Academic literature on the topic 'Incorporation de P2O5. MoO3. ZrO2'

To explore green methodology for the synthesis of mixed oxide, its catalytic activity and temperature stability of series of ZrO2/MoO3 and ZrO2 were prepared by sol-gel method and characterized by XRD, FT-IR, X-ray photoelectron spectroscopy (XPS), temperature programmed Desorption (TPD), Raman spectroscopy and transmission electron microscopes (TEM). These mixed oxides were showed high stability with nanocrystalline nature. Due to highly acidic nature of the catalysts, ultra sound assisted synthesis of substituted pyrazoles was carried out successfully with high yield. The reaction was carried out in solvent free medium, which showed green approach and energy saving reaction. Condensation of dibenzoyl methane and hydrazine to form substituted pyrazoles with 97.7% yield. The acid strength and acid amount of synthesized catalysts were determined by temperature programmed desoprtion (TPD), incorporation of zirconia into the molybdenum, network has changed its surface acid properties due to the Zr2+ and Mo6+ ions. After addition of ZrO2 on MoO3, it showed weak and strong acid sites.

Ce travail de thèse s’inscrit dans le projet DEM’N’MELT dont le but est de vitrifier des déchets de moyenne ou haute activité issus du démantèlement d’installations nucléaires. Les compositions de déchet considérées dans ce manuscrit, riches en P2O5, MoO3 et ZrO2 et dont l’activité résulte essentiellement du 137Cs, sont basées sur celles des déchets générés par le démantèlement de l’usine UP1 de Marcoule. Leur principale caractéristique est leur variabilité de composition. L’objectif est d’étudier l’incorporation de ces déchets dans un verre aluminoborosilicaté riche en alcalins à 1100 °C.Le premier axe d’étude consiste à se placer dans un système proche du système industriel (11 oxydes). Il a mis en évidence que MoO3 et P2O5 sont les deux principaux constituants du déchet conduisant à des séparations de phases et/ou des cristallisations. Celles-ci peuvent, dans le cas des phases molybdates, contenir du Cs. Aux teneurs envisagées, ZrO2 s’incorpore quant à lui dans la matrice sans générer d’hétérogénéités.Le deuxième axe se concentre sur l’étude structurale et microstructurale des mécanismes d’incorporation de P2O5 et MoO3 dans un système simplifié (6-7 oxydes). Ces éléments sont tout d’abord considérés seuls puis incorporés conjointement. Il apparaît que P et Mo s’insèrent majoritairement sous forme d’entités isolées (PO43- et MoO42-) du réseau vitreux et que leur incorporation conjointe augmente la tendance à la cristallisation du système
This work belongs to the DEM’N’MELT project, which is dedicated to the vitrification of intermediate or high level radioactive wastes coming from the dismantling of nuclear facilities. The waste compositions of this study, rich in P2O5, MoO3 et ZrO2 which activity is mainly due to 137Cs are close to the ones of the shutdown UP1 facility (Marcoule). Their main feature is the variability of their composition. This work objective is to study the incorporation of these wastes in an aluminoborosilicate glass rich in alkali oxides at 1100 °C.The first part of the study will be dedicated to a system close to the industrial one (11 oxides). It highlights that MoO3 and P2O5 are the main waste constituents responsible for phase separation or crystallization. Moreover, molybdate crystalline phases can contain Cs. ZrO2 is incorporated in the glassy matrix without leading to heterogeneities.Then, a simplified system (6-7 oxides) is studied along with the structural and microstructural incorporation mecanisms of P2O5 and MoO3. These oxides are first considered alone and then added simultaneously. This second study highlights that P et Mo mainly lead to the formation of entities isolated from the glassy network and that their simultaneous addition increases the crystallization tendency