Highly efficient hydrogen production using a self-sustained ammonia decomposition system

Ammonia (NH₃) is a promising carbon-free hydrogen (H₂) carrier that can facilitate the safe and economical use of H₂ through its transportation and on-demand cracking· NH₃ cracking is endothermic in nature and thus needs energy input. However, it would be highly advantageous to operate the cracker without an external energy supply, especially in rural, remote, or emergency areas. Herein, a self-sustained system for NH₃ decomposition was designed and fabricated to provide a continuous production of H₂ at moderate temperatures. Once initiated, the system was fed only with pure NH₃ that was fully decomposed by a Ru-based catalyst to H₂ and N₂ gas mixture. Part of the decomposition product was combusted with air in an optimized H₂ burner, providing the required heat for NH₃ decomposition. The design of the H₂ burner included an H₂/air distribution arrangement to facilitate a well-controlled, uniform heat distribution. Self-sustained NH₃ decomposition was successfully demonstrated using 600 sccm NH₃ for more than 6 h, showing > 99 % NH₃ conversion and ∼ 82 % reforming efficiency. Steady state operation revealed negligible NO_X content in the exhaust. This work provides a viable route for the development of self-sustained NH₃ decomposition systems for portable and onboard NH₃-driven power units.