Renewable fuels play a key role in the Swiss energy landscape. While the amount of renewable biogas is just 1% as of 2018, the Swiss gas industry aims to increase this amount up to 30% in the heating market until 2030. The SMARTCAT project focusses on a biogas upgrade: two novel catalytic CO2 methanation concepts are explored and established to provide solutions to typical degadation mechanisms, that is catalytic and microstructural degradation from operation temperature and typical poisons as well as an insufficient methane yield.
At first, a perovskite-type catalyst whose host matrix is capable of reversibly exsolve and reincorporate the catalytic active metal nanostructures when redox cycled. The proof-of-concept is given here and it is shown that such concept can be operated at less than 2.5 wt% of nickel at 450-500 °C with a methane yield of about 80% under stoichiometric conditions. This is about 450 °C lower than initial operation temperature of the very first material composition. Redox cycling needs to take place at 650°C, keeping in mind, that lower temperatures limit the cation diffusion in the ceramic host. However, the microstructure is fully recovered on an hourly time level, allowing an extended lifetime of catalysts and counteract microstructure degradation.
Secondly, improvement of the methanation efficiency is tackled by sorption enhanced catalysis, providing a full CO2 conversion to methane: A yield of 100% of dry CH4 is reached without any practical relevant amounts of CO2, CO, or humidity at temperatures as low as 300°C and that without any additional separation steps. To shift the technology readiness level from proof-of-concept to a technology relevant level, a 1 kW demonstrator was constructed and operated to receive operation relevant process parameters on the methanation and diffusion controlled drying. A modular concept is established which solved this, ready for transfer into a demonstration plant.
