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Heterogeneous catalysis is an essential technology for the production of fuels and chemicals. The demand for fossil fuels, and in particular liquid fuels for transportation, is expected to grow in the next two decades while limitations on CO2 emissions are likely to become a major constraint for the production. Gas-to-liquids technology has the potential to reduce the overall CO2 footprint of liquid fuels and to produce ultra clean fuels. The Fischer-Tropsch (FT) synthesis, i.e. the catalytic conversion of CO and H2 to long-chain hydrocarbons, is an important component of the gas-to-liquids process. Nanosized cobalt particles on a support material are used to catalyze FT and the structure of the nanoparticles can strongly affect their catalytic performance.

This thesis describes research on a controlled catalyst preparation method, to facilitate relating the structure of the cobalt nanoparticles to their catalytic performance. The method for synthesis of model catalysts is a colloidal synthesis of cobalt nanoparticles in a solution, followed by attachment of the nanoparticles to a support. By performing nanoparticle synthesis and attachment separately, the structure of the nanoparticles can be highly controlled. Traditionally, cobalt nanoparticles are formed directly on the support material, resulting in less control over their structure. Important findings include a method for attaching and fully activating cobalt nanoparticles, strong effects of the support and nanoparticle size on nanoparticle stability and catalytic performance, reduced activity of disk-shaped compared to spherical cobalt nanoparticles and a method for controlling so-called strong metal-support interactions, which doubled the cobalt-specific surface and FT activity.