References of "Pirard, Jean-Paul"
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See detailSynthesis of Pd/SiO2, Ag/SiO2, and Cu/SiO2 cogelled xerogel catalysts: study of metal dispersion and catalytic activity
Lambert, Stéphanie ULg; Cellier, Caroline; Grange, Paul et al

in Journal of Catalysis (2004), 221(2), 335-346

Pd/SiO2, Ag/SiO2, and Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Pd, Ag, and Cu with 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS). It ... [more ▼]

Pd/SiO2, Ag/SiO2, and Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Pd, Ag, and Cu with 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS). It appears that the metal complex acts as a nucleation agent in the formation of silica particles. The resulting catalysts are then composed of completely accessible metallic crystallites with a diameter of about 3 nm located inside silica particles exhibiting a monodisperse microporous distribution. The metal dispersion has been determined from CO and O-2 chemisorption, TEM, and X-ray diffraction. Although metallic particles are located inside silica particles, their complete accessibility, via the micropore network, has been shown. 1,2-Dichloroethane hydrodechlorination over Pd/SiO2 catalysts mainly produces ethane and the specific hydrodechlorination rate per gram of Pd decreases when metal loading increases. Hydrodechlorination over Pd/SiO2 catalysts is a structure-insensitive reaction with regard to the ensemble size concept. Benzene oxidation over Ag/SiO2 and Cu/SiO2 catalysts produces H2O and CO2 only and specific oxidation rate per gram of metal decreases when silver and copper loadings increase. Furthermore, it is concluded that benzene oxidation is a structure-insensitive reaction. (C) 2003 Elsevier Inc. All rights reserved. [less ▲]

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See detailComparison of different methods for characterizing multi-walled carbon nanotubes
Gommes, Cédric ULg; Blacher, Silvia ULg; Dupont-Pavlovsky, N. et al

in Colloids and Surfaces A : Physicochemical and Engineering Aspects (2004), 241(1-3), 155-164

Four complementary and independent methods are used to characterize nanotube samples: (i) TEM observation coupled with image analysis, (ii) nitrogen and krypton adsorption isotherm analysis, (iii ... [more ▼]

Four complementary and independent methods are used to characterize nanotube samples: (i) TEM observation coupled with image analysis, (ii) nitrogen and krypton adsorption isotherm analysis, (iii) thermogravimetry and (iv) wide angle X-ray scattering. The methodology is discussed on the basis of two multi-walled carbon nanotube samples produced by the CCVD technique with very different reaction rates. It is shown that the total amount of deposited carbon is larger for the sample produced at the higher rate, that the fraction of nanotubes in the deposited carbon does not seem to be significantly different, but that the crystallinity of the nanotubes wall is larger for the sample produced at the lowest reaction rate. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailSynthesis of Pyrazolylpyridine Derivatives Bearing a Tethered Alkoxysilyl Group.
Sacco Luigi; Lambert, Stéphanie ULg; Pirard, Jean-Paul ULg et al

in Synthesis (2004), 5

A synthesis of a new serie of trimethoxysilyl-tethered N-substituted 3,5-dialkylpyrazolylpyridines is reported. The silyl spacers allow the grafting of ligands onto silica via formation of covalent bonds ... [more ▼]

A synthesis of a new serie of trimethoxysilyl-tethered N-substituted 3,5-dialkylpyrazolylpyridines is reported. The silyl spacers allow the grafting of ligands onto silica via formation of covalent bonds as well as the synthesis of xerogels. [less ▲]

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See detailElaboration of new formulations to remove micropollutants in MSWI flue gas
Brasseur, Alain; Gambin, Amandine; Laudet, Alain et al

in Chemosphere (2004), 56(8), 745-756

This study consists in identifying and testing potential inorganic substitutes to carbon based materials commonly used as adsorbents for the removal of organic pollutants such as dioxins and furans ... [more ▼]

This study consists in identifying and testing potential inorganic substitutes to carbon based materials commonly used as adsorbents for the removal of organic pollutants such as dioxins and furans released from Municipal Solid Waste Incinerators (MSWI). Although carbon materials enable to reach the current regulation in terms of dioxins and furans emissions, they exhibit a potential auto ignition risk when present in hot flue gases. Here, the adsorption potential of carbon based products is compared to the one of some inorganic materials. Chlorobenzene was chosen as a reference molecule to compare the removal performance of the different adsorbents. This comparison was based on the determination of the adsorption energies derived from temperature programmed desorption (TPD) experiments. In the first part of this study, five inorganic materials were selected according to their chlorobenzene adsorption performance compared to those of carbon based products currently used to remove micropollutants from MSWI flue gases. In the second part of the study, the influence of the inlet concentration of adsorbate on the adsorption potential of sorbents is investigated. Actually, the organic compound concentration was decreased in order to be closer to those met in MSWI. Furthermore, the adsorption experiments were performed with other adsorbates whose molecular mass or chlorine content are higher. Thanks to these adsorption results a new organic free formulation has been proposed for the removal of micropollutants. Tests carried out on an industrial scale, demonstrated that this product enables to reach the current norm concerning dioxins and furans emissions. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPorous carbon xerogels with texture tailored by pH control during sol-gel process
Job, Nathalie ULg; Pirard, René ULg; Marien, José ULg et al

in Carbon (2004), 42(3), 619-628

Despite commonly accepted ideas, evaporative drying does not always completely destroy the pore texture of phenolic gel. This work shows that very porous carbon materials can be synthesized by evaporative ... [more ▼]

Despite commonly accepted ideas, evaporative drying does not always completely destroy the pore texture of phenolic gel. This work shows that very porous carbon materials can be synthesized by evaporative drying and pyrolysis of aqueous resorcinol-formaldehyde gels provided that the operating variables are correctly chosen. Moreover, in this manner monoliths can be easily produced. The pore texture of the materials was studied before and after pyrolysis in order to determine which synthesis and/or pyrolysis variables have an influence on the final texture of the carbon. Results show that it is possible to tailor the morphology of these materials by varying the initial pH of the precursors solution in a narrow range. Micro-macroporous, micro-mesoporous, microporous or totally non-porous carbon materials were obtained. The specific surface area is independent from the initial pH whereas the total void volume varies from 0.4 to 1.4 cm(3)/g when the initial pH decreases from 6.25 to 5.45. These materials can be used as catalysts supports or for electrochemical applications, the texture control being an interesting advantage. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailAlignment of glial cells stimulates directional neurite growth of cns neurons in vitro
Deumens, R.; Koopmans, G. C.; Den Bakker, C. G. J. et al

in Neuroscience (2004), 125(3), 591-604

Olfactory ensheathing cells (OECs) together with olfactory nerve fibroblasts (ONFs) and neonatal astrocytes are potent stimulators of neurite growth in adulthood and during development, respectively ... [more ▼]

Olfactory ensheathing cells (OECs) together with olfactory nerve fibroblasts (ONFs) and neonatal astrocytes are potent stimulators of neurite growth in adulthood and during development, respectively. Since it is known that alignment of glial cells is important for the correct outgrowth of axon tracts, it was hypothesized that the alignment of glial cells stimulates directional and enhanced neurite outgrowth. Adult OEC/ONF and neonatal astrocytes were cultured either on biodegradable poly(D,L)-lactide matrices or in Petri dishes for 4 days. Thereafter neonatal cerebral cortical neurons were added. After a 2-days coculture period the cultures were fixed and processed for a combined MAP-2 and phosphorylated neurofilament (RT97) staining. The neurite growth (neurite elongation and neurite formation) and the neurite direction were assessed. We show that (1) OEC/ONF cultures are more potent in stimulating the length of the longest neurite of cocultured neurons, (2) alignment of glial is achieved in vitro on our biomatrices, (3) aligned glial/biomatrix complexes do not enhance neurite growth, and (4) aligned glial/biomatrix complexes direct neurite outgrowth. These data have significant implications for in vivo experiments focusing on glial transplantation. Transplanting glial/biomatrix complexes may stimulate the directional regrowth of severed axons across a lesion site. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved. [less ▲]

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See detailSynthesis of transition metal-doped carbon xerogels by solubilization of metal salts in resorcinol-formaldehyde aqueous solution
Job, Nathalie ULg; Pirard, René ULg; Marien, José ULg et al

in Carbon (2004), 42(15), 3217-3227

The pore texture of carbon materials obtained from evaporative drying and pyrolysis of resorcinol-formaldehyde aqueous gels is controlled by the initial pH of the precursors solution. In order to produce ... [more ▼]

The pore texture of carbon materials obtained from evaporative drying and pyrolysis of resorcinol-formaldehyde aqueous gels is controlled by the initial pH of the precursors solution. In order to produce transition metal-containing carbons with tailored texture, various metallic salts were dissolved in the precursors solution. When necessary, a complexing agent (HEDTA or DTPA) was added to render the metal ions soluble. Ni, Fe and I'd loaded carbon xerogels were synthesized and their pore texture was studied after evaporative drying and after pyrolysis. The carbon texture was also studied with regard to the nature of the metal and the amount of complexing agent. The solubilization of transition metal salts in the resorcinol-formaldehyde aqueous solution does not prevent the texture regulation, even though this texture control is influenced: the limits of the pH interval leading to micro mesoporous carbon materials can slightly differ when a metal salt and/or a complexing agent are added. The pH range shift depends mainly on the amount and nature of the complexing agent, but also slightly on the nature of the metal ion. Nevertheless, the metal particles obtained are rather big (diameter > 15 nm). For catalytic applications, the metal dispersion must be enhanced, especially in the case of expensive metals. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailMeasurement of shrinkage and cracks associated to convective drying of soft materials by X-ray microtomography
Léonard, Angélique ULg; Blacher, Silvia ULg; Marchot, Pierre ULg et al

in Drying Technology (2004), 22(7), 1695-1708

Traditionally, the measurement of shrinkage occurring during drying is performed by destructive or poorly accurate techniques such as volume displacement methods. Cracks detection and quantification are ... [more ▼]

Traditionally, the measurement of shrinkage occurring during drying is performed by destructive or poorly accurate techniques such as volume displacement methods. Cracks detection and quantification are realised either by destructive techniques or sophisticated but expensive nondestructive ones (NMR imaging). X-ray microtomography in combination with image analysis provides an accurate, nondestructive and easy to use technique to determine simultaneously shrinkage and crack extent. Results reported in this article concern drying of wastewater sludges whose management will become a real challenge in the years to come. These results show a clear relation between drying kinetics and crack development. This could be related to the development of internal diffusional limitations inducing moisture gradients and mechanical stresses leading to cracks formation. [less ▲]

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See detailBall milling effect on the structure of single-wall carbon nanotubes
Pierard, N.; Fonseca, Antonio; Colomer, Jean-François et al

in Carbon (2004), 42(8-9), 1691-1697

The vibratory mill is used to decrease the single-wall carbon nanotubes (SWNTs) length and to increase their specific surface area. Electron microscopy, Raman spectroscopy, X-ray diffraction and BET ... [more ▼]

The vibratory mill is used to decrease the single-wall carbon nanotubes (SWNTs) length and to increase their specific surface area. Electron microscopy, Raman spectroscopy, X-ray diffraction and BET measurements indicated that the optimum time of treatment seems to be 2 h. After that, the SWNTs quality decreases, with a complete disruption of the tubular structure leading to multi-layered polyaromatic carbon materials observed after 50 h. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailImprovement of metal dispersion in Pd/SiO2 cogelled xerogel catalysts for 1,2-dichloroethane hydrodechlorination
Lambert, Stéphanie ULg; Polard, Jean-François; Pirard, Jean-Paul ULg et al

in Applied Catalysis B : Environmental (2004), 50

The study of the influence of synthesis operating variables (nature and concentration of complexing silane, palladium percentage, temperatures of gelling, aging and vacuum drying of xerogels, molar ratio ... [more ▼]

The study of the influence of synthesis operating variables (nature and concentration of complexing silane, palladium percentage, temperatures of gelling, aging and vacuum drying of xerogels, molar ratio between the complexing silane and palladium, molar concentration of ammonia solution, and use of tetramethylammonium hydroxide as base instead of NH3) allows improving metal dispersion in Pd/SiO2 cogelled xerogel catalysts. The use of 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) or 3-(2-aminoethylamino)propyltriethoxysilane (EDAES) to complex palladium in an ethanolic solution containing tetraethoxy si lane (TEOS) and an ammonia solution of 0.54 mol/l allows obtaining a Pd/SiO2 xerogel catalyst with a mean metal particle diameter of 2.4 nm located inside silica particles. Indeed, complexes Pd(EDA(E)S)(x)(n+) induce a nucleation mechanism because of their higher reactivity compared to the network-reagent (TEOS). Although metal particles are located inside the silica particles, their complete accessibility, via the micropore network, has been shown. 1,2-dichloroethane hydrodechlorination over Pd/SiO2 catalysts mainly produces ethane and the specific hydrodechlorination rate per gram of palladium increases proportionally with palladium dispersion. Hydrodechlorination over Pd/SiO2 cogelled xerogel catalysts is a structure insensitive reaction with regard to the ensemble size concept. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailInfluence of the operating conditions on the production rate of multi-walled carbon nanotubes in a CVD reactor
Gommes, Cédric ULg; Blacher, Silvia ULg; Bossuot, C. et al

in Carbon (2004), 42(8-9), 1473-1482

A kinetic study is presented for the synthesis of multi-walled carbon nanotubes in a semi-continuous chemical vapor deposition reactor. The study is based on the use of a mass spectrometer that allows the ... [more ▼]

A kinetic study is presented for the synthesis of multi-walled carbon nanotubes in a semi-continuous chemical vapor deposition reactor. The study is based on the use of a mass spectrometer that allows the reaction rate to be inferred from the exhaust gas composition measurements. The tested reactor operating variables are the length and thickness of the catalytic bed, the total feed flow and the molar fraction of hydrocarbon in the feed. The results of the study are analyzed using well known reactor engineering models, which allows the origin of the observed physical limitations to be ascertained. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPd-Ag/SiO2 and Pd-Cu/SiO2 cogelled xerogel catalysts for selective hydrodechlorination of 1,2-dichloroethane into ethylene
Lambert, Stéphanie ULg; Ferauche, Fabrice; Brasseur, Alain et al

Conference (2004)

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See detailImprovement of metal dispersion in Pd/SiO2 cogelled xerogel catalysts
Lambert, Stéphanie ULg; Polard, Jean-François; Ferauche, Fabrice et al

Poster (2004)

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