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Abstract

Molybdenum oxides generally are of great technical interest. Besides the enormous importance in heterogeneous catalysis the optical and electronic properties of molybdenum oxides have received considerable attention because of potential applications in information displays and gas sensors. Molybdenum oxide based catalysts are used for partial oxidation reactions of hydrocarbons e.g. unsaturated aldehydes to carbon acids. Catalytic selective oxidation reactions belong to the most important industrial processes and make one quarter of the world-wide catalytic performed reactions. Sol-gel chemistry is widely used to synthesize metal oxides by inorganic polymerisation of molecular precursors in organic media (alcohols, hydrocarbons). The low synthesis temperatures often lead to the formation of oxides with amorphous or metastable phases which are not observed using other synthesis routes. The sol-gel synthesis of molybdenum oxides has received relatively little attention, especially in comparison to transition metal oxides such as TiO2, V2O5 and WO3. The overall aim of this work is the rational preparation of molybdenum based oxides via sol-gel synthesis of alkoxide precursors. On the one hand the work concentrates on the mechanisms of solid formation from solution by in-situ measurements (Raman, IR and UV-vis) and on the other hand new synthesis methods for high surface molybdenum oxides are investigated.