Reaction Rate Enhancement During the Electrocatalytic Synthesis of Ammonia in a BaZr0.7Ce0.2Y0.1O2.9 Solid Electrolyte Cell

• Published in: Topics in catalysis 2015-11, Vol.58 (18-20), p.1193-1201
• Main Authors: Vasileiou, E., Kyriakou, V., Garagounis, I., Vourros, A., Manerbino, A., Coors, W. G., Stoukides, M.
• Format: Article
• Language: English
• Subjects: Catalysis; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Original Paper; Pharmacy; Physical Chemistry
• ISSN: 1022-5528; 1572-9028
• DOI: 10.1007/s11244-015-0491-9

The catalytic and electrocatalytic synthesis of ammonia was studied in a proton conducting double-chamber solid electrolyte cell. The BaZr 0.7 Ce 0.2 Y 0.1 O 2.9 (BZCY72) proton conducting ceramic was used as the electrolyte with a Ni-BZCY72 cermet and a Pt film serving as cathodic and anodic electrodes, respectively. The reaction was studied at atmospheric pressure and at temperatures between 450 and 700 °C, under both, open- and closed-circuit conditions. A peculiar reaction rate enhancement was observed when the cell returned to open-circuit after operating under closed-circuit for a certain time. A possible explanation of this new phenomenon is that a fraction of protons electrochemically transported to the cathode, is “stored” in the Ni-BZCY72 electrode in the form of a highly reactive hydride which, upon current interruption, reacts with adsorbed N species to produce ammonia.