The Experts below are selected from a list of 1977 Experts worldwide ranked by ideXlab platform
Dina Yakusheva - One of the best experts on this subject based on the ideXlab platform.
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Adsorption of chlorobenzene vapor on V_2O_5/Al_2O_3 catalyst under dynamic conditions
Adsorption, 2008Co-Authors: L. D. Asnin, Anatoly Fedorov, Dina YakushevaAbstract:Adsorption dynamics of chlorobenzene vapors on a 5% V_2O_5/Al_2O_3 catalyst has been investigated using the Frontal Chromatography technique. The uptakes of chlorobenzene have been measured as a function of vapor concentration and adsorption equilibrium has been found to follow formally the Langmuir isotherm. The breakthrough time proved to be a linear function of the column length as expected. Breakthrough profiles have been reported for different experimental conditions and quantitatively fitted by a reduced lumped diffusion model. This model provides an analytical solution that facilitates engineering calculations. Model parameters show complex behavior as functions of stream characteristics and depend on column length. When empirical expressions relating model mass transfer coefficients with influencing variables are found the model demonstrates good accuracy in predicting column performance.
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Adsorption of chlorobenzene vapor on V2O5/Al2O3 catalyst under dynamic conditions
Adsorption, 2008Co-Authors: L. D. Asnin, Anatoly V. Fedorov, Dina YakushevaAbstract:Adsorption dynamics of chlorobenzene vapors on a 5% V2O5/Al2O3 catalyst has been investigated using the Frontal Chromatography technique. The uptakes of chlorobenzene have been measured as a function of vapor concentration and adsorption equilibrium has been found to follow formally the Langmuir isotherm. The breakthrough time proved to be a linear function of the column length as expected. Breakthrough profiles have been reported for different experimental conditions and quantitatively fitted by a reduced lumped diffusion model. This model provides an analytical solution that facilitates engineering calculations. Model parameters show complex behavior as functions of stream characteristics and depend on column length. When empirical expressions relating model mass transfer coefficients with influencing variables are found the model demonstrates good accuracy in predicting column performance.
L. D. Asnin - One of the best experts on this subject based on the ideXlab platform.
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Adsorption of chlorobenzene vapor on V_2O_5/Al_2O_3 catalyst under dynamic conditions
Adsorption, 2008Co-Authors: L. D. Asnin, Anatoly Fedorov, Dina YakushevaAbstract:Adsorption dynamics of chlorobenzene vapors on a 5% V_2O_5/Al_2O_3 catalyst has been investigated using the Frontal Chromatography technique. The uptakes of chlorobenzene have been measured as a function of vapor concentration and adsorption equilibrium has been found to follow formally the Langmuir isotherm. The breakthrough time proved to be a linear function of the column length as expected. Breakthrough profiles have been reported for different experimental conditions and quantitatively fitted by a reduced lumped diffusion model. This model provides an analytical solution that facilitates engineering calculations. Model parameters show complex behavior as functions of stream characteristics and depend on column length. When empirical expressions relating model mass transfer coefficients with influencing variables are found the model demonstrates good accuracy in predicting column performance.
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Adsorption of chlorobenzene vapor on V2O5/Al2O3 catalyst under dynamic conditions
Adsorption, 2008Co-Authors: L. D. Asnin, Anatoly V. Fedorov, Dina YakushevaAbstract:Adsorption dynamics of chlorobenzene vapors on a 5% V2O5/Al2O3 catalyst has been investigated using the Frontal Chromatography technique. The uptakes of chlorobenzene have been measured as a function of vapor concentration and adsorption equilibrium has been found to follow formally the Langmuir isotherm. The breakthrough time proved to be a linear function of the column length as expected. Breakthrough profiles have been reported for different experimental conditions and quantitatively fitted by a reduced lumped diffusion model. This model provides an analytical solution that facilitates engineering calculations. Model parameters show complex behavior as functions of stream characteristics and depend on column length. When empirical expressions relating model mass transfer coefficients with influencing variables are found the model demonstrates good accuracy in predicting column performance.
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Adsorption of chlorobenzene on V_2O_5/Al_2O_3 catalyst under dynamic conditions
Russian Journal of Applied Chemistry, 2007Co-Authors: L. D. Asnin, A. A. Fedorov, Yu. S. ChekryshkinAbstract:Frontal Chromatography was used to study the adsorption dynamics and adsorption equilibrium of chlorobenzene on a 5% V_2O_5/Al_2O_3 catalyst at temperatures of 50 and 100°C. The mixed-diffusion model was employed to describe the elution curve and evaluate the effective coefficients of external mass exchange and diffusion within transport pores.
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Adsorption of chlorobenzene on V2O5/Al2O3 catalyst under dynamic conditions
Russian Journal of Applied Chemistry, 2007Co-Authors: L. D. Asnin, A. A. Fedorov, Yu. S. ChekryshkinAbstract:Frontal Chromatography was used to study the adsorption dynamics and adsorption equilibrium of chlorobenzene on a 5% V2O5/Al2O3 catalyst at temperatures of 50 and 100°C. The mixed-diffusion model was employed to describe the elution curve and evaluate the effective coefficients of external mass exchange and diffusion within transport pores.
Martin Muhler - One of the best experts on this subject based on the ideXlab platform.
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Effect of Constant‐Rate Reduction on the Performance of a Ternary Cu/ZnO/Al2O3 Catalyst in Methanol Synthesis
Chemie Ingenieur Technik, 2014Co-Authors: Holger Ruland, Wilma Busser, Horst Otto, Martin MuhlerAbstract:A multi-functional flow set-up was developed for the rate- and temperature-controlled reduction of copper catalysts, their application in high-pressure methanol synthesis and the determination of the copper surface area by N2O Frontal Chromatography. The influence of constant-rate reduction on the catalytic properties of a ternary Cu/ZnO/Al2O3 catalyst was investigated. The temperature during the constant-rate reduction was found to decrease, indicating autocatalytic kinetics, but no significant catalytic effect of the milder reduction conditions was observed compared with a slow linear heating ramp.
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Parallelized N2O Frontal Chromatography for the fast determination of copper surface areas.
Journal of combinatorial chemistry, 2008Co-Authors: Stefan Olejnik, Christian Baltes, Martin Muhler, Ferdi SchüthAbstract:A parallel reactor setup in combination with a spatially resolving Fourier transform infrared focal plane array detector (FTIR-FPA) system in rapid scan mode has been developed which is capable of analyzing simultaneously the specific surface area of 15 copper catalysts. The system allows the reliable determination of copper surface areas with an error of about +/-1 m(2)/g. Problems are encountered with very fluffy catalyst powders, since this leads to excessive pressure drop over the catalyst bed. The error brought about by this effect can be eliminated by taking into account the flow deviations between channels in such cases.
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THE BACK-TITRATION OF CHEMISORBED ATOMIC OXYGEN ON COPPER BY CARBON MONOXIDE INVESTIGATED BY MICROCALORIMETRY AND TRANSIENT KINETICS
Journal of Thermal Analysis and Calorimetry, 2008Co-Authors: R. Naumann D’alnoncourt, Barbara Graf, Xinyu Xia, Martin MuhlerAbstract:The back-titration of atomic oxygen chemisorbed on metallic copper using carbon monoxide is investigated by microcalorimetry. Results from simulations based on a microkinetic model of the back-titration are used for processing of microcalorimetric data. In addition, surface oxidation of copper by nitrous oxide is investigated by microcalorimetry. The results are compared with results obtained by nitrous oxide reactive Frontal Chromatography and by static oxygen adsorption studied by microcalorimetry. The heat of adsorption of nitrous oxide on copper amounts to 304 kJ mol−1, and the heat of adsorption of carbon monoxide on surfaceoxidized copper is in the range from 120 to 70 kJ mol−1.
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The preparation of Cu/Al2O3 catalysts via CVD in a fluidized-bed reactor
Surface & Coatings Technology, 2007Co-Authors: Raoul Naumann D'alnoncourt, Michael Becker, Jelena Sekulic, Roland A. Fischer, Martin MuhlerAbstract:Abstract Our ongoing study aims at the preparation of a copper catalyst of industrial interest via chemical vapor deposition of metal–organic precursors in a fluidized-bed reactor. In the present contribution, the preparation of Cu/Al2O3 model catalysts is reported. The used CVD precursors are Cu(II) dialkylamino-2-propoxides containing methyl and ethyl groups, respectively. The substrate used for deposition is a commercial alumina usually applied for Chromatography. The samples are characterized using temperature-programmed reduction, reactive Frontal Chromatography using nitrous oxide, thermogravimetry, elemental analysis and X-ray diffraction. Although high copper loadings up to 10% can be achieved under the applied conditions, no free copper surface area can be found after reduction of catalyst samples.
M.-o. Simonnot - One of the best experts on this subject based on the ideXlab platform.
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Eluto-Frontal Chromatography to simulate chemical weathering of COx by low-molecular-weight organic compounds and early pedogenesis processes
European Journal of Soil Science, 2009Co-Authors: N. Scholtus, E. Leclerc, P. De Donato, J.l. Morel, M.-o. SimonnotAbstract:Excavation of geological materials by civil engineering operations generates fresh parent rocks that are transferred from the deep layers to the surface in a very short time. Thus they are exposed to pedogenetic factors. Prediction of the characteristics and functioning (e.g. plant support and water filter) and impacts of the newly formed soils requires the knowledge of the pedogenetic processes affecting the parent materials (i.e. weathering, transport and neoformation). Reactive transport is here used to assess weathering processes of geological materials produced from the excavation of an underground laboratory in the Callovo-Oxfordian (COx) layer, subsequently disposed of on the soil surface and covered with plants. The COx layer (c. 150-100 million years) is mainly composed of quartz, calcite, dolomite and argillite (complex mixtures of phyllosilicates). COx samples collected between −456.6 and −482.5 m were submitted to eluto-Frontal Chromatography experiments in the presence of simple organic molecules exhibiting a range of chemical reactivity (i.e. acetate, oxalate, histidine and EDTA). Breakthrough curves of compounds contained in the COx material and mathematical modelling allowed the identification of the major chemical reactions taking place during weathering. Results showed that acidic and complexing organic compounds induced the partial solubilization of minerals and in some cases secondary precipitations. The early pedogenesis processes induced a strong release of minerals (Na, Ca, Mg) and transformation of clay minerals. Further evolution of COx material is dependent on the presence of carbonates, leading to carbonated soils such as Calcosols. Reactive transport experiments showed that early pedogenetic processes are of most importance as they produced strong changes in the parent material composition and released significant amounts of solutes into the soil solution.
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Eluto-Frontal Chromatography to simulate chemical weathering of COx by low-molecular-weight organic compounds and early pedogenesis processes
European Journal of Soil Science, 2008Co-Authors: N. Scholtus, E. Leclerc, P. De Donato, J.l. Morel, M.-o. SimonnotAbstract:Summary Excavation of geological materials by civil engineering operations generates fresh parent rocks that are transferred from the deep layers to the surface in a very short time. Thus they are exposed to pedogenetic factors. Prediction of the characteristics and functioning (e.g. plant support and water filter) and impacts of the newly formed soils requires the knowledge of the pedogenetic processes affecting the parent materials (i.e. weathering, transport and neoformation). Reactive transport is here used to assess weathering processes of geological materials produced from the excavation of an underground laboratory in the Callovo-Oxfordian (COx) layer, subsequently disposed of on the soil surface and covered with plants. The COx layer (c. 150–100 million years) is mainly composed of quartz, calcite, dolomite and argillite (complex mixtures of phyllosilicates). COx samples collected between −456.6 and −482.5 m were submitted to eluto-Frontal Chromatography experiments in the presence of simple organic molecules exhibiting a range of chemical reactivity (i.e. acetate, oxalate, histidine and EDTA). Breakthrough curves of compounds contained in the COx material and mathematical modelling allowed the identification of the major chemical reactions taking place during weathering. Results showed that acidic and complexing organic compounds induced the partial solubilization of minerals and in some cases secondary precipitations. The early pedogenesis processes induced a strong release of minerals (Na, Ca, Mg) and transformation of clay minerals. Further evolution of COx material is dependent on the presence of carbonates, leading to carbonated soils such as Calcosols. Reactive transport experiments showed that early pedogenetic processes are of most importance as they produced strong changes in the parent material composition and released significant amounts of solutes into the soil solution. La chromatographie eluto-Frontale pour simuler l’alteration chimique du COx par des composes organiques de faible masse et les premiers stades de la pedogenese Resume Les materiaux geologiques excaves par les operations de genie civil constituent les roches meres brutalement exposees aux facteurs pedogenetiques generant des sols technologiques, i.e. Technosols. La prediction de la composition, du fonctionnement (e.g. support de vegetation, qualite des eaux) et de l’impact de ces nouveaux profils necessitent de connaitre les processus pedogenetiques qui prennent siege, notamment l’alteration, le transport et la neoformation. Le transport reactif, derive du genie des procedes et en particulier de la chromatographie, est ici utilise pour predire l’alteration de materiaux geologiques issus de la construction d’un laboratoire souterrain dans le Callovo-Oxfordien (COx), deposes a la surface et soumis a la vegetalisation. Les roches de la couche du COx (-150 a -100 millions d’annees) contiennent principalement du quartz, de la calcite, de la dolomite et des argilites, melange de phyllosilicates. Des echantillons de COx collectes entre −456.6 et −482.5 m ont ete soumis a des experiences de chromatographie eluto-Frontale en presence de composes organiques simples de reactivite chimique croissante (acetate, oxalate, histidine et EDTA). La mesure des courbes de percee et leur modelisation mathematique ont permis d’identifier les reactions chimiques predominantes et les mineraux formes. Les resultats ont montre que les composes acides et complexants entrainaient la solubilisation partielle de mineraux et dans certains cas des precipitations secondaires. Les premiers stades de la pedogenese s’accompagnent de la mise en solution de quantites importantes d’elements (e.g. Na, Ca, Mg) et la transformation des mineraux argileux. L’evolution du COx est controlee principalement par les carbonates et amene a la formation de sols carbonates de type Calcosol. En conclusion, le transport reactif montre que les premiers stades de la pedogenese sont cruciaux car ils induisent des changements importants de la phase minerale et le relargage massif de solutes.
Peter Mcloughlin - One of the best experts on this subject based on the ideXlab platform.
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Molecularly imprinted polymers for corticosteroids: impact of polymer format on recognition behaviour
Microchimica Acta, 2013Co-Authors: Laurence Fitzhenry, Panagiotis Manesiotis, Patrick Duggan, Peter McloughlinAbstract:A comparative study was performed on different polymeric formats for targeting corticosteroids, focusing on the use of bulk monolith and precipitation polymerisation strategies. Hydrocortisone-17-butyrate was selected as the template and methacrylic acid as the functional monomer, following ^1H NMR investigation of the pre-polymerisation mixture. Three different cross-linkers were tested, ranging from moderate to highly hydrophobic. The synthesised bulk and precipitated imprinted polymers were physically characterised by nitrogen sorption and evaluated by means of HPLC and Frontal Chromatography against a range of template analogues. While some degree of selectivity for the template was achieved for all tested polymers, the ones based on the tri-functional cross-linking monomer trimethylolpropane trimethacrylate exhibited the longest retention for all corticosteroids, especially in the precipitated format, which suggested broader group selectivity. Figure An investigation into polymer format suitability for the molecular imprinting of corticosteroids.
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Molecularly imprinted polymers for corticosteroids: impact of polymer format on recognition behaviour
Mikrochimica Acta, 2013Co-Authors: Laurence Fitzhenry, Panagiotis Manesiotis, Patrick Duggan, Peter McloughlinAbstract:A comparative study was performed on different polymeric formats for targeting corticosteroids, focusing on the use of bulk monolith and precipitation polymerisation strategies. Hydrocortisone-17-butyrate was selected as the template and methacrylic acid as the functional monomer, following 1H NMR investigation of the pre-polymerisation mixture. Three different cross-linkers were tested, ranging from moderate to highly hydrophobic. The synthesised bulk and precipitated imprinted polymers were physically characterised by nitrogen sorption and evaluated by means of HPLC and Frontal Chromatography against a range of template analogues. While some degree of selectivity for the template was achieved for all tested polymers, the ones based on the tri-functional cross-linking monomer trimethylolpropane trimethacrylate exhibited the longest retention for all corticosteroids, especially in the precipitated format, which suggested broader group selectivity.
