo-Gravimetric Analyzer and a six-flow reactor; the structural morphology of soot was examined via Transmission Electron Microscopy. The soot oxidation temperature was found to be dependent to a great extent on the type of the diesel fuel, when oxygen is the only oxidant with or without a Pt-catalyst upstream. Soot oxidation in the presence of NO and a Pt-catalyst upstream resulted in a reduction in the oxidation temperature; this environment also led to smaller differentiation between the soot samples compared with the pure oxygen conditions. The amount of sulfur in the fuel had only a minor impact on the soot oxidation temperature, whereas the aromatic compound content affected this temperature significantly. A low-aromatic fuel results in a soot with a significantly higher oxidation temperature than a fuel with a large amount of aromatics (particularly diaromatics). This may have an impact on induced diesel soot abatement and regeneration strategies in automotive Diesel Particulate Filters as well as on the design of a new class of diesel fuels. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968308 Exemplaires
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Titre : Particle number and size emissions from a small displacement automotive diesel engine : Bioderived vs conventional fossil fuels Type de document : texte imprimé Auteurs : Federico Millo, Auteur ; Davide Simone Vezza, Auteur ; Theodoros Vlachos, Auteur Année de publication : 2012 Article en page(s) : pp. 7565-7572 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fossil fuel Diesel engine Particle number Résumé : Experimental work has been carried out on a small displacement Euro 5 automotive diesel engine fueled alternatively with ultralow sulfur diesel (ULSD) and with two blends (30% vol) of ULSD, with two different fatty acid methyl esters (FAME) obtained from rapeseed methyl ester (RME) and jatropha methyl ester (JME). The engine-out particulate matter (PM) emissions have been characterized in terms of number and mass size distributions; measurements were performed under different engine operating conditions that are representative of the New European Driving Cycle (NEDC), including cold start of the engine. No significant differences were detected in the particle numbers (PN) for the different fuels under steady-state operating conditions, while a moderate reduction in particle mass size distribution was observed for the biofuel blends. The effects on PN emissions due to shifts in the engine operating points on the calibration maps, caused by the different fuel characteristics, have been shown to be significantly larger than the effects due to the different combustion characteristics of the biofuel blends, thus highlighting the need for a specific adjustment of the engine calihration. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968309
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7565-7572[article] Particle number and size emissions from a small displacement automotive diesel engine : Bioderived vs conventional fossil fuels [texte imprimé] / Federico Millo, Auteur ; Davide Simone Vezza, Auteur ; Theodoros Vlachos, Auteur . - 2012 . - pp. 7565-7572.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7565-7572
Mots-clés : Fossil fuel Diesel engine Particle number Résumé : Experimental work has been carried out on a small displacement Euro 5 automotive diesel engine fueled alternatively with ultralow sulfur diesel (ULSD) and with two blends (30% vol) of ULSD, with two different fatty acid methyl esters (FAME) obtained from rapeseed methyl ester (RME) and jatropha methyl ester (JME). The engine-out particulate matter (PM) emissions have been characterized in terms of number and mass size distributions; measurements were performed under different engine operating conditions that are representative of the New European Driving Cycle (NEDC), including cold start of the engine. No significant differences were detected in the particle numbers (PN) for the different fuels under steady-state operating conditions, while a moderate reduction in particle mass size distribution was observed for the biofuel blends. The effects on PN emissions due to shifts in the engine operating points on the calibration maps, caused by the different fuel characteristics, have been shown to be significantly larger than the effects due to the different combustion characteristics of the biofuel blends, thus highlighting the need for a specific adjustment of the engine calihration. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968309 Exemplaires
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Titre : Experimental and modeling analysis of the thermal behavior of an autothermal C3H8 catalytic partial oxidation reformer Type de document : texte imprimé Auteurs : Dario Livio, Auteur ; Alessandro Donazzi, Auteur ; Alessandra Beretta, Auteur Année de publication : 2012 Article en page(s) : pp. 7573–7583 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermal behavior Partial oxidation Résumé : In this work, a spatially resolved sampling technique is applied to characterize the performance of a C3H8 CPO reformer and to compare it with that of a CH4 reformer. The case of Rh-coated honeycomb catalysts is examined. The axial profiles show that higher temperatures are reached in C3H8 CPO, especially at the reactor inlet. Surface hot-spot temperatures around 950 °C lead the catalyst to rapid loss of activity. A detailed model analysis is also applied to better understand the reasons for the observed differences of the thermal behavior. On one hand, the heat release via oxidation reactions is controlled by O2 mass transfer rate and thus proportional to O2 inlet concentration, which is 20% higher in the C3H8/air mixture at equal C/O ratio. On the other hand, while CH4 steam reforming is partly chemically controlled, C3H8 steam reforming is mainly limited by gas–solid diffusion. Thus, a less efficient balance between exo- and endothermic reactions occurs in the case of C3H8 CPO, and this results in much higher hot-spot temperatures. As a consequence, specific strategies for the optimization of the thermal behavior are required depending on the fuel. Modeling of the C3H8 CPO results shows that an increased catalyst load or a suitable aspect ratio of the reactor, combined with a decrease of the flow rate, produces a beneficial moderation of the hot-spot temperature of the catalytic wall. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202098q
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7573–7583[article] Experimental and modeling analysis of the thermal behavior of an autothermal C3H8 catalytic partial oxidation reformer [texte imprimé] / Dario Livio, Auteur ; Alessandro Donazzi, Auteur ; Alessandra Beretta, Auteur . - 2012 . - pp. 7573–7583.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7573–7583
Mots-clés : Thermal behavior Partial oxidation Résumé : In this work, a spatially resolved sampling technique is applied to characterize the performance of a C3H8 CPO reformer and to compare it with that of a CH4 reformer. The case of Rh-coated honeycomb catalysts is examined. The axial profiles show that higher temperatures are reached in C3H8 CPO, especially at the reactor inlet. Surface hot-spot temperatures around 950 °C lead the catalyst to rapid loss of activity. A detailed model analysis is also applied to better understand the reasons for the observed differences of the thermal behavior. On one hand, the heat release via oxidation reactions is controlled by O2 mass transfer rate and thus proportional to O2 inlet concentration, which is 20% higher in the C3H8/air mixture at equal C/O ratio. On the other hand, while CH4 steam reforming is partly chemically controlled, C3H8 steam reforming is mainly limited by gas–solid diffusion. Thus, a less efficient balance between exo- and endothermic reactions occurs in the case of C3H8 CPO, and this results in much higher hot-spot temperatures. As a consequence, specific strategies for the optimization of the thermal behavior are required depending on the fuel. Modeling of the C3H8 CPO results shows that an increased catalyst load or a suitable aspect ratio of the reactor, combined with a decrease of the flow rate, produces a beneficial moderation of the hot-spot temperature of the catalytic wall. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202098q Exemplaires
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Titre : Kinetic study of diesel soot combustion with perovskite catalysts Type de document : texte imprimé Auteurs : Simelys Hernandez, Auteur Année de publication : 2012 Article en page(s) : pp. 7584-7589 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst Combustion Soot Kinetics Résumé : The objective of this paper is to analyze the kinetics of soot combustion, promoted by several catalysts, through differential scanning calorimetry (DSC) and thermogravimetic analysis (TGA). All the catalysts are substoichiometric or alkalimetal substituted perovskites (La0.9CrO3, La0.8CrO3, La0.9Rb0.1CrO3, La0.9Na0.1CrC3, La0.9Ku0.1CrO3,La0.8Cr0.9Li0.1O3) on the basis of the LaCrO3 standard, which was found to be active for this reaction in previous studies conducted by our group. Different model-free iso-conversion methods with the DSC data were used to determine the activation energies. Instead, thermogravimetric data were employed to determine the oxygen reaction order. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968311
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7584-7589[article] Kinetic study of diesel soot combustion with perovskite catalysts [texte imprimé] / Simelys Hernandez, Auteur . - 2012 . - pp. 7584-7589.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7584-7589
Mots-clés : Catalyst Combustion Soot Kinetics Résumé : The objective of this paper is to analyze the kinetics of soot combustion, promoted by several catalysts, through differential scanning calorimetry (DSC) and thermogravimetic analysis (TGA). All the catalysts are substoichiometric or alkalimetal substituted perovskites (La0.9CrO3, La0.8CrO3, La0.9Rb0.1CrO3, La0.9Na0.1CrC3, La0.9Ku0.1CrO3,La0.8Cr0.9Li0.1O3) on the basis of the LaCrO3 standard, which was found to be active for this reaction in previous studies conducted by our group. Different model-free iso-conversion methods with the DSC data were used to determine the activation energies. Instead, thermogravimetric data were employed to determine the oxygen reaction order. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968311 Exemplaires
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Titre : Conductive monolithic catalysts : Development and industrial pilot tests for the oxidation of o - xylene to phthalic anhydride Type de document : texte imprimé Auteurs : Gianpiero Groppi, Auteur ; Enrico Tronconi, Auteur ; Carlotta Cortelli, Auteur Année de publication : 2012 Article en page(s) : pp. 7590-7596 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Oxidation Catalyst Monolithic construction Résumé : We present herein results from a campaign (>1500 h) of o-xylene oxidation runs in a 1 in. single-tube technical fixed- bed pilot reactor (i.d = 24.6 mm) loaded with 16 washcoated (V2O5/TiO2) monolithic catalysts with Al honeycomb supports (each 10 cm long) and operated at typical industrial conditions for PA (phthalic anhydride) production. The highly conductive monolithic supports afforded substantially reduced axial T-gradients in comparison with reference runs in the same pilot reactor loaded with conventional egg-shell ring catalyst pellets, the maximum T-difference with the salt bath being halved at the same hot spot temperature (∼440 °C) and the mean bed temperature being about 20 °C higher. Temperature gradients were still moderate at an o-xylene feed concentration of 80 g/Nm3 (at Qair = 4 N m3/h), which represents an upper limit for industrial PA packed-bed reactors loaded with the same V2O5/TiO2 catalyst coated onto ring pellets. Operation at higher o-xylene feed contents (up to 95 g/Nm3) was found feasible. The Al honeycomb catalysts were successfully unloaded at the end ofthe runs. The strong (∼2-fold) enhancement of radial heat transfer rates associated with the adoption of highly conductive monolith catalyst supports is thus herein demonstrated at a fully representative industrial scale for the first time. It can be exploited, for instance, either to increase the o-aylene feed concentration, possibly above 100 g/Nm3 (and the PA productivity accordingly), within a retrofitting strategy, or to design new reactors with larger tube diameters, resulting in reduced investment costs. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968312
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7590-7596[article] Conductive monolithic catalysts : Development and industrial pilot tests for the oxidation of o - xylene to phthalic anhydride [texte imprimé] / Gianpiero Groppi, Auteur ; Enrico Tronconi, Auteur ; Carlotta Cortelli, Auteur . - 2012 . - pp. 7590-7596.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7590-7596
Mots-clés : Oxidation Catalyst Monolithic construction Résumé : We present herein results from a campaign (>1500 h) of o-xylene oxidation runs in a 1 in. single-tube technical fixed- bed pilot reactor (i.d = 24.6 mm) loaded with 16 washcoated (V2O5/TiO2) monolithic catalysts with Al honeycomb supports (each 10 cm long) and operated at typical industrial conditions for PA (phthalic anhydride) production. The highly conductive monolithic supports afforded substantially reduced axial T-gradients in comparison with reference runs in the same pilot reactor loaded with conventional egg-shell ring catalyst pellets, the maximum T-difference with the salt bath being halved at the same hot spot temperature (∼440 °C) and the mean bed temperature being about 20 °C higher. Temperature gradients were still moderate at an o-xylene feed concentration of 80 g/Nm3 (at Qair = 4 N m3/h), which represents an upper limit for industrial PA packed-bed reactors loaded with the same V2O5/TiO2 catalyst coated onto ring pellets. Operation at higher o-xylene feed contents (up to 95 g/Nm3) was found feasible. The Al honeycomb catalysts were successfully unloaded at the end ofthe runs. The strong (∼2-fold) enhancement of radial heat transfer rates associated with the adoption of highly conductive monolith catalyst supports is thus herein demonstrated at a fully representative industrial scale for the first time. It can be exploited, for instance, either to increase the o-aylene feed concentration, possibly above 100 g/Nm3 (and the PA productivity accordingly), within a retrofitting strategy, or to design new reactors with larger tube diameters, resulting in reduced investment costs. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968312 Exemplaires
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Titre : Pathways for N2 and N2O formation during the reduction of NOx over Pt – Ba/Al2O3 LNT catalysts investigated by labeling isotopic experiments Type de document : texte imprimé Auteurs : L. Lietti, Auteur ; N. Artioli, Auteur ; L. Righini, Auteur Année de publication : 2012 Article en page(s) : pp. 7597-7605 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst Résumé : Mechanistic aspects involved in the formation of N2 and of N2O during the reduction of gas-phase NO and of NOx stored over a model PtBa/Al2O3 NSR catalyst are investigated using unlabeled ammonia and labeled NO. The reduction of the stored NOx species (labeled nitrites and nitrates) with NH3 leads to the selective formation of N2 as a major product and of small amounts of nitrous oxide. Based on the nitrogen isotopic distribution, it appears that N2 formation occurs primarily through the statistical coupling of N-atoms formed by dissociation of NOx- and NH3-related surface intermediates, although an SCR- pathway (involving the coupling of NH3- and NO-derived ad-species) is also likely to occur. It appears as well that the formation of nitrous oxide involves either the coupling of two adsorbed NO molecules or the recombination of an adsorbed NO molecule with an adsorbed NHx fragment. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968313
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7597-7605[article] Pathways for N2 and N2O formation during the reduction of NOx over Pt – Ba/Al2O3 LNT catalysts investigated by labeling isotopic experiments [texte imprimé] / L. Lietti, Auteur ; N. Artioli, Auteur ; L. Righini, Auteur . - 2012 . - pp. 7597-7605.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7597-7605
Mots-clés : Catalyst Résumé : Mechanistic aspects involved in the formation of N2 and of N2O during the reduction of gas-phase NO and of NOx stored over a model PtBa/Al2O3 NSR catalyst are investigated using unlabeled ammonia and labeled NO. The reduction of the stored NOx species (labeled nitrites and nitrates) with NH3 leads to the selective formation of N2 as a major product and of small amounts of nitrous oxide. Based on the nitrogen isotopic distribution, it appears that N2 formation occurs primarily through the statistical coupling of N-atoms formed by dissociation of NOx- and NH3-related surface intermediates, although an SCR- pathway (involving the coupling of NH3- and NO-derived ad-species) is also likely to occur. It appears as well that the formation of nitrous oxide involves either the coupling of two adsorbed NO molecules or the recombination of an adsorbed NO molecule with an adsorbed NHx fragment. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968313 Exemplaires
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Titre : Effect of emulsifier type and disruption chamber geometry on the fabrication of food nanoemulsions by high pressure homogenization Type de document : texte imprimé Auteurs : Francesco Donsì, Auteur ; Mariarenata Sessa, Auteur ; Giovanna Ferrari, Auteur Année de publication : 2012 Article en page(s) : pp. 7606-7618 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Homogenization Food industry Disruption Emulsifier Résumé : Production of food nanoemulsions by high pressure homogenization (HPH) is investigated, focusing on the effect on droplet nanonization of emulsifier type and concentration, as well as of the geometry of the homogenization chamber. Several food-grade emulsifiers were characterized, in comparison with artificial ones, in terms of their interfacial and dynamic properties, by pendant drop measurements. The kinetics of the emulsification process was determined by dynamic light scattering measurements on the emulsions produced at different pressure levels (70―280 MPa) and number ofHPH passes, in four different homogenization chamber geometries. The results show that the kinetic parameters of the emulsification process can be primarily correlated with the interfacial and dynamic properties of the emulsifiers, while the fluid-dynamics regime establishing in the homogenization chamber contributes only to a lesser extent. Nevertheless, the correct design of the homogenization chamber may help in obtaining uniform fluid-dynamic conditions, which ensure a narrow droplet size distribution. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968314
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7606-7618[article] Effect of emulsifier type and disruption chamber geometry on the fabrication of food nanoemulsions by high pressure homogenization [texte imprimé] / Francesco Donsì, Auteur ; Mariarenata Sessa, Auteur ; Giovanna Ferrari, Auteur . - 2012 . - pp. 7606-7618.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7606-7618
Mots-clés : Homogenization Food industry Disruption Emulsifier Résumé : Production of food nanoemulsions by high pressure homogenization (HPH) is investigated, focusing on the effect on droplet nanonization of emulsifier type and concentration, as well as of the geometry of the homogenization chamber. Several food-grade emulsifiers were characterized, in comparison with artificial ones, in terms of their interfacial and dynamic properties, by pendant drop measurements. The kinetics of the emulsification process was determined by dynamic light scattering measurements on the emulsions produced at different pressure levels (70―280 MPa) and number ofHPH passes, in four different homogenization chamber geometries. The results show that the kinetic parameters of the emulsification process can be primarily correlated with the interfacial and dynamic properties of the emulsifiers, while the fluid-dynamics regime establishing in the homogenization chamber contributes only to a lesser extent. Nevertheless, the correct design of the homogenization chamber may help in obtaining uniform fluid-dynamic conditions, which ensure a narrow droplet size distribution. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968314 Exemplaires
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Titre : Five dead and five injured in a dimethyl terephthalate plant accident : Serious errors in the plant design coupled with incorrect maintenance management Type de document : texte imprimé Auteurs : N. Piccinini, Auteur ; M. Demichela, Auteur Année de publication : 2012 Article en page(s) : pp. 7619-7627 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Maintenance Design Accident Résumé : At 2:10 in the afternoon of 25 July 1968, an explosion in a tank at the SIR (Societa Italiana Resine) petrochemical industry in Porto Torres (Sassari, Sardinia) caused the death of five people and the injury of five others. This article reports the events that led to the accident and explains the analysis activities that led to the reconstruction of the dynamics of the accident. The reconstruction of the etiology of the accident has been synthesized in an Incidental Sequence Diagram, a similar logical tree to the Fault Tree, in which the serious errors in the plant design are highlighted together with the poor management of some of the maintenance works. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968315
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7619-7627[article] Five dead and five injured in a dimethyl terephthalate plant accident : Serious errors in the plant design coupled with incorrect maintenance management [texte imprimé] / N. Piccinini, Auteur ; M. Demichela, Auteur . - 2012 . - pp. 7619-7627.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7619-7627
Mots-clés : Maintenance Design Accident Résumé : At 2:10 in the afternoon of 25 July 1968, an explosion in a tank at the SIR (Societa Italiana Resine) petrochemical industry in Porto Torres (Sassari, Sardinia) caused the death of five people and the injury of five others. This article reports the events that led to the accident and explains the analysis activities that led to the reconstruction of the dynamics of the accident. The reconstruction of the etiology of the accident has been synthesized in an Incidental Sequence Diagram, a similar logical tree to the Fault Tree, in which the serious errors in the plant design are highlighted together with the poor management of some of the maintenance works. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968315 Exemplaires
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Titre : Why research into explosion mechanisms of flammable cloud is still necessary : Reducing uncertainty will make risk assessment and decision making stronger Type de document : texte imprimé Auteurs : Hans J. Pasman, Auteur Année de publication : 2012 Article en page(s) : pp. 7628–7635 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Explosion mechanisms flammable Résumé : Maintaining the process industry, including power plants, has become crucial to our way of life. The process industry, however, involves large quantities of hazardous substances that when spilt may present a threat to cause an explosion, a sustained fire, or a toxic cloud. These potential threats to life, structures, and the environment can be balanced by a variety of measures and ultimately by sufficient space. The central problem in spatial planning and licensing of plants containing substantial amounts of hazardous substances or planning transportation routes of these substances is to make decisions about safe distances in an environment of conflicting interests and large uncertainties, which are sometimes accompanied by emotions and “strong” perceptions. The uncertainties are due to incomplete knowledge about what can go wrong, how wrong it can go, and how likely it can go wrong. Improvements are sought in accordance with the International Risk Governance Council framework, learning from experiences elsewhere, maintaining robustness, but where required taking account of case specifics, including safety measures, improved models, and data and stakeholder outreach. Separate judgment of severity of consequences including injuries and other damage, and of likelihood categorized in probability classes accounts to some extent for uncertainty. Where possible the system of analysis shall be kept simple and affordable. Simplicity presumes, however, detailed knowledge of the mechanisms. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201165g
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7628–7635[article] Why research into explosion mechanisms of flammable cloud is still necessary : Reducing uncertainty will make risk assessment and decision making stronger [texte imprimé] / Hans J. Pasman, Auteur . - 2012 . - pp. 7628–7635.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7628–7635
Mots-clés : Explosion mechanisms flammable Résumé : Maintaining the process industry, including power plants, has become crucial to our way of life. The process industry, however, involves large quantities of hazardous substances that when spilt may present a threat to cause an explosion, a sustained fire, or a toxic cloud. These potential threats to life, structures, and the environment can be balanced by a variety of measures and ultimately by sufficient space. The central problem in spatial planning and licensing of plants containing substantial amounts of hazardous substances or planning transportation routes of these substances is to make decisions about safe distances in an environment of conflicting interests and large uncertainties, which are sometimes accompanied by emotions and “strong” perceptions. The uncertainties are due to incomplete knowledge about what can go wrong, how wrong it can go, and how likely it can go wrong. Improvements are sought in accordance with the International Risk Governance Council framework, learning from experiences elsewhere, maintaining robustness, but where required taking account of case specifics, including safety measures, improved models, and data and stakeholder outreach. Separate judgment of severity of consequences including injuries and other damage, and of likelihood categorized in probability classes accounts to some extent for uncertainty. Where possible the system of analysis shall be kept simple and affordable. Simplicity presumes, however, detailed knowledge of the mechanisms. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201165g Exemplaires
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Titre : Aspect ratio effects in unvented and vented dust explosions Type de document : texte imprimé Auteurs : F. Tamanini, Auteur Année de publication : 2012 Article en page(s) : pp. 7636–7642 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Dust explosions Résumé : The sizing of vents for explosion protection of equipment and buildings depends on many characteristics of the system, including details of the geometry of the protected enclosure. Its aspect ratio (H/D) has been recognized as an important parameter, with the general result that volumes of greater H/D require larger vent areas. Published data on dust explosions in elongated enclosures have been used to develop a new correlation for this effect. The data are for two dusts, cornstarch and wheat flour, and were obtained from tests in volumes of 1, 9.4, and 20 m3, for a range of aspect ratios. The experimental results, which have been analyzed using modeling techniques developed at FM Global, have yielded a correlation that is validated against more than 200 points and includes the effect of the location of the ignition source. Comparisons with the formulas recommended in VDI 3673 (2002) (also EN 14491, 2006) and NFPA 68 (2007) have shown these alternative methods to yield predictions that either overpredict (VDI and EN) or are in general agreement (NFPA) with those from the present correlation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2015747
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7636–7642[article] Aspect ratio effects in unvented and vented dust explosions [texte imprimé] / F. Tamanini, Auteur . - 2012 . - pp. 7636–7642.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7636–7642
Mots-clés : Dust explosions Résumé : The sizing of vents for explosion protection of equipment and buildings depends on many characteristics of the system, including details of the geometry of the protected enclosure. Its aspect ratio (H/D) has been recognized as an important parameter, with the general result that volumes of greater H/D require larger vent areas. Published data on dust explosions in elongated enclosures have been used to develop a new correlation for this effect. The data are for two dusts, cornstarch and wheat flour, and were obtained from tests in volumes of 1, 9.4, and 20 m3, for a range of aspect ratios. The experimental results, which have been analyzed using modeling techniques developed at FM Global, have yielded a correlation that is validated against more than 200 points and includes the effect of the location of the ignition source. Comparisons with the formulas recommended in VDI 3673 (2002) (also EN 14491, 2006) and NFPA 68 (2007) have shown these alternative methods to yield predictions that either overpredict (VDI and EN) or are in general agreement (NFPA) with those from the present correlation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2015747 Exemplaires
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Titre : Influence of large obstacles and mitigation barriers on heavy gas cloud dispersion : A liquefied natural gas case - study Type de document : texte imprimé Auteurs : Valentina Busini, Auteur ; Massimiliano Lino, Auteur ; Renato Rota, Auteur Année de publication : 2012 Article en page(s) : pp. 7643–7650 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Liquefied natural gas Résumé : The study of the consequences of heavy gases releases is of paramount importance in the safety analysis because of the large damage areas involved. The Computational Fluid Dynamics (CFD) models, unlike the integral ones that are simpler and faster, allow for a complete description of complex geometries, such as those involved in industrial plants or urban areas. In this work, the effect of typical large obstacles present in a real plant has been studied. Moreover, to verify the effectiveness of mitigation barriers on the dispersion of clouds produced by massive release of heavy gases, several types of walls have been investigated by analyzing the induced changes in the hazardous area. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201591b
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7643–7650[article] Influence of large obstacles and mitigation barriers on heavy gas cloud dispersion : A liquefied natural gas case - study [texte imprimé] / Valentina Busini, Auteur ; Massimiliano Lino, Auteur ; Renato Rota, Auteur . - 2012 . - pp. 7643–7650.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7643–7650
Mots-clés : Liquefied natural gas Résumé : The study of the consequences of heavy gases releases is of paramount importance in the safety analysis because of the large damage areas involved. The Computational Fluid Dynamics (CFD) models, unlike the integral ones that are simpler and faster, allow for a complete description of complex geometries, such as those involved in industrial plants or urban areas. In this work, the effect of typical large obstacles present in a real plant has been studied. Moreover, to verify the effectiveness of mitigation barriers on the dispersion of clouds produced by massive release of heavy gases, several types of walls have been investigated by analyzing the induced changes in the hazardous area. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201591b Exemplaires
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Titre : Review of the explosibility of nontraditional dusts Type de document : texte imprimé Auteurs : S. Morgan Worsfold, Auteur ; Paul R. Amyotte, Auteur ; Faisal I. Khan, Auteur Année de publication : 2012 Article en page(s) : pp. 7651–7655 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Explosion dusts Résumé : This paper explores the explosion characteristics of three nontraditional dusts: nanomaterials, flocculent materials, and hybrid mixtures. Nanomaterials have a high likelihood of explosion with minimum ignition energies potentially less than 1 mJ. These low ignition energies may therefore allow nanomaterials to ignite due to electrostatic sparks, collision, or mechanical friction. The severity of nanomaterial explosions is affected by agglomeration and coagulation of the particles. Flocculent materials with a high length-to-diameter ratio exhibit explosion behavior patterns similar to those for spherical dusts. The length of flocculent particles plays a role in explosion likelihood which is not yet fully understood. High voltage discharge during the electrostatic flocking process is a common flocculent ignition hazard. Hybrid mixtures of a combustible dust and a flammable gas/vapor display a higher explosion severity and a lower minimum explosible concentration than that of the dust alone. Violent hybrid explosions may occur even if the dust and the gas/vapor are below their respective lean limit concentrations. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201614b
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7651–7655[article] Review of the explosibility of nontraditional dusts [texte imprimé] / S. Morgan Worsfold, Auteur ; Paul R. Amyotte, Auteur ; Faisal I. Khan, Auteur . - 2012 . - pp. 7651–7655.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7651–7655
Mots-clés : Explosion dusts Résumé : This paper explores the explosion characteristics of three nontraditional dusts: nanomaterials, flocculent materials, and hybrid mixtures. Nanomaterials have a high likelihood of explosion with minimum ignition energies potentially less than 1 mJ. These low ignition energies may therefore allow nanomaterials to ignite due to electrostatic sparks, collision, or mechanical friction. The severity of nanomaterial explosions is affected by agglomeration and coagulation of the particles. Flocculent materials with a high length-to-diameter ratio exhibit explosion behavior patterns similar to those for spherical dusts. The length of flocculent particles plays a role in explosion likelihood which is not yet fully understood. High voltage discharge during the electrostatic flocking process is a common flocculent ignition hazard. Hybrid mixtures of a combustible dust and a flammable gas/vapor display a higher explosion severity and a lower minimum explosible concentration than that of the dust alone. Violent hybrid explosions may occur even if the dust and the gas/vapor are below their respective lean limit concentrations. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201614b Exemplaires
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Titre : Comparing pyrolysis gases and dusts explosivities : A clue to understanding hybrid mixtures explosions? Type de document : texte imprimé Auteurs : Olivier Dufaud, Auteur ; Manon Poupeau, Auteur ; Imad Khalili, Auteur Année de publication : 2012 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Explosions Explosivity Dust Pyrolysis Résumé : During the explosion of an organic dust cloud, the following steps are usually encountered: particle heating; its devolatilization/pyrolysis; and, then, a homogeneous combustion of the pyrolysis gases. In order to highlight the influence of the pyrolysis step in such explosions, experiments have been carried out on wheat starch powders and their pyrolysis gases. The maximum rate of pressure rise of the gases reaches 2830 bar s―1, whereas it remains lower than 400 bar s―1 for the starch at the same fuel equivalence ratio. Such a difference can be explained by the predominance of the pyrolysis step, but also, to a lesser extent, by changes in the initial turbulence level of the suspension. A model based on the Hash pyrolysis mechanisms of cellulosic compounds and their combustion has been developed to represent the evolution of the explosion pressure of such powders. Applications to the case of gas/dust hybrid mixtures are also discussed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968320
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012)[article] Comparing pyrolysis gases and dusts explosivities : A clue to understanding hybrid mixtures explosions? [texte imprimé] / Olivier Dufaud, Auteur ; Manon Poupeau, Auteur ; Imad Khalili, Auteur . - 2012.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012)
Mots-clés : Explosions Explosivity Dust Pyrolysis Résumé : During the explosion of an organic dust cloud, the following steps are usually encountered: particle heating; its devolatilization/pyrolysis; and, then, a homogeneous combustion of the pyrolysis gases. In order to highlight the influence of the pyrolysis step in such explosions, experiments have been carried out on wheat starch powders and their pyrolysis gases. The maximum rate of pressure rise of the gases reaches 2830 bar s―1, whereas it remains lower than 400 bar s―1 for the starch at the same fuel equivalence ratio. Such a difference can be explained by the predominance of the pyrolysis step, but also, to a lesser extent, by changes in the initial turbulence level of the suspension. A model based on the Hash pyrolysis mechanisms of cellulosic compounds and their combustion has been developed to represent the evolution of the explosion pressure of such powders. Applications to the case of gas/dust hybrid mixtures are also discussed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968320 Exemplaires
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Titre : Combined effect of ignition energy and Initial turbulence on the explosion behavior of lean gas/dust - air mixtures Type de document : texte imprimé Auteurs : Almerinda Di Benedetto, Auteur ; Anita Garcia-Agreda, Auteur ; Paola Russo, Auteur Année de publication : 2012 Article en page(s) : pp. 7663-7670 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Dust Explosions Turbulence Ignition Résumé : Explosions of hybrid mixtures of methane and nicotinic acid are investigated near the lower-flammability-limit conditions. The effect on the maximum pressure and deflagration index of the ignition energy and, then, of the ignition source in combination with the turbulence is analyzed. In correspondence of limit conditions for pure methane and pure nicotinic acid, the variation of both the ignition energy and the turbulence was found to affect the behavior of the explosion. It was observed that the deflagration index is determined to be independent from the ignition energy, even though the dependence on the turbulence still remains. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968321
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7663-7670[article] Combined effect of ignition energy and Initial turbulence on the explosion behavior of lean gas/dust - air mixtures [texte imprimé] / Almerinda Di Benedetto, Auteur ; Anita Garcia-Agreda, Auteur ; Paola Russo, Auteur . - 2012 . - pp. 7663-7670.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7663-7670
Mots-clés : Dust Explosions Turbulence Ignition Résumé : Explosions of hybrid mixtures of methane and nicotinic acid are investigated near the lower-flammability-limit conditions. The effect on the maximum pressure and deflagration index of the ignition energy and, then, of the ignition source in combination with the turbulence is analyzed. In correspondence of limit conditions for pure methane and pure nicotinic acid, the variation of both the ignition energy and the turbulence was found to affect the behavior of the explosion. It was observed that the deflagration index is determined to be independent from the ignition energy, even though the dependence on the turbulence still remains. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968321 Exemplaires
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Titre : Explosions of syngas/CO2 mixtures in oxygen - enriched air Type de document : texte imprimé Auteurs : Ernesto Salzano, Auteur ; Anna Basco, Auteur ; Francesco Cammarota, Auteur Année de publication : 2012 Article en page(s) : pp. 7671–7678 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Syngas combustion Résumé : Most of the scientific works on syngas combustion deal with dry air as oxidizer, whereas very few studies have been carried out on syngas combustion in oxygen-enriched air (i.e., oxy-combustion). In this work, the explosion behavior (peak pressure and burning velocity) for H2/CO/O2/N2/CO2 mixtures has been evaluated experimentally and numerically, for different H2/CO ratios, fuel (H2+CO) concentrations with respect to O2, molar percentages of CO2, and for values of the oxygen-enrichment factor, E (= O2/O2+N2), ranging from 0.21 (i.e., air) to 1 (i.e., pure oxygen). The Sandia PREMIX module of the CHEMKIN package, coupled to the detailed Davis reaction scheme, was used to calculate the unstretched laminar burning velocity. Results have shown a good agreement with the experimental data. Through ad hoc simulations, the role of CO2 has been also evaluated. Furthermore, the ranges of validity of the additivity rule for the burning velocity have been identified. All tests show the typical trend of pressure time history of explosions occurring in a closed combustion chamber. However, some compositions show anomalous impulses that could not be explained by classical theory for deflagration/detonation. Explanation for this behavior is based on results of previous works by the same authors on combustion-induced Rapid Phase Transition (c-RPT). ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201734u
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7671–7678[article] Explosions of syngas/CO2 mixtures in oxygen - enriched air [texte imprimé] / Ernesto Salzano, Auteur ; Anna Basco, Auteur ; Francesco Cammarota, Auteur . - 2012 . - pp. 7671–7678.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7671–7678
Mots-clés : Syngas combustion Résumé : Most of the scientific works on syngas combustion deal with dry air as oxidizer, whereas very few studies have been carried out on syngas combustion in oxygen-enriched air (i.e., oxy-combustion). In this work, the explosion behavior (peak pressure and burning velocity) for H2/CO/O2/N2/CO2 mixtures has been evaluated experimentally and numerically, for different H2/CO ratios, fuel (H2+CO) concentrations with respect to O2, molar percentages of CO2, and for values of the oxygen-enrichment factor, E (= O2/O2+N2), ranging from 0.21 (i.e., air) to 1 (i.e., pure oxygen). The Sandia PREMIX module of the CHEMKIN package, coupled to the detailed Davis reaction scheme, was used to calculate the unstretched laminar burning velocity. Results have shown a good agreement with the experimental data. Through ad hoc simulations, the role of CO2 has been also evaluated. Furthermore, the ranges of validity of the additivity rule for the burning velocity have been identified. All tests show the typical trend of pressure time history of explosions occurring in a closed combustion chamber. However, some compositions show anomalous impulses that could not be explained by classical theory for deflagration/detonation. Explanation for this behavior is based on results of previous works by the same authors on combustion-induced Rapid Phase Transition (c-RPT). ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201734u Exemplaires
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Titre : Performance assessment of passive fire protection materials Type de document : texte imprimé Auteurs : Mercedes Gomez-Mares, Auteur ; Alessandro Tugnoli, Auteur ; Gabriele Landucci, Auteur Année de publication : 2012 Article en page(s) : pp. 7679-7689 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fire protection Résumé : The performance of fireproofing materials in providing effective protection from fire strongly depends on the thermophysical properties and on the behavior of the material during fire exposure. Not only active insulators but also nonactive coatings may undergo significant changes in their structure and properties when exposed to high temperatures. The present study focused on the measurement of some key properties for a set of three reference fireproofing materials of different nature. The changes in morphology and in the physical properties during fire exposure were investigated and they were dramatic for the case of active fireproofing materials. For these materials, the time required to reach a steady-state condition in the heat transfer may be significant. The use of a simple heat-transfer model, based on the experimental data obtained for the reference materials studied, demonstrated the importance of accounting for changes in the physical properties, paving the way to further applications in advanced studies of the fireproofing performance in complex geometries and critical scenarios. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201867v
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7679-7689[article] Performance assessment of passive fire protection materials [texte imprimé] / Mercedes Gomez-Mares, Auteur ; Alessandro Tugnoli, Auteur ; Gabriele Landucci, Auteur . - 2012 . - pp. 7679-7689.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7679-7689
Mots-clés : Fire protection Résumé : The performance of fireproofing materials in providing effective protection from fire strongly depends on the thermophysical properties and on the behavior of the material during fire exposure. Not only active insulators but also nonactive coatings may undergo significant changes in their structure and properties when exposed to high temperatures. The present study focused on the measurement of some key properties for a set of three reference fireproofing materials of different nature. The changes in morphology and in the physical properties during fire exposure were investigated and they were dramatic for the case of active fireproofing materials. For these materials, the time required to reach a steady-state condition in the heat transfer may be significant. The use of a simple heat-transfer model, based on the experimental data obtained for the reference materials studied, demonstrated the importance of accounting for changes in the physical properties, paving the way to further applications in advanced studies of the fireproofing performance in complex geometries and critical scenarios. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201867v Exemplaires
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Titre : A comparative study of turbulent premixed flames propagating past repeated obstacles Type de document : texte imprimé Auteurs : A. R. Masri, Auteur ; A. AlHarbi, Auteur ; S. Meares, Auteur Année de publication : 2012 Article en page(s) : pp.7690–7703 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Turbulent Flames Résumé : This paper presents a comparison of the overpressures and pressure gradients obtained in turbulent premixed flames of liquified petroleum gas (LPG), compressed natural gas (CNG), and hydrogen propagating past solid obstacles. The fuel-air mixture is initially at rest and is ignited at the base of a vented chamber. For each fuel a total of eighteen configurations are studied here with various permutations of three baffles plates and an obstacle with a square cross section providing a blockage ratio of either 0.24 or 0.5. High speed laser induced fluorescence from OH (LIF-OH) imaging is also performed at a repetition rate of 5kHz providing new measurements of the evolution of the flame front along the middle section of the chamber. It is found that for all fuels the peak pressure as well as the rate change of pressure increases not only with increasing blockage ratio induced by the increasing blockage ratio, but also with decreasing separation between successive baffles. The peak pressure and its rate of change in hydrogen flames are over an order of magnitude higher than those obtained in LPG and CNG fuels. High speed images of LIF-OH show that the degree of wrinkling and contortion in the flame front also increases significantly with increasing blockages. It is evident from the LIF-OH images that the flame front relaminarises as the separation between successive obstacles increase hence explaining the pressure decrease with increasing separation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201928g
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7690–7703[article] A comparative study of turbulent premixed flames propagating past repeated obstacles [texte imprimé] / A. R. Masri, Auteur ; A. AlHarbi, Auteur ; S. Meares, Auteur . - 2012 . - pp.7690–7703.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7690–7703
Mots-clés : Turbulent Flames Résumé : This paper presents a comparison of the overpressures and pressure gradients obtained in turbulent premixed flames of liquified petroleum gas (LPG), compressed natural gas (CNG), and hydrogen propagating past solid obstacles. The fuel-air mixture is initially at rest and is ignited at the base of a vented chamber. For each fuel a total of eighteen configurations are studied here with various permutations of three baffles plates and an obstacle with a square cross section providing a blockage ratio of either 0.24 or 0.5. High speed laser induced fluorescence from OH (LIF-OH) imaging is also performed at a repetition rate of 5kHz providing new measurements of the evolution of the flame front along the middle section of the chamber. It is found that for all fuels the peak pressure as well as the rate change of pressure increases not only with increasing blockage ratio induced by the increasing blockage ratio, but also with decreasing separation between successive baffles. The peak pressure and its rate of change in hydrogen flames are over an order of magnitude higher than those obtained in LPG and CNG fuels. High speed images of LIF-OH show that the degree of wrinkling and contortion in the flame front also increases significantly with increasing blockages. It is evident from the LIF-OH images that the flame front relaminarises as the separation between successive obstacles increase hence explaining the pressure decrease with increasing separation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201928g Exemplaires
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Titre : Sensitivity to the presence of the combustion submodel for large eddy simulation of transient premixed flame – vortex interactions Type de document : texte imprimé Auteurs : Valeria Di Sarli, Auteur ; Almerinda Di Benedetto, Auteur Année de publication : 2012 Article en page(s) : pp. 7704–7712 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Combustion Transient flame Résumé : In this paper, the sensitivity of large eddy simulation (LES) to the presence of the combustion submodel was investigated for transient interactions between premixed flame fronts and toroidal vortex structures generated at the wake of a circular orifice. To this end, LES computations were run, with and without the combustion submodel, for two orifice diameters: 40 mm and 20 mm. Nonuniform unstructured grids with a cell characteristic length varying in the range of 0.5–1 mm were used. In going from the 40-mm orifice to the 20-mm orifice, both the size and velocity of the vortex increase, leading to a different regime of interaction with the flame: the vortex only wrinkles the flame front in the 40-mm case (wrinkled regime) and also disrupts the continuity of the front, giving rise to the formation of separate reaction zones (i.e., flame pockets that leave the main front), in the 20-mm case (breakthrough regime). It has been found that the impact of the combustion submodel on LES predictions is strongly dependent on the regime of interaction. Results for the 40-mm orifice are substantially the same, regardless of the presence of the combustion submodel. Conversely, at the wake of the 20-mm orifice, the intensity of the flame–vortex interaction is such that the combustion submodel is strictly needed to reproduce both the qualitative (evolution of the pockets formed and their interaction with the main front) and quantitative (flame speed) characteristics of the flame propagation correctly. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202061u
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7704–7712[article] Sensitivity to the presence of the combustion submodel for large eddy simulation of transient premixed flame – vortex interactions [texte imprimé] / Valeria Di Sarli, Auteur ; Almerinda Di Benedetto, Auteur . - 2012 . - pp. 7704–7712.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7704–7712
Mots-clés : Combustion Transient flame Résumé : In this paper, the sensitivity of large eddy simulation (LES) to the presence of the combustion submodel was investigated for transient interactions between premixed flame fronts and toroidal vortex structures generated at the wake of a circular orifice. To this end, LES computations were run, with and without the combustion submodel, for two orifice diameters: 40 mm and 20 mm. Nonuniform unstructured grids with a cell characteristic length varying in the range of 0.5–1 mm were used. In going from the 40-mm orifice to the 20-mm orifice, both the size and velocity of the vortex increase, leading to a different regime of interaction with the flame: the vortex only wrinkles the flame front in the 40-mm case (wrinkled regime) and also disrupts the continuity of the front, giving rise to the formation of separate reaction zones (i.e., flame pockets that leave the main front), in the 20-mm case (breakthrough regime). It has been found that the impact of the combustion submodel on LES predictions is strongly dependent on the regime of interaction. Results for the 40-mm orifice are substantially the same, regardless of the presence of the combustion submodel. Conversely, at the wake of the 20-mm orifice, the intensity of the flame–vortex interaction is such that the combustion submodel is strictly needed to reproduce both the qualitative (evolution of the pockets formed and their interaction with the main front) and quantitative (flame speed) characteristics of the flame propagation correctly. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202061u Exemplaires
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Titre : Analysis of an explosion in a wool - processing plant Type de document : texte imprimé Auteurs : Piero Salatino, Auteur ; Almerinda Di Benedetto, Auteur ; Riccardo Chirone, Auteur Année de publication : 2012 Article en page(s) : pp. 7713–7718 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Analysis explosion wool Résumé : A major accident occurred in an Italian wool factory in 2001, culminating with a severe explosion, despite that wool is recognized as the most flame-resistant among the natural textile fibers. The analysis of this exceptional event suggests that, in addition to classical explosion parameters, three key phenomena related to the process jointly contributed to trigger the otherwise unexpected combustion of wool flock suspensions. The first and more important phenomenon is represented by the segregation of dust mixtures occurring during processing of textile fibers and storage of byproduct. Segregation may isolate and concentrate the lighter component of wool processing byproduct as a flammable dust. The main conclusion of our analysis is that, when performing risk assessment, sampling of all materials is a necessary step, since flammability and explosivity of raw materials may not be representative of the safety of the whole process. The second phenomenon is the enhancement of the combustion of the flammable dust layered on nets as they are subjected to cross-flow of air. The enhancement may be such as to promote transition from smoldering to flaming combustion of the dust layer. The third phenomenon is related to the interaction among the flame, the induced turbulence, dust dispersion into clouds and the layout of the plant. The combination of these phenomena promoted a deflagration of unexpected severity. In this paper, the dynamics of the explosion is analyzed in the light of the occurrence of the above cited phenomena. Purposely designed experimental tests have been performed to support the key role of segregation, formation, and ignition of the flammable cloud. Results clarify that real-world dust explosion accidents may be more severe than it could be anticipated on the basis of standard laboratory tests. A procedure for risk analysis is given to predict explosions of flocking materials. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2023614
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7713–7718[article] Analysis of an explosion in a wool - processing plant [texte imprimé] / Piero Salatino, Auteur ; Almerinda Di Benedetto, Auteur ; Riccardo Chirone, Auteur . - 2012 . - pp. 7713–7718.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7713–7718
Mots-clés : Analysis explosion wool Résumé : A major accident occurred in an Italian wool factory in 2001, culminating with a severe explosion, despite that wool is recognized as the most flame-resistant among the natural textile fibers. The analysis of this exceptional event suggests that, in addition to classical explosion parameters, three key phenomena related to the process jointly contributed to trigger the otherwise unexpected combustion of wool flock suspensions. The first and more important phenomenon is represented by the segregation of dust mixtures occurring during processing of textile fibers and storage of byproduct. Segregation may isolate and concentrate the lighter component of wool processing byproduct as a flammable dust. The main conclusion of our analysis is that, when performing risk assessment, sampling of all materials is a necessary step, since flammability and explosivity of raw materials may not be representative of the safety of the whole process. The second phenomenon is the enhancement of the combustion of the flammable dust layered on nets as they are subjected to cross-flow of air. The enhancement may be such as to promote transition from smoldering to flaming combustion of the dust layer. The third phenomenon is related to the interaction among the flame, the induced turbulence, dust dispersion into clouds and the layout of the plant. The combination of these phenomena promoted a deflagration of unexpected severity. In this paper, the dynamics of the explosion is analyzed in the light of the occurrence of the above cited phenomena. Purposely designed experimental tests have been performed to support the key role of segregation, formation, and ignition of the flammable cloud. Results clarify that real-world dust explosion accidents may be more severe than it could be anticipated on the basis of standard laboratory tests. A procedure for risk analysis is given to predict explosions of flocking materials. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2023614 Exemplaires
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Titre : Thermal degradation of aqueous piperazine for CO2 capture. 1. effect of process conditions and comparison of thermal stability of CO2 capture amines Type de document : texte imprimé Auteurs : Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur Année de publication : 2012 Article en page(s) : pp. 7719–7725 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermal degradation Aqueous piperazine stability Résumé : The effect of process conditions on the rate of thermal degradation of concentrated, aqueous piperazine (PZ) was investigated. At 150 °C, 8 m (m) PZ degrades with a first order rate constant, k1, of 6.1 × 10–9 s–1. Thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity demonstrated an Arrhenius dependence on temperature with an activation energy of 184 kJ/mol. Degradation at 175 °C was negligible with no dissolved CO2, while the k1 increased from 65 to 71 × 10–9 s–1 at 0.1 to 0.4 mol CO2/mol alkalinity and decreased to 24 × 10–9 s–1 at 0.47 mol CO2/mol alkalinity. In an industrial system with a simple stripper, losses due to thermal degradation are expected to be 0.043 mmol PZ/mol CO2 captured. In the case of a 2-stage flash, losses are expected to be only 0.0086 mmol PZ/mol CO2 captured. A Maximum Estimated Stripper Temperature (MEST) was calculated for a variety of amines to provide the same thermal degradation rate of MEA at 120 °C based on first order rate constants for amine loss during thermal degradation and the expected Arrhenius dependence on temperature for all amines. Substituted and unsubstituted 6-member amine rings were found to be the most thermally stable. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201916x
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7719–7725[article] Thermal degradation of aqueous piperazine for CO2 capture. 1. effect of process conditions and comparison of thermal stability of CO2 capture amines [texte imprimé] / Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur . - 2012 . - pp. 7719–7725.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7719–7725
Mots-clés : Thermal degradation Aqueous piperazine stability Résumé : The effect of process conditions on the rate of thermal degradation of concentrated, aqueous piperazine (PZ) was investigated. At 150 °C, 8 m (m) PZ degrades with a first order rate constant, k1, of 6.1 × 10–9 s–1. Thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity demonstrated an Arrhenius dependence on temperature with an activation energy of 184 kJ/mol. Degradation at 175 °C was negligible with no dissolved CO2, while the k1 increased from 65 to 71 × 10–9 s–1 at 0.1 to 0.4 mol CO2/mol alkalinity and decreased to 24 × 10–9 s–1 at 0.47 mol CO2/mol alkalinity. In an industrial system with a simple stripper, losses due to thermal degradation are expected to be 0.043 mmol PZ/mol CO2 captured. In the case of a 2-stage flash, losses are expected to be only 0.0086 mmol PZ/mol CO2 captured. A Maximum Estimated Stripper Temperature (MEST) was calculated for a variety of amines to provide the same thermal degradation rate of MEA at 120 °C based on first order rate constants for amine loss during thermal degradation and the expected Arrhenius dependence on temperature for all amines. Substituted and unsubstituted 6-member amine rings were found to be the most thermally stable. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201916x Exemplaires
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Titre : Thermal degradation of aqueous piperazine for CO2 capture : 2. Product types and generation rates Type de document : texte imprimé Auteurs : Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur Année de publication : 2012 Article en page(s) : pp. 7726–7735 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermal degradation Aqueous piperazine Résumé : The generation of degradation products at 135 to 175 °C was investigated for concentrated, aqueous piperazine (PZ) loaded with CO2. From 135 to 175 °C, N-formylpiperazine, ammonium, N-(2-aminoethyl)piperazine, and 2-imidazolidone were found to be the most abundant products. These species accounted for 63% of nitrogen and 49% of carbon lost as PZ and CO2 during degradation. Thermal degradation of PZ is believed to be initiated by the nucleophilic attack of PZ at the α-carbon to a protonated amino function on H+PZ to create a ring opened PZ structure. H+PZ was found to be the active and likely initiating species required for the initial reactions of thermal degradation. Further SN2 substitution reactions can produce a variety of products. CO2 is not required for thermal degradation to proceed but is reduced to create formate or formyl amides, reacts with amines to form stable ureas, and dictates the overall product mix. The mechanism for CO2 reduction to formate or formyl amides is not clear but indicates the severity of thermal degradation conditions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201917c
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7726–7735[article] Thermal degradation of aqueous piperazine for CO2 capture : 2. Product types and generation rates [texte imprimé] / Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur . - 2012 . - pp. 7726–7735.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7726–7735
Mots-clés : Thermal degradation Aqueous piperazine Résumé : The generation of degradation products at 135 to 175 °C was investigated for concentrated, aqueous piperazine (PZ) loaded with CO2. From 135 to 175 °C, N-formylpiperazine, ammonium, N-(2-aminoethyl)piperazine, and 2-imidazolidone were found to be the most abundant products. These species accounted for 63% of nitrogen and 49% of carbon lost as PZ and CO2 during degradation. Thermal degradation of PZ is believed to be initiated by the nucleophilic attack of PZ at the α-carbon to a protonated amino function on H+PZ to create a ring opened PZ structure. H+PZ was found to be the active and likely initiating species required for the initial reactions of thermal degradation. Further SN2 substitution reactions can produce a variety of products. CO2 is not required for thermal degradation to proceed but is reduced to create formate or formyl amides, reacts with amines to form stable ureas, and dictates the overall product mix. The mechanism for CO2 reduction to formate or formyl amides is not clear but indicates the severity of thermal degradation conditions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201917c Exemplaires
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Titre : Crystallization kinetics of monosodium aluminate hydrate in concentrated sodium aluminate solutions Type de document : texte imprimé Auteurs : Shaowei You, Auteur ; Yifei Zhang, Auteur ; Shaotao Cao, Auteur Année de publication : 2012 Article en page(s) : pp. 7736–7741 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Crystallization Kinetics Résumé : The nucleation, growth, and agglomeration of monosodium aluminate hydrate (MAH) crystallization in concentrated sodium aluminate solutions were investigated in a steady-state mixed-suspension–mixed-product-removal (MSMPR) crystallizer, and the mechanism was analyzed in detail. The crystal growth was diffusion- and surface-integration-controlled, and the secondary nucleation, as a result of crystal–agitator and crystal–crystallizer collisions, was determined further. The agglomeration kernel, expressed in terms of mean residence time, growth rate, and suspension density, was found to have a positive order of about 0.52 in the suspension density, indicating that the agglomeration kernel increased at higher frequencies of collisions between particles. The growth rate of MAH was found to be higher than that of gibbsite in active NaAl(OH)4–NaHCO3 systems, but the nucleation rate of MAH was lower than that of gibbsite in seeded-hydrolysis processes. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202622h
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7736–7741[article] Crystallization kinetics of monosodium aluminate hydrate in concentrated sodium aluminate solutions [texte imprimé] / Shaowei You, Auteur ; Yifei Zhang, Auteur ; Shaotao Cao, Auteur . - 2012 . - pp. 7736–7741.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7736–7741
Mots-clés : Crystallization Kinetics Résumé : The nucleation, growth, and agglomeration of monosodium aluminate hydrate (MAH) crystallization in concentrated sodium aluminate solutions were investigated in a steady-state mixed-suspension–mixed-product-removal (MSMPR) crystallizer, and the mechanism was analyzed in detail. The crystal growth was diffusion- and surface-integration-controlled, and the secondary nucleation, as a result of crystal–agitator and crystal–crystallizer collisions, was determined further. The agglomeration kernel, expressed in terms of mean residence time, growth rate, and suspension density, was found to have a positive order of about 0.52 in the suspension density, indicating that the agglomeration kernel increased at higher frequencies of collisions between particles. The growth rate of MAH was found to be higher than that of gibbsite in active NaAl(OH)4–NaHCO3 systems, but the nucleation rate of MAH was lower than that of gibbsite in seeded-hydrolysis processes. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202622h Exemplaires
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Titre : Rapid quantification of sodium dithionite by ion chromatography Type de document : texte imprimé Auteurs : Travis James, Auteur ; Allen Apblett, Auteur ; Nicholas F. Materer, Auteur Année de publication : 2012 Article en page(s) : pp. 7742-7746 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Ion chromatography Résumé : Sodium dithionite is an oxidizable sulfur oxyanion often employed as a reducing agent in environmental and synthetic chemistry. This industrially important reagent slowly decomposes into a variety of sulfur oxyanions. Thus, a rapid method to assess purity of a given sample is crucial. Despite the importance of this material to the wood pulping and textile industries, a rapid, reliable method to quantify dithionite remains a challenge. Current methodologies require extensive bench-top chemistry. Ion chromatography can provide a simple one-step method that can easily be automated to rapidly and accurately determine the concentration of dithionite. The results are in excellent agreement with those obtained using a multistep iodometric titration. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968330
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7742-7746[article] Rapid quantification of sodium dithionite by ion chromatography [texte imprimé] / Travis James, Auteur ; Allen Apblett, Auteur ; Nicholas F. Materer, Auteur . - 2012 . - pp. 7742-7746.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7742-7746
Mots-clés : Ion chromatography Résumé : Sodium dithionite is an oxidizable sulfur oxyanion often employed as a reducing agent in environmental and synthetic chemistry. This industrially important reagent slowly decomposes into a variety of sulfur oxyanions. Thus, a rapid method to assess purity of a given sample is crucial. Despite the importance of this material to the wood pulping and textile industries, a rapid, reliable method to quantify dithionite remains a challenge. Current methodologies require extensive bench-top chemistry. Ion chromatography can provide a simple one-step method that can easily be automated to rapidly and accurately determine the concentration of dithionite. The results are in excellent agreement with those obtained using a multistep iodometric titration. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968330 Exemplaires
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Titre : Methane oxidative coupling : Synthesis of membrane reactor networks Type de document : texte imprimé Auteurs : H. R. Godini, Auteur ; S. Jaso, Auteur ; Shengnan Xiao, Auteur Année de publication : 2012 Article en page(s) : pp. 7747-7761 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Membrane reactor Oxidative coupling Résumé : In this work, the performance of the methane oxidative coupling process based on different alternative reactor structures including fixed-bed reactor, two different feeding-structures of porous packed bed membrane reactor, and different conceptual network combinations of them was analyzed in a comprehensive model-based study. In this context, a contour-based graphical visualizing method accompanied by multiscenario generation and exanrination approach was exploited so as to systematically screen out the high achievable process performances and the corresponding reactor network specifications. As performance indicators, several objective measures including the highest achievable values for yield, selectivity and methane conversion were applied over a high number of design scenarios. Thereby, several sets of structural and operating parameters were evaluated. The investigated parameters are temperature, membrane thicknesses, types of catalysts, amount of inert packing in the catalyst bed, the flow rate of oxygen-rich stream entering the reactor system (total methane to oxygen ratio), distribution of the oxygen rich stream through the reactor blocks (local methane to oxygen ratio), distribution of the total methane-rich feed stream into the reactor blocks, and the contact time represented by the reactor length. A high C2-yield of 31% and 88% C2- selectivity were observed at the same time, and thus, highlighting the performance potential of the reactor network. Moreover, the proposed method enables one to consider operating aspects such as hot spot formation during the analysis and screening procedure. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968331
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7747-7761[article] Methane oxidative coupling : Synthesis of membrane reactor networks [texte imprimé] / H. R. Godini, Auteur ; S. Jaso, Auteur ; Shengnan Xiao, Auteur . - 2012 . - pp. 7747-7761.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7747-7761
Mots-clés : Membrane reactor Oxidative coupling Résumé : In this work, the performance of the methane oxidative coupling process based on different alternative reactor structures including fixed-bed reactor, two different feeding-structures of porous packed bed membrane reactor, and different conceptual network combinations of them was analyzed in a comprehensive model-based study. In this context, a contour-based graphical visualizing method accompanied by multiscenario generation and exanrination approach was exploited so as to systematically screen out the high achievable process performances and the corresponding reactor network specifications. As performance indicators, several objective measures including the highest achievable values for yield, selectivity and methane conversion were applied over a high number of design scenarios. Thereby, several sets of structural and operating parameters were evaluated. The investigated parameters are temperature, membrane thicknesses, types of catalysts, amount of inert packing in the catalyst bed, the flow rate of oxygen-rich stream entering the reactor system (total methane to oxygen ratio), distribution of the oxygen rich stream through the reactor blocks (local methane to oxygen ratio), distribution of the total methane-rich feed stream into the reactor blocks, and the contact time represented by the reactor length. A high C2-yield of 31% and 88% C2- selectivity were observed at the same time, and thus, highlighting the performance potential of the reactor network. Moreover, the proposed method enables one to consider operating aspects such as hot spot formation during the analysis and screening procedure. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968331 Exemplaires
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Titre : Measurement of mechanical properties of an electroless Ni – B coating using nanoindentation Type de document : texte imprimé Auteurs : Carlos Dominguez-Rios, Auteur ; Abel Hurtado-Macias, Auteur ; Roal Torres-Sanchez, Auteur Année de publication : 2012 Article en page(s) : pp. 7762-7768 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Mechanical properties Résumé : Structure and mechanical properties of electroless nickel-boride (Nt—B) thin film coatings on S7 steel substrate were studied in as-plated and annealed samples. The electroless bath does not contain Pb, Cd, or Ta in the stabilizer agents. The mechanical properties of the Ni—B coatings were obtained from nanoindentation measurements. Models by Korsusky and King were used to obtain hardness and elastic modulus, respectively. The structure of the coatings was observed by atomic force and scanning electron microscopy and XRD. Bath composition, plating time, annealing temperature, and time were considered in order to prepare coatings with optimal mechanical properties. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968332
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7762-7768[article] Measurement of mechanical properties of an electroless Ni – B coating using nanoindentation [texte imprimé] / Carlos Dominguez-Rios, Auteur ; Abel Hurtado-Macias, Auteur ; Roal Torres-Sanchez, Auteur . - 2012 . - pp. 7762-7768.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7762-7768
Mots-clés : Mechanical properties Résumé : Structure and mechanical properties of electroless nickel-boride (Nt—B) thin film coatings on S7 steel substrate were studied in as-plated and annealed samples. The electroless bath does not contain Pb, Cd, or Ta in the stabilizer agents. The mechanical properties of the Ni—B coatings were obtained from nanoindentation measurements. Models by Korsusky and King were used to obtain hardness and elastic modulus, respectively. The structure of the coatings was observed by atomic force and scanning electron microscopy and XRD. Bath composition, plating time, annealing temperature, and time were considered in order to prepare coatings with optimal mechanical properties. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968332 Exemplaires
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Titre : Cross - linking structural effect of hydrogel based on 2 - hydroxyethyl methacrylate Type de document : texte imprimé Auteurs : Loredana E. Nita, Auteur ; Manuela T. Nistor, Auteur ; Aurica P. Chiriac, Auteur Année de publication : 2012 Article en page(s) : pp. 7769-7776 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydrogel Hydroxyethyl Résumé : The study presents the possibility to prepare copolymers based on 2-hydroxyethyl methacrylate using two variants of comonomers: ethylene glycol dimethacrylate (1) and 3,9-divinyl-2,4,8,10.tetraoxaspiro[5.5]-undecane (2) that act as crosslinkers for the methacrylate networks generation. The chemical structure of the copolymers—synthesized through redox polymerization process using ammonium persulfate and N,N,N',N'-tetramethylethylenediamine as initiator pair was confirmed by FT-IR spectroscopy. The transparent gel structures were prepared in ethylene glycol. The influence of the comonomers type upon gel copolymers formation was put into evidence by the swelling behavior of the polymeric structure. The morphological information concerning the studied polymeric compounds by SEM evidenced the differences between the hydrogels with respect to cross-linker type and its amount in the monomer feed. Also the thermal stability is a function of the type and amount of the cross-linker. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2029317
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7769-7776[article] Cross - linking structural effect of hydrogel based on 2 - hydroxyethyl methacrylate [texte imprimé] / Loredana E. Nita, Auteur ; Manuela T. Nistor, Auteur ; Aurica P. Chiriac, Auteur . - 2012 . - pp. 7769-7776.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7769-7776
Mots-clés : Hydrogel Hydroxyethyl Résumé : The study presents the possibility to prepare copolymers based on 2-hydroxyethyl methacrylate using two variants of comonomers: ethylene glycol dimethacrylate (1) and 3,9-divinyl-2,4,8,10.tetraoxaspiro[5.5]-undecane (2) that act as crosslinkers for the methacrylate networks generation. The chemical structure of the copolymers—synthesized through redox polymerization process using ammonium persulfate and N,N,N',N'-tetramethylethylenediamine as initiator pair was confirmed by FT-IR spectroscopy. The transparent gel structures were prepared in ethylene glycol. The influence of the comonomers type upon gel copolymers formation was put into evidence by the swelling behavior of the polymeric structure. The morphological information concerning the studied polymeric compounds by SEM evidenced the differences between the hydrogels with respect to cross-linker type and its amount in the monomer feed. Also the thermal stability is a function of the type and amount of the cross-linker. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2029317 Exemplaires
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Titre : Passivation of sponge iron and GAC in Fe0 / GAC mixed - potential corrosion reactor Type de document : texte imprimé Auteurs : Bo Lai, Auteur ; Yuexi Zhou, Auteur ; Ping Yang, Auteur Année de publication : 2012 Article en page(s) : pp. 7777-7785 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Reactor Corrosion Passivation Résumé : The Fe°/GAC mixed-potential corrosion reactor was used to treat the complicated, toxic, and refractory ABS resin wastewater. In the 100 days continuous run, the effect of the packing particles passivation on the treatment efficiency of the Fe°/ GAC mixed-potential corrosion reactor was investigated seriously. The formation mechanism of the compounds in passive film was investigated first by SEM, EDS, and X-ray dot-mapping, which was the precondition for the control of the passivation of packing particles. The results show that the passive film consisted of five kinds of compounds such as Fe3(PO)2.8H2O, FePO4 ·3H2O, Fe2O3, Fe3O4, and FeS, which obstructed the formation of macroscopic galvanic cells between sponge iron (Fe°) and GAC and decreased the COD treatment efficiency of the Fe°/GAC mixed-potential corrosion reactor from 45 to 55% to 0%. The formation of passive film mainly resulted from the elements of S and P, which were from the SO42― and PO43― in ABS resin wastewater. Therefore, the inorganic ions in wastewater, especially for SO42― and PO43―, should be removed first before the treatment of the Fe°/GAC mixed-potential corrosion reactor. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968334
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7777-7785[article] Passivation of sponge iron and GAC in Fe0 / GAC mixed - potential corrosion reactor [texte imprimé] / Bo Lai, Auteur ; Yuexi Zhou, Auteur ; Ping Yang, Auteur . - 2012 . - pp. 7777-7785.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7777-7785
Mots-clés : Reactor Corrosion Passivation Résumé : The Fe°/GAC mixed-potential corrosion reactor was used to treat the complicated, toxic, and refractory ABS resin wastewater. In the 100 days continuous run, the effect of the packing particles passivation on the treatment efficiency of the Fe°/ GAC mixed-potential corrosion reactor was investigated seriously. The formation mechanism of the compounds in passive film was investigated first by SEM, EDS, and X-ray dot-mapping, which was the precondition for the control of the passivation of packing particles. The results show that the passive film consisted of five kinds of compounds such as Fe3(PO)2.8H2O, FePO4 ·3H2O, Fe2O3, Fe3O4, and FeS, which obstructed the formation of macroscopic galvanic cells between sponge iron (Fe°) and GAC and decreased the COD treatment efficiency of the Fe°/GAC mixed-potential corrosion reactor from 45 to 55% to 0%. The formation of passive film mainly resulted from the elements of S and P, which were from the SO42― and PO43― in ABS resin wastewater. Therefore, the inorganic ions in wastewater, especially for SO42― and PO43―, should be removed first before the treatment of the Fe°/GAC mixed-potential corrosion reactor. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968334 Exemplaires
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Titre : Compatibilizing effects of maleated poly (lactic acid) (PLA) on properties of PLA / soy protein composites Type de document : texte imprimé Auteurs : Rui Zhu, Auteur ; Hongzhi Liu, Auteur ; Jinwen Zhang, Auteur Année de publication : 2012 Article en page(s) : pp. 7786-7792 Langues : Anglais (eng) Mots-clés : Composite material Résumé : Poly(lactic acid) (PLA)/soy protein concentrate (SPC) composites were prepared using a twin-screw extruder. Extra amounts of water and glycerol were added to SPC prior to compounding with PLA to ensure that SPC behaved like a thermoplastic during subsequent mixing. Free radical grafting of maleic anhydride (MA) onto PLA was performed by reactive extrusion, and PLA-g-MA was used as a compatibilizer in the composites. The effects of compatibilizer concentration and degree of functionality on the tensile, morphological, and thermal properties of PLA/SPC composites were studied. The tensile strength of the composites containing 4 phr compatibilizer increased by 19% compared to that of the uncompatibilized one. Also, the presence of compatibilizer resulted in finer domain sizes of SPC and a lower damping peak, both of which suggested that good interfacial adhesion between the two phases was achieved. Differential scanning calorimetry analysis indicated that SPC induced and accelerated cold crystallization of PLA. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968335l
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7786-7792[article] Compatibilizing effects of maleated poly (lactic acid) (PLA) on properties of PLA / soy protein composites [texte imprimé] / Rui Zhu, Auteur ; Hongzhi Liu, Auteur ; Jinwen Zhang, Auteur . - 2012 . - pp. 7786-7792.
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7786-7792
Mots-clés : Composite material Résumé : Poly(lactic acid) (PLA)/soy protein concentrate (SPC) composites were prepared using a twin-screw extruder. Extra amounts of water and glycerol were added to SPC prior to compounding with PLA to ensure that SPC behaved like a thermoplastic during subsequent mixing. Free radical grafting of maleic anhydride (MA) onto PLA was performed by reactive extrusion, and PLA-g-MA was used as a compatibilizer in the composites. The effects of compatibilizer concentration and degree of functionality on the tensile, morphological, and thermal properties of PLA/SPC composites were studied. The tensile strength of the composites containing 4 phr compatibilizer increased by 19% compared to that of the uncompatibilized one. Also, the presence of compatibilizer resulted in finer domain sizes of SPC and a lower damping peak, both of which suggested that good interfacial adhesion between the two phases was achieved. Differential scanning calorimetry analysis indicated that SPC induced and accelerated cold crystallization of PLA. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968335l Exemplaires
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Titre : Synthesis and properties of organic – inorganic hybrid materials based on glycerol Type de document : texte imprimé Auteurs : Ignacio E. dell’Erba, Auteur ; Cristina E. Hoppe, Auteur ; Roberto J. J. Williams, Auteur Année de publication : 2012 Article en page(s) : pp. 7793–7799 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Organic–inorganic hybrid materials Résumé : The great supply of glycerol as a byproduct of the production of biodiesel has motivated interest in its use in new applications. In this study, we report the synthesis and properties of organic–inorganic hybrid materials based on glycerol. Glycerol (Gly) was reacted with 3-isocyanatopropyltriethoxysilane (IPTES) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst, using a molar ratio (r = IPTES/Gly) between 0.75 and 3. The sol–gel polycondensation of the resulting precursors in the presence of a formic acid solution led to transparent solid materials with a biphasic structure consisting of glycerol-rich domains dispersed in the organic–inorganic hybrid matrix. An increase in the r value changed the hybrid materials from hydrophilic to hydrophobic. The contact angle of water droplets varied from 43.6° for r = 0.75 to 95.1° for r = 3. Each of the materials exhibited a broad glass-to-rubber transition, with the maximum of the damping peak located in the 54–70 °C range. The relatively intense tan δ peaks of the hybrid materials suggest their possible use in devices requiring vibrational damping. The maximum damping capacity corresponded to the hybrid with r = 1.5, which exhibited a loss area LA (area under the loss modulus peak) of 13.5 GPa·K. High values of the rubbery modulus were observed, varying from 130 MPa for r = 0.75 to 720 MPa for r = 3. Values of the glassy modulus were also high, and the maximum value was observed for the hybrid with r = 1.5. The hybrid materials could also be colored through the incorporation of a very small amount of functionalized gold nanoparticles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300393n
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7793–7799[article] Synthesis and properties of organic – inorganic hybrid materials based on glycerol [texte imprimé] / Ignacio E. dell’Erba, Auteur ; Cristina E. Hoppe, Auteur ; Roberto J. J. Williams, Auteur . - 2012 . - pp. 7793–7799.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7793–7799
Mots-clés : Organic–inorganic hybrid materials Résumé : The great supply of glycerol as a byproduct of the production of biodiesel has motivated interest in its use in new applications. In this study, we report the synthesis and properties of organic–inorganic hybrid materials based on glycerol. Glycerol (Gly) was reacted with 3-isocyanatopropyltriethoxysilane (IPTES) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst, using a molar ratio (r = IPTES/Gly) between 0.75 and 3. The sol–gel polycondensation of the resulting precursors in the presence of a formic acid solution led to transparent solid materials with a biphasic structure consisting of glycerol-rich domains dispersed in the organic–inorganic hybrid matrix. An increase in the r value changed the hybrid materials from hydrophilic to hydrophobic. The contact angle of water droplets varied from 43.6° for r = 0.75 to 95.1° for r = 3. Each of the materials exhibited a broad glass-to-rubber transition, with the maximum of the damping peak located in the 54–70 °C range. The relatively intense tan δ peaks of the hybrid materials suggest their possible use in devices requiring vibrational damping. The maximum damping capacity corresponded to the hybrid with r = 1.5, which exhibited a loss area LA (area under the loss modulus peak) of 13.5 GPa·K. High values of the rubbery modulus were observed, varying from 130 MPa for r = 0.75 to 720 MPa for r = 3. Values of the glassy modulus were also high, and the maximum value was observed for the hybrid with r = 1.5. The hybrid materials could also be colored through the incorporation of a very small amount of functionalized gold nanoparticles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300393n Exemplaires
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Titre : Scheduling in the FMCG industry : An industrial case study Type de document : texte imprimé Auteurs : Martijn A. H. van Elzakker, Auteur ; Edwin Zondervan, Auteur ; Neha B. Raikar, Auteur Année de publication : 2012 Article en page(s) : pp. 7800–7815 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Scheduling Industry Résumé : A problem-specific model is presented for the short-term scheduling problem in the Fast Moving Consumer Goods (FMCG) industry. To increase the computational efficiency, the limited intermediate inventory is modeled indirectly by relating mixing and packing intervals. In addition, the model size is reduced by exploiting the process characteristics by dedicating time intervals to product types. The efficiency and flexibility of the formulation is demonstrated using ten examples based on an ice cream scheduling case study. The examples contain 62–73 batches of 8 products that must be produced within a 120-h horizon. All cases can be solved to optimality within 170 s. The addition of a periodic cleaning requirement on the mixing lines significantly increases the complexity of the problem. An algorithm is proposed that solves to optimality within half an hour 9 out of 10 cases with periodic cleaning. For the 10th case the makespan obtained was 0.6% higher than the theoretical minimum makespan. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202106k
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7800–7815[article] Scheduling in the FMCG industry : An industrial case study [texte imprimé] / Martijn A. H. van Elzakker, Auteur ; Edwin Zondervan, Auteur ; Neha B. Raikar, Auteur . - 2012 . - pp. 7800–7815.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7800–7815
Mots-clés : Scheduling Industry Résumé : A problem-specific model is presented for the short-term scheduling problem in the Fast Moving Consumer Goods (FMCG) industry. To increase the computational efficiency, the limited intermediate inventory is modeled indirectly by relating mixing and packing intervals. In addition, the model size is reduced by exploiting the process characteristics by dedicating time intervals to product types. The efficiency and flexibility of the formulation is demonstrated using ten examples based on an ice cream scheduling case study. The examples contain 62–73 batches of 8 products that must be produced within a 120-h horizon. All cases can be solved to optimality within 170 s. The addition of a periodic cleaning requirement on the mixing lines significantly increases the complexity of the problem. An algorithm is proposed that solves to optimality within half an hour 9 out of 10 cases with periodic cleaning. For the 10th case the makespan obtained was 0.6% higher than the theoretical minimum makespan. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202106k Exemplaires
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Titre : Analysis of flow and mixing characteristics of planar asymmetric split - and - recombine (P - SAR) micromixers with fan - shaped cavities Type de document : texte imprimé Auteurs : Guodong Xia, Auteur ; Jian Li, Auteur ; Xinping Tian, Auteur Année de publication : 2012 Article en page(s) : pp.7816–7827 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Micromixer Planar asymmetric Résumé : A modified micromixer design based on the concept of multidirectional vortices and unbalanced splitting and recombining of fluid streams is described in this work. The purpose of this study was to demonstrate that the combination of unbalanced inertial collisions, multidirectional vortices, and converging/diverging flow caused by the fan-shaped cavities contributes to the improvement of the mixing effectiveness. By using computational fluid dynamics (CFD), numerous studies of the mixing performance and flow features were completed at moderately low Reynolds numbers ranging from 1 to 80. Experimental analysis of the mass transfer and mixing quality along this modified micromixer was performed to validate the numerical results. The computational and experimental results for the concentration distributions and flow patterns reveal the following trends: (i) The combination of transverse Dean vortices effect (vertical plane) and expansion vortices (horizontal plane) effectively contribute to the considerable improvement of the mixing performance. The experimental results were consistent with the numerical results in this respect. (ii) The geometric parameters and the arrangement of the fan-shaped cavity structure are two important factors affecting the mixing performance. When the fan-shaped cavity channel is 3 times as wide as the major subchannel, the mixing index of this type of micromixer was found to reach around 75% at Reynolds numbers larger than 60. Furthermore, we also analyzed the relation between mixing efficiency and pressure drop simultaneously. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2026234
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7816–7827[article] Analysis of flow and mixing characteristics of planar asymmetric split - and - recombine (P - SAR) micromixers with fan - shaped cavities [texte imprimé] / Guodong Xia, Auteur ; Jian Li, Auteur ; Xinping Tian, Auteur . - 2012 . - pp.7816–7827.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7816–7827
Mots-clés : Micromixer Planar asymmetric Résumé : A modified micromixer design based on the concept of multidirectional vortices and unbalanced splitting and recombining of fluid streams is described in this work. The purpose of this study was to demonstrate that the combination of unbalanced inertial collisions, multidirectional vortices, and converging/diverging flow caused by the fan-shaped cavities contributes to the improvement of the mixing effectiveness. By using computational fluid dynamics (CFD), numerous studies of the mixing performance and flow features were completed at moderately low Reynolds numbers ranging from 1 to 80. Experimental analysis of the mass transfer and mixing quality along this modified micromixer was performed to validate the numerical results. The computational and experimental results for the concentration distributions and flow patterns reveal the following trends: (i) The combination of transverse Dean vortices effect (vertical plane) and expansion vortices (horizontal plane) effectively contribute to the considerable improvement of the mixing performance. The experimental results were consistent with the numerical results in this respect. (ii) The geometric parameters and the arrangement of the fan-shaped cavity structure are two important factors affecting the mixing performance. When the fan-shaped cavity channel is 3 times as wide as the major subchannel, the mixing index of this type of micromixer was found to reach around 75% at Reynolds numbers larger than 60. Furthermore, we also analyzed the relation between mixing efficiency and pressure drop simultaneously. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2026234 Exemplaires
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Titre : Three - dimensional temperature distribution of impinging flames in an opposed multiburner gasifier Type de document : texte imprimé Auteurs : Yan Gong, Auteur ; Qinghua Guo, Auteur ; Qinfeng Liang, Auteur Année de publication : 2012 Article en page(s) : pp. 7828–7837 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Gasification Résumé : Based on the bench-scale opposed multiburner (OMB) gasifier, a new combination of the optical sectioning tomography (OST) and two-color method has been proposed and applied to reconstruct the three-dimensional (3-D) temperature distribution of the gasifier by employing a single charge-coupled device (CCD) camera installed on the top of the gasifier. The reconstruction method is first applied in diesel gasification and the reconstructed results are validated by calibrated thermocouples and a side imaging system; thus the 3-D temperature distribution of coal–water slurry (CWS) gasification is reconstructed. The results show that the temperature distribution is more spatially homogeneous and the average temperature is higher with blurry contours of flame than that of diesel. The overall temperature of the gasifier rises with the increase of oxygen to carbon ratio, and the high temperature region which ranges from 1700 to 2200 K remains in the axis of the gasifier steadily and remains a safe distance from the refractory wall, which makes the temperature of the refractory wall below 1550 K and makes the participating medium maintain a stable condition for gasification. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2028602
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7828–7837[article] Three - dimensional temperature distribution of impinging flames in an opposed multiburner gasifier [texte imprimé] / Yan Gong, Auteur ; Qinghua Guo, Auteur ; Qinfeng Liang, Auteur . - 2012 . - pp. 7828–7837.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7828–7837
Mots-clés : Gasification Résumé : Based on the bench-scale opposed multiburner (OMB) gasifier, a new combination of the optical sectioning tomography (OST) and two-color method has been proposed and applied to reconstruct the three-dimensional (3-D) temperature distribution of the gasifier by employing a single charge-coupled device (CCD) camera installed on the top of the gasifier. The reconstruction method is first applied in diesel gasification and the reconstructed results are validated by calibrated thermocouples and a side imaging system; thus the 3-D temperature distribution of coal–water slurry (CWS) gasification is reconstructed. The results show that the temperature distribution is more spatially homogeneous and the average temperature is higher with blurry contours of flame than that of diesel. The overall temperature of the gasifier rises with the increase of oxygen to carbon ratio, and the high temperature region which ranges from 1700 to 2200 K remains in the axis of the gasifier steadily and remains a safe distance from the refractory wall, which makes the temperature of the refractory wall below 1550 K and makes the participating medium maintain a stable condition for gasification. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2028602 Exemplaires
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Titre : Critical properties and normal boiling temperature of ionic liquids. update and a new consistency test Type de document : texte imprimé Auteurs : José O. Valderrama, Auteur ; Luis A. Forero, Auteur ; Roberto E. Rojas, Auteur Année de publication : 2012 Article en page(s) : pp. 7838-7844 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Ionic liquid Boiling Critical property Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama and Rojas in 2009 to estimate the critical properties of ionic liquids is revised and an additional test for determining the consistency of the estimated properties is proposed. The new testing method includes the calculation of the saturation pressure at the normal boiling temperature using an equation of state and an accurate model to represent the temperature function of the attractive term in the equation of state. In determining the vapor pressure, the critical temperature, the critical pressure, the critical volume, and the acentric factor determined by group contribution are included. The proposed method complements the previous density test of the authors that tested the critical temperature, the critical volume, and the normal boiling temperature only. A total of 1130 ionic liquids are considered in this work, and double checking, using the density and the normal vapor pressure, is applied. Also, a spreadsheet file that allows any reader to calculate and check the critical properties of other ionic liquids containing any of the 44 groups defined by the method is provided. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968340
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7838-7844[article] Critical properties and normal boiling temperature of ionic liquids. update and a new consistency test [texte imprimé] / José O. Valderrama, Auteur ; Luis A. Forero, Auteur ; Roberto E. Rojas, Auteur . - 2012 . - pp. 7838-7844.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7838-7844
Mots-clés : Ionic liquid Boiling Critical property Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama and Rojas in 2009 to estimate the critical properties of ionic liquids is revised and an additional test for determining the consistency of the estimated properties is proposed. The new testing method includes the calculation of the saturation pressure at the normal boiling temperature using an equation of state and an accurate model to represent the temperature function of the attractive term in the equation of state. In determining the vapor pressure, the critical temperature, the critical pressure, the critical volume, and the acentric factor determined by group contribution are included. The proposed method complements the previous density test of the authors that tested the critical temperature, the critical volume, and the normal boiling temperature only. A total of 1130 ionic liquids are considered in this work, and double checking, using the density and the normal vapor pressure, is applied. Also, a spreadsheet file that allows any reader to calculate and check the critical properties of other ionic liquids containing any of the 44 groups defined by the method is provided. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968340 Exemplaires
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