Development of functionalized materials through sol-gel route for applications in catalysis and surface protection
In this work, materials have been produced by sol-gel route. This synthesis way has been used for immobilization on a support of a function focused on green chemistry. The different functions are related with different applications that allow to illustrate the versatility and the flexibility of this sol-gel process. The two applications are: - Photocatalysis: Synthesis of material with photocatalytic property or with an additional property - Cyclocarbonation: Synthesis of an immobilized catalyst for polyurethane production through a green process The first application concerns the use of a photocatalyst that allows to degrade volatile organic compounds (VOC). The main photocatalyst is TiO2. It has been studied as a powder or as a film deposited on a support. A comparison of these two shapes has shown that an identical photocatalyst can have different performances depending on the final shape. A catalyst must be considered in its totality and with its environment rather than as a chemical composition only. To increase the photocatalyst performances, modifications have been added as the Zn doping to increase the photocatalytic activity and the superhydrophilicity. These new photocatalysts have been compared with pure ZnO and bilayer films composed of TiO2 and of ZnO. Different photocatalytic tests have been performed and depending on the test the best photocatalyst was different. Then, to increase the economic interest, some dopant have been used. In addition of the improvement of the photocatalytic activity and superhydrophilicity, theses dopants add a new property such as electrical conductivity and anticorrosion. First, metallic silver has been incorporated to add antistatic property and to increase the photocatalytic activity. The photocatalytic property has been improved, superhydrophilicity has been kept but no antistatic property was observed. Multiwall carbon nanotubes (MWCNTs) have been tested with TiO2 to increase the electrical conductivity. This doping is efficient because MWCNTs increase the conductivity, the photocatalytic activity and maintain the superhydrophilicity. In addition, anticorrosive property has been observed on stainless steel in a preliminary study with the MWCNTs incorporation. The second study is focused on the heterogeneous cyclocarbonation catalyst synthesis to produce, in fine, polyurethane. The catalyst was immobilized on different matrices that are inert from catalytic point of view but that have a potential activator effect. First, with the preselected catalyst, different supports have been investigated. The comparison between the supports has highlighted the activator effect and the texture influence (accessibility of the active sites) on cyclocarbonation yields. Then, with the optimal matrix, different catalysts from a same family have been grafted to choose the best catalyst. Therefore, it has been possible to define the best catalyst and the best support. With this combination, a kinetic study has been performed to determine the best experimental conditions to produce cyclocarbonates.
sol-gel, easy-to-clean, cyclocarbonation, Engineering, computing & technology, Materials science & engineering, Ingénierie, informatique & technologie, Science des matériaux & ingénierie
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