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Adsorption and diffusion of methanol, glycerol, and their mixtures in a metal organic framework / Yang, Li in Industrial & engineering chemistry research, Vol. 50 N° 24 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 24 (Décembre 2011) . - pp. 14084-14089 Titre : Adsorption and diffusion of methanol, glycerol, and their mixtures in a metal organic framework Type de document : texte imprimé Auteurs : Yang, Li, Auteur ; Stanley I. Sandler, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2012 Article en page(s) : pp. 14084-14089 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Diffusion  Adsorption Résumé : Grand Canonical Monte Carlo (GCMC) simulation has been used to study the adsorption of methanol, glycerol, and their mixtures in the metal organic framework IRMOF-1, and canonical ensemble molecular dynamics simulation was used to study their diffusion in that adsorbent. In particular, we consider the adsorption of pure glycerol in IRMOF-1 at several different temperatures and the diffusion of pure glycerol in IRMOF-1 at infinite dilution. Then, we study the influence of the methanol as solvent and how different concentrations of methanol affect the behavior of glycerol in IRMOF-1. It It is found that the glycerol is easily adsorbed into IRMOF-1, and a small concentration of adsorbed methanol promotes glycerol adsorption. The effect of methanol on the glycerol diffusivity depends on temperature and methanol concentration. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25299876 [article] Adsorption and diffusion of methanol, glycerol, and their mixtures in a metal organic framework [texte imprimé] / Yang, Li, Auteur ; Stanley I. Sandler, Auteur ; Dionisios G. Vlachos, Auteur . - 2012 . - pp. 14084-14089. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 24 (Décembre 2011) . - pp. 14084-14089 Mots-clés : Diffusion  Adsorption Résumé : Grand Canonical Monte Carlo (GCMC) simulation has been used to study the adsorption of methanol, glycerol, and their mixtures in the metal organic framework IRMOF-1, and canonical ensemble molecular dynamics simulation was used to study their diffusion in that adsorbent. In particular, we consider the adsorption of pure glycerol in IRMOF-1 at several different temperatures and the diffusion of pure glycerol in IRMOF-1 at infinite dilution. Then, we study the influence of the methanol as solvent and how different concentrations of methanol affect the behavior of glycerol in IRMOF-1. It It is found that the glycerol is easily adsorbed into IRMOF-1, and a small concentration of adsorbed methanol promotes glycerol adsorption. The effect of methanol on the glycerol diffusivity depends on temperature and methanol concentration. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25299876

Controlling homogeneous chemistry in homogeneous-heterogeneous reactors / Georgios D. Stefanidis in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 5962–5968 Titre : Controlling homogeneous chemistry in homogeneous-heterogeneous reactors : application to propane combustion Type de document : texte imprimé Auteurs : Georgios D. Stefanidis, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2009 Article en page(s) : pp. 5962–5968 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Homogeneous  chemistry  Homogeneous-heterogeneous  reactors  Two-dimensional  computational  fluid  dynamics  model Résumé : Operation strategies for controlling the extent of homogeneous chemistry in homogeneous−heterogeneous (HH) reactors were developed for a catalytic plate microreactor using a two-dimensional computational fluid dynamics model for propane combustion on Pt as our prototype system. The effect of the reactor gap size (distance between plates) was analyzed. We found that homogeneous chemistry is sustained for gaps well below the quenching diameter as a result of enhanced catalyst-induced heating. This finding has important ramifications for catalyst lifetime and safety and could be used to produce chemicals, for example, in oxidative dehydrogenation and oxidative coupling reactions. The homogeneous chemistry contribution decreases with decreasing gap size. Catalytic chemistry alone can occur under suitable flow rates, compositions, and heat loss/heat exchange rates. The synergism or competition between homogeneous and catalytic chemistries is delineated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801480m [article] Controlling homogeneous chemistry in homogeneous-heterogeneous reactors : application to propane combustion [texte imprimé] / Georgios D. Stefanidis, Auteur ; Dionisios G. Vlachos, Auteur . - 2009 . - pp. 5962–5968. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 5962–5968 Mots-clés : Homogeneous  chemistry  Homogeneous-heterogeneous  reactors  Two-dimensional  computational  fluid  dynamics  model Résumé : Operation strategies for controlling the extent of homogeneous chemistry in homogeneous−heterogeneous (HH) reactors were developed for a catalytic plate microreactor using a two-dimensional computational fluid dynamics model for propane combustion on Pt as our prototype system. The effect of the reactor gap size (distance between plates) was analyzed. We found that homogeneous chemistry is sustained for gaps well below the quenching diameter as a result of enhanced catalyst-induced heating. This finding has important ramifications for catalyst lifetime and safety and could be used to produce chemicals, for example, in oxidative dehydrogenation and oxidative coupling reactions. The homogeneous chemistry contribution decreases with decreasing gap size. Catalytic chemistry alone can occur under suitable flow rates, compositions, and heat loss/heat exchange rates. The synergism or competition between homogeneous and catalytic chemistries is delineated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801480m

Density functional theory study of methane oxidation and reforming on Pt(111) and Pt(211) / Ying Chen in Industrial & engineering chemistry research, Vol. 51 N° 38 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 38 (Septembre 2012) . - pp. 12244–12252 Titre : Density functional theory study of methane oxidation and reforming on Pt(111) and Pt(211) Type de document : texte imprimé Auteurs : Ying Chen, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2012 Article en page(s) : pp. 12244–12252 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Methane  Oxidation Résumé : The activation barriers of elementary-like reactions pertaining to the oxidation and reforming of methane on Pt(111) and Pt(211) surfaces have been calculated using periodic density functional theory (DFT) calculations. We have investigated the adsorption of CHx(x=1–3)OH and CHx(x=1–3)O, all the O and OH-assisted dehydrogenation reactions of CHx(x=1–4), all the C–O bond coupling reactions forming C1 oxygenates, and their subsequent dehydrogenation. It has been found that (i) COH and CHO are the most stable C1 oxygenates on Pt(111) and Pt(211), repectively; (ii) In the presence of O on Pt(211), oxidative dehydrogenation of CH by O is more kinetically favorable than the pyrolytic CH dehydrogenation; (iii) CO can be generated by oxidation of C with a low reaction barrier on Pt(211); (iv) The reactions involving OH and the dehydrogenation of CHx(x=1–3)OH and CHx(x=1–3)O appear to be secondary reaction pathways on Pt. Based on the activation barriers, we conclude that the major reaction pathways on Pt(111) and Pt(211) are CH4 (g) → CH3ad → CH2ad → CHad → Cad, Cad + Oad → COad and CH4 (g) → CH3ad → CH2ad → CHad, CHad + Oad → Cad, CHad + Oad → COad, respectively. Low coordination sites, such as steps, exhibit lower barriers for pyrolytic dehydrogenation except for the reaction CH2ad + * → CHad + Had that is preferred on terraces. In addition, they are lower barrier sites in the oxidation of C and CH and, thus, are expected to play a key role in partial and total oxidation of methane. In methane steam reforming, OHad may play a role only in the last step of C oxidation and certainly in the water-gas shift reaction, and, thus, this process consists of nearly decoupled methane catalytic pyrolysis and water-gas shift reactions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301792g [article] Density functional theory study of methane oxidation and reforming on Pt(111) and Pt(211) [texte imprimé] / Ying Chen, Auteur ; Dionisios G. Vlachos, Auteur . - 2012 . - pp. 12244–12252. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 38 (Septembre 2012) . - pp. 12244–12252 Mots-clés : Methane  Oxidation Résumé : The activation barriers of elementary-like reactions pertaining to the oxidation and reforming of methane on Pt(111) and Pt(211) surfaces have been calculated using periodic density functional theory (DFT) calculations. We have investigated the adsorption of CHx(x=1–3)OH and CHx(x=1–3)O, all the O and OH-assisted dehydrogenation reactions of CHx(x=1–4), all the C–O bond coupling reactions forming C1 oxygenates, and their subsequent dehydrogenation. It has been found that (i) COH and CHO are the most stable C1 oxygenates on Pt(111) and Pt(211), repectively; (ii) In the presence of O on Pt(211), oxidative dehydrogenation of CH by O is more kinetically favorable than the pyrolytic CH dehydrogenation; (iii) CO can be generated by oxidation of C with a low reaction barrier on Pt(211); (iv) The reactions involving OH and the dehydrogenation of CHx(x=1–3)OH and CHx(x=1–3)O appear to be secondary reaction pathways on Pt. Based on the activation barriers, we conclude that the major reaction pathways on Pt(111) and Pt(211) are CH4 (g) → CH3ad → CH2ad → CHad → Cad, Cad + Oad → COad and CH4 (g) → CH3ad → CH2ad → CHad, CHad + Oad → Cad, CHad + Oad → COad, respectively. Low coordination sites, such as steps, exhibit lower barriers for pyrolytic dehydrogenation except for the reaction CH2ad + * → CHad + Had that is preferred on terraces. In addition, they are lower barrier sites in the oxidation of C and CH and, thus, are expected to play a key role in partial and total oxidation of methane. In methane steam reforming, OHad may play a role only in the last step of C oxidation and certainly in the water-gas shift reaction, and, thus, this process consists of nearly decoupled methane catalytic pyrolysis and water-gas shift reactions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301792g

Design and fabrication of a high-throughput microreactor and its evaluation for highly exothermic reactions / Nageswara Rao Peela in Industrial & engineering chemistry research, Vol. 51 N° 50 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 50 (Décembre 2012) . - pp. 16270–16277 Titre : Design and fabrication of a high-throughput microreactor and its evaluation for highly exothermic reactions Type de document : texte imprimé Auteurs : Nageswara Rao Peela, Auteur ; Ivan C. Lee, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2013 Article en page(s) : pp. 16270–16277 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Microreactor Résumé : The effect of distributor and channel positions on flow uniformity in a high-throughput reactor is studied using a COMSOL MULTIPHYSICS, CFD package. The best design is subsequently fabricated and evaluated for propane total oxidation reaction at low conversions. Comparison of our design with a literature design is also presented. The results indicate that the conical distributor performs significantly better in terms of flow uniformity as compared to the commonly used disc shaped distributor. The flow uniformity is improved when the central channel is removed from the design, indicating that the channel arrangement also affects the flow uniformity. The experimental results on flow uniformity are in good agreement with simulation. The deviation in conversion of propane from channel to channel is within experimental error, indicating that the reactor can reliably screen catalysts and deliver kinetics. A half a dozen catalysts were tested for complete propane oxidation using the developed technology. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie302093u [article] Design and fabrication of a high-throughput microreactor and its evaluation for highly exothermic reactions [texte imprimé] / Nageswara Rao Peela, Auteur ; Ivan C. Lee, Auteur ; Dionisios G. Vlachos, Auteur . - 2013 . - pp. 16270–16277. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 50 (Décembre 2012) . - pp. 16270–16277 Mots-clés : Microreactor Résumé : The effect of distributor and channel positions on flow uniformity in a high-throughput reactor is studied using a COMSOL MULTIPHYSICS, CFD package. The best design is subsequently fabricated and evaluated for propane total oxidation reaction at low conversions. Comparison of our design with a literature design is also presented. The results indicate that the conical distributor performs significantly better in terms of flow uniformity as compared to the commonly used disc shaped distributor. The flow uniformity is improved when the central channel is removed from the design, indicating that the channel arrangement also affects the flow uniformity. The experimental results on flow uniformity are in good agreement with simulation. The deviation in conversion of propane from channel to channel is within experimental error, indicating that the reactor can reliably screen catalysts and deliver kinetics. A half a dozen catalysts were tested for complete propane oxidation using the developed technology. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie302093u

Millisecond production of hydrogen from alternative, high hydrogen density fuels in a cocurrent multifunctional microreactor / Niket S. Kaisare in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1749–1760 Titre : Millisecond production of hydrogen from alternative, high hydrogen density fuels in a cocurrent multifunctional microreactor Type de document : texte imprimé Auteurs : Niket S. Kaisare, Auteur ; Georgios D. Stefanidis, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2009 Article en page(s) : pp. 1749–1760 Note générale : Chemical enginnering Langues : Anglais (eng) Mots-clés : Pseudo-2-dimensional  model  Hydrogen  Catalytic  ammonia  Platinum Résumé : A pseudo-2-dimensional model is used for modeling a multifunctional microreactor for hydrogen generation by coupling catalytic ammonia decomposition on ruthenium with catalytic propane combustion on platinum. The two reactions are carried out in adjacent parallel plate channels in a cocurrent flow mode. Operating lines defining the attainable region are computed. The high temperatures and fast heat transfer ensure that both reactions go to completion in as low as submillisecond contact times and enable compact hydrogen production for portable and distributed power generation. The ammonia decomposition reaction tends to be limited by the intrinsic rate of reaction, whereas catalytic combustion is also affected by mass and heat diffusion. We have found that moderate and high conductivity materials are preferable because they support a rather wide attainable region. We show that one such device could enable variable hydrogen supply for variable power needs. A simple operating strategy to dial in the desirable power is proposed, which ensures high thermal efficiency (∼75% once-through efficiency of the integrated device and ∼85% reformer efficiency, both without any heat recuperation), wall isothermicity, and high conversions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800392z [article] Millisecond production of hydrogen from alternative, high hydrogen density fuels in a cocurrent multifunctional microreactor [texte imprimé] / Niket S. Kaisare, Auteur ; Georgios D. Stefanidis, Auteur ; Dionisios G. Vlachos, Auteur . - 2009 . - pp. 1749–1760. Chemical enginnering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1749–1760 Mots-clés : Pseudo-2-dimensional  model  Hydrogen  Catalytic  ammonia  Platinum Résumé : A pseudo-2-dimensional model is used for modeling a multifunctional microreactor for hydrogen generation by coupling catalytic ammonia decomposition on ruthenium with catalytic propane combustion on platinum. The two reactions are carried out in adjacent parallel plate channels in a cocurrent flow mode. Operating lines defining the attainable region are computed. The high temperatures and fast heat transfer ensure that both reactions go to completion in as low as submillisecond contact times and enable compact hydrogen production for portable and distributed power generation. The ammonia decomposition reaction tends to be limited by the intrinsic rate of reaction, whereas catalytic combustion is also affected by mass and heat diffusion. We have found that moderate and high conductivity materials are preferable because they support a rather wide attainable region. We show that one such device could enable variable hydrogen supply for variable power needs. A simple operating strategy to dial in the desirable power is proposed, which ensures high thermal efficiency (∼75% once-through efficiency of the integrated device and ∼85% reformer efficiency, both without any heat recuperation), wall isothermicity, and high conversions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800392z

Multiscale model and informatics-based optimal design of experiments / Vinay Prasad in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008) 

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Scale - out of microreactor stacks for portable and distributed processing / Matthew S. Mettler in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

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