Préparation de matériaux nanostructurés. Application à l’oxydation d’une molécule organique modèle

Abstract

This Thesis has been divided in the study of two main topics. The first part was devoted to the study of mesoporous materials which present a potential mainly in the heterogeneous selective oxidation. We gave a particular attention to the synthesis of mesoporous materials: manganosilicates of SBA-15 type via different strategies, cobalt silicates by assembly of preformed CoS-1 precursors with triblock copolymer P123 in strong acidic media by a two steps procedure, and manganese oxide MnxOy by the nanocasting route using SBA-15 material as hard template via a solid-liquid route crystallization. MnxOy and SBA-15 were then doped with Ag via different strategies. This study clearly shows that the structural and textural properties of these mesoporous materials depend on the synthesis strategy of manganosilicates, Ag/SBA-15 and Ag/MnxOy, and the silver loading for Ag/SBA-15 and Ag/MnxOy. The second part of this Thesis was the evaluation of these materials in the cyclohexane oxidation in the liquid phase. We have studied the influence of different reaction parameters, the catalysts synthesis strategy and the silver loading in terms of activity and selectivity of prepared catalysts. All the catalysts are selective towards cyclohexanone and cyclohexanol. The highest activity of 4%-Ag/MnxOy could be ascribed to the synergetic effect between Ag and Mn species. Moreover this catalyst is very stable after four cycles of reuse; therefore, it is of much interest as a potential catalyst for the selective oxidation of bulky molecules.