Hydrogen production via ammonia decomposition: membrane reactor performance and comparative analysis

Electricity, the driving force of modern civilization, is primarily reliant on non-renewable resources, which contribute significantly to global pollution. While renewable energy sources such as solar, wind, and hydropower currently make up a smaller fraction of the global energy mix, their adoption is steadily increasing. This shift emphasizes the importance of balancing environmental sustainability with energy efficiency. Among the cutting-edge solutions, hydrogen as an energy carrier holds great promise for the future energy landscape. Its advantages lie in its clean, efficient use, offering a potential path to reduce reliance on environmentally damaging practices. This study examines the role of ammonia as a hydrogen energy carrier. The first chapter discusses the challenges associated with hydrogen transport and storage, positioning ammonia as a strong candidate for overcoming these issues. Ammonia is converted into hydrogen at moderately high temperatures, necessitating the use of an appropriate catalyst and reactor to minimize production costs. The second chapter reviews relevant literature on this subject, analysing various catalysts, the thermodynamics of the process, reactor technologies, and the most effective combinations of these parameters for industrial-scale ammonia cracking. Since nitrogen is also produced during this process, hydrogen must be purified before it can be used immediately. Palladium or palladium-alloy membrane reactors are considered the most effective for producing high-purity hydrogen. The third chapter, therefore, explores palladium-based membranes in depth, covering everything from their synthesis to reactor technologies. The fourth chapter presents laboratory experiments on ammonia decomposition carried out at the University of Messina (UniMe) and Eindhoven University of Technology (TU/e). The aim is to show how using 10% diluted ammonia in a reactor with an ultrafine palladium membrane, combined with a 1% Ru – based catalyst bed, can maximize efficiency and enable reproducibility on an industrial scale.