| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 106 === Ruthenium oxide, RuO2, with a rutile crystal structure, is a well-known catalyst for selective oxidation reaction. However, RuO2 nanoparticles are inclined to deactivation owing to the occurrence of aggregation or sintering during heat treatment. Consequently, RuO2 should be dispersed on a support and the interaction between RuO2 and support would govern the catalytic activity and the tendency of sintering. Rutile TiO2 could be a suitable support material for the possible structure compatibility. In this study, a deposition-precipitation method (DP) with two alkaline precipitating reagents, sodium hydroxide and urea, is used to synthesize supported RuO2 catalysts. Different pretreatment conditions are also examined, resulting in RuO2 of different particle size on TiO2. Two oxidation reactions with molecular oxygen are tested; one is liquid-phase oxidation of 1-phenylethanol and the other is gas-phase oxidation of ammonia.
From the oxidation of 1-phenylethanol, as-prepared supported amorphous hydrated RuOx possesses the highest activity among the tested samples. Also, the precipitating alkaline reagent has no influence on the reactivity. In addition, changing the crystal phase of TiO2 support to anatase can promote the reactivity significantly. The pseudo 1st-order rate constant not only depends on the amount of active hydrated RuOx but the RuOx-TiO2 support interaction. On the other hand, the reactivity to oxidation of ammonia is independent on the support crystal structure but is possible related to the particle size of RuO2.
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