Mo-Based perovskites for an active proton conducting SOEC: a Carbon-Free approach to ammonia synthesis.

In this work is exposed the development of highly functional materials within a critical raw material-free approach, with a particular aim toward the contribution in the carbon-free development of an active solid oxide cell (SOEC) able to product ammonia. This purpose comes from a current need as renewable electricity prices continue to decline, interest grows in alternative routes for the synthesis of sustainable fuels and chemicals, including ammonia. Considering demand for fertilizers, as well as its future potential as a dispatchable energy vector, sustainable synthesis of ammonia is being explored as an alternative to the carbon-intensive fossil-fuel-driven Haber–Bosch process. Among other options NH3 is considered to be a long-distance and low-carbon energy carrier that can be used as a long-term (days to months) energy storage vector. So, the design, synthesis and characterization of electrodes materials able to operate in a reversible solid oxide cell is needed as a new option in the near future, considering materials capable to operate in both fuel- and electrolytic-cell mode in a proton conducting cell. The proton conducting type seems the more promising way for ammonia production than the classic anion conducting as the activation energy for the protons movement is lower than the respective for oxide. The materials of choice for this purpose are variations of state of art perovskite LSFM, with Mo (Molybdenum) as substituent for a better catalytic activity and the introduction of Ba for electrolyte affinity ad conductive purposes. Precisely the two structures in analysis are BaSrFe1,5Mo0,5O6 and BaSrCo0,2Mo1,8O6 where Co is introduced as dopant for better catalytic activity. The synthesis is provided with water-based wet chemistry procedures (Pechini method) to obtain high purity and control molybdenum insertion into the perovskite lattice. Materials are characterized with XPS, XRD, SEM, EDX, TPR, BET and the functional characterization of NH3 presence is revealed through IR spectroscopy, gas-chromatography and mass-spectroscopy.