Ammonia (NH3) plays a crucial role in modern agriculture, primarily produced through the Haber-Bosch process. For over a century, this method has relied on the iron-based catalyst known as 'Promoted-Fe,' which has remained unmatched in efficiency. However, a research team from the Institute of Science Tokyo has made a groundbreaking advancement in catalyst design that could transform ammonia production.
Published on January 23, 2025, in the journal Advanced Science, the study led by Professor Michikazu Hara introduces a new catalyst structure that significantly enhances NH3 production rates. Traditional catalysts typically consist of transition metal particles on a low-density support, which, while increasing the active surface area, limits the catalyst's volume efficiency.
The innovative approach from the Tokyo team involved creating catalysts with an inverse structure, featuring larger iron particles enhanced with aluminum hydride (AlH) and potassium (K+). This design allows for a higher ammonia production rate per catalyst volume, achieving rates approximately three times greater than Promoted-Fe. Remarkably, this new catalyst operates efficiently even at temperatures below 200 °C, a range where traditional methods fail.
Hara notes, "The new catalyst not only surpasses Promoted-Fe in performance but also maintains stability, producing ammonia without activity loss over 2,000 hours." The research indicates that the inverse structure enhances electron donation and increases active sites, facilitating more efficient nitrogen cleavage, the rate-limiting step in ammonia synthesis.
This advancement has significant implications for industrial ammonia production, especially in the context of climate change mitigation. The ease of manufacturing these catalysts from abundant materials could lead to more sustainable agricultural practices and reduced environmental impact.
The Institute of Science Tokyo, formed from the merger of Tokyo Medical and Dental University and Tokyo Institute of Technology, aims to advance science for societal benefit, making this discovery a vital step towards enhancing global food security and sustainability.