Impact of Trace Water on the Macroscopic Activity of Commercial Ammonia Cracking Catalysts Under Process‐Relevant Conditions

ABSTRACT Nickel‐based catalysts are widely employed in industrial ammonia cracking, however, their performance stability under process‐relevant operating conditions, particularly in the presence of trace water, remains poorly understood. This study investigates the macroscopic impact of trace water impurities on catalyst activity at elevated pressures and temperatures. A cyclic testing protocol decouples permanent degradation from reversible activity loss. Results reveal that while dry thermal stress causes negligible permanent deactivation, hydrothermal stress causes a significant, irreversible drop in macroscopic activity. Additionally, trace water induces a reversible activity drop. Ultimately, these findings demonstrate that dry testing can overestimate industrially relevant catalyst performance. Consequently, to ensure reliable industrial scale‐up, catalyst evaluation should transition to process‐representative, trace water containing feeds.