New Insights in the Activation and Deactivation of Cobalt-Titania Fischer-Tropsch Synthesis Catalysts

The ever-increasing demand for transportation fuels, the higher environmental awareness as well as the depletion of easily accessible crude oil reserves have turned the attention towards the development of new catalytic technologies that can produce ultra-clean synthetic fuels from more sustainable feedstocks, including municipal waste, biomass as well as natural gas. Cobalt-based Fischer-Tropsch Synthesis (FTS) represents a viable option to produce transportation fuels with low concentration of sulphur, nitrogen, aromatics and naphthenes. However, one of the main issues in Co-based FTS is the deactivation of the solid catalyst with increasing time-on-stream, which has evidently a large impact on its industrial use. Despite decades of research on Co-based FTS catalysts, our fundamental understanding regarding the different deactivation routes has remained elusive. This is partly due to the difficulty of performing long-term in situ and/or operando spectroscopic measurements at relevant industrial conditions (i.e., elevated temperatures and pressures) that can provide physicochemical insights about the deactivation process. In this PhD thesis, the development of powerful characterization methods has led to new physicochemical insights about not only catalyst deactivation, but also on the activation process of the catalyst material. In what follows, I will highlight the main findings of this PhD thesis work and also present some new ideas for potential future research.