Breakthrough in Ammonia Synthesis: Ruthenium-Based Catalysts Show Promise

New research published in ChemSusChem has highlighted the potential of ruthenium-based catalysts in reducing the energy requirements for industrial ammonia synthesis. According to the study, a combination of high temperature and pressure is typically necessary to achieve efficient educt conversion, but the use of ruthenium-based catalysts promoted with alkali metals may lower the energy barrier associated with nitrogen dissociation. Operando X-ray absorption spectroscopy revealed that promotion by cesium leads to a higher content of metallic ruthenium, resulting in higher ammonia concentrations at the reactor outlet.

Key Takeaways:

• Ruthenium-based catalysts promoted with alkali metals have the potential to lower the energy barrier associated with nitrogen dissociation during industrial ammonia synthesis.
• Operando X-ray absorption spectroscopy revealed that promotion by cesium leads to a higher content of metallic ruthenium, resulting in higher ammonia concentrations at the reactor outlet.
• The irreversible deactivation of the catalyst is traced back to the leaching of cesium species, which has a disproportionate effect on the catalytic activity.
• The study was conducted by researchers from the Karlsruhe Institute of Technology (KIT) and involved the use of impregnated RuCs/MgO and Ru/MgO catalysts.
• The study found that interconversion of three types of ruthenium species occurs during reduction and ammonia synthesis, including RuO, highly dispersed RuO, and metallic Ru.

Statistics:

• The study was conducted at pressures up to 19 bar(a) in pure gas feed.
• The catalysts were exposed to traces of oxygen, resulting in a gradual transformation of bare cesium cations to hydrated species [Cs(HO)].
• The study found that the leaching of cesium species has a disproportionate effect on the catalytic activity, leading to irreversible deactivation.
• The research was Peer-reviewed and published in the journal ChemSusChem.
• The study highlighted the potential of ruthenium-based catalysts in reducing the energy requirements for industrial ammonia synthesis.

Sources:

• Structure-Activity Relationships in RuCs/MgO Catalysts During Ammonia Synthesis. ChemSusChem, 2025.
• Karlsruhe Institute of Technology (KIT) Reports Findings in Chemicals and Chemistry (Structure-Activity Relationships in RuCs/MgO Catalysts During Ammonia Synthesis). Chemicals & Chemistry. August 8, 2025; p 2066.
• NewsRx. (2025, August 8). Karlsruhe Institute of Technology (KIT) Reports Findings in Chemicals and Chemistry. Chemicals & Chemistry.