Photocatalysis using zeolite is a relatively new process for the degradation of pollutants. Zeolites are crystalline structures with a network of interconnected tunnels and cages. The cavities in zeolites confine reactants to a particularly shaped space. Therefore, they act as a selective medium, directing the photochemical reactions to specific products. During photocatalysis zeolites serve either as inert supports for the photocatalitically active semiconductors or as porous adsorbents. In most cases the semiconductor is loaded in the zeolite and the resulting powder is illuminated to become an active catalyst. Photocatalysts adsorbed in zeolites have a higher efficiency than the photocatalyst on its own. This effect has been found for a variety of organic s such as benzene, azo dyes, propizamide, substituted toluenes, phenols, and pyridine that are photooxidised by TiO2. Despite the great interest and the applicability of this type of systems, little is known on the mechanism of catalysis. In this proposa l I put forward a research project aimed at reaching a sound grasp of the molecular aspects of photocatalysis in zeolites by means of a combination of computational methods.
The final goal is to develop a molecular mechanism that can explain selective phot ocatalysis with zeolites as shape selective heterogeneous photocatalysts. Only a few of the more than 100 zeolites synthesized are currently used in photocatalysis. A deeper understanding of the underlying mechanisms can be used to evaluate the efficiency of many other zeolites and can lead to cheaper and more efficient photooxidation of pollutants.
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