Metallic Nanoparticles and their Application in Heterogeneous Catalysis for Environmental Sciences

This thesis provides a comprehensive concept on how catalysis can tackle climate change and global warming by reducing greenhouse gases using three different approaches. In a first approach, gold nanoparticles were synthesized by means of a colloidal synthesis method and subsequently transformed to 3D gold structures, which allowed for the selective oxidative coupling of methanol to methyl formate and by this, reducing the emission of carbon dioxide (CO2) as a side-product. In a second approach, the wetness incipient impregnation method was utilized to obtain a palladium catalyst supported on aluminum oxide, which was investigated for its activity in the lean methane oxidation at elevated pressures and temperatures. Elevated pressures allowed overall higher combustion rates of methane to CO2, which is, in perspective, less harmful as a greenhouse gas than methane. The last approach tackled the reduction of CO2, using this greenhouse gas as a feedstock to reduce it electrochemically over nanoparticulate copper and gold catalyst, which were synthesized using the chemical solution deposition method followed by an in-situ electrochemical reduction. The final products of this reaction can be hydrocarbons, which can be utilized as fuels or chemicals. All in all, the idea was to find catalysts and methods to contribute to the reduction of potential greenhouse gases and finally closing the carbon cycle for a more sustainable and greener future of planet Earth.