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

Abstract 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.