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ADSORPTION DU NICKEL SUR LES OXYDES METALLIQUES

Auteur : Nora OUAFAK
Année : 2007
Domaine : Physique
Type : Mémoire de magister
Etablissement : Université de Constantine 1
Résumé en PDF : (résumé en pdf)
Fulltext en PDF : (.pdf)
Mots clés : Nanoparticules; NiMg2; MgNi2; Ni/Oxyde; Catalysts; Radiolysis, Benzene hydrogenation.

Résumé :

This work studies the nickel anchored on several oxides, in the aim to be used asbenzene hydrogenation catalyst. The metal ions, adsorbed on the oxide surface, are reducedunder ? radiation in aqueous solution. The radiolytic way has been proven to be powerful toolfor obtaining dispersed nanoparticules in colloidal state, deposited on a solid support or inheterogeneous state. This process makes it possible to control the size of the particles, theirlocalization on the surface or into volume.In the dispersed systems, the surface phenomena play an impotant role. Theadsorption of ions or molecules on the surface of the aggregates can modify their propertiesand improve their activity. This is why we paid attention to the step of nickel adsorption onthe oxides by looking for the optimal condition in order to obtain an electrostatic interactionbetween the metal ions and the surface of the support, favorable to a homogeneous anddurable nickel dispersion. This step was followed by UV-visible spectrophotometry and pHmetry.In the second step, the irradiated samples are characterized by various technics (MEB,analyzes X and XRD). For the MgO support, Mg2Ni phases and Ni2Mg of nanometric sizewere evidenced. These intermetallic compounds are of first importance in the energy field.The nanoparticules of Ni/ZrO2 tested in catalysis in the benzene hydrogenationreaction exhibit good catalytic properties. They are more active in decreasing temperaturethan in increasing ones, indicating an anhencement of the catalytic activity during working.