Showing results 61 to 80 of 148
  The nonlinear optical, magnetic, and Mossbauer spectral properties of some iron(III) doped silica xerogels; Rosso, Vanessa  ; Renotte, Yvon et alin Journal of Materials Science (2006), 41(10), 2839-2849 Iron(III) species dispersed in silica have been synthesized with a sol-gel process. The iron(III) was introduced as the acetylacetonate complex into a solution of tetraethoxysilane to yield, after ... [more ▼] Iron(III) species dispersed in silica have been synthesized with a sol-gel process. The iron(III) was introduced as the acetylacetonate complex into a solution of tetraethoxysilane to yield, after evaporative drying, pellets or monoliths. Two gels were dried very slowly over a period of five months in order to prepare a defect free monolith useful for nonlinear optical studies. Z-scan experimental studies on the resulting, transparent, monolithic, doped solid revealed an optical Kerr effect, a third order nonlinear optical phenomenon showing a linear dependence of the refractive index on the irradiance with a nonlinear refractive index, n(2), of -1.95 x 10(-11) cm(2)/W. Magnetic susceptibility studies between 4.2 and 295 K revealed paramagnetic behavior with a Curie constant of 4.433 (emu/mol)K and a Weiss temperature of -7.1 K. Magnetization studies at 5 K and at applied fields of up to 4 T and Mossbauer spectral studies between 4.2 and 295 K revealed a 50:50 mixture of paramagnetic species and nanoparticles with an average particle radius of 1.3 +/- 0.2 nm. A blocking temperature of 70 K and a magnetic anisotropy energy of 2.4 x 10(5) J/m(3) stop are derived from the Mossbauer spectra. (c) 2006 Springer Science + Business Media, Inc. [less ▲] Detailed reference viewed: 52 (10 ULg)Metal catalysts suppported on texture-tailored carbon xerogelsJob, Nathalie ; Léonard, Angélique ; et alin Studies in Surface Science and Catalysis (2006), 162 Detailed reference viewed: 46 (4 ULg)Avoiding mass transfer limitations in carbon supported catalysis by using carbon xerogel as supportsJob, Nathalie ; Heinrichs, Benoît ; Léonard, Angélique et alin Chemistry for Sustainable Development (2006), 14 Detailed reference viewed: 15 (4 ULg)Élimination des limitations de transfert de matière en catalyse supportée sur carbone par utilisation de supports de type xérogel de carboneJob, Nathalie ; Heinrichs, Benoît ; Léonard, Angélique et alConference (2006) Detailed reference viewed: 12 (0 ULg)Metal catalysts supported on texture tailored carbon xerogelsJob, Nathalie ; Léonard, Angélique ; Pirard, René et alConference (2006) Detailed reference viewed: 20 (4 ULg)Spectroscopie Mössbauer, propriétés magnétiques et optiques non-linéaires de xérogels dopés par des nanoparticules ferriques; Rosso, Vanessa ; Renotte, Yvon et alPoster (2006) Detailed reference viewed: 29 (2 ULg)The nonlinear optical, magnetic, and Mössbauer spectral properties of some iron(III) doped silica xerogels; Rosso, Vanessa ; Renotte, Yvon et alConference (2006) Detailed reference viewed: 18 (1 ULg)Immobilizing metal nanoparticles in porous silica through sol-gel processHeinrichs, Benoît ; ; Lambert, Stéphanie et alPoster (2006) Detailed reference viewed: 22 (5 ULg)Avoiding mass transfer limitations in carbon supported catalysis by using carbon xerogel type supportsJob, Nathalie ; Heinrichs, Benoît ; Léonard, Angélique et alConference (2006) Detailed reference viewed: 13 (0 ULg)Metal and alloy nanoparticles trapped in porous silica via sol-gel processHeinrichs, Benoît ; Lambert, Stéphanie ; Pirard, Jean-Paul Conference (2006) Detailed reference viewed: 10 (4 ULg)Large-scale synthesis and shaping of xerogel catalystsAlié, Christelle ; ; et alPoster (2006) Detailed reference viewed: 14 (3 ULg)Immobilizing metal nanoparticles in porous silica through sol-gel processHeinrichs, Benoît ; ; Lambert, Stéphanie et alin Studies in Surface Science and Catalysis (2006), 162 Detailed reference viewed: 1 (1 ULg)Large-scale synthesis and forming of xerogel catalystsAlié, Christelle ; ; et alin Studies in Surface Science and Catalysis (2006), 162 Detailed reference viewed: 16 (4 ULg)Carbon xerogels as catalyst supports: study of mass transferJob, Nathalie ; Heinrichs, Benoît ; Lambert, Stéphanie et alin AIChE Journal (2006), 52 Detailed reference viewed: 18 (3 ULg)Iron(III) species dispersed in porous silica through sol-gel chemistry: nature, size, and catalytic activityHeinrichs, Benoît ; ; et alConference (2006) Detailed reference viewed: 10 (4 ULg)Ag/SiO2, Cu/SiO2 and Pd/SiO2 cogelled xerogel catalysts for benzene combusion : relationships between operating synthesis variables and catalytic activityLambert, Stéphanie ; Pirard, Jean-Paul ; Heinrichs, Benoît et alin Catalytic Combustion, volume 2 (2005, September 11) Detailed reference viewed: 16 (7 ULg)Reactivity of precious metal and transition metal oxide catalysts towards the total oxidation of volatile organic compounds containing nitrogen or sulfur atom (N-VOCs or S-VOCs); ; et al in Catalytic Combustion, volume 2 (2005, September) Detailed reference viewed: 25 (7 ULg)Hydrodechlorination of 1,2-dichloroethane on Pd-Ag catalysts supported on tailored texture carbon xerogelsJob, Nathalie ; Heinrichs, Benoît ; et alin Catalysis Today (2005), 102 Porous carbon xerogels synthesized in a previous study were investigated as catalysts supports. The support chosen was a micro-mesoporous carbon xerogel obtained from the pyrolysis of a resorcinol ... [more ▼] Porous carbon xerogels synthesized in a previous study were investigated as catalysts supports. The support chosen was a micro-mesoporous carbon xerogel obtained from the pyrolysis of a resorcinol-formaldehyde resin whose synthesis variables were fixed at suitable values. Palladium and silver were deposited on this tailored texture carbon by co-impregnation using a solution of palladium and silver nitrates in nitric acid and water. Several catalysts were prepared with various Pd and Ag global contents, the latters being measured experimentally. Alloy particles, detected in all bimetallic samples, were studied by a combination of various techniques that enabled us to obtain their size as well as their bulk and surface composition. When present, the fraction of unalloyed silver was also calculated. The characterization data were related to the results of catalytic tests obtained for selective hydrodechlorination of 1,2-dichloroethane into ethylene. Results show that when the Ag content is too high, pure Ag particles are formed and the alloy composition remains constant. As a consequence, the surface composition of the alloy is constant as well and the catalytic tests lead to similar results. (c) 2005 Elsevier B.V. All rights reserved. [less ▲] Detailed reference viewed: 43 (6 ULg)Pd-Ag/SiO2 and Pd-Cu/SiO2 cogelled xerogel catalysts for selective hydrodechlorination of 1,2-dichloroethane into ethyleneLambert, Stéphanie ; ; et alin Catalysis Today (2005), 100(3-4), 283-289 While 1,2-dichloroethane hydrodechlorination over pure palladium mainly produces ethane, increasing silver or copper content in bimetallic catalysts results in an increase in ethylene selectivity. The ... [more ▼] While 1,2-dichloroethane hydrodechlorination over pure palladium mainly produces ethane, increasing silver or copper content in bimetallic catalysts results in an increase in ethylene selectivity. The specific consumption rate of 1,2-dichloroethane decreases when silver or copper loading increases. The turnover frequency, that is, the number of catalytic cycle per active site (palladium atom and its surrounding silver or copper atoms) and per second, seems to be independent of surface composition of alloy particles and 1,2-dichloroethane hydrodechlorination is insensitive to the atom's nature (silver or copper). (c) 2004 Elsevier B.V. All rights reserved. [less ▲] Detailed reference viewed: 12 (4 ULg)Formation and structural characteristics of Pd-Ag/SiO2 and Pd-Cu/SiO2 catalysts synthesized by cogelationLambert, Stéphanie ; Gommes, Cédric ; Alié, Christelle et alin Journal of Non-Crystalline Solids (2005), 351(52-54), 3839-3853 Pd-Ag/SiO2 and Pd-Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of either Pd and Ag or Pd and Cu with 3-(2-aminoethylamino)propyltrimethoxysilane ... [more ▼] Pd-Ag/SiO2 and Pd-Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of either Pd and Ag or Pd and Cu with 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS). After an extensive study of the influences of synthesis operating variables over structural characteristics of gels, highly dispersed bimetallic Pd-Ag/SiO2 and Pd-Cu/SiO2 xerogel catalysts were obtained. These samples are then composed of completely accessible Pd-Ag and Pd-Cu alloy crystallites with sizes of 2-3.5 nm located inside silica particles exhibiting a monodisperse microporous distribution. It appears also that the metal complex acts as a nucleation agent in the formation of silica particles. (c) 2005 Elsevier B.V. All rights reserved. [less ▲] Detailed reference viewed: 31 (6 ULg) |
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