Documents disponibles écrits par cet auteur

Biomass catalytic steam gasification thermodynamics analysis and reaction experiments in a CREC riser simulator / Enrique Salaices in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6834–6844 Titre : Biomass catalytic steam gasification thermodynamics analysis and reaction experiments in a CREC riser simulator Type de document : texte imprimé Auteurs : Enrique Salaices, Auteur ; Benito Serrano, Auteur ; Hugo De Lasa, Auteur Année de publication : 2010 Article en page(s) : pp 6834–6844 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalytic  Thermodynamics  Gasification. Résumé : A thermodynamic equilibrium model based on evaluations involving C, H, and O element balances and various product species up to C6 hydrocarbons is reported in this study. This model establishes the effects of biomass composition, temperature, and steam on the various gas product molar fractions. On this basis, most significant parameters determining the chemical interconversions and distribution of chemical species are identified. On the basis of the proposed equilibrium model and using glucose as a model biomass species [C6H12O6], an optimum gasification temperature close to 800 °C and a steam/biomass ratio between 0.5 and 0.7 g/g is established. This study has the special value of comparing thermodynamic equilibrium predictions with experimental data obtained in a CREC riser simulator using a fluidizable Ni−Al2O3 catalyst. Results are relevant for scaled-up gasifiers. They show that for reaction times longer than 30 s chemical species are essentially equilibrated and that the proposed model does provide adequate description of various product fractions. Data obtained also demonstrate the shortcomings of equilibrium models for gasifiers with reaction times shorter than 10 s and the need for nonequilibrium models to describe gasifier performance at such conditions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901710n [article] Biomass catalytic steam gasification thermodynamics analysis and reaction experiments in a CREC riser simulator [texte imprimé] / Enrique Salaices, Auteur ; Benito Serrano, Auteur ; Hugo De Lasa, Auteur . - 2010 . - pp 6834–6844. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6834–6844 Mots-clés : Catalytic  Thermodynamics  Gasification. Résumé : A thermodynamic equilibrium model based on evaluations involving C, H, and O element balances and various product species up to C6 hydrocarbons is reported in this study. This model establishes the effects of biomass composition, temperature, and steam on the various gas product molar fractions. On this basis, most significant parameters determining the chemical interconversions and distribution of chemical species are identified. On the basis of the proposed equilibrium model and using glucose as a model biomass species [C6H12O6], an optimum gasification temperature close to 800 °C and a steam/biomass ratio between 0.5 and 0.7 g/g is established. This study has the special value of comparing thermodynamic equilibrium predictions with experimental data obtained in a CREC riser simulator using a fluidizable Ni−Al2O3 catalyst. Results are relevant for scaled-up gasifiers. They show that for reaction times longer than 30 s chemical species are essentially equilibrated and that the proposed model does provide adequate description of various product fractions. Data obtained also demonstrate the shortcomings of equilibrium models for gasifiers with reaction times shorter than 10 s and the need for nonequilibrium models to describe gasifier performance at such conditions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901710n

Energy efficiency in photocatalytic reactors for the full span of reaction times / Benito Serrano in Industrial & engineering chemistry research, Vol. 48 N° 22 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 9864–9876 Titre : Energy efficiency in photocatalytic reactors for the full span of reaction times Type de document : texte imprimé Auteurs : Benito Serrano, Auteur ; Aaron Ortiz, Auteur ; Jesus Moreira, Auteur Année de publication : 2010 Article en page(s) : pp. 9864–9876 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Photocatalytic  reactors  Kinetic  modeling  Parallel−series  reaction  network Résumé : OH• radicals react in photocatalytic reactors via adsorbed species on the catalytic surface through complex reaction mechanisms leading to complete mineralization of organic molecules. Our research group has recently contributed with kinetic modeling of the photocatalytic network using a parallel−series reaction network. This kinetic approach helps toward the assessment of the photocatalytic thermodynamic efficiency factors (PTEF) and quantum yields (QY). Efficiency calculations consider stoichiometric relationships involving observable chemical species and OH• groups. These stoichiometric equations set the OH• requirements for reaching a particular intermediate species and for the complete mineralization of them. On this basis, the PTEF and QY factors for phenol photoconversion point toward a high degree of photon utilization as in the case of Photo-CREC units and, as a result, confirm the value of photocatalysis for the conversion of organic pollutants in water. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900353n [article] Energy efficiency in photocatalytic reactors for the full span of reaction times [texte imprimé] / Benito Serrano, Auteur ; Aaron Ortiz, Auteur ; Jesus Moreira, Auteur . - 2010 . - pp. 9864–9876. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 9864–9876 Mots-clés : Photocatalytic  reactors  Kinetic  modeling  Parallel−series  reaction  network Résumé : OH• radicals react in photocatalytic reactors via adsorbed species on the catalytic surface through complex reaction mechanisms leading to complete mineralization of organic molecules. Our research group has recently contributed with kinetic modeling of the photocatalytic network using a parallel−series reaction network. This kinetic approach helps toward the assessment of the photocatalytic thermodynamic efficiency factors (PTEF) and quantum yields (QY). Efficiency calculations consider stoichiometric relationships involving observable chemical species and OH• groups. These stoichiometric equations set the OH• requirements for reaching a particular intermediate species and for the complete mineralization of them. On this basis, the PTEF and QY factors for phenol photoconversion point toward a high degree of photon utilization as in the case of Photo-CREC units and, as a result, confirm the value of photocatalysis for the conversion of organic pollutants in water. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900353n

Evaluation of photon absorption in an aqueous Ti02 slurry reactor using monte carlo simulations and macroscopic balance / Jesus Moreira 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. 10524-10534 Titre : Evaluation of photon absorption in an aqueous Ti02 slurry reactor using monte carlo simulations and macroscopic balance Type de document : texte imprimé Auteurs : Jesus Moreira, Auteur ; Benito Serrano, Auteur ; Aaron Ortiz, Auteur Année de publication : 2011 Article en page(s) : pp. 10524-10534 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Monte  Carlo  method  Particle  suspension  Reactor  Photon  absorption Résumé : The radiation field in an annular photocatalytic reactor is simulated using a Monte Carlo method (MC) for two TiO2 suspensions in water. Simulations are performed by using both the spectral distribution and the wavelength-averaged scattering and absorption coefficients. The Henyey-Greenstein phase function is adopted to represent forward, isotropic, and backward scattering modes. It is assumed that the UV lamp reflects the backscattered photons by the slurred medium. Photoabsorption rates using MC simulations and spectral distribution of the optical coefficients agree closely with experimental observations from a macroscopic balance. It is found that the scattering mode of the probability density function is not a critical factor for a consistent representation of the radiation field. MC simulation for the optimal catalyst concentration reveals that the maximum LVREA is reached at a concentration of 0.14 g L―1 for TiO2 Degussa P25. From this concentration, the apparent optical thickness is determined to be 2.8476 which is in agreement with the optimal one previously reported. This concentration is comparable to that determined experimentally for phenol photocatalytic degradation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447945 [article] Evaluation of photon absorption in an aqueous Ti02 slurry reactor using monte carlo simulations and macroscopic balance [texte imprimé] / Jesus Moreira, Auteur ; Benito Serrano, Auteur ; Aaron Ortiz, Auteur . - 2011 . - pp. 10524-10534. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10524-10534 Mots-clés : Monte  Carlo  method  Particle  suspension  Reactor  Photon  absorption Résumé : The radiation field in an annular photocatalytic reactor is simulated using a Monte Carlo method (MC) for two TiO2 suspensions in water. Simulations are performed by using both the spectral distribution and the wavelength-averaged scattering and absorption coefficients. The Henyey-Greenstein phase function is adopted to represent forward, isotropic, and backward scattering modes. It is assumed that the UV lamp reflects the backscattered photons by the slurred medium. Photoabsorption rates using MC simulations and spectral distribution of the optical coefficients agree closely with experimental observations from a macroscopic balance. It is found that the scattering mode of the probability density function is not a critical factor for a consistent representation of the radiation field. MC simulation for the optimal catalyst concentration reveals that the maximum LVREA is reached at a concentration of 0.14 g L―1 for TiO2 Degussa P25. From this concentration, the apparent optical thickness is determined to be 2.8476 which is in agreement with the optimal one previously reported. This concentration is comparable to that determined experimentally for phenol photocatalytic degradation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447945

Photocatalytic thermodynamic efficiency factors. practical limits in photocatalytic reactors / Benito Serrano in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6824–6833 Titre : Photocatalytic thermodynamic efficiency factors. practical limits in photocatalytic reactors Type de document : texte imprimé Auteurs : Benito Serrano, Auteur ; Aaron Ortiz, Auteur ; Jesus Moreira, Auteur Année de publication : 2010 Article en page(s) : pp 6824–6833 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photocatalytic  reactors  Thermodynamic. Résumé : The photocatalytic thermodynamic efficiency factor (PTEF) is a parameter that can be used in photocatalytic reactors to establish photon energy utilization as the ratio of the energy used to generate OH• free radicals and the energy absorbed by the TiO2 photocatalyst. The PTEF evaluation requires the assessment of the total rate of OH• free radicals at any given time during the photoconversion of organic species. A key parameter in this assessment is the availability of the complete spectrum of measurable chemical species including various intermediates. Quantification of different chemical species and their evolution with irradiation time allow via stoichiometric relationships the calculation of the OH• radicals consumed in the photocatalytic reactor. PTEFs and quantum yields (QY) were reported recently for phenol photocatalytic conversion in water media (free of iron ions) displaying 71% and 19% maximum QYs and PTEFs, respectively.19 In the present study, the QY and PTEF are reviewed further, considering the photoconversion of phenol in water media enhanced by iron ions. It is shown using the more realistic RN2 model that the maximum QYs and PTEFs reach up to 85% and 23% levels, respectively. These encouraging efficiency factors demonstrate the favorable prospects of photocatalysis and Photo-CREC Water reactors operated under optimum photocatalyst loading conditions (0.14 g/L), with only a small fraction of the total absorbed photons potentially lost in photon recombination. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017034 [article] Photocatalytic thermodynamic efficiency factors. practical limits in photocatalytic reactors [texte imprimé] / Benito Serrano, Auteur ; Aaron Ortiz, Auteur ; Jesus Moreira, Auteur . - 2010 . - pp 6824–6833. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6824–6833 Mots-clés : Photocatalytic  reactors  Thermodynamic. Résumé : The photocatalytic thermodynamic efficiency factor (PTEF) is a parameter that can be used in photocatalytic reactors to establish photon energy utilization as the ratio of the energy used to generate OH• free radicals and the energy absorbed by the TiO2 photocatalyst. The PTEF evaluation requires the assessment of the total rate of OH• free radicals at any given time during the photoconversion of organic species. A key parameter in this assessment is the availability of the complete spectrum of measurable chemical species including various intermediates. Quantification of different chemical species and their evolution with irradiation time allow via stoichiometric relationships the calculation of the OH• radicals consumed in the photocatalytic reactor. PTEFs and quantum yields (QY) were reported recently for phenol photocatalytic conversion in water media (free of iron ions) displaying 71% and 19% maximum QYs and PTEFs, respectively.19 In the present study, the QY and PTEF are reviewed further, considering the photoconversion of phenol in water media enhanced by iron ions. It is shown using the more realistic RN2 model that the maximum QYs and PTEFs reach up to 85% and 23% levels, respectively. These encouraging efficiency factors demonstrate the favorable prospects of photocatalysis and Photo-CREC Water reactors operated under optimum photocatalyst loading conditions (0.14 g/L), with only a small fraction of the total absorbed photons potentially lost in photon recombination. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017034