Cobalt Catalyzed Fischer-Tropsch-Synthesis: Systematic Studies of Carbon Support Effects on Catalyst Activity and Deactivation

• Applicant: Dr. Felix Herold
• Subject Area: Technical Chemistry
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 471263729

The emerging transition of the raw material base of the current economic system from fossil to renewable resources requires the development of chemical processes that allow the production of fuels and raw materials for the chemical industry from biomass, waste or carbon dioxide. One of the available technologies to meet this challenge is the Fischer-Tropsch synthesis (FTS), which produces hydrocarbons from synthesis gas, and thus exhibits high importance within a future circular economy. One of the most promising catalyst systems for FTS is based on cobalt nanoparticles dispersed on a suitable support. The most fundamental problem of this catalyst system is the rapid deactivation, owing to the re-oxidation of the metallic cobalt (Co) and sintering, i.e., the reduction of the active surface area of the Co nanoparticles. In terms of deactivation-resistant catalysts, the catalyst support is a key component: In addition to increasing the active Co surface area by dispersion, it promotes reducibility while stabilizing the active nanoparticles against deactivation by sintering. In this context, carbon represents an attractive support material, as carbon materials are characterized by high surface areas, chemical resistance, and almost unlimited possibilities for targeted manipulation of structure and surface chemistry. However, due to the large number of influencing factors, the comparison of individual catalyst supports is often challenging, with the most fundamental influencing factor being the size of the co-nanoparticles on the carbon support. Conventional preparation methods only allow poor control over the Co particle size, with fundamental relationships between support properties as well as FTS activity and deactivation behavior remaining unresolved.Against this background, we propose a systematic approach to disentangle carbon support effects on catalyst performance and, in particular, catalyst deactivation. In this context, the influence of carbon structure, surface oxides, and heteroatom doping will be studied in isolation and without interference from Co-particle size effects.Key strategy the combination fo well-defined carbon support materials with a separate colloid-based Co-nanoparticle synthesis aimed at separating support properties from Co-particle size effects. Selected model supports will be synthesized, loaded with defined Co nanoparticles and investigated in FTS. By linking catalyst activity, selectivity and deactivation with comprehensive (in situ) characterization, fundamental insights into the cobalt-carbon interaction will be achieved.

• DFG Programme: WBP Fellowship
• International Connection: Norway
• Host: Professor Magnus Rønning, Ph.D.