Autothermal recirculating reactor (ARR) with Cu-BN composite as a stable reactor material for sustainable hydrogen release from ammonia

Ammonia (NH₃) has been proposed as a viable hydrogen (H₂) carrier, but high reaction temperature and endothermic nature of NH₃ decomposition require an efficient reaction system to maximize useable energy from NH₃. Adoption of carbon-free heat sources and efficient heat transfer to the reaction bed are crucial for sustainable H₂ release. Herein, the autothermal recirculating reactor (ARR) concept with the fractional utilization of the reformate H₂ as a clean combustion fuel is proposed and experimentally investigated. Additionally, BN-coated Cu as a composite reactor material is developed for heat transfer enhancement of high-temperature H₂ release reaction in a thermally-coupled NH₃ decomposition and H₂ combustion system. Coating performance against chemical degradation of Cu has been tested and confirmed. High NH₃ conversion of >99.6% and reforming efficiency of 70.95%, even with high fraction of heat loss owing to small scale validation, show feasibility of the as-proposed reformer. Operation of the suggested system is envisaged with self-sustained heat supply for production of 84 W of electrical power. Also, the as-proposed reactor concept and material are suggested to serve in other endothermic H₂ release reactions from various H₂ carriers (methane, methanol, LOHC, etc) for potential application in power generation as well as high-purity H₂ production.