Documents disponibles écrits par cet auteur

Hybrid hydrotalcite−sulfonated poly(ether ether ketone) cation-exchange membranes prepared by in situ sulfonation / Tae Wook Kim in Industrial & engineering chemistry research, Vol. 50 N° 7 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 7 (Avril 2011) . - pp. 3880–3888 Titre : Hybrid hydrotalcite−sulfonated poly(ether ether ketone) cation-exchange membranes prepared by in situ sulfonation Type de document : texte imprimé Auteurs : Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur Année de publication : 2011 Article en page(s) : pp. 3880–3888 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrotalcite  Methanol  fuel  cells Résumé : Direct methanol fuel cells (DMFC), which operate using methanol as a fuel, are attracting considerable attention recently. However, DMFC face a major technical hurdle, namely, methanol crossover through the polymer electrolyte membrane. For example, the commercial Nafion membranes, in addition to being expensive, also often allow more than 40% of the methanol to be lost through crossover during fuel cell operation. Our study’s goal, therefore, was to develop a new, cost-effective membrane with superior methanol barrier properties to Nafion but which also maintains reasonable proton conductivity. We have prepared membranes by in situ sulfonation of hybrid poly(ether ether ketone) (PEEK) and hydrotalcite (HT) films. These composite HT−SPEEK polymer membranes show high conductivity and low methanol diffusivity and are comparable in their performance with commercial Nafion membranes. Their properties depend strongly on the sulfonation reaction time and the fraction of hydrotalcite contained in the original polymer film prior to its sulfonation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1019563 [article] Hybrid hydrotalcite−sulfonated poly(ether ether ketone) cation-exchange membranes prepared by in situ sulfonation [texte imprimé] / Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur . - 2011 . - pp. 3880–3888. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 7 (Avril 2011) . - pp. 3880–3888 Mots-clés : Hydrotalcite  Methanol  fuel  cells Résumé : Direct methanol fuel cells (DMFC), which operate using methanol as a fuel, are attracting considerable attention recently. However, DMFC face a major technical hurdle, namely, methanol crossover through the polymer electrolyte membrane. For example, the commercial Nafion membranes, in addition to being expensive, also often allow more than 40% of the methanol to be lost through crossover during fuel cell operation. Our study’s goal, therefore, was to develop a new, cost-effective membrane with superior methanol barrier properties to Nafion but which also maintains reasonable proton conductivity. We have prepared membranes by in situ sulfonation of hybrid poly(ether ether ketone) (PEEK) and hydrotalcite (HT) films. These composite HT−SPEEK polymer membranes show high conductivity and low methanol diffusivity and are comparable in their performance with commercial Nafion membranes. Their properties depend strongly on the sulfonation reaction time and the fraction of hydrotalcite contained in the original polymer film prior to its sulfonation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1019563

Preparation and characterization of hybrid hydrotalcite-sulfonated polyetheretherketone (SPEEK) cation-exchange membranes / Tae Wook Kim in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9504–9513 Titre : Preparation and characterization of hybrid hydrotalcite-sulfonated polyetheretherketone (SPEEK) cation-exchange membranes Type de document : texte imprimé Auteurs : Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur Année de publication : 2010 Article en page(s) : pp. 9504–9513 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Direct  methanol  fuel  cells  Cost-effective  membrane  Hydrotalcite  particles  Sulfonated  poly(ether  ether  ketone) Résumé : Direct methanol fuel cells (DMFCs) can be operated using liquid methanol directly as a fuel. However, DMFCs face two major technical hurdles, namely, slow anodic methanol oxidation kinetics and methanol crossover across the polymer electrolyte membrane. Commercial membranes, such as Nafion, are expensive and more than 40% of the methanol is often lost through crossover during fuel-cell operation. Therefore, our study’s long-term goal is to develop a new, cost-effective membrane with superior methanol barrier properties, and reasonable proton conductivity. As part of this effort, we have prepared composite membranes by incorporating hydrotalcite (HT) particles into sulfonated poly(ether ether ketone) (SPEEK). Their properties are strongly dependent on the degree of sulfonation of the polymer matrix, and on the weight fraction of HT particles present in the hybrid membrane. Some of these HT-SPEEK hybrid membranes exhibit good properties, with the addition of the HT filler increasing the proton conductivity, while simultaneously decreasing the methanol permeability. The log(C/P) performance index of some of these membranes (where C/P is the ratio of the proton conductivity of the membrane divided by its methanol permeability) is comparable to that of the commercially available Nafion membranes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801839u [article] Preparation and characterization of hybrid hydrotalcite-sulfonated polyetheretherketone (SPEEK) cation-exchange membranes [texte imprimé] / Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur . - 2010 . - pp. 9504–9513. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9504–9513 Mots-clés : Direct  methanol  fuel  cells  Cost-effective  membrane  Hydrotalcite  particles  Sulfonated  poly(ether  ether  ketone) Résumé : Direct methanol fuel cells (DMFCs) can be operated using liquid methanol directly as a fuel. However, DMFCs face two major technical hurdles, namely, slow anodic methanol oxidation kinetics and methanol crossover across the polymer electrolyte membrane. Commercial membranes, such as Nafion, are expensive and more than 40% of the methanol is often lost through crossover during fuel-cell operation. Therefore, our study’s long-term goal is to develop a new, cost-effective membrane with superior methanol barrier properties, and reasonable proton conductivity. As part of this effort, we have prepared composite membranes by incorporating hydrotalcite (HT) particles into sulfonated poly(ether ether ketone) (SPEEK). Their properties are strongly dependent on the degree of sulfonation of the polymer matrix, and on the weight fraction of HT particles present in the hybrid membrane. Some of these HT-SPEEK hybrid membranes exhibit good properties, with the addition of the HT filler increasing the proton conductivity, while simultaneously decreasing the methanol permeability. The log(C/P) performance index of some of these membranes (where C/P is the ratio of the proton conductivity of the membrane divided by its methanol permeability) is comparable to that of the commercially available Nafion membranes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801839u

Preparation of hydrotalcite thin films using an electrophoretic technique / Tae Wook Kim in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9127–9132 Titre : Preparation of hydrotalcite thin films using an electrophoretic technique Type de document : texte imprimé Auteurs : Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur Année de publication : 2009 Article en page(s) : p. 9127–9132 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Preparation  of  Hydrotalcite  Electrophoretic  Technique Résumé : Electrophoretic deposition (EPD) was utilized as a new method for the preparation of hydrotalcite (HT) thin films. The films were deposited on macroporous alumina substrates and on alumina substrates that had been previously coated by conventional dip-coating techniques using slurries of HT colloidal particles. Their permeation properties were investigated by single- and mixed-gas permeation tests, and the films were shown to be permselective toward CO2, which is consistent with prior studies of these materials, which show them to be effective CO2 adsorbents. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071446s [article] Preparation of hydrotalcite thin films using an electrophoretic technique [texte imprimé] / Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur . - 2009 . - p. 9127–9132. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9127–9132 Mots-clés : Preparation  of  Hydrotalcite  Electrophoretic  Technique Résumé : Electrophoretic deposition (EPD) was utilized as a new method for the preparation of hydrotalcite (HT) thin films. The films were deposited on macroporous alumina substrates and on alumina substrates that had been previously coated by conventional dip-coating techniques using slurries of HT colloidal particles. Their permeation properties were investigated by single- and mixed-gas permeation tests, and the films were shown to be permselective toward CO2, which is consistent with prior studies of these materials, which show them to be effective CO2 adsorbents. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071446s

The preparation and characterization of hydrotalcite thin films / Tae Wook Kim in Industrial & engineering chemistry research, Vol. 48 N° 12 (Juin 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5794–5801 Titre : The preparation and characterization of hydrotalcite thin films Type de document : texte imprimé Auteurs : Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur Année de publication : 2009 Article en page(s) : pp. 5794–5801 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2-selective  inorganic  membranes  Thin  films  Hydrotalcites Résumé : Owing to the recent focus on reducing CO2 emissions, the preparation and characterization of CO2-selective inorganic membranes and thin films has received considerable attention. Hydrotalcites (HT) are, potentially, good materials for preparing CO2-selective inorganic membranes and films due to their high CO2 adsorption capacity at elevated temperatures and their good thermal stability. The purpose of this study, therefore, was to prepare CO2-selective HT films and to understand their transport characteristics. A vacuum-suction method was used for the synthesis of the HT films, and their properties were characterized using both single and mixed-gas permeation tests, as well as by nitrogen adsorption and by SEM and XRD. The HT films are microporous, as indicated by both the adsorption data, as well as by the fact that the ideal selectivities of pairs of inert gases (e.g., He, N2, and Ar) through the membrane are higher than the Knudsen values. However, the as-prepared materials contain a substantial fraction of voids and pinholes. Plugging these voids and pinholes using a silicone coating results in CO2-permselective films, which exhibit CO2/N2 and CO2/He ideal separation factors of 34.4 and 12.4, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900371r [article] The preparation and characterization of hydrotalcite thin films [texte imprimé] / Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur . - 2009 . - pp. 5794–5801. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5794–5801 Mots-clés : CO2-selective  inorganic  membranes  Thin  films  Hydrotalcites Résumé : Owing to the recent focus on reducing CO2 emissions, the preparation and characterization of CO2-selective inorganic membranes and thin films has received considerable attention. Hydrotalcites (HT) are, potentially, good materials for preparing CO2-selective inorganic membranes and films due to their high CO2 adsorption capacity at elevated temperatures and their good thermal stability. The purpose of this study, therefore, was to prepare CO2-selective HT films and to understand their transport characteristics. A vacuum-suction method was used for the synthesis of the HT films, and their properties were characterized using both single and mixed-gas permeation tests, as well as by nitrogen adsorption and by SEM and XRD. The HT films are microporous, as indicated by both the adsorption data, as well as by the fact that the ideal selectivities of pairs of inert gases (e.g., He, N2, and Ar) through the membrane are higher than the Knudsen values. However, the as-prepared materials contain a substantial fraction of voids and pinholes. Plugging these voids and pinholes using a silicone coating results in CO2-permselective films, which exhibit CO2/N2 and CO2/He ideal separation factors of 34.4 and 12.4, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900371r