Exploration of Alkali Metal-Induced Effects on Promoting Ammonia Decomposition Performance

While ammonia serves as a carbon-free hydrogen carrier, addressing challenges in hydrogen energy storage and transportation, the present technology for thermocatalytic ammonia decomposition encounters constraints owing to elevated decomposition temperatures. Alkali metal promoters have been demonstrated to effectively lower the reaction temperature. However, their precise role in the process of ammonia dehydrogenation remains not fully understood. Herein, we investigated the impact of alkali metals by incorporating various base treatments (with (i.e., KOH) or without alkali metals (i.e., NH3<middle dot>H2O)) during the deposition process. The results indicate that compared to samples without alkali metal treatment, catalysts with added alkali metals (5 wt % Ru/CeO2-NP(KOH)) show a 16.7% improvement in ammonia decomposition efficiency and a 5.54 mmol g(cat)(-1) min(-1) increase in hydrogen production rate under the same test conditions (500 degrees C, gas hourly space velocity (GHSV) of 30,000 mL g(cat)(-1) h(-1)). This phenomenon may be attributed to the dual promotion of alkali metal K in regulating both vacancy defects and metal active sites. The regulatory mechanism of alkali metal activity proposed by us not only provides a better understanding of the specific role of alkali metals in the reaction process but also holds significant implications for guiding the design of novel catalysts.