TY - THES ID - 135694643 TI - Ammonia as hydrogen carrier: exploration of electrochemical cracking to hydrogen AU - Vandaele, Willem AU - Roeffaers, Maarten AU - KU Leuven. Faculteit Bio-ingenieurswetenschappen. Opleiding Master in de bio-ingenieurswetenschappen. Katalytische technologie (programma voor studenten gestart in 2018-2019 of later) (Leuven) PY - 2023 PB - Leuven KU Leuven. Faculteit Bio-ingenieurswetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:135694643 AB - The dependency on fossil fuels and associated greenhouse gas emissions force us to move towards renewable energy sources. A part of the solution lies in the use of hydrogen as an energy carrier. Water can be split, by electrolysis from renewable sources, into hydrogen and oxygen. The production of renewable energy is time and area dependent. Moreover, vast amounts of hydrogen will be needed to drive the steel industry, automotive, ammonia,…. The major challenge in storing and transporting hydrogen is overcoming the high energy needed. Therefore alternatives are needed. Hydrogen-carrying chemical molecules possess hydrogen in their structure. Out of the different storage methods analyzed in this thesis, hydrogen-carrying chemical molecules have the highest hydrogen storage capacity and can be stored and be transported in less energy-demanding conditions. One of the most promising hydrogen carriers is ammonia. Being well familiar with handling and shipping vast amounts of ammonia globally, the infrastructure for ammonia transport is already established. Ammonia is produced from hydrogen and nitrogen in the Haber-Bosch process and can easily be converted back to hydrogen and nitrogen by various routes. A main advantage is the fact that nitrogen is the dehydrogenated carrier which is endlessly supplied and can vent into the atmosphere without any problem, contrary to other (carbon-based) carriers such as methanol, where carbon dioxide is produced beside hydrogen. This thesis investigates the cracking of ammonia to hydrogen and nitrogen by electrocatalysis, which is the most cost-effective option in a decentralized Ammoniato-Hydrogen scenario. Three cell designs are discussed, tested and optimized. A solvent screening shows that DMSO is a suitable solvent due to the high ammonia and electrolyte solubility, conductivity and safety of use. A drawback is the limited oxidation potential of DMSO, which may not be exceeded since it yields hydrogen at the cathode according to our control experiments. To reduce the overall resistance caused by the solution, a proton exchange membrane is used, allowing the electrodes to be in close proximity. For the oxidation of ammonia to nitrogen in solution, Pt electrodes delivered the highest yield, followed by Pd wire and Au in addition to investigating the cracking of ammonia in the liquid. Gaseous, preliminary experiments were performed using Gas Diffusion Electrodes. Here it was shown again that Pt-based electrodes are superior to Au-based electrodes. Further investigation is needed to have more insights into the mechanism and to validate all the data. ER -