References of "Douven, Sigrid"
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See detailThe range of validity of sorption kinetic models
Douven, Sigrid ULg; Pàez Martinez, Carlos ULg; Gommes, Cédric ULg

in Journal of Colloid & Interface Science (2015), 448

Several hundred papers are published yearly reporting liquid-phase adsorption kinetics data. In general the data is analyzed using a variety of standard models such as the pseudo first- and second-order ... [more ▼]

Several hundred papers are published yearly reporting liquid-phase adsorption kinetics data. In general the data is analyzed using a variety of standard models such as the pseudo first- and second-order models and the Intraparticle-Diffusion model. The validity of these models is often assessed empirically via their ability to fit the data, independently of their physicochemical soundness. The aim of the present paper is to rationalize the analysis of liquid-phase adsorption kinetics data, and to investigate experimental factors that influence the adsorption kinetics, in addition to the characteristics of the adsorbent material itself. For that purpose we use a simple Langmuir adsorption–diffusion model, which enables us to identify three dimensionless numbers that characterize the working regime of any batch adsorption experiment: an adsorption Thiele modulus, a saturation modulus, and a loading modulus. The standard models are found to be particular cases of the general adsorption–diffusion model for specific values of the dimensionless numbers. This provides sound physicochemical criteria for the validity of the models. Based on our modeling, we also propose a general yet simple data analysis procedure to practically estimate the diffusion coefficient in adsorbent pellets starting from adsorption halftimes. [less ▲]

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See detailDevelopment of Highly Active doped Titania Photocatalysts by Aqueous Sol-Gel Processing
Malengreaux, Charline ULg; Douven, Sigrid ULg; Poelman, Dirk et al

Poster (2012, December)

Detailed reference viewed: 37 (15 ULg)
See detailDevelopment of Highly Active doped Titania Photocatalysts by Aqueous Sol-Gel Processing
Malengreaux, Charline ULg; Douven, Sigrid ULg; Poelman, Dirk et al

Poster (2012, November)

Detailed reference viewed: 27 (13 ULg)
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See detailCarbon nanotube synthesis by CCVD process: kinetic study on a Ni-Mo/MgO catalyst
Douven, Sigrid ULg; Pirard, Sophie ULg; Chan, Fang-Yue et al

Poster (2012, October)

Detailed reference viewed: 13 (0 ULg)
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See detailSynthèse de MWNT dans un réacteur continu incliné rotatif à lit mobile par procédé CCVD
Douven, Sigrid ULg; Pirard, Sophie ULg; Chan, Fang-Yue et al

Conference (2012, October)

Detailed reference viewed: 29 (8 ULg)
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See detailLarge-scale synthesis of multi-walled carbon nanotubes in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition process using methane as carbon source
Douven, Sigrid ULg; Pirard, Sophie ULg; Chan, Fang-Yue et al

in Chemical Engineering Journal (2012)

Multi-walled carbon nanotubes (CNTs) were produced in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition of methane on a bimetallic Ni-Mo/MgO catalyst whose ... [more ▼]

Multi-walled carbon nanotubes (CNTs) were produced in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition of methane on a bimetallic Ni-Mo/MgO catalyst whose activity remains constant in the course of time. Measurements performed on the continuous reactor were validated to ensure that the installation worked correctly and that measurements were precise enough. The performance of the reactor was simulated using a model based on the chemical reactor engineering approach. Hypotheses of the model were verified, and a kinetic study was performed to obtain a kinetic rate expression and to determine the catalytic activity as a function of time. The purity level of produced CNTs depends on the desired properties of the product, so the operating conditions are linked to the purity level that is required. A minimal purity level corresponds to high carbon production, and a maximal purity level corresponds to high specific productivity. It was shown that operating conditions had to be fixed to reach a given specific productivity or a given carbon production, and the optimized operating conditions leading to those two opposite purity level objectives were established. [less ▲]

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See detailCarbon nanotubes synthesis by CCVD process : kinetic study on a Fe-Co/Al2O3 catalyst
Pirard, Sophie ULg; Douven, Sigrid ULg; Bossuot, Christophe et al

Poster (2007, August)

Detailed reference viewed: 5 (1 ULg)
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See detailCarbon nanotubes synthesis by CCVD process : kinetic study on a Fe-Co/Al2O3 catalyst
Pirard, Sophie; Douven, Sigrid ULg; Bossuot, Christophe et al

in Carbon (2007), 45(6), 1167-1175

A kinetic study was performed to describe the initial specific rate of multi-walled carbon nanotube synthesis by catalytic chemical vapor deposition (CCVD) on a bimetallic cobalt-iron catalyst at high ... [more ▼]

A kinetic study was performed to describe the initial specific rate of multi-walled carbon nanotube synthesis by catalytic chemical vapor deposition (CCVD) on a bimetallic cobalt-iron catalyst at high temperature using ethylene decomposition to solid carbon and gaseous hydrogen. The study uses a mass spectrometer that allows reaction rate to be inferred from the exhaust gas composition measurements. The aim is to obtain a better understanding of the elementary steps involved in the production of carbon nanotubes so as to derive phenomenological kinetic models in agreement with experimental data. The best models assume the elimination of the first hydrogen atom from adsorbed ethylene as rate determining step and involve a hydrogen adsorption weak enough to be neglected. It was proved that hydrogen partial pressure has no influence on initial reaction rate of carbon nanotube synthesis with the catalyst used for this study. Activation energy and ethylene adsorption enthalpy were found to be equal to around 130 and - 130 kJ mol(-1), respectively. (C) 2007 Elsevier Ltd. All rights reserved. [less ▲]

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See detailAnalysis of kinetic models of multi-walled CNT synthesis
Pirard, Sophie ULg; Douven, Sigrid ULg; Pirard, Jean-Paul ULg

in Carbon (2007), 45(15), 3050-3052

Detailed reference viewed: 51 (12 ULg)
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See detailA kinetic study of multi-walled carbon nanotube synthesis by catalytic chemical vapor deposition using a Fe-Co/Al2O3 catalyst
Pirard, Sophie ULg; Douven, Sigrid ULg; Bossuot, Christophe et al

in Carbon (2007), 45(6), 1167-1175

A kinetic study was performed to describe the initial specific rate of multi-walled carbon nanotube synthesis by catalytic chemical vapor deposition (CCVD) on a bimetallic cobalt-iron catalyst at high ... [more ▼]

A kinetic study was performed to describe the initial specific rate of multi-walled carbon nanotube synthesis by catalytic chemical vapor deposition (CCVD) on a bimetallic cobalt-iron catalyst at high temperature using ethylene decomposition to solid carbon and gaseous hydrogen. The study uses a mass spectrometer that allows reaction rate to be inferred from the exhaust gas composition measurements. The aim is to obtain a better understanding of the elementary steps involved in the production of carbon nanotubes so as to derive phenomenological kinetic models in agreement with experimental data. The best models assume the elimination of the first hydrogen atom from adsorbed ethylene as rate determining step and involve a hydrogen adsorption weak enough to be neglected. It was proved that hydrogen partial pressure has no influence on initial reaction rate of carbon nanotube synthesis with the catalyst used for this study. Activation energy and ethylene adsorption enthalpy were found to be equal to around 130 and - 130 kJ mol(-1), respectively. (C) 2007 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 105 (2 ULg)
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See detailCarbon nanotubes synthesis by CCVD process : kinetic study on a Fe-Co/Al2O3 catalyst
Pirard, Sophie ULg; Douven, Sigrid ULg; Bossuot, Christophe et al

Conference (2006, June)

Detailed reference viewed: 3 (0 ULg)
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See detailKinetic study on a Fe-Co/Al2O3 catalyst for carbon nanotube synthesis by CCVD process
Pirard, Sophie ULg; Douven, Sigrid ULg; Bosuot, Christophe et al

Poster (2006, April)

Detailed reference viewed: 15 (0 ULg)
Peer Reviewed
See detailCarbon nanotubes synthesis by CCVD process : kinetic study on a Fe-Co/Al2O3 catalyst
Pirard, Sophie ULg; Douven, Sigrid ULg; Bossuot, Christophe et al

Poster (2005, October)

Detailed reference viewed: 4 (0 ULg)