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Title
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The photocatalytic reduction of CO2 with H2 over modified Ti-Beta zeolites
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Author
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Abstract
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| The earth has been warming up at an unprecedented pace during the last decades, which is majorly caused by increasing greenhouse gases. High CO2 concentrations in the atmosphere led to worldwide awareness of environmentally conscious thinking and acting to reduce this compound and other greenhouse gases. CO2 conversion makes valorization possible through valuable chemicals and fuels. This cradle-to-cradle philosophy is necessary in our current society, both reducing atmospheric greenhouse gases and simultaneously partly responding to the need for alternative fuels. This is fundamental as continuous increase of anthropogenic greenhouse gases are one of the most important issues of this and future generations. In this thesis, the photocatalytic reduction of CO2 with H2 in the gas phase over modified Ti-Beta zeolites is studied. The goal of this thesis is the development of improved photocatalytic materials for CO2 applications in the gas phase and to overcome limitations posed by the use of TiO2 and classical semiconductors. Different methods for CO2 utilization and conversion have been discussed. Furthermore, an overview on the mechanism of photocatalysis and the limitations of the use of TiO2, as well as the strategies to overcome those limitations have been described. In particular, the superior photocatalytic activity of isolated tetrahedrally coordinated Ti-species in combination with the high surface area of zeolites has been highlighted. The importance of a well-designed photocatalytic reactor and its influence on the turnover frequencies (TOFs) of the reaction products are also described. The experimental work focusses on the optimization of the synthesis method and the Ti loading of the Ti-Beta zeolites. Next, the synthesized zeolites are tested in a photocatalytic reactor and the influences of the material properties on the product TOFs are discussed. In order to further enhance the photocatalytic properties and the product selectivities of the catalysts, noble metal nanoparticles (Pt and Pd) are deposited onto the Ti-Beta zeolites. Finally, alternative catalysts (e.g. 3D printed structures and Z-scheme catalysts) are tested in the photocatalytic reactor and compared to the highest performing Ti-Beta catalysts. In conclusion, this PhD has put a step forward in the development of novel and highly active photocatalytic materials, with improved performance compared to classical pure TiO2, for the photocatalytic reduction of CO2 in the gas phase. |
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Language
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English
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Publication
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Antwerpen
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Universiteit Antwerpen, Faculteit Wetenschappen, Departement Chemie
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2021
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Volume/pages
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224 p.
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Note
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Cool, Pegie [Supervisor]
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Full text (publisher's version - intranet only)
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