The Influence of the Pyrolysis Temperature on the Material Properties of Cobalt and Nickel Containing Precursor Derived Ceramics and their Catalytic Use for CO2 Methanation and Fischer–Tropsch Synthesis

Abstract

Ni and Co containing precursor derived ceramics (ceramers) were prepared from a polysiloxane based preparation route. All catalysts were characterised by BET, XRD and TEM as well as by water and heptane adsorption and tested for CO2 methanation and Fischer–Tropsch synthesis. Different pyrolysis temperatures between 400 and 600 °C were used to get catalysts with different surface hydrophilicities. With increasing synthesis temperature less organic groups remain on the surface, resulting in a more hydrophilic catalyst. For all Ni containing ceramers, well dispersed particles in the range of 3 nm were formed and comparable surface areas were found. The catalysts with the lowest tendency towards water adsorption showed the highest activity for CO2 methanation. In contrast to the Ni catalysts, for the Co containing ceramers particle formation was dependent on the pyrolysis temperature. While no metallic particles were formed at 400 °C, small particles in the range of ~5 nm were obtained, using a pyrolysis temperature of 500 °C. Increasing the pyrolysis temperature to 600 °C, the particle size increased to ~10 nm. First tests for CO2 methanation and Fischer–Tropsch reaction were successfully carried out and the catalysts with the less hydrophilic surface showed higher activity and a higher selectivity towards C5+-products.