References of "Pirard, Jean-Paul"
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See detailStudy of photocatalytic decomposition of hydrogen peroxide over ramsdellite-MnO2 by O2-pressure monitoring
Páez Martínez, Carlos ULg; Liquet, Dimitri ULg; Calberg, Cédric ULg et al

in Catalysis Communications (2011), 15

The catalytic and photocatalytic activities of ramsdellite type manganese oxide, R-MnO2 were studied from the initial rate of decomposition of H2O2 in aqueous solution. The kinetic study was followed by ... [more ▼]

The catalytic and photocatalytic activities of ramsdellite type manganese oxide, R-MnO2 were studied from the initial rate of decomposition of H2O2 in aqueous solution. The kinetic study was followed by the production of O2 via gas pressure monitoring (O2-monitored method), in the dark and under visible light irradiation (λ≥400 nm), at 20 °C. Experimental data showed that the rate of H2O2 decomposition, under visible light irradiation and in the dark, obeys the first order kinetic law.While in the dark the H2O2 decomposition rate bymass unit was around 6.88 mmol g−1 s−1, under visible light irradiation theH2O2 decomposition rate achieved a maximal value of 15.13 mmol g−1 s−1. The increase in the H2O2 decomposition, by effect of the visible light, was observed in ranges of catalyst concentrations from 16 to 374 mg L−1. These results reflect the potential of R-MnO2 as a photoactive catalyst, being a consequence of presumed photoreduction of Mn4+centers. [less ▲]

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See detailImprovement in the methylene blue adsorption capacity and photocatalytic activity of H2-reduced rutile-TiO2 caused by Ni(II)porphyrin preadsorption
Páez Martínez, Carlos ULg; Lambert, Stéphanie ULg; Poelman, Dirk et al

in Applied Catalysis B : Environmental (2011), 106

H2-reduced rutile-TiO2 xerogel (Ti-700), obtained via the sol–gel process, was found to strongly adsorb the Ni(II)-5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin (NiTCPP) from a methanolic solution ... [more ▼]

H2-reduced rutile-TiO2 xerogel (Ti-700), obtained via the sol–gel process, was found to strongly adsorb the Ni(II)-5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin (NiTCPP) from a methanolic solution, despite its very low specific surface area (SBET ≈ 2 m2 g−1). UV/vis spectroscopy analysis showed that after calcination at 700 ◦C and reduction under H2 flow at 400 ◦C, the TiO2-xerogel increased its NiTCPP-adsorption capacity by surface area unit by up to 120 times. The effect of the porphyrin presence in the catalytic performances of TiO2-xerogels was studied through three kinetics models: (i) the pseudo-first-order kinetic model; (ii) the pseudo-second-order kinetic model, which are used to describe the adsorption rate based on the adsorption capacity of the catalysts; and (iii) the Langmuir–Hinshelwood kinetic model which is used to describe the photocatalytic degradation rate of methylene blue (MB). A significant improvement in the efficiency of Ti-700 was observed after the porphyrin-adsorption process (NiTCPP/Ti-700): MB-adsorption capacity at equilibrium and the apparent MB-photoconversion constant, kapp, of NiTCPP/Ti-700 were both up to 2 times higher than those observed for the Ti-700. [less ▲]

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See detailKrypton adsorption as a suitable tool for surface characterization of multi-walled CNTs
Zilli, Dario; Bonelli, P.; Gommes, Cédric ULg et al

in Carbon (2011), 49

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See detailThree-dimensional void space structure of activated carbon packed beds
Almazan Almazan, Maria Del Carmen; Léonard, Angélique ULg; Job, Nathalie ULg et al

in Journal of Porous Materials (2011), 18

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See detailInfluence of carbon xerogel textural properties on the dynamic adsorption of methyl iodide
Almazán-Almazán, M. C.; López-Domingo, F. J.; Domingo-García, M. et al

in Chemical Engineering Journal (2011), 173(1), 19-28

X-ray microtomography coupled to image analysis has been used to study the influence of the adsorbent pore texture and the experimental conditions on the dynamic adsorption of methyl iodide in packed ... [more ▼]

X-ray microtomography coupled to image analysis has been used to study the influence of the adsorbent pore texture and the experimental conditions on the dynamic adsorption of methyl iodide in packed filters. By applying this imaging technique the internal axial adsorption profiles for increasing exposure times to the gas stream are analysed. This experimental technique establishes a new technology to study in situ the dynamic adsorption of volatile compounds. Resorcinol-formaldehyde based carbon xerogels have been used as adsorbents, as their pore texture can be tuned by changing the synthesis conditions. The textural characteristics of the adsorbents (surface areas and pore volumes) have been assessed by using nitrogen and carbon dioxide adsorption as well as mercury porosimetry. The methyl iodide dynamic adsorption results show that, for the same gas flow rate and CH3I inlet concentration, the adsorbed amount is highly dependent on large pore volumes. Thus, samples with almost the same micropore volumes (adsorption volumes) have different methyl iodide adsorption capacities, which are related to, the above mentioned, large pores. The influence of both the gas carrier flow rate and the methyl iodide inlet concentration on the adsorption can be explained using the so-called linear driving force model. This approach takes into account the fact that internal transport limitations are directly related to the pore texture. Moreover, the simulation of the dynamic adsorption process has allowed relating the simulated axial concentration profiles to the experimental X-ray microtomography data. [less ▲]

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See detailEffects of additives and solvents on the gel formation rate and on the texture of P- and Si-doped TiO2 materials
Bodson, Céline ULg; Lambert, Stéphanie ULg; Alié, Christelle ULg et al

in Microporous and Mesoporous Materials (2010), 134

Organic/inorganic hybrid TiO2 xerogels have been synthesized from titanium tetraisopropoxide and an organosilylated or organophosphorylated additive either in 2-methoxyethanol or isopropanol. The ... [more ▼]

Organic/inorganic hybrid TiO2 xerogels have been synthesized from titanium tetraisopropoxide and an organosilylated or organophosphorylated additive either in 2-methoxyethanol or isopropanol. The mechanisms of formation of the gels have been studied before gelation by liquid NMR spectroscopy and connected to their structure after drying analyzed by Raman spectroscopy, solid state NMR and N2 adsorption/desorption. The effects of the additives and solvents on the gel formation rate and on the texture of the xerogel have been addressed. [less ▲]

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See detailA comparison of physical activation of carbon xerogels with carbon dioxide with chemical activation using hydroxides
Contreras, María S; Páez, Carlos A; Zubizarreta, Leire et al

in Carbon (2010), 48(11), 3157-3168

Carbon xerogels synthesized with a fixed resorcinol/sodium carbonate molar ratio (R/C) were physically activated using CO2. The effect of activation temperature and activation time on the final properties ... [more ▼]

Carbon xerogels synthesized with a fixed resorcinol/sodium carbonate molar ratio (R/C) were physically activated using CO2. The effect of activation temperature and activation time on the final properties of the activated carbon xerogels was evaluated. The specific surface area increases from ~600 m2 g-1 to 2000 m2 g-1 and more by increasing the temperature and duration of the activation step. A comparison between physical activation with CO2 and chemical activation with hydroxides was also performed: it was found that both processes produce an increase of the micropore volume and specific surface area without altering the meso-macroporosity developed during the synthesis. However, chemical activation can lead to the development of the narrow microporosity mainly whereas, in physical activation, the widening of the narrow micropores takes place whatever the process conditions. [less ▲]

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See detailFunctionalization of carbon xerogels for the preparation of Pd/C catalysts by grafting of Pd complex
Diverchy, C.; Hermans, S.; Job, Nathalie ULg et al

Poster (2010, July 11)

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See detailSynthesis and characterization of highly loaded Pt/carbon xerogel catalysts prepared by Strong Electrostatic Adsorption method
Job, Nathalie ULg; Maillard, F.; Chatenet, M. et al

Conference (2010, July 11)

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See detailActivated-carbon-xerogel/TiO2-P25 composite photocatalysts with high activity for the degradation of p-nitrophenol
Páez Martínez, Carlos ULg; Contreras, María; Olivera-Fuentes, Claudio et al

Poster (2010, July)

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See detailQuantitative study of catalytic activity and catalytic deactivation of Fe–Co/Al2O3 catalysts for multi-walled carbon nanotube synthesis by the CCVD process
Pirard, Sophie ULg; Heyen, Georges ULg; Pirard, Jean-Paul ULg

in Applied Catalysis A : General (2010), 382

The catalytic deactivation during multi-walled carbon nanotube (MWNT) synthesis by the CCVD process and the influence of hydrogen on it were quantified. Initial specific reaction rate, relative specific ... [more ▼]

The catalytic deactivation during multi-walled carbon nanotube (MWNT) synthesis by the CCVD process and the influence of hydrogen on it were quantified. Initial specific reaction rate, relative specific productivity and catalytic deactivation were studied. Carbon source was ethylene, and a bimetallic iron–cobalt catalyst supported on alumina was used. The catalytic deactivation was modeled by a decreasing hyperbolic law, reflecting the progressive accumulation of amorphous carbon on active sites. While the initial specific reaction rate was found not to be influenced by hydrogen, catalytic deactivation was found to be modified in the presence of hydrogen, which delayed and slowed down the deactivation by avoiding amorphous carbon deposition, thus leading to a greater relative specific productivity of carbon nanotubes. [less ▲]

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See detailImage analysis of pearlite spheroidization based on the morphological characterization of cementite particles
Nutal, Nicolas; Gommes, Cédric ULg; Blacher, Silvia ULg et al

in Image Analysis and Stereology (2010), 29

Pearlite spheroidization is a metallurgical process in steels by which cementite lamellaer decompose into spheroids, a process accompanied by a decrease of the Vickers hardness of the samples. In thi ... [more ▼]

Pearlite spheroidization is a metallurgical process in steels by which cementite lamellaer decompose into spheroids, a process accompanied by a decrease of the Vickers hardness of the samples. In thi study, different methods are compared for measuring cementite particles length and width from scanning electron micrographs. Based on a test-image, a so-called ribbon-like method is proposed for measuring particles length and width, and for discriminating lamellae from spheroids. Differently heat-treated samples are prepared and characterized. The results of analysis are used to rationalize the evolution of the microstructure of the samples. Compared to teh calssical DeHoff shape factor, it is shown that new insight into the spheroidization process is gained by analysing the lamellar length and widh distributions. [less ▲]

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See detailCondensation-Induced Decrease of Small-Angle X-ray Scattering Intensity in Gelling Silica Solutions
Gommes, Cédric ULg; Pirard, Jean-Paul ULg; Goderis, Bart

in Journal of Physical Chemistry C: Nanomaterials, Interfaces, and Hard Matter (2010), 114

We propose a mathematical modeling of the total SAXS intensity in silica sol-gel processes in terms of hydrolysis and condensation reactions, as well as of microsyneresis. The results are used to ... [more ▼]

We propose a mathematical modeling of the total SAXS intensity in silica sol-gel processes in terms of hydrolysis and condensation reactions, as well as of microsyneresis. The results are used to rationalize previously published SAXS data of TEOS solutions reacting with organically modified trialkoxysilanes. We notably show that the decrease in SAXS intensity reported for these samples at the end of gelation is a consequence of condensation reactions. The water released by the latter reactions contributes to reduce the electron density difference between the silica and the solvent phases of the gels [less ▲]

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See detailSynthesis and characterization of highly loaded Pt/carbon xerogel catalysts prepared by Strong Electrostatic Adsorption method
Job, Nathalie ULg; Maillard, Frédéric; Chatenet, Marian et al

in Studies in Surface Science and Catalysis (2010), 175

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See detailNi-doped carbon xerogels for H2 storage
Zubizarreta, Leire; Menendez, J. A.; Job, Nathalie ULg et al

in Carbon (2010), 48

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See detailFunctionalization of carbon xerogels for the preparation of Pd/C catalysts by grafting of Pd complex
Diverchy, Chantal; Hermans, Sophie; Job, Nathalie ULg et al

in Studies in Surface Science and Catalysis (2010), 175

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