Potassium-promoted Ru-MCM-41 catalyst via in situ loading for effective low-temperature ammonia decomposition.

A potassium (K)-promoted Ru-based siliceous molecular sieve catalyst, K-nRu-MCM-41, was successfully synthesized via a hydrothermal method. The combined analysis of XRD, FT-IR and XPS data revealed that Ru exists in the framework of the molecular sieves as RuO₂ species, leading to structural alterations. SEM and TEM images demonstrated that Ru doping disrupts the morphology of the molecular sieves, while K addition effectively preserves the original morphology and further enhances particle dispersion. The ammonia decomposition performance test indicated that K promotes the activity of the molecular sieve catalysts. At 450 °C and 12 000 mL g_cat⁻¹ h⁻¹, K-4Ru-MCM-41 achieved 82.7% ammonia conversion and 253.6 mmol g_Ru⁻¹ min⁻¹ hydrogen production, respectively, which was a 7.6% increase in ammonia conversion compared with 4Ru-MCM-41. Furthermore, the K-4Ru-MCM-41 catalyst exhibited excellent reusability, maintaining its stable catalytic activity performance after 30 h. [ABSTRACT FROM AUTHOR]