THERMAL AND ELECTRICAL PROPERTIES OF YTTRIUM-DOPED BARIUM ZIRCONATE-CERATE PROTONIC CERAMIC ELECTROLYTES FOR HYDROGEN PUMP APPLICATIONS

Kurzfassung

The transition toward low-carbon energy systems has intensified the search for sustainable hydrogen production routes, with the HADES project focusing on the electrochemical decomposition of ammonia. This dissertation centers on the comprehensive experimental characterization of the BZCY721 (BaZr0.7Ce0.2Y0.1O2.95) protonic ceramic electrolyte, which offers an optimized balance between chemical stability and conductivity. The research involved sample synthesis and processing, phase purity verification via XRD, microstructural analysis by SEM, and specific surface area determination through the BET method. The core of the investigation consisted of Thermogravimetric Analysis (TGA) in both equilibrium and transient modes to establish a unified dataset for the posterior extraction of 17 independent kinetic and thermodynamic parameters. The study successfully mapped the materials non-stoichiometry and its thermodynamic trends for defect incorporation across a wide range of temperatures and atmospheres relevant to ammonia decomposition process. Despite technical challenges involving gas flow controller malfunctions, rigorous recalculation of partial pressures ensured data accuracy. A central achievement was the precise identification of the stages of mass response, allowing for a clear distinction between transient relaxation behaviors and stable equilibrium states, which ensures the reliability of the dataset for subsequent reactor modeling. This study provides the essential empirical foundation for validating BZCY721 performance in membrane reactors for the hydrogen economy.