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Accurate high - temperature reaction networks for alternative fuels / Kevin M Van Geem in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10399-10420 Titre : Accurate high - temperature reaction networks for alternative fuels : Butanol isomers Type de document : texte imprimé Auteurs : Kevin M Van Geem, Auteur ; Steven P. Pyl, Auteur ; Guy B. Marin, Auteur Année de publication : 2011 Article en page(s) : pp. 10399-10420 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : High  temperature  Isomers Résumé : Oxygenated hydrocarbons, particularly alcohol compounds, are being studied extensively as alternatives and additives to conventional fuels due to their propensity of decreasing soot formation and improving the octane number of gasoline. However, oxygenated fuels also increase the production of toxic byproducts, such as formaldehyde. To gain a better understanding of the oxygenated functional group's influence on combustion properties-e.g., ignition delay at temperatures above the negative temperature coefficient regime, and the rate of benzene production, which is the common precursor to soot formation-a detailed pressure-dependent reaction network for n-butanol, sec-butanol, and tert-butanol consisting of 281 species and 3608 reactions is presented. The reaction network is validated against shock tube ignition delays and doped methane flame concentration profiles reported previously in the literature, in addition to newly acquired pyrolysis data. Good agreement between simulated and experimental data is achieved in all cases. Flux and sensitivity analyses for each set of experiments have been performed, and high-pressure-limit reaction rate coefficients for important pathways, e.g., the dehydration reactions of the butanol isomers, have been computed using statistical mechanics and quantum chemistry. The different alcohol decomposition pathways, i.e., the pathways from primary, secondary, and tertiary alcohols, are discussed. Furthermore, comparisons between ethanol and n-butanol, two primary alcohols, are presented, as they relate to ignition delay. ISSN : 0888-5885 En ligne : http://www.mendeley.com/research/accurate-hightemperature-reaction-networks-alte [...] [article] Accurate high - temperature reaction networks for alternative fuels : Butanol isomers [texte imprimé] / Kevin M Van Geem, Auteur ; Steven P. Pyl, Auteur ; Guy B. Marin, Auteur . - 2011 . - pp. 10399-10420. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10399-10420 Mots-clés : High  temperature  Isomers Résumé : Oxygenated hydrocarbons, particularly alcohol compounds, are being studied extensively as alternatives and additives to conventional fuels due to their propensity of decreasing soot formation and improving the octane number of gasoline. However, oxygenated fuels also increase the production of toxic byproducts, such as formaldehyde. To gain a better understanding of the oxygenated functional group's influence on combustion properties-e.g., ignition delay at temperatures above the negative temperature coefficient regime, and the rate of benzene production, which is the common precursor to soot formation-a detailed pressure-dependent reaction network for n-butanol, sec-butanol, and tert-butanol consisting of 281 species and 3608 reactions is presented. The reaction network is validated against shock tube ignition delays and doped methane flame concentration profiles reported previously in the literature, in addition to newly acquired pyrolysis data. Good agreement between simulated and experimental data is achieved in all cases. Flux and sensitivity analyses for each set of experiments have been performed, and high-pressure-limit reaction rate coefficients for important pathways, e.g., the dehydration reactions of the butanol isomers, have been computed using statistical mechanics and quantum chemistry. The different alcohol decomposition pathways, i.e., the pathways from primary, secondary, and tertiary alcohols, are discussed. Furthermore, comparisons between ethanol and n-butanol, two primary alcohols, are presented, as they relate to ignition delay. ISSN : 0888-5885 En ligne : http://www.mendeley.com/research/accurate-hightemperature-reaction-networks-alte [...]

Modeling of toluene acetylation with acetic anhydride on H-USY zeolite / Eileen A. Dejaegere in Industrial & engineering chemistry research, Vol. 50 N° 21 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11822-11832 Titre : Modeling of toluene acetylation with acetic anhydride on H-USY zeolite Type de document : texte imprimé Auteurs : Eileen A. Dejaegere, Auteur ; Joris W. Thybaut, Auteur ; Guy B. Marin, Auteur Année de publication : 2011 Article en page(s) : pp. 11822-11832 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Zeolite  Acetylation  Modeling Résumé : The liquid-phase acetylation of toluene with acetic anhydride was carried out in a continuous-flow reactor over H-USY zeolites with different Si/Al ratios at 180 °C, at different contact times and feed compositions. H-USY is an active catalyst for this reaction because the main reaction products at all times on stream are the desired methylacetophenone (MAP) and its reaction byproduct acetic acid Within the different MAP isomers, the selectivity toward 4-MAP equals 85%. Although the initial acetic anhydride conversion is 100%, the zeolite is subject to deactivation. Small amounts of side products such as methylbenzoic acid and isopropenyltoluene were also identified and their formation explained. The data and insights obtained during these experiments were used to obtain models describing the formation of MAP and the other components present in the reactor effluent. The most plausible model, obtained via model discrimination, was validated at different reaction conditions and takes into account adsorption of the chemical compounds, the catalytic reactions, and deactivation of the catalyst. It also includes hydrolysis of acetic anhydride and the formation of side products originating from MAP. According to this model, catalyst deactivation starts from MAP and acetic anhydride, whereby acetic acid is liberated. Fitting of the model to the experimental data shows that the kinetic constant for the formation of 4-MAP is comparable to that of the deactivation reaction. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697498 [article] Modeling of toluene acetylation with acetic anhydride on H-USY zeolite [texte imprimé] / Eileen A. Dejaegere, Auteur ; Joris W. Thybaut, Auteur ; Guy B. Marin, Auteur . - 2011 . - pp. 11822-11832. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11822-11832 Mots-clés : Zeolite  Acetylation  Modeling Résumé : The liquid-phase acetylation of toluene with acetic anhydride was carried out in a continuous-flow reactor over H-USY zeolites with different Si/Al ratios at 180 °C, at different contact times and feed compositions. H-USY is an active catalyst for this reaction because the main reaction products at all times on stream are the desired methylacetophenone (MAP) and its reaction byproduct acetic acid Within the different MAP isomers, the selectivity toward 4-MAP equals 85%. Although the initial acetic anhydride conversion is 100%, the zeolite is subject to deactivation. Small amounts of side products such as methylbenzoic acid and isopropenyltoluene were also identified and their formation explained. The data and insights obtained during these experiments were used to obtain models describing the formation of MAP and the other components present in the reactor effluent. The most plausible model, obtained via model discrimination, was validated at different reaction conditions and takes into account adsorption of the chemical compounds, the catalytic reactions, and deactivation of the catalyst. It also includes hydrolysis of acetic anhydride and the formation of side products originating from MAP. According to this model, catalyst deactivation starts from MAP and acetic anhydride, whereby acetic acid is liberated. Fitting of the model to the experimental data shows that the kinetic constant for the formation of 4-MAP is comparable to that of the deactivation reaction. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697498

Modeling the coke formation in the convection section tubes of a steam cracker / Sandra C. K. De Schepper in Industrial & engineering chemistry research, Vol. 49 N° 12 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5752–5764 Titre : Modeling the coke formation in the convection section tubes of a steam cracker Type de document : texte imprimé Auteurs : Sandra C. K. De Schepper, Auteur ; Geraldine J. Heynderickx, Auteur ; Guy B. Marin, Auteur Année de publication : 2010 Article en page(s) : pp. 5752–5764 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Steam  cracker  Liquid  hydrocarbon  droplets  CFD  code Résumé : The presence of liquid hydrocarbon droplets in the convection section of a steam cracker may cause serious fouling problems due to coke formation, especially in high temperature zones. In order to investigate these fouling problems, a model has been developed and implemented in a CFD code to accurately simulate the behavior of a hydrocarbon droplet impinging on a hot surface. The impact energy of the droplet and the hot surface temperature are found to determine the impact behavior. On the basis of the newly developed model, the positions where droplets preferentially collide with the convection section tube walls and liquid material is deposited are determined. Furthermore, a kinetic model describing coke formation out of liquid hydrocarbon droplets in the temperature range of 450−700 K has been developed to calculate the rate of coke formation in each zone of the convection section tube. The calculated coke layer thickness on the most vulnerable tube locations and the industrially available values correspond remarkably well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100091e [article] Modeling the coke formation in the convection section tubes of a steam cracker [texte imprimé] / Sandra C. K. De Schepper, Auteur ; Geraldine J. Heynderickx, Auteur ; Guy B. Marin, Auteur . - 2010 . - pp. 5752–5764. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5752–5764 Mots-clés : Steam  cracker  Liquid  hydrocarbon  droplets  CFD  code Résumé : The presence of liquid hydrocarbon droplets in the convection section of a steam cracker may cause serious fouling problems due to coke formation, especially in high temperature zones. In order to investigate these fouling problems, a model has been developed and implemented in a CFD code to accurately simulate the behavior of a hydrocarbon droplet impinging on a hot surface. The impact energy of the droplet and the hot surface temperature are found to determine the impact behavior. On the basis of the newly developed model, the positions where droplets preferentially collide with the convection section tube walls and liquid material is deposited are determined. Furthermore, a kinetic model describing coke formation out of liquid hydrocarbon droplets in the temperature range of 450−700 K has been developed to calculate the rate of coke formation in each zone of the convection section tube. The calculated coke layer thickness on the most vulnerable tube locations and the industrially available values correspond remarkably well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100091e

Single - event microKinetics of aromatics hydrogenation on Pt / H - ZSM22 / Tapan Bera in Industrial & engineering chemistry research, Vol. 50 N° 23 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp.12933–12945 Titre : Single - event microKinetics of aromatics hydrogenation on Pt / H - ZSM22 Type de document : texte imprimé Auteurs : Tapan Bera, Auteur ; Joris W. Thybaut, Auteur ; Guy B. Marin, Auteur Année de publication : 2012 Article en page(s) : pp.12933–12945 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : MicroKinetics  Hydrogenation Résumé : A fundamental Single-Event MicroKinetic (SEMK) model for the hydrogenation of aromatic components on a Pt catalyst has been developed. It is based on the Horiuti-Polanyi mechanism considering atomic hydrogen addition steps to the (partially hydrogenated) aromatic species on the catalyst surface. The reaction network used accounts for the position at which the hydrogen atoms are added to the ring. In accordance with a quantum chemical assessment of the reaction pathway it was assumed that the kinetic parameters only depend on the saturation degree of the nearest neighbor carbon atoms and the branching degree of the carbon atom involved in the hydrogen atom addition. Six reactions families, of which three occur in the reaction network for benzene, are considered. The total number of 18 model parameters was reduced to 7 by calculation of the pre-exponential factors and by accounting for thermodynamic constraints. Experimental benzene hydrogenation data measured at temperatures in the range from 423 to 498 K, benzene inlet partial pressures in the range from 10 to 60 kPa, and hydrogen inlet partial pressures from 100 to 600 kPa on Pt catalyst have been regressed. In accordance with quantum chemical, statistical, and thermodynamic calculations, the selected version of the model gives the best description of the data with an F value of 4150. According to this selected SEMK model, the activation energies for the hydrogen addition to a carbon atom between two unsaturated or two saturated carbon atoms are identical and lower than the activation energy for hydrogen addition to a carbon atom between an unsaturated and saturated hydrogen atom. The estimated chemisorption enthalpy of hydrogen amounts to −59.4 kJ mol–1 and corresponds with an average surface coverage of 30%. A value of −56.0 kJ mol–1 for the chemisorption enthalpy of benzene is obtained. The total surface coverage by hydrocarbon species amounts to 60% under typical reaction conditions, without a pronounced Most Abundant Surface Intermediate (MASI). DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200541q [article] Single - event microKinetics of aromatics hydrogenation on Pt / H - ZSM22 [texte imprimé] / Tapan Bera, Auteur ; Joris W. Thybaut, Auteur ; Guy B. Marin, Auteur . - 2012 . - pp.12933–12945. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp.12933–12945 Mots-clés : MicroKinetics  Hydrogenation Résumé : A fundamental Single-Event MicroKinetic (SEMK) model for the hydrogenation of aromatic components on a Pt catalyst has been developed. It is based on the Horiuti-Polanyi mechanism considering atomic hydrogen addition steps to the (partially hydrogenated) aromatic species on the catalyst surface. The reaction network used accounts for the position at which the hydrogen atoms are added to the ring. In accordance with a quantum chemical assessment of the reaction pathway it was assumed that the kinetic parameters only depend on the saturation degree of the nearest neighbor carbon atoms and the branching degree of the carbon atom involved in the hydrogen atom addition. Six reactions families, of which three occur in the reaction network for benzene, are considered. The total number of 18 model parameters was reduced to 7 by calculation of the pre-exponential factors and by accounting for thermodynamic constraints. Experimental benzene hydrogenation data measured at temperatures in the range from 423 to 498 K, benzene inlet partial pressures in the range from 10 to 60 kPa, and hydrogen inlet partial pressures from 100 to 600 kPa on Pt catalyst have been regressed. In accordance with quantum chemical, statistical, and thermodynamic calculations, the selected version of the model gives the best description of the data with an F value of 4150. According to this selected SEMK model, the activation energies for the hydrogen addition to a carbon atom between two unsaturated or two saturated carbon atoms are identical and lower than the activation energy for hydrogen addition to a carbon atom between an unsaturated and saturated hydrogen atom. The estimated chemisorption enthalpy of hydrogen amounts to −59.4 kJ mol–1 and corresponds with an average surface coverage of 30%. A value of −56.0 kJ mol–1 for the chemisorption enthalpy of benzene is obtained. The total surface coverage by hydrocarbon species amounts to 60% under typical reaction conditions, without a pronounced Most Abundant Surface Intermediate (MASI). DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200541q