Reversible Segregation of Nickel from Perovskite-type Oxides - Applications in Energy Processes

In this thesis, Ni catalysts derived from perovskite-type metal oxides (PMO, general formula ABO3, A=lanthanide or earth alkaline element, B=transition metal) are investigated as a potential class of materials, which are able to overcome thechallenges of catalyst deactivation through sintering. The reversible segregation of Ni from PMOs under reducing atmospheres and the reincorporation of the same under oxidizing feeds potentially stabilize Ni catalysts over redox cycles and may allow the complete regeneration of catalysts while suppressing Ni particle sintering. It is the aim of this thesis to demonstrate the working principle of such PMO-derived Ni catalysts and optimise this property within two different temperature regimes targeting the removal of coke deposits from Ni-based methanation catalysts at temperatures of ca. 600°C as well as the removal of sulfur from an active SOFC anode material at working temperatures of ca. 800°C.