References of "Job, Nathalie"
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See detailCompressing some sol-gel materials reduces their stiffness: a textural analysis
Gommes, Cédric ULg; Job, Nathalie ULg; Blacher, Silvia ULg et al

in Studies in Surface Science and Catalysis (2007), 160

The mechanical behaviour of two series of silica and of resorcinol xerogels is analyzed by mercury porosimetry. The data are expressed as pressure-density curves, which enables textural information to be ... [more ▼]

The mechanical behaviour of two series of silica and of resorcinol xerogels is analyzed by mercury porosimetry. The data are expressed as pressure-density curves, which enables textural information to be obtained. In particular, it is shown that some of the analyzed samples exhibit a marked lowering of their mechanical stiffness upon compression. This observation is analyzed in terms of the collapse of the sample’s porosity and of the heterogeneity of the microstructure. [less ▲]

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See detailSynthesis of transition metal-doped carbon xerogels by cogelation
Job, Nathalie ULg; Pirard, René ULg; Vertruyen, Bénédicte ULg et al

in Journal of Non-Crystalline Solids (2007), 353(24-25), 2333-2345

The cogelation process, i.e. the co-polymerization of a metal complex with the gel precursors, was used for the synthesis of transition metal-doped resorcinol-formaldehyde gels. The aim of this process is ... [more ▼]

The cogelation process, i.e. the co-polymerization of a metal complex with the gel precursors, was used for the synthesis of transition metal-doped resorcinol-formaldehyde gels. The aim of this process is to anchor the metal to the polymer so that the former does not sinter during the pyrolysis step leading to porous carbon. Cu-, Ni-, Pd- or Pt-loaded gels were prepared by this technique. After drying and pyrolysis, Pd and Pt were obtained as metal nanoparticles (2-5 nm in diameter) inserted in the carbon nodules, when the complexing agent and the synthesis conditions were well chosen. These small metal particles were inaccessible to reactive gases, probably due to carbon deposit at the metal surface during pyrolysis: CO almost did not chemisorb. Oxidation of the support or pyrolysis under reductive atmosphere was applied to the metal-doped gels and carbons in order to make the surface of the metal particles accessible, but these treatments develop the macropores only. The cogelation process is then suitable to prepare metal nanoparticles protected from the outside by encapsulation in the carbon matrix. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailSol-gel synthesis of supported metals
Heinrichs, Benoît ULg; Lambert, Stéphanie ULg; Job, Nathalie ULg et al

in Regalbuto, John R. (Ed.) Catalyst Preparation : Science and Engineering (2007)

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See detailCarbon xerogels as catalyst supports for PEM fuel cell cathode
Job, Nathalie ULg; Marie, Julien; Lambert, Stéphanie ULg et al

Conference (2007)

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See detailTowards the production of carbon xerogel monoliths by optimizing convective drying conditions
Job, Nathalie ULg; Sabatier, Françoise; Pirard, Jean-Paul ULg et al

in Carbon (2006), 44(12), 2534-2542

Resorcinol-formaldehyde hydrogels prepared at various resorcinol/sodium carbonate ratios, R/C, were convectively air dried. The influence of the drying operating conditions, i.e. air temperature and ... [more ▼]

Resorcinol-formaldehyde hydrogels prepared at various resorcinol/sodium carbonate ratios, R/C, were convectively air dried. The influence of the drying operating conditions, i.e. air temperature and velocity, on the pore texture, shrinkage and cracking of the dried gels were investigated. Shrinkage was found to be isotropic. The shrinkage behaviour and the textural properties of the gels are independent of the drying operating conditions, but are completely determined by the value of the synthesis variables. The analysis of the drying kinetics shows two main drying periods. During the first phase, shrinkage occurs and the external surface of the material remains completely wet: heat and mass transfers are limited by external resistances located in a boundary layer. When shrinkage stops, the second period begins: the evaporation front recedes inside the solid and internal transfer limitations prevail. The drying time can be reduced by increasing the air temperature and/or velocity, but the temperature increase is limited when monolithicity is required, especially when the pores are small. For example, at a temperature of 160 degrees C and a velocity of 2 m/s, about 1 h is needed to dry a 2.8 cm in diameter and 1 cm in height cylinder containing macropores (pore width > 50 nm after drying). The same cylinder presenting small mesopores (pore width = 10-15 nm after drying) requires 20 h at 30 degrees C and 2 m/s to reach complete dryness without the development of cracks. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

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See detailTime-resolved SAXS study of the formation of resorcinol-formaldehyde aqueous gels
Job, Nathalie ULg; Gommes, Cédric ULg; Goderis, B. et al

Poster (2006, August 06)

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See detailSynthesis optimization of organic xerogels produced from convective air-drying of resorcinol-formaldehyde gels
Job, Nathalie ULg; Panariello, Fabian; Marien, José ULg et al

in Journal of Non-Crystalline Solids (2006), 352(1), 24-34

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied ... [more ▼]

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied in order to optimize the synthesis conditions. The convective air-drying process was used, and the drying duration was studied with regard to the synthesis conditions. The aging time has no effect on the pore texture after 24 h at 90 degrees C or 48 h at 70 C, whatever the R/C value. The synthesis-aging step can be shortened by increasing the temperature. Nevertheless, the pore size tends then to decrease, especially when R/C is high, but this can be counterbalanced by increasing R/C. Moreover, bubbles often appear in the gel at high synthesis temperature, which limits the temperature to about 70 degrees C in the case of monolithic parts. At 70 degrees C and with an air velocity of 2 m/s, the elimination of 90% of the solvent requires 1 h drying when the pore size reaches 400-600 nm, 2.5 h for 50 nm wide pores and 3 h when the pore size decreases to 15-20 nm. The drying duration does not exceed 8 h in all cases and could be shortened by increasing the temperature at the end of the process. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailMetal catalysts suppported on texture-tailored carbon xerogels
Job, Nathalie ULg; Léonard, Angélique ULg; Colomer, Jean-François et al

in Studies in Surface Science and Catalysis (2006), 162

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See detailHighly dispersed platinum catalysts prepared by impregnation of texture-tailored carbon xerogels
Job, Nathalie ULg; Ribeiro Pereira, Manuel Fernando; Lambert, Stéphanie ULg et al

in Journal of Catalysis (2006), 240(2), 160-171

Pt/C catalysts were prepared by impregnation of carbon xerogels with H2PtCl6 aqueous solutions. Three supports with various pore textures were used: two micro-mesoporous (maximum pore size = 10 and 40 nm ... [more ▼]

Pt/C catalysts were prepared by impregnation of carbon xerogels with H2PtCl6 aqueous solutions. Three supports with various pore textures were used: two micro-mesoporous (maximum pore size = 10 and 40 nm, respectively) and one micro-macroporous (maximum pore size = 70 nm). After impregnation, drying and reduction, the metal particles were at most 1-1.5 nm in diameter. The Pt dispersion was close to 100% in the case of the xerogel with large mesopores. For the two other supports, a small fraction of Pt was trapped in blocked micropores. The specific catalytic activity obtained for benzene hydrogenation was 4-10 times higher than that obtained with active charcoal-supported catalysts prepared by a similar method. The high dispersion of Pt was attributed to the presence in the xerogel of large mesopore or macropore volumes, which facilitates impregnation, and a low amount of oxygenated surface groups. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

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See detailCu/carbon xerogel catalysts for the selective catalytic reduction of NO by NH3 : effect of the pore texture
Cabiac, A.; Job, Nathalie ULg; Pirard, Jean-Paul ULg et al

in Journal of Chemistry for Sustainable Development (2006), 6

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See detailCarbon xerogels as catalyst supports: study of mass transfer
Job, Nathalie ULg; Heinrichs, Benoît ULg; Lambert, Stéphanie ULg et al

in AIChE Journal (2006), 52

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