Catalytic Ammonia Cracking at High Pressure─An Experimental Bench-Scale Study Using a Commercial Catalyst

Hydrogen is a promising fuel for the energy transition, but transporting it globally remains a challenge. Ammonia cracking enables localized hydrogen production using existing ammonia infrastructure. Although ammonia decomposition works best at high temperatures and low pressures, delivering hydrogen to pipelines requires pressures exceeding 50 barg. This makes high-pressure hydrogen production from ammonia an industrially relevant topic, especially given the high cost of hydrogen compression. This study presents results of bench-scale testing of a high-pressure catalytic ammonia cracker. The cracker was tested at pressures of 10, 30, 50, and 70 barg and reaction temperatures of 450, 500, 550, 600, 650, and 700 °C. The reactor was operated at flow rates ranging from 0.3 to 2 gNH3/min with a catalyst loading of 111.5 g. The highest ammonia conversion of 95.5% was achieved at a weight-space-time yield (WSTY) of 0.028 gH2/gcat/h and a W/F value of 105 gcath/molNH3 at 700 °C and 70 barg. An approximately 90% conversion of ammonia was achieved under the same temperature and pressure conditions but with a higher feed flow rate, corresponding to a W/F value of 16 gcath/molNH3 to 63 gcath/molNH3. These findings provide a good basis for further investigations into the kinetics of high-pressure ammonia decomposition, supporting the development of an optimized process system for scale-up and cost reduction.